[ttml10se] prepare final PER archive ttml1-WD-20130709-PER
authorGlenn Adams <glenn@skynav.com>
Fri, 28 Jun 2013 00:19:59 -0600
changeset 418 2bdd57e9fc8f
parent 417 3757c307d61d
child 419 b9e9a2c34610
[ttml10se] prepare final PER archive
ttml10/spec/PER-ttaf1-dfxp-201305DD.html
ttml10/spec/PER-ttaf1-dfxp-201305DD.zip
ttml10/spec/PER-ttaf1-dfxp-20130709.zip
ttml10/spec/PER-ttaf1-dfxp-20130709/PER-ttaf1-dfxp-20130709.html
ttml10/spec/PER-ttaf1-dfxp-20130709/images/backgroundColor.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/color.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/direction.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/displayAlign.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/display_0.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/display_1.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/display_2.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/display_3.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/display_4.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/extent.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/fontFamily.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/fontSize.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/fontStyle.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/fontWeight.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/lineHeight.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/model.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/opacity_0.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/opacity_1.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/opacity_2.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/opacity_3.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/opacity_4.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/origin.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/overflow.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/padding.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/streaming.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle1.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle2.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle3.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle4.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle5.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle6.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle7.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle8.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/subtitle9.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/textAlign.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/textDecoration.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/textOutline.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/unicodeBidi.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/visibility_0.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/visibility_1.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/visibility_2.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/visibility_3.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/wrapOption.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/writingMode.png
ttml10/spec/PER-ttaf1-dfxp-20130709/images/zIndex.png
ttml10/spec/PER-ttaf1-dfxp-20130709/rnc/schema.zip
ttml10/spec/PER-ttaf1-dfxp-20130709/xsd/schema.zip
ttml10/spec/PER-ttaf1-dfxp-201307DD.html
ttml10/spec/PER-ttaf1-dfxp-201307DD.zip
ttml10/spec/build.xml
ttml10/spec/entities.dtd
ttml10/spec/entitiesper.dtd
ttml10/spec/statusper.xml
ttml10/spec/ttaf1-dfxp.html
ttml10/spec/ttaf1-dfxp.xml
--- a/ttml10/spec/PER-ttaf1-dfxp-201305DD.html	Thu Jun 27 10:35:37 2013 -0600
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,19945 +0,0 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
-<html lang="en-us">
-<head>
-  <meta name="generator" content=
-  "HTML Tidy for Linux/x86 (vers 25 March 2009), see www.w3.org">
-  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
-  <title>Timed Text Markup Language (TTML) 1.0 (Second Edition)</title>
-  <style type="text/css">
-  code           { font-family: monospace; }
-
-  div.constraint,
-  div.issue,
-  div.note,
-  div.notice     { margin-left: 2em; }
-
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-  ol.enumla      { list-style-type: lower-alpha; }
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-  ol.enumua      { list-style-type: upper-alpha; }
-  ol.enumur      { list-style-type: upper-roman; }
-
-
-  div.exampleInner pre { margin-left: 1em;
-                       margin-top: 0em; margin-bottom: 0em}
-  div.exampleOuter {border: 4px double gray;
-                  margin: 0em; padding: 0em}
-  div.exampleInner { background-color: #d5dee3;
-                   border-top-width: 4px;
-                   border-top-style: double;
-                   border-top-color: #d3d3d3;
-                   border-bottom-width: 4px;
-                   border-bottom-style: double;
-                   border-bottom-color: #d3d3d3;
-                   padding: 4px; margin: 0em }
-  div.exampleWrapper { margin: 4px }
-  div.exampleHeader { font-weight: bold;
-                    margin: 4px}
-
-  li p { margin-top: 0.3em; margin-bottom: 0.3em; }
-  div.issue { border: 2px solid black; background-color: #ffff66; padding: 0em 1em; margin: 0em 0em }
-  table.ednote { border-collapse: collapse; border: 2px solid black; width: 85% }
-  table.ednote td { background-color: #ddaa66; border: 2px solid black }
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-  table.acronyms td.def { width: 65% }
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-  table.semantics { border: 0px solid black; width: 85%; border-collapse: collapse }
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-  table.semantics td {
-  border-left: 0px solid black;
-  border-right: 0px solid black;
-  border-top: 4px double #d3d3d3;
-  border-bottom: 4px double #d3d3d3;
-  background-color: #ccffcc
-  }
-  table.semantics code.formulae {
-  padding: 1em;
-  border: 1px dashed #005a9c;
-  line-height: 1.1em;
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-  .strong { font-weight: bold }
-  .reqattr { font-weight: bold }
-  .optattr { font-style: italic }
-  </style>
-  <link rel="stylesheet" type="text/css" href=
-  "http://www.w3.org/StyleSheets/TR/W3C-PER.css">
-</head>
-
-<body>
-  <div class="head">
-    <p><a href="http://www.w3.org/"><img src="http://www.w3.org/Icons/w3c_home" alt="W3C"
-    height="48" width="72"></a></p>
-
-    <h1><a id="title" name="title"></a>Timed Text Markup Language (TTML) 1.0 (Second
-    Edition)</h1>
-
-    <h2><a id="w3c-doctype" name="w3c-doctype"></a>W3C Proposed Edited Recommendation DD
-    May 2013</h2>
-
-    <dl>
-      <dt>This version:</dt>
-
-      <dd><a href=
-      "http://www.w3.org/TR/2013/PER-ttaf1-dfxp-201305DD/">http://www.w3.org/TR/2013/PER-ttaf1-dfxp-201305DD/</a></dd>
-
-      <dt>Latest version:</dt>
-
-      <dd><a href=
-      "http://www.w3.org/TR/ttaf1-dfxp/">http://www.w3.org/TR/ttaf1-dfxp/</a></dd>
-
-      <dt>Previous version:</dt>
-
-      <dd><a href=
-      "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/</a></dd>
-
-      <dt>Editor:</dt>
-
-      <dd>Glenn Adams, Cox Communications, Inc.</dd>
-
-      <dt>Contributing Authors:</dt>
-
-      <dd>Mike Dolan, Invited Expert</dd>
-
-      <dd>Geoff Freed, WGBH National Center for Accessible Media</dd>
-
-      <dd>Sean Hayes, Microsoft</dd>
-
-      <dd>Erik Hodge, RealNetworks</dd>
-
-      <dd>David Kirby, British Broadcasting Corporation (BBC)</dd>
-
-      <dd>Thierry Michel, W3C</dd>
-
-      <dd>Dave Singer, Apple Computer</dd>
-    </dl>
-
-    <p>Please refer to the <a href=
-    "https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttml-issues.html">errata</a>
-    for this document, which may include normative corrections.</p>
-
-    <p>See also <a href=
-    "http://www.w3.org/2003/03/Translations/byTechnology?technology=ttaf1-dfxp"><strong>translations</strong></a>.</p>
-
-    <p class="copyright"><a href=
-    "http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>&nbsp;©&nbsp;2013&nbsp;<a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup>
-    (<a href="http://www.csail.mit.edu/"><acronym title=
-    "Massachusetts Institute of Technology">MIT</acronym></a>, <a href=
-    "http://www.ercim.eu/"><acronym title=
-    "European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>,
-    <a href="http://www.keio.ac.jp/">Keio</a>, <a href=
-    "http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a href=
-    "http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
-    <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
-    and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a>
-    rules apply.</p>
-  </div>
-  <hr>
-
-  <div>
-    <h2><a id="abstract" name="abstract"></a>Abstract</h2>
-
-    <p>This document specifies the Timed Text Markup Language (TTML) in terms of a
-    vocabulary and semantics thereof.</p>
-
-    <p>The Timed Text Markup Language is a content type that represents timed text media
-    for the purpose of interchange among authoring systems. Timed text is textual
-    information that is intrinsically or extrinsically associated with timing
-    information.</p>
-
-    <p>It is intended to be used for the purpose of transcoding or exchanging timed text
-    information among legacy distribution content formats presently in use for subtitling
-    and captioning functions.</p>
-
-    <p>In addition to being used for interchange among legacy distribution content
-    formats, TTML Content may be used directly as a distribution format, for example,
-    providing a standard content format to reference from a <code>&lt;track&gt;</code>
-    element in an HTML5 document, or a <code>&lt;text&gt;</code> or
-    <code>&lt;textstream&gt;</code> media element in a <a href="#smil21">[SMIL 2.1]</a>
-    document.</p>
-  </div>
-
-  <div>
-    <h2><a id="status" name="status"></a>Status of this Document</h2>
-
-    <p><em>This section describes the status of this document at the time of its
-    publication. Other documents may supersede this document. A list of current W3C
-    publications and the latest revision of this technical report can be found in the
-    <a href="http://www.w3.org/TR/">W3C technical reports index</a> at
-    http://www.w3.org/TR/.</em></p>
-
-    <p>This document, published on DD May 2013, is a <a href=
-    "http://www.w3.org/2005/10/Process-20051014/tr.html#ProposedEditedRec">Proposed
-    Edited Recommendation</a> of the W3C. This second edition is not a new version of
-    this specification; its purpose is to clarify a number of issues that have become
-    apparent since the first edition was published.</p>
-
-    <p>This document has been produced by the <a href=
-    "http://www.w3.org/AudioVideo/TT/">Timed Text (TT) Working Group</a> as part of the
-    W3C <a href="http://www.w3.org/2008/WebVideo/">Video in the Web Activity</a>,
-    following the procedures set out for the W3C <a href=
-    "http://www.w3.org/Consortium/Process/">Process</a>. The authors of this document are
-    listed in the header of this document.</p>
-
-    <p>Publication as a Proposed Edited Recommendation does not imply endorsement by the
-    W3C Membership. This is a draft document and may be updated, replaced or obsoleted by
-    other documents at any time. It is inappropriate to cite this document as other than
-    work in progress.</p>
-
-    <p>W3C Advisory Committee Members are invited to send formal review comments on this
-    Proposed Edited Recommendation to the W3C Team until DD June 2013. Members of the W3C
-    Advisory Committee will find the appropriate review form for this document by
-    consulting their <a href="http://www.w3.org/2002/09/wbs/myQuestionnaires">list of WBS
-    questionnaires</a>.</p>
-
-    <p>This document incorporates changes made against the <a href=
-    "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">Recommendation</a> of 18
-    November 2010 that resolve all errata known at the date of publication. A list of the
-    errata that have been applied is provided in <a href=
-    "https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttml-changes.html#change-history-rec-to-2e-per">
-    Changes from Recommendation to Proposed Edited Recommendation (2nd Ed.)</a>.</p>
-
-    <p>Please report errors in and submit comments on this document to the W3C Timed Text
-    public comments mailing list, <a href=
-    "mailto:public-tt-comments@w3.org">public-tt-comments@w3.org</a>. Please include the
-    string <code>[ttml10se]</code> at the beginning of the subject line of your report.
-    Each email message should contain only one error report. Archives of the comments and
-    responses are available at <a href=
-    "http://lists.w3.org/Archives/Public/public-tt-comments/">http://lists.w3.org/Archives/Public/public-tt-comments/</a>.</p>
-
-    <p>An updated <a href="http://www.w3.org/2009/05/dfxp-results.html">implementation
-    report</a> will be made available, but the decision of the Director to transition
-    this document to Proposed Edited Recommendation did not depend on the existence of
-    that report.</p>
-
-    <p>The Timed Text Working Group plans to submit this specification for consideration
-    as a W3C Recommendation (Second Edition) as soon as the Working Group has responded
-    formally to all issues raised during the PER period against this document.</p>
-
-    <p>This document was produced by a group operating under the <a href=
-    "http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent
-    Policy</a>. W3C maintains a <a href=
-    "http://www.w3.org/2004/01/pp-impl/34314/status#disclosures" rel="disclosure">public
-    list of any patent disclosures</a> made in connection with the deliverables of the
-    group; that page also includes instructions for disclosing a patent. An individual
-    who has actual knowledge of a patent which the individual believes contains <a href=
-    "http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
-    Claim(s)</a> must disclose the information in accordance with <a href=
-    "http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of
-    the W3C Patent Policy</a>.</p>
-  </div>
-
-  <div class="toc">
-    <h2><a id="contents" name="contents"></a>Table of Contents</h2>
-
-    <p class="toc">1 <a href="#intro">Introduction</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;1.1 <a href="#model">System Model</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;1.2 <a href="#example">Document Example</a><br>
-    2 <a href="#definitions">Definitions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;2.1 <a href="#acronyms">Acronyms</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;2.2 <a href="#terms">Terminology</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;2.3 <a href="#conventions">Documentation Conventions</a><br>
-    3 <a href="#conformance">Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;3.1 <a href="#conformance-content">Content
-    Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;3.2 <a href="#conformance-processor">Processor
-    Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.1 <a href=
-    "#conformance-generic-processor">Generic Processor Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.2 <a href=
-    "#conformance-transformation-processor">Transformation Processor Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.3 <a href=
-    "#conformance-presentation-processor">Presentation Processor Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;3.3 <a href="#claims">Claims</a><br>
-    4 <a href="#doctypes">Document Types</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;4.1 <a href="#ttml-content-doctype">TTML Content</a><br>
-    5 <a href="#vocabulary">Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;5.1 <a href="#vocabulary-namespaces">Namespaces</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;5.2 <a href="#vocabulary-profiles">Profiles</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;5.3 <a href="#vocabulary-overview">Catalog</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.3.1 <a href=
-    "#core-vocabulary-overview">Core Catalog</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.3.2 <a href=
-    "#extension-vocabulary-overview">Extension Catalog</a><br>
-    6 <a href="#parameters">Parameters</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;6.1 <a href="#parameter-element-vocabulary">Parameter Element
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.1 <a href=
-    "#parameter-vocabulary-profile">ttp:profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.2 <a href=
-    "#parameter-vocabulary-features">ttp:features</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.3 <a href=
-    "#parameter-vocabulary-feature">ttp:feature</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.4 <a href=
-    "#parameter-vocabulary-extensions">ttp:extensions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.5 <a href=
-    "#parameter-vocabulary-extension">ttp:extension</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;6.2 <a href="#parameter-attribute-vocabulary">Parameter
-    Attribute Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.1 <a href=
-    "#parameter-attribute-cellResolution">ttp:cellResolution</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.2 <a href=
-    "#parameter-attribute-clockMode">ttp:clockMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.3 <a href=
-    "#parameter-attribute-dropMode">ttp:dropMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.4 <a href=
-    "#parameter-attribute-frameRate">ttp:frameRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.5 <a href=
-    "#parameter-attribute-frameRateMultiplier">ttp:frameRateMultiplier</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.6 <a href=
-    "#parameter-attribute-markerMode">ttp:markerMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.7 <a href=
-    "#parameter-attribute-pixelAspectRatio">ttp:pixelAspectRatio</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.8 <a href=
-    "#parameter-attribute-profile">ttp:profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.9 <a href=
-    "#parameter-attribute-subFrameRate">ttp:subFrameRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.10 <a href=
-    "#parameter-attribute-tickRate">ttp:tickRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.11 <a href=
-    "#parameter-attribute-timeBase">ttp:timeBase</a><br>
-    7 <a href="#content">Content</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;7.1 <a href="#content-element-vocabulary">Content Element
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.1 <a href=
-    "#document-structure-vocabulary-tt">tt</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.2 <a href=
-    "#document-structure-vocabulary-head">head</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.3 <a href=
-    "#document-structure-vocabulary-body">body</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.4 <a href=
-    "#content-vocabulary-div">div</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.5 <a href=
-    "#content-vocabulary-p">p</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.6 <a href=
-    "#content-vocabulary-span">span</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.7 <a href=
-    "#content-vocabulary-br">br</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;7.2 <a href="#content-attribute-vocabulary">Content Attribute
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.1 <a href=
-    "#content-attribute-id">xml:id</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.2 <a href=
-    "#content-attribute-lang">xml:lang</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.3 <a href=
-    "#content-attribute-space">xml:space</a><br>
-    8 <a href="#styling">Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;8.1 <a href="#styling-element-vocabulary">Styling Element
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.1.1 <a href=
-    "#styling-vocabulary-styling">styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.1.2 <a href=
-    "#styling-vocabulary-style">style</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;8.2 <a href="#styling-attribute-vocabulary">Styling Attribute
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.1 <a href=
-    "#style-attribute-style">style</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.2 <a href=
-    "#style-attribute-backgroundColor">tts:backgroundColor</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.3 <a href=
-    "#style-attribute-color">tts:color</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.4 <a href=
-    "#style-attribute-direction">tts:direction</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.5 <a href=
-    "#style-attribute-display">tts:display</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.6 <a href=
-    "#style-attribute-displayAlign">tts:displayAlign</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.7 <a href=
-    "#style-attribute-extent">tts:extent</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.8 <a href=
-    "#style-attribute-fontFamily">tts:fontFamily</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.9 <a href=
-    "#style-attribute-fontSize">tts:fontSize</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.10 <a href=
-    "#style-attribute-fontStyle">tts:fontStyle</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.11 <a href=
-    "#style-attribute-fontWeight">tts:fontWeight</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.12 <a href=
-    "#style-attribute-lineHeight">tts:lineHeight</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.13 <a href=
-    "#style-attribute-opacity">tts:opacity</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.14 <a href=
-    "#style-attribute-origin">tts:origin</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.15 <a href=
-    "#style-attribute-overflow">tts:overflow</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.16 <a href=
-    "#style-attribute-padding">tts:padding</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.17 <a href=
-    "#style-attribute-showBackground">tts:showBackground</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.18 <a href=
-    "#style-attribute-textAlign">tts:textAlign</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.19 <a href=
-    "#style-attribute-textDecoration">tts:textDecoration</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.20 <a href=
-    "#style-attribute-textOutline">tts:textOutline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.21 <a href=
-    "#style-attribute-unicodeBidi">tts:unicodeBidi</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.22 <a href=
-    "#style-attribute-visibility">tts:visibility</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.23 <a href=
-    "#style-attribute-wrapOption">tts:wrapOption</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.24 <a href=
-    "#style-attribute-writingMode">tts:writingMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.25 <a href=
-    "#style-attribute-zIndex">tts:zIndex</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;8.3 <a href="#styling-style-value-expressions">Style Value
-    Expressions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.1 <a href=
-    "#style-value-alpha">&lt;alpha&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.2 <a href=
-    "#style-value-color">&lt;color&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.3 <a href=
-    "#style-value-digit">&lt;digit&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.4 <a href=
-    "#style-value-duration">&lt;duration&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.5 <a href=
-    "#style-value-familyName">&lt;familyName&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.6 <a href=
-    "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.7 <a href=
-    "#style-value-hexDigit">&lt;hexDigit&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.8 <a href=
-    "#style-value-integer">&lt;integer&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.9 <a href=
-    "#style-value-length">&lt;length&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.10 <a href=
-    "#style-value-namedColor">&lt;namedColor&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.11 <a href=
-    "#style-value-quotedString">&lt;quotedString&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.12 <a href=
-    "#style-value-string">&lt;string&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;8.4 <a href="#semantics-style-resolution">Style
-    Resolution</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1 <a href=
-    "#semantics-style-association">Style Association</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.1
-    <a href="#semantics-style-association-inline">Inline Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.2
-    <a href="#semantics-style-association-referential">Referential Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.3
-    <a href="#semantics-style-association-chained-referential">Chained Referential
-    Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.4
-    <a href="#semantics-style-association-nested">Nested Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2 <a href=
-    "#semantics-style-inheritance">Style Inheritance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2.1
-    <a href="#semantics-style-inheritance-content">Content Style Inheritance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2.2
-    <a href="#semantics-style-inheritance-region">Region Style Inheritance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3 <a href=
-    "#semantics-style-resolution-value-categories">Style Resolution Value
-    Categories</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.1
-    <a href="#semantics-style-resolved-value-category-specified">Specified Values</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.2
-    <a href="#semantics-style-resolved-value-category-computed">Computed Values</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.3
-    <a href="#semantics-style-resolved-value-category-actual">Actual Values</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4 <a href=
-    "#semantics-style-resolution-processing">Style Resolution Processing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.1
-    <a href="#semantics-style-resolution-processing-definitions">Conceptual
-    Definitions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.2
-    <a href="#semantics-style-resolution-processing-sss">Specified Style Set
-    Processing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.3
-    <a href="#semantics-style-resolution-processing-css">Computed Style Set
-    Processing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.4
-    <a href="#semantics-style-resolution-process-overall">Style Resolution
-    Process</a><br>
-    9 <a href="#layout">Layout</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;9.1 <a href="#layout-element-vocabulary">Layout Element
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.1.1 <a href=
-    "#layout-vocabulary-layout">layout</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.1.2 <a href=
-    "#layout-vocabulary-region">region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;9.2 <a href="#layout-attribute-vocabulary">Layout Attribute
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.2.1 <a href=
-    "#layout-attribute-region">region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;9.3 <a href="#semantics-region-layout">Region Layout and
-    Presentation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.1 <a href=
-    "#semantics-default-region">Default Region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.2 <a href=
-    "#semantics-region-layout-step-1">Intermediate Synchronic Document
-    Construction</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.3 <a href=
-    "#semantics-region-layout-step-2">Synchronic Flow Processing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.4 <a href=
-    "#semantics-region-layout-example">Elaborated Example (Informative)</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;9.4 <a href="#semantics-line-layout">Line Layout</a><br>
-    10 <a href="#timing">Timing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;10.1 <a href="#timing-element-vocabulary">Timing Element
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;10.2 <a href="#timing-attribute-vocabulary">Timing Attribute
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.1 <a href=
-    "#timing-attribute-begin">begin</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.2 <a href=
-    "#timing-attribute-end">end</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.3 <a href=
-    "#timing-attribute-dur">dur</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.4 <a href=
-    "#timing-attribute-timeContainer">timeContainer</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;10.3 <a href="#timing-time-value-expressions">Time Value
-    Expressions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.3.1 <a href=
-    "#timing-value-timeExpression">&lt;timeExpression&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;10.4 <a href="#timing-time-intervals">Time Intervals</a><br>
-    11 <a href="#animation">Animation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;11.1 <a href="#animation-element-vocabulary">Animation
-    Element Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;11.1.1 <a href=
-    "#animation-vocabulary-set">set</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;11.2 <a href="#animation-attribute-vocabulary">Animation
-    Attribute Vocabulary</a><br>
-    12 <a href="#metadata">Metadata</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;12.1 <a href="#metadata-element-vocabulary">Metadata Element
-    Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.1 <a href=
-    "#metadata-vocabulary-metadata">metadata</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.2 <a href=
-    "#metadata-vocabulary-title">ttm:title</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.3 <a href=
-    "#metadata-vocabulary-desc">ttm:desc</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.4 <a href=
-    "#metadata-vocabulary-copyright">ttm:copyright</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.5 <a href=
-    "#metadata-vocabulary-agent">ttm:agent</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.6 <a href=
-    "#metadata-vocabulary-name">ttm:name</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.7 <a href=
-    "#metadata-vocabulary-actor">ttm:actor</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;12.2 <a href="#metadata-attribute-vocabulary">Metadata
-    Attribute Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.2.1 <a href=
-    "#metadata-attribute-agent">ttm:agent</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.2.2 <a href=
-    "#metadata-attribute-role">ttm:role</a><br></p>
-
-    <h3><a id="appendices" name="appendices"></a>Appendices</h3>
-
-    <p class="toc">A <a href="#reduced-infoset">Reduced XML Infoset</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;A.1 <a href="#reduced-infoset-document">Document Information
-    Item</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;A.2 <a href="#reduced-infoset-element">Element Information
-    Item</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;A.3 <a href="#reduced-infoset-attribute">Attribute
-    Information Item</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;A.4 <a href="#reduced-infoset-character">Character
-    Information Item</a><br>
-    B <a href="#schemas">Schemas</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;B.1 <a href="#ttml-schema-rnc">Relax NG Compact (RNC)
-    Schema</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;B.2 <a href="#ttml-schema-xsd">XML Schema Definition (XSD)
-    Schema</a><br>
-    C <a href="#media-types-registration">Media Type Registration</a><br>
-    D <a href="#features">Features</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;D.1 <a href="#feature-designations">Feature
-    Designations</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.1 <a href=
-    "#feature-animation">#animation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.2 <a href=
-    "#feature-backgroundColor">#backgroundColor</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.3 <a href=
-    "#feature-backgroundColor-block">#backgroundColor-block</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.4 <a href=
-    "#feature-backgroundColor-inline">#backgroundColor-inline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.5 <a href=
-    "#feature-backgroundColor-region">#backgroundColor-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.6 <a href=
-    "#feature-bidi">#bidi</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.7 <a href=
-    "#feature-cellResolution">#cellResolution</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.8 <a href=
-    "#feature-clockMode">#clockMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.9 <a href=
-    "#feature-clockMode-gps">#clockMode-gps</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.10 <a href=
-    "#feature-clockMode-local">#clockMode-local</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.11 <a href=
-    "#feature-clockMode-utc">#clockMode-utc</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.12 <a href=
-    "#feature-color">#color</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.13 <a href=
-    "#feature-content">#content</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.14 <a href=
-    "#feature-core">#core</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.15 <a href=
-    "#feature-direction">#direction</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.16 <a href=
-    "#feature-display">#display</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.17 <a href=
-    "#feature-display-block">#display-block</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.18 <a href=
-    "#feature-display-inline">#display-inline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.19 <a href=
-    "#feature-display-region">#display-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.20 <a href=
-    "#feature-displayAlign">#displayAlign</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.21 <a href=
-    "#feature-dropMode">#dropMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.22 <a href=
-    "#feature-dropMode-dropNTSC">#dropMode-dropNTSC</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.23 <a href=
-    "#feature-dropMode-dropPAL">#dropMode-dropPAL</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.24 <a href=
-    "#feature-dropMode-nonDrop">#dropMode-nonDrop</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.25 <a href=
-    "#feature-extent">#extent</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.26 <a href=
-    "#feature-extent-region">#extent-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.27 <a href=
-    "#feature-extent-root">#extent-root</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.28 <a href=
-    "#feature-fontFamily">#fontFamily</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.29 <a href=
-    "#feature-fontFamily-generic">#fontFamily-generic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.30 <a href=
-    "#feature-fontFamily-non-generic">#fontFamily-non-generic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.31 <a href=
-    "#feature-fontSize">#fontSize</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.32 <a href=
-    "#feature-fontSize-anamorphic">#fontSize-anamorphic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.33 <a href=
-    "#feature-fontSize-isomorphic">#fontSize-isomorphic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.34 <a href=
-    "#feature-fontStyle">#fontStyle</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.35 <a href=
-    "#feature-fontStyle-italic">#fontStyle-italic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.36 <a href=
-    "#feature-fontStyle-oblique">#fontStyle-oblique</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.37 <a href=
-    "#feature-fontWeight">#fontWeight</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.38 <a href=
-    "#feature-fontWeight-bold">#fontWeight-bold</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.39 <a href=
-    "#feature-frameRate">#frameRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.40 <a href=
-    "#feature-frameRateMultiplier">#frameRateMultiplier</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.41 <a href=
-    "#feature-layout">#layout</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.42 <a href=
-    "#feature-length">#length</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.43 <a href=
-    "#feature-length-cell">#length-cell</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.44 <a href=
-    "#feature-length-em">#length-em</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.45 <a href=
-    "#feature-length-integer">#length-integer</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.46 <a href=
-    "#feature-length-negative">#length-negative</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.47 <a href=
-    "#feature-length-percentage">#length-percentage</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.48 <a href=
-    "#feature-length-pixel">#length-pixel</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.49 <a href=
-    "#feature-length-positive">#length-positive</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.50 <a href=
-    "#feature-length-real">#length-real</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.51 <a href=
-    "#feature-lineBreak-uax14">#lineBreak-uax14</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.52 <a href=
-    "#feature-lineHeight">#lineHeight</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.53 <a href=
-    "#feature-markerMode">#markerMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.54 <a href=
-    "#feature-markerMode-continuous">#markerMode-continuous</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.55 <a href=
-    "#feature-markerMode-discontinuous">#markerMode-discontinuous</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.56 <a href=
-    "#feature-metadata">#metadata</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.57 <a href=
-    "#feature-nested-div">#nested-div</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.58 <a href=
-    "#feature-nested-span">#nested-span</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.59 <a href=
-    "#feature-opacity">#opacity</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.60 <a href=
-    "#feature-origin">#origin</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.61 <a href=
-    "#feature-overflow">#overflow</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.62 <a href=
-    "#feature-overflow-visible">#overflow-visible</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.63 <a href=
-    "#feature-padding">#padding</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.64 <a href=
-    "#feature-padding-1">#padding-1</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.65 <a href=
-    "#feature-padding-2">#padding-2</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.66 <a href=
-    "#feature-padding-3">#padding-3</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.67 <a href=
-    "#feature-padding-4">#padding-4</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.68 <a href=
-    "#feature-pixelAspectRatio">#pixelAspectRatio</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.69 <a href=
-    "#feature-presentation">#presentation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.70 <a href=
-    "#feature-profile">#profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.71 <a href=
-    "#feature-showBackground">#showBackground</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.72 <a href=
-    "#feature-structure">#structure</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.73 <a href=
-    "#feature-styling">#styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.74 <a href=
-    "#feature-styling-chained">#styling-chained</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.75 <a href=
-    "#feature-styling-inheritance-content">#styling-inheritance-content</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.76 <a href=
-    "#feature-styling-inheritance-region">#styling-inheritance-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.77 <a href=
-    "#feature-styling-inline">#styling-inline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.78 <a href=
-    "#feature-styling-nested">#styling-nested</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.79 <a href=
-    "#feature-styling-referential">#styling-referential</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.80 <a href=
-    "#feature-subFrameRate">#subFrameRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.81 <a href=
-    "#feature-textAlign">#textAlign</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.82 <a href=
-    "#feature-textAlign-absolute">#textAlign-absolute</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.83 <a href=
-    "#feature-textAlign-relative">#textAlign-relative</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.84 <a href=
-    "#feature-textDecoration">#textDecoration</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.85 <a href=
-    "#feature-textDecoration-over">#textDecoration-over</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.86 <a href=
-    "#feature-textDecoration-through">#textDecoration-through</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.87 <a href=
-    "#feature-textDecoration-under">#textDecoration-under</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.88 <a href=
-    "#feature-textOutline">#textOutline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.89 <a href=
-    "#feature-textOutline-blurred">#textOutline-blurred</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.90 <a href=
-    "#feature-textOutline-unblurred">#textOutline-unblurred</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.91 <a href=
-    "#feature-tickRate">#tickRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.92 <a href=
-    "#feature-timeBase-clock">#timeBase-clock</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.93 <a href=
-    "#feature-timeBase-media">#timeBase-media</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.94 <a href=
-    "#feature-timeBase-smpte">#timeBase-smpte</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.95 <a href=
-    "#feature-timeContainer">#timeContainer</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.96 <a href=
-    "#feature-time-clock">#time-clock</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.97 <a href=
-    "#feature-time-clock-with-frames">#time-clock-with-frames</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.98 <a href=
-    "#feature-time-offset">#time-offset</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.99 <a href=
-    "#feature-time-offset-with-frames">#time-offset-with-frames</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.100 <a href=
-    "#feature-time-offset-with-ticks">#time-offset-with-ticks</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.101 <a href=
-    "#feature-timing">#timing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.102 <a href=
-    "#feature-transformation">#transformation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.103 <a href=
-    "#feature-unicodeBidi">#unicodeBidi</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.104 <a href=
-    "#feature-visibility">#visibility</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.105 <a href=
-    "#feature-visibility-block">#visibility-block</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.106 <a href=
-    "#feature-visibility-inline">#visibility-inline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.107 <a href=
-    "#feature-visibility-region">#visibility-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.108 <a href=
-    "#feature-wrapOption">#wrapOption</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.109 <a href=
-    "#feature-writingMode">#writingMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.110 <a href=
-    "#feature-writingMode-vertical">#writingMode-vertical</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.111 <a href=
-    "#feature-writingMode-horizontal">#writingMode-horizontal</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.112 <a href=
-    "#feature-writingMode-horizontal-lr">#writingMode-horizontal-lr</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.113 <a href=
-    "#feature-writingMode-horizontal-rl">#writingMode-horizontal-rl</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.114 <a href=
-    "#feature-zIndex">#zIndex</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;D.2 <a href="#feature-support">Feature Support</a><br>
-    E <a href="#extensions">Extensions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;E.1 <a href="#extension-designations">Extension
-    Designations</a><br>
-    F <a href="#profiles">Profiles</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;F.1 <a href="#profile-dfxp-transformation">DFXP
-    Transformation Profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;F.2 <a href="#profile-dfxp-presentation">DFXP Presentation
-    Profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;F.3 <a href="#profile-dfxp-full">DFXP Full Profile</a><br>
-    G <a href="#references">References</a><br>
-    H <a href="#other-references">Other References</a> (Non-Normative)<br>
-    I <a href="#requirements">Requirements</a> (Non-Normative)<br>
-    J <a href="#derivation">Vocabulary Derivation</a> (Non-Normative)<br>
-    &nbsp;&nbsp;&nbsp;&nbsp;J.1 <a href="#d3e18280">Element Derivation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;J.2 <a href="#d3e18759">Attribute Derivation</a><br>
-    K <a href="#qa">QA Framework Compliance</a> (Non-Normative)<br>
-    &nbsp;&nbsp;&nbsp;&nbsp;K.1 <a href="#d3e19629">Requirements</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;K.2 <a href="#d3e19793">Guidelines</a><br>
-    L <a href="#streaming">Streaming TTML Content</a> (Non-Normative)<br>
-    M <a href="#concrete-encoding">Concrete Encoding</a> (Non-Normative)<br>
-    N <a href="#time-expression-semantics">Time Expression Semantics</a>
-    (Non-Normative)<br>
-    &nbsp;&nbsp;&nbsp;&nbsp;N.1 <a href="#time-expression-semantics-clock">Clock Time
-    Base</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;N.2 <a href="#time-expression-semantics-media">Media Time
-    Base</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;N.3 <a href="#time-expression-semantics-smpte">SMPTE Time
-    Base</a><br>
-    O <a href="#common-styling">Common Caption Style Examples</a> (Non-Normative)<br>
-    &nbsp;&nbsp;&nbsp;&nbsp;O.1 <a href="#pop-on-example">Pop-On Caption Example</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;O.2 <a href="#roll-up-example">Roll-Up Caption
-    Example</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;O.3 <a href="#paint-on-example">Paint-On Caption
-    Example</a><br>
-    P <a href="#acknowledgments">Acknowledgments</a> (Non-Normative)<br></p>
-  </div>
-  <hr>
-
-  <div class="body">
-    <div class="div1">
-      <h2><a id="intro" name="intro"></a>1 Introduction</h2>
-
-      <p><em>Unless specified otherwise, this section and its sub-sections are
-      non-normative.</em></p>
-
-      <p>The Timed Text Markup Language (TTML) 1.0 provides a standardized representation
-      of a particular subset of textual information with which stylistic, layout, and
-      timing semantics are associated by an author or an authoring system for the purpose
-      of interchange and processing.</p>
-
-      <p>TTML is expressly designed to meet only a limited set of requirements
-      established by <a href="#ttaf1-req">[TTAF1-REQ]</a>, and summarized in <a href=
-      "#requirements"><b>I Requirements</b></a>. In particular, only those requirements
-      which service the need of performing interchange with existing, legacy distribution
-      systems are satisfied.</p>
-
-      <p>In addition to being used for interchange among legacy distribution content
-      formats, TTML Content may be used directly as a distribution format (as implied by
-      the acronym DFXP), providing, for example, a standard content format to reference
-      from a <code>&lt;track&gt;</code> element in an HTML5 document, or a
-      <code>&lt;text&gt;</code> or <code>&lt;textstream&gt;</code> media element in a
-      <a href="#smil21">[SMIL 2.1]</a> document. Certain properties of TTML support
-      streamability of content, as described in <a href="#streaming"><b>L Streaming TTML
-      Content</b></a>.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>While TTML was not expressly designed for direct (embedded) integration into
-        an HTML or a SMIL document instance, such integration is not precluded.</p>
-      </div>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>In some contexts of use, it may be appropriate to employ animated content to
-        depict sign language representations of the same content as expressed by a Timed
-        Text <em>Document Instance</em>. This use case is not explicitly addressed by
-        TTML mechanisms, but may be addressed by some external multimedia integration
-        technology, such as SMIL.</p>
-      </div>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>In previous drafts of this specification, TTML was referred to as DFXP
-        (Distribution Format Exchange Profile). This latter term is retained for
-        historical reasons in certain contexts, such as profile names and designators,
-        and the short name <code>ttaf1-dfxp</code> used in URLs to refer to this
-        specification.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="model" name="model"></a>1.1 System Model</h3>
-
-        <p>Use of TTML is intended to function in a wider context of Timed Text Authoring
-        and Distribution mechanisms that are based upon the system model depicted in
-        <a href="#model-graphic"><b>Figure 1 – System Model</b></a>, wherein the Timed
-        Text Markup Language serves as a bidirectional interchange format among a
-        heterogeneous collection of authoring systems, and as a unidirectional
-        interchange format to a heterogeneous collection of distribution formats after
-        undergoing transcoding or compilation to the target distribution formats as
-        required, and where one particular distribution format is TTML (labeled as "DFXP"
-        in the figure).</p><a id="model-graphic" name="model-graphic"></a>
-
-        <table class="example-images">
-          <caption>
-            Figure 1 – System Model
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/model.png" alt="System Model"></td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-
-      <div class="div2">
-        <h3><a id="example" name="example"></a>1.2 Document Example</h3>
-
-        <p>A TTML <em>Document Instance</em> consists of a <code>tt</code> document
-        element that contains a header and a body, where the header specifies document
-        level metadata, styling definitions and layout definitions, and the body
-        specifies text content intermixed with references to style and layout information
-        and inline styling and timing information.</p><a id=
-        "ttml-example-document-structure" name="ttml-example-document-structure"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Document Structure
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
-  &lt;head&gt;
-    &lt;metadata/&gt;
-    &lt;styling/&gt;
-    &lt;layout/&gt;
-  &lt;/head&gt;
-  &lt;body/&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Document level metadata may specify a document title, description, and
-        copyright information. In addition, arbitrary metadata drawn from other
-        namespaces may be specified.</p><a id="ttml-example-metadata" name=
-        "ttml-example-metadata"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Metadata
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
-  &lt;ttm:title&gt;Timed Text TTML Example&lt;/ttm:title&gt;
-  &lt;ttm:copyright&gt;The Authors (c) 2006&lt;/ttm:copyright&gt;
-&lt;/metadata&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Styling information may be specified in the form of style specification
-        definitions that are referenced by layout and content information, specified
-        inline with content information, or both.</p>
-
-        <p>In <a href="#ttml-example-styling"><b>Example Fragment – TTML Styling</b></a>,
-        four style sets of specifications are defined, with one set serving as a
-        collection of default styles.</p><a id="ttml-example-styling" name=
-        "ttml-example-styling"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Styling
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;styling xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;!-- s1 specifies default color, font, and text alignment --&gt;
-  &lt;style xml:id="s1"
-    tts:color="white"
-    tts:fontFamily="proportionalSansSerif"
-    tts:fontSize="22px"
-    tts:textAlign="center"
-  /&gt;
-  &lt;!-- alternative using yellow text but otherwise the same as style s1 --&gt;
-  &lt;style xml:id="s2" style="s1" tts:color="yellow"/&gt;
-  &lt;!-- a style based on s1 but justified to the right --&gt;
-  &lt;style xml:id="s1Right" style="s1" tts:textAlign="end" /&gt;     
-  &lt;!-- a style based on s2 but justified to the left --&gt;
-  &lt;style xml:id="s2Left" style="s2" tts:textAlign="start" /&gt;
-&lt;/styling&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Layout information defines one or more regions into which content is intended
-        to be presented. A region definition may reference one or more sets of style
-        specifications in order to permit content flowed in the region to inherit from
-        these styles. In <a href="#ttml-example-layout"><b>Example Fragment – TTML
-        Layout</b></a>, the region definition makes reference to style specification
-        <code>s1</code> augmented by specific inline styles which, together, allow
-        content flowed into the region to inherit from the region's styles (in the case
-        that a style is not already explicitly specified on content or inherited via the
-        content hierarchy.)</p><a id="ttml-example-layout" name=
-        "ttml-example-layout"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Layout
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;layout xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;region xml:id="subtitleArea"
-    style="s1"
-    tts:extent="560px 62px"
-    tts:padding="5px 3px"
-    tts:backgroundColor="black"
-    tts:displayAlign="after"
-  /&gt;
-&lt;/layout&gt;  
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The content of a <em>Document Instance</em> is expressed in its body, which is
-        organized in terms of block and inline text elements. The hierarchical
-        organization of content elements serves a primary role in determining both
-        spatial and temporal relationships. For example, in <a href=
-        "#ttml-example-body"><b>Example Fragment – TTML Body</b></a>, each paragraph
-        (<code>p</code> element) is flowed into its target region in the specified
-        lexical order; furthermore, the active time interval of each paragraph is timed
-        in accordance to its parent or sibling according to the applicable time
-        containment semantics — in this case, the division parent is interpreted (by
-        default) as a parallel time container.</p><a id="ttml-example-body" name=
-        "ttml-example-body"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Body
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;body region="subtitleArea"&gt;
-  &lt;div&gt;
-    &lt;p xml:id="subtitle1" begin="0.76s" end="3.45s"&gt;
-      It seems a paradox, does it not,
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle2" begin="5.0s" end="10.0s"&gt;
-      that the image formed on&lt;br/&gt;
-      the Retina should be inverted?
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle3" begin="10.0s" end="16.0s" style="s2"&gt;
-      It is puzzling, why is it&lt;br/&gt;
-      we do not see things upside-down?
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle4" begin="17.2s" end="23.0s"&gt;
-      You have never heard the Theory,&lt;br/&gt;
-      then, that the Brain also is inverted?
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle5" begin="23.0s" end="27.0s" style="s2"&gt;
-      No indeed! What a beautiful fact!
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle6a" begin="28.0s" end="34.6s" style="s2Left"&gt;
-      But how is it proved?
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle6b" begin="28.0s" end="34.6s" style="s1Right"&gt;
-      Thus: what we call
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle7" begin="34.6s" end="45.0s" style="s1Right"&gt;
-      the vertex of the Brain&lt;br/&gt;
-      is really its base
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle8" begin="45.0s" end="52.0s" style="s1Right"&gt;
-      and what we call its base&lt;br/&gt;
-      is really its vertex,
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle9a" begin="53.5s" end="58.7s"&gt;
-      it is simply a question of nomenclature.
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle9b" begin="53.5s" end="58.7s" style="s2"&gt;
-      How truly delightful!
-    &lt;/p&gt;
-  &lt;/div&gt;    
-&lt;/body&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The first subtitle <a href="#ttml-example-subtitle-1"><b>Subtitle 1 – Time
-        Interval [0.76, 3.45)</b></a> is presented during the time interval 0.76 to 3.45
-        seconds. This subtitle inherits its font family, font size, foreground color, and
-        text alignment from the region into which it is presented. Since no region is
-        explicitly specified on the paragraph, the nearest ancestor that specifies a
-        region determines the targeted region. Note also that content is presented at the
-        bottom (after edge) of the containing region due to the
-        <code>tts:displayAlign="after"</code> being specified on the region
-        definition.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The notation "[<em>X</em>,<em>Y</em>]" denotes a closed interval from
-          <em>X</em> to <em>Y</em>, including <em>X</em> and <em>Y</em>;
-          "[<em>X</em>,<em>Y</em>)" denotes a right half-open interval from <em>X</em> to
-          <em>Y</em>, including <em>X</em> but not including <em>Y</em>;
-          "(<em>X</em>,<em>Y</em>]" denotes a left half-open interval from <em>X</em> to
-          <em>Y</em>, not including <em>X</em> but including <em>Y</em>;
-          "(<em>X</em>,<em>Y</em>)" denotes an open interval from <em>X</em> to
-          <em>Y</em>, not including <em>X</em> or <em>Y</em>.</p>
-        </div><a id="ttml-example-subtitle-1" name="ttml-example-subtitle-1"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 1 – Time Interval [0.76, 3.45)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle1.png" alt="Subtitle 1"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The second subtitle continues with the default style, except that it contains
-        two lines of text with an intervening author-specified line break. Note the
-        affect of the use of <code>tts:textAlign="center"</code> to specify the
-        paragraph's alignment in the inline progression direction.</p><a id=
-        "ttml-example-subtitle-2" name="ttml-example-subtitle-2"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 2 – Time Interval [5.0, 10.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle2.png" alt="Subtitle 2"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The third subtitle continues, using a variant style which overrides the
-        default style's foreground color with a different color.</p><a id=
-        "ttml-example-subtitle-3" name="ttml-example-subtitle-3"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 3 – Time Interval [10.0, 16.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle3.png" alt="Subtitle 3"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The fourth subtitle reverts to the default style.</p><a id=
-        "ttml-example-subtitle-4" name="ttml-example-subtitle-4"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 4 – Time Interval [17.2, 23.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle4.png" alt="Subtitle 4"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The fifth subtitle continues, again using a variant style which overrides the
-        default style's foreground color with a different color.</p><a id=
-        "ttml-example-subtitle-5" name="ttml-example-subtitle-5"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 5 – Time Interval [23.0, 27.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle5.png" alt="Subtitle 5"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>During the next active time interval, two distinct subtitles are
-        simultaneously active, with the paragraphs expressing each subtitle using
-        different styles that override color and paragraph text alignment of the default
-        style. Note that the flow order is determined by the lexical order of elements as
-        they appear in the content hierarchy.</p><a id="ttml-example-subtitle-6" name=
-        "ttml-example-subtitle-6"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitles 6a and 6b – Time Interval [28.0, 34.6)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle6.png" alt="Subtitles 6a and 6b"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The next subtitle is specified in a similar manner using a style override to
-        give the paragraph right (end) justification in the inline progression
-        direction.</p><a id="ttml-example-subtitle-7" name="ttml-example-subtitle-7"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 7 – Time Interval [34.6, 45.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle7.png" alt="Subtitles 7a and 7b"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The eighth subtitle uses the same style override as the previous subtitle in
-        order to maintain the right (end) justification of the paragraph.</p><a id=
-        "ttml-example-subtitle-8" name="ttml-example-subtitle-8"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 8 – Time Interval [47.3, 49.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle8.png" alt="Subtitle 8"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>During the final (ninth) active time interval, two distinct subtitles are
-        again simultaneously active, but with a different style applied to the second
-        paragraph to override the default color. Note that the flow order is determined
-        by the lexical order of elements as they appear in the content
-        hierarchy.</p><a id="ttml-example-subtitle-9" name="ttml-example-subtitle-9"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitles 9a and 9b – Time Interval [53.5, 58.7)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle9.png" alt="Subtitles 9a and 9b"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The examples shown above demonstrate the primary types of information that may
-        be authored using TTML: metadata, styling, layout, timing, and content. In
-        typical cases, styling and layout information are separately specified in a
-        <em>Document Instance</em>. Content information is expressed in a hierarchical
-        fashion that embodies the organization of both spatial (flow) and timing
-        information. Content makes direct or indirect references to styling and layout
-        information and may specify inline overrides to styling.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="definitions" name="definitions"></a>2 Definitions</h2>
-
-      <div class="div2">
-        <h3><a id="acronyms" name="acronyms"></a>2.1 Acronyms</h3>
-
-        <table class="acronyms" summary="Glossary List">
-          <tr>
-            <td class="label"><b>DFXP</b></td>
-
-            <td class="def">
-              <p>Distribution Format Exchange Profile</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TT</b></td>
-
-            <td class="def">
-              <p>Timed Text</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TTML</b></td>
-
-            <td class="def">
-              <p>Timed Text Markup Language</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TT AS</b></td>
-
-            <td class="def">
-              <p>Timed Text Authoring System</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TT AF</b></td>
-
-            <td class="def">
-              <p>Timed Text Authoring Format</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TT WG</b></td>
-
-            <td class="def">
-              <p>Timed Text Working Group</p>
-            </td>
-          </tr>
-        </table>
-      </div>
-
-      <div class="div2">
-        <h3><a id="terms" name="terms"></a>2.2 Terminology</h3>
-
-        <dl>
-          <dt class="label">Abstract Document Instance</dt>
-
-          <dd>
-            <p>An instance of an abstract data set as represented by a <em>Reduced XML
-            Infoset</em>.</p>
-          </dd>
-
-          <dt class="label">Abstract Document Type</dt>
-
-          <dd>
-            <p>A set of constraints that defines a class of <em>XML Information Sets</em>
-            <a href="#infoset">[XML InfoSet]</a>.</p>
-          </dd>
-
-          <dt class="label">Attribute Information Item</dt>
-
-          <dd>
-            <p>Each specified or defaulted attribute of an XML document corresponds with
-            an attribute information item as defined by <a href="#infoset">[XML
-            InfoSet]</a>, §2.3.</p>
-          </dd>
-
-          <dt class="label">Character Information Item</dt>
-
-          <dd>
-            <p>Each data character appearing in an XML document corresponds with a
-            character information item as defined by <a href="#infoset">[XML
-            InfoSet]</a>, §2.6.</p>
-          </dd>
-
-          <dt class="label">Content Processor</dt>
-
-          <dd>
-            <p>A processing system capable of importing (receiving) Timed Text Markup
-            Language content for the purpose of transforming, presenting, or otherwise
-            processing the content.</p>
-          </dd>
-
-          <dt class="label">Content Profile</dt>
-
-          <dd>
-            <p>A collection of features and extensions that are (or may be) employed by
-            Timed Text Markup Language content.</p>
-          </dd>
-
-          <dt class="label">Content Region</dt>
-
-          <dd>
-            <p>A logical region into which rendered content is placed when modeling or
-            performing presentation processing.</p>
-          </dd>
-
-          <dt class="label">Document Instance</dt>
-
-          <dd>
-            <p>A concrete realization of a Timed Text Markup Language document, where the
-            concrete form is specific to the context of reference. For example, a
-            sequence of bytes that represents an XML serialization of a Timed Text
-            document, an internal, parsed representation of such a Timed Text document,
-            etc.</p>
-          </dd>
-
-          <dt class="label">Document Interchange Context</dt>
-
-          <dd>
-            <p>The implied context or environment external to a <em>Content
-            Processor</em> in which document interchange occurs, and in which out-of-band
-            protocols or specifications may define certain behavioral defaults, such as
-            an implied <em>Content Profile</em>.</p>
-          </dd>
-
-          <dt class="label">Document Processing Context</dt>
-
-          <dd>
-            <p>The implied context or environment internal to a <em>Content
-            Processor</em> in which document processing occurs, and in which out-of-band
-            protocols or specifications may define certain behavioral defaults, such as
-            the establishment or creation of a <em>Synthetic Document Syncbase</em>.</p>
-          </dd>
-
-          <dt class="label">Element Information Item</dt>
-
-          <dd>
-            <p>Each element appearing in an XML document corresponds with an element
-            information item as defined by <a href="#infoset">[XML InfoSet]</a>,
-            §2.2.</p>
-          </dd>
-
-          <dt class="label">Exchange Profile</dt>
-
-          <dd>
-            <p>A content profile that serves a set of needs for content interchange.</p>
-          </dd>
-
-          <dt class="label">Extension</dt>
-
-          <dd>
-            <p>A syntactic or semantic expression or capability that is defined and
-            labeled (using a extension designation) in another (public or private)
-            specification.</p>
-          </dd>
-
-          <dt class="label">Feature</dt>
-
-          <dd>
-            <p>A syntactic or semantic expression or capability that is defined and
-            labeled (using a feature designation) in this specification (or a future
-            revision of this specification).</p>
-          </dd>
-
-          <dt class="label">Presentation Processor</dt>
-
-          <dd>
-            <p>A <em>Content Processor</em> which purpose is to layout, format, and
-            render, i.e., to present, <em>Timed Text Markup Language</em> content by
-            applying the presentation semantics defined in this specification.</p>
-          </dd>
-
-          <dt class="label">Processor</dt>
-
-          <dd>
-            <p>See <em>Content Processor</em>.</p>
-          </dd>
-
-          <dt class="label">Processor Profile</dt>
-
-          <dd>
-            <p>A collection of features and extensions that must or may be implemented
-            (supported) by a content processor.</p>
-          </dd>
-
-          <dt class="label">Profile Definition Document</dt>
-
-          <dd>
-            <p>A document that defines a specific collection of features and extensions
-            for which support is required or optional in a recipient content
-            processor.</p>
-          </dd>
-
-          <dt class="label">Region</dt>
-
-          <dd>
-            <p>A logical construct that models authorial intention regarding desired or
-            potential presentation processing, and which is represented as a rectangular
-            area of a presentation surface into which content is composed and rendered
-            during presentation processing.</p>
-          </dd>
-
-          <dt class="label">Reduced XML Infoset</dt>
-
-          <dd>
-            <p>An XML Information Set <a href="#infoset">[XML InfoSet]</a> that satisfies
-            the constraints specify by <a href="#reduced-infoset"><b>A Reduced XML
-            Infoset</b></a>.</p>
-          </dd>
-
-          <dt class="label">Related Media Object</dt>
-
-          <dd>
-            <p>A (possibly null) media object associated with or otherwise related to a
-            <em>Document Instance</em>. For example, an aggregate audio/video media
-            object for which a <em>Document Instance</em> provides caption or subtitle
-            information, and with which that <em>Document Instance</em> is
-            associated.</p>
-          </dd>
-
-          <dt class="label">Root Container Region</dt>
-
-          <dd>
-            <p>A logical region that establishes a coordinate system into which
-            <em>Document Instance</em> content regions are placed and optionally
-            clipped.</p>
-          </dd>
-
-          <dt class="label">Root Temporal Extent</dt>
-
-          <dd>
-            <p>The temporal extent (interval) defined by the temporal beginning and
-            ending of a <em>Document Instance</em> in relationship with some external
-            application or presentation context.</p>
-          </dd>
-
-          <dt class="label">SMPTE Time Code</dt>
-
-          <dd>
-            <p>A time code whose format and semantics are established by <a href=
-            "#smpte12m">[SMPTE 12M]</a>, which may be embedded into or otherwise
-            associated with media content, such as a broadcast audio/video stream.</p>
-          </dd>
-
-          <dt class="label">Synthetic Document Syncbase</dt>
-
-          <dd>
-            <p>A document level <a href=
-            "http://www.w3.org/TR/2005/REC-SMIL2-20051213/smil-timing.html#Timing-Syncbases">
-            syncbase</a> <a href="#smil21">[SMIL 2.1]</a>, § 10.7.1, synthesized or
-            otherwise established by the <em>Document Processing Context</em> in
-            accordance with the <em>Related Media Object</em> or other processing
-            criteria.</p>
-          </dd>
-
-          <dt class="label">Synthetic SMPTE Document Syncbase</dt>
-
-          <dd>
-            <p>A <em>Synthetic Document Syncbase</em> constructed from <em>SMPTE Time
-            Code</em> values embedded in or associated with the <em>Related Media
-            Object</em> or otherwise determined by the <em>Document Processing
-            Context</em>.</p>
-          </dd>
-
-          <dt class="label">Timed Text</dt>
-
-          <dd>
-            <p>Textual information that is intrinsically or extrinsically associated with
-            timing information.</p>
-          </dd>
-
-          <dt class="label">Timed Text Markup Language</dt>
-
-          <dd>
-            <p>A content type that represents timed text media for the purpose of
-            interchange among authoring systems.</p>
-          </dd>
-
-          <dt class="label">Timed Text Authoring System</dt>
-
-          <dd>
-            <p>A content authoring system capable of importing and exporting Timed Text
-            Markup Language content.</p>
-          </dd>
-
-          <dt class="label">Transformation Processor</dt>
-
-          <dd>
-            <p>A <em>Content Processor</em> which purpose is to transform or otherwise
-            rewrite <em>Timed Text Markup Language</em> content to either <em>Timed Text
-            Markup Language</em> or to another (arbitrary) content format. An example of
-            the first is a processor that removes or rewrites TTML features so as to
-            conform to a profile of TTML. An example of the latter is a processor that
-            translates TTML into a completely different timed text format. Because this
-            specification does not otherwise define a target profile or format for
-            transformation processing, no further transformation semantics are defined by
-            this specification.</p>
-          </dd>
-
-          <dt class="label">Valid Abstract Document Instance</dt>
-
-          <dd>
-            <p>An <em>Abstract Document Instance</em> which has been assessed for
-            validity and found to be valid as defined by <a href="#doctypes"><b>4
-            Document Types</b></a>.</p>
-          </dd>
-        </dl>
-      </div>
-
-      <div class="div2">
-        <h3><a id="conventions" name="conventions"></a>2.3 Documentation Conventions</h3>
-
-        <p>Within normative prose in this specification, the words <em>may</em>,
-        <em>should</em>, and <em>must</em> are defined as follows:</p>
-
-        <dl class="conformance-keywords">
-          <dt class="label">may</dt>
-
-          <dd>
-            <p>Conforming documents and/or TTML processors are permitted to, but need not
-            behave as described.</p>
-          </dd>
-
-          <dt class="label">should</dt>
-
-          <dd>
-            <p>Conforming documents and/or TTML processors are strongly recommended to,
-            but need not behave as described.</p>
-          </dd>
-
-          <dt class="label">must</dt>
-
-          <dd>
-            <p>Conforming documents and/or TTML processors are required to behave as
-            described; otherwise, they are in error.</p>
-          </dd>
-        </dl>
-
-        <p>If normative specification language takes an imperative form, then it is to be
-        treated as if the term <span class="strong">must</span> applies. Furthermore, if
-        normative language takes a declarative form, and this language is governed by
-        <span class="strong">must</span>, then it is also to be treated as if the term
-        <span class="strong">must</span> applies.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>For example, the phrases "treat X as an error" and "consider X as an error"
-          are to be read as mandatory requirements in the context of use. Similarly, if
-          the specification prose is "X must apply", "X applies", or "X is mandatory",
-          and "X" is further defined as "X is Y and Z", then, by transitive closure, this
-          last declarative phrase is to be read as "Y is mandatory" and "Z is mandatory"
-          in the context of use.</p>
-        </div>
-
-        <p>All normative syntactic definitions of XML representations and other related
-        terms are depicted with a light yellow-orange background color and labeled as
-        "XML Representation" or "Syntax Representation", such as in the
-        following:</p><a id="elt-syntax-example" name="elt-syntax-example"></a>
-
-        <table class="syntax">
-          <caption>
-            XML Representation – Element Information Item: example
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;example
-  <span class="reqattr">count</span> = integer
-  size = (<em>large</em>|<em>medium</em>|<em>small</em>) : medium&gt;
-  <em>Content:</em> (all | any*)
-&lt;/example&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>In an XML representation, bold-face attribute names (e.g. <span class=
-        "strong">count</span> above) indicate a required attribute information item, and
-        the rest are optional. Where an attribute information item has an enumerated type
-        definition, the values are shown separated by vertical bars, as for
-        <code>size</code> above; if there is a default value, it is shown following a
-        colon. Where an attribute information item has a built-in simple type definition
-        defined in <a href="#xsd-2">[XML Schema Part 2]</a>, a hyperlink to its
-        definition therein is given.</p>
-
-        <p>The allowed content of the information item is shown as a grammar fragment,
-        using the Kleene operators <code>?</code>, <code>*</code> and <code>+</code>.
-        Each element name therein is a hyperlink to its own illustration.</p>
-
-        <p>All content of this specification that is not explicitly marked as
-        non-normative is considered to be normative. If a section or appendix header
-        contains the expression "Non-Normative", then the entirety of the section or
-        appendix is considered non-normative.</p>
-
-        <p>All paragraphs marked as a <span class="strong">Note</span> are considered
-        non-normative.</p>
-
-        <p>Example code fragments are depicted with a light blue-green background color
-        and labeled as "Example Fragment", such as in the following:</p><a id=
-        "example-fragment-1" name="example-fragment-1"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – Sample
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
-  &lt;head&gt;
-    &lt;metadata/&gt;
-    &lt;styling/&gt;
-    &lt;layout/&gt;
-  &lt;/head&gt;
-  &lt;body/&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="conformance" name="conformance"></a>3 Conformance</h2>
-
-      <p>This section specifies the general conformance requirements for TTML Content and
-      processors.</p>
-
-      <div class="div2">
-        <h3><a id="conformance-content" name="conformance-content"></a>3.1 Content
-        Conformance</h3>
-
-        <p>A TTML <em>Document Instance</em> conforms to this specification if the
-        following criteria are satisfied:</p>
-
-        <ol class="enumar">
-          <li>
-            <p>When transporting a <em>Document Instance</em> in a <em>Document
-            Interchange Context</em> in which a Media Type <a href="#media-types">[Media
-            Types]</a> identifies the content type of the interchanged <em>Document
-            Instance</em>, then the specified media type is
-            <code>application/ttml+xml</code> in conformance with <a href="#rfc3023">[XML
-            Media Types]</a> § 7, with which an optional <code>profile</code> parameter
-            may appear, the value of which conforms to a profile designator as defined by
-            <a href="#vocabulary-profiles"><b>5.2 Profiles</b></a>.</p>
-          </li>
-
-          <li>
-            <p>The <em>Document Instance</em> is or can be represented as a Reduced XML
-            Infoset as defined by <a href="#reduced-infoset"><b>A Reduced XML
-            Infoset</b></a>.</p>
-          </li>
-
-          <li>
-            <p>The Reduced XML Infoset that corresponds to the <em>Document Instance</em>
-            is or can be associated with one of the <em>Abstract Document Types</em>
-            defined by <a href="#doctypes"><b>4 Document Types</b></a>.</p>
-          </li>
-
-          <li>
-            <p>The <em>Reduced XML Infoset</em> that corresponds to the <em>Document
-            Instance</em> is a <em>Valid Abstract Document Instance</em> of the
-            associated <em>Abstract Document Type</em>.</p>
-          </li>
-
-          <li>
-            <p>The <em>Reduced XML Infoset</em> satisfies all additional mandatory
-            syntactic and semantic constraints defined by this specification. In
-            addition, this Infoset should satisfy the web content accessibility
-            guidelines specified by <a href="#wcag">[WCAG]</a>.</p>
-          </li>
-        </ol>
-      </div>
-
-      <div class="div2">
-        <h3><a id="conformance-processor" name="conformance-processor"></a>3.2 Processor
-        Conformance</h3>
-
-        <div class="div3">
-          <h4><a id="conformance-generic-processor" name=
-          "conformance-generic-processor"></a>3.2.1 Generic Processor Conformance</h4>
-
-          <p>A TTML <em>Content Processor</em> conforms to this specification if the
-          following generic processor criteria are satisfied:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>The processor provides at least one mechanism for notionally
-              instantiating a Reduced XML Infoset representation of a conformant
-              <em>Document Instance</em>.</p>
-            </li>
-
-            <li>
-              <p>If a process does or can perform validation of a candidate <em>Document
-              Instance</em>, then it provides at least one mechanism to implicitly or
-              explicitly associate the <em>Reduced XML Infoset</em> representation of a
-              conformant <em>Document Instance</em> with one of the <em>Abstract Document
-              Types</em> defined by <a href="#doctypes"><b>4 Document Types</b></a>.</p>
-            </li>
-
-            <li>
-              <p>The processor does not <em>a priori</em> reject or abort the processing
-              of a conformant <em>Document Instance</em> unless the processor does not
-              support some required (mandatory) feature specified or implied by a TTML
-              Content profile declared to apply to the <em>Document Instance</em>.</p>
-            </li>
-
-            <li>
-              <p>The processor supports all mandatory processing semantics defined by
-              this specification.</p>
-
-              <div class="note">
-                <p class="prefix"><b>Note:</b></p>
-
-                <p>The phrase <em>mandatory semantics</em> refers to all explicit use of
-                the conformance key phrases <span class="strong">must</span> and
-                <span class="strong">must not</span> as well as any declarative statement
-                that can be reasonably inferred from such key phrases. For example, these
-                mandatory semantics include support for all features marked as mandatory
-                in <a href="#feature-support"><b>D.2 Feature Support</b></a>.</p>
-              </div>
-            </li>
-
-            <li>
-              <p>If the processor supports some optional processing semantics defined by
-              this specification, then it does so in a manner consistent with the defined
-              semantics.</p>
-
-              <div class="note">
-                <p class="prefix"><b>Note:</b></p>
-
-                <p>The phrase <em>optional semantics</em> refers to all explicit use of
-                the conformance key phrases <span class="strong">should</span>,
-                <span class="strong">should not</span>, <span class="strong">may</span>,
-                and <span class="strong">may not</span>, as well as any declarative
-                statement that can be reasonably inferred from such key phrases. For
-                example, these optional semantics include support for all features marked
-                as optional in <a href="#feature-support"><b>D.2 Feature
-                Support</b></a>.</p>
-              </div>
-            </li>
-          </ol>
-        </div>
-
-        <div class="div3">
-          <h4><a id="conformance-transformation-processor" name=
-          "conformance-transformation-processor"></a>3.2.2 Transformation Processor
-          Conformance</h4>
-
-          <p>A TTML <em>Content Processor</em> is a conformant TTML <em>Transformation
-          Processor</em> if the following criteria are satisfied:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>The processor satisfies all requirements specified by <a href=
-              "#conformance-generic-processor"><b>3.2.1 Generic Processor
-              Conformance</b></a>.</p>
-            </li>
-
-            <li>
-              <p>The processor supports the DFXP Transformation profile as specified by
-              <a href="#profile-dfxp-transformation"><b>F.1 DFXP Transformation
-              Profile</b></a>.</p>
-            </li>
-          </ol>
-        </div>
-
-        <div class="div3">
-          <h4><a id="conformance-presentation-processor" name=
-          "conformance-presentation-processor"></a>3.2.3 Presentation Processor
-          Conformance</h4>
-
-          <p>A TTML <em>Content Processor</em> is a conformant TTML <em>Presentation
-          Processor</em> if the following criteria are satisfied:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>The processor satisfies all requirements specified by <a href=
-              "#conformance-generic-processor"><b>3.2.1 Generic Processor
-              Conformance</b></a>.</p>
-            </li>
-
-            <li>
-              <p>The processor supports the DFXP Presentation profile as specified by
-              <a href="#profile-dfxp-presentation"><b>F.2 DFXP Presentation
-              Profile</b></a>.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="claims" name="claims"></a>3.3 Claims</h3>
-
-        <p>Any claim of compliance with respect to the conformance of a TTML <em>Document
-        Instance</em> or <em>Content Processor</em> must make reference to an
-        implementation compliance statement (ICS).</p>
-
-        <p>An implementation compliance statement must identify all mandatory and
-        optional features of this specification that are satisfied by the document
-        instance or the content processor implementation. In particular, the statement
-        must identify the utilized or supported TTML vocabulary profile(s) as defined by
-        <a href="#vocabulary-profiles"><b>5.2 Profiles</b></a>, and, if a subset or
-        superset profile is used or supported, then what features are excluded or
-        included in the subset or superset profile.</p>
-
-        <p>A <em>Document Instance</em> for which a compliance claim is made must specify
-        either (1) a <code>ttp:profile</code> attribute on its root <code>tt</code>
-        element as defined by <a href="#parameter-attribute-profile"><b>6.2.8
-        ttp:profile</b></a> or (2) a <code>ttp:profile</code> element as a child of the
-        <code>head</code> element as defined by <a href=
-        "#parameter-vocabulary-profile"><b>6.1.1 ttp:profile</b></a>.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="doctypes" name="doctypes"></a>4 Document Types</h2>
-
-      <p>This section defines the following TTML <em>Abstract Document Types</em>:</p>
-
-      <ul>
-        <li>
-          <p><a href="#ttml-content-doctype"><b>4.1 TTML Content</b></a></p>
-        </li>
-      </ul>
-
-      <p>Each <em>Abstract Document Type</em> consists of the following constraints:</p>
-
-      <ul>
-        <li>
-          <p>a non-empty collection of element types, where each element type consists of
-          a name, a (possibly empty) collection of attributes, and a content
-          specification</p>
-        </li>
-
-        <li>
-          <p>a non-empty collection of element types that may appear as the document
-          element</p>
-        </li>
-      </ul>
-
-      <p>An <em>Abstract Document Instance</em> may be assessed in terms of validity, and
-      is considered to be a <em>Valid Abstract Document Instance</em> if it satisfies the
-      following condition: if after</p>
-
-      <ol class="enumar">
-        <li>
-          <p>pruning all element information items whose names are not members of the
-          collection of element types defined by the associated <em>Abstract Document
-          Type</em>, then</p>
-        </li>
-
-        <li>
-          <p>pruning character information item children from any remaining element in
-          case that all character children of the element denote XML whitespace
-          characters and the element's type is defined as empty in the associated
-          <em>Abstract Document Type</em>, and then</p>
-        </li>
-
-        <li>
-          <p>pruning all attribute information items having expanded names such that the
-          namespace URI of the expanded names are not listed in <a href=
-          "#namespace-vocab-table"><b>Table 1 – Namespaces</b></a>,</p>
-        </li>
-      </ol>
-
-      <p>then the document element is one of the document element types permitted by the
-      associated <em>Abstract Document Type</em>, the descendants of the document element
-      satisfy their respective element type's content specifications, all required
-      attributes are present, and the declared value of each attribute satisfies the type
-      declared by the associated <em>Abstract Document Type</em>.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>While a conformant processor may not <em>a priori</em> reject a conformant
-        <em>Document Instance</em> that adheres to a supported content profile, a given
-        <em>Document Instance</em> may be constrained by the author or authoring tool to
-        satisfy a more restrictive definition of validity.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="ttml-content-doctype" name="ttml-content-doctype"></a>4.1 TTML
-        Content</h3>
-
-        <p>TTML Content is an <em>Abstract Document Type</em> of a profile of the Timed
-        Text Markup Language intended to be used for interchange among distribution
-        systems. This document type is defined in terms of the element and attribute
-        vocabulary specified in <a href="#vocabulary"><b>5 Vocabulary</b></a>.</p>
-
-        <p>This specification references two types of schemas that may be used to
-        validate a superset/subset of conformant TTML Content <em>Document
-        Instances</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#ttml-schema-rnc"><b>B.1 Relax NG Compact (RNC)
-            Schema</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#ttml-schema-xsd"><b>B.2 XML Schema Definition (XSD)
-            Schema</b></a></p>
-          </li>
-        </ul>
-
-        <p>The (root) document element of a TTML Content <em>Document Instance</em> must
-        be a <code>tt</code> element, as defined by <a href=
-        "#document-structure-vocabulary-tt"><b>7.1.1 tt</b></a>.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The schemas referenced by this specification do not validate all syntactic
-          constraints defined by this specification, and, as such, represent a superset
-          of conformant TTML Content. In particular, performing validation with one of
-          the above referenced schemas may result in a <em>false positive</em> indication
-          of validity. For example, both the RNC and XSD schemas specify that a
-          <code>tts:fontFamily</code> attribute must satisfy the <code>xs:string</code>
-          XSD data type; however, this data type is a superset of the values permitted to
-          be used with the <code>tts:fontFamily</code> attribute.</p>
-
-          <p>In addition, the RNC schema may produce a <em>false negative</em> indication
-          of validity when using the <code>xml:id</code> attribute with an element in a
-          foreign namespace, thus representing a subset of conformant TTML Content. This
-          is due to a specific limitation in expressing wildcard patterns involving
-          <code>xsd:ID</code> typed attributes in Relax NG schemas. Note that this
-          specification defines the formal validity of a <em>Document Instance</em> to be
-          based on an <em>Abstract Document Instance</em> from which all foreign
-          namespace elements and attributes have been removed. Therefore, the exceptional
-          reporting of this false negative does not impact the formal assessment of
-          <em>Document Instance</em> validity.</p>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="vocabulary" name="vocabulary"></a>5 Vocabulary</h2>
-
-      <p>This section defines the namespaces, profiles, and vocabulary (as an element and
-      attribute catalog) of the Timed Text Markup Language (TTML) as follows:</p>
-
-      <ul>
-        <li>
-          <p><a href="#vocabulary-namespaces"><b>5.1 Namespaces</b></a></p>
-        </li>
-
-        <li>
-          <p><a href="#vocabulary-profiles"><b>5.2 Profiles</b></a></p>
-        </li>
-
-        <li>
-          <p><a href="#vocabulary-overview"><b>5.3 Catalog</b></a></p>
-        </li>
-      </ul>
-
-      <div class="div2">
-        <h3><a id="vocabulary-namespaces" name="vocabulary-namespaces"></a>5.1
-        Namespaces</h3>
-
-        <p>The Timed Text Markup Language (TTML) employs a number of XML Namespaces
-        <a href="#xmlns10">[XML Namespaces 1.0]</a> for elements and certain global
-        attributes. The following table specifies this set of namespaces and indicates
-        the default prefix used within this specification and the normative URI that
-        denotes each namespace.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>In a specific <em>Document Instance</em>, it is not required that the
-          default prefixes shown below are used. Any prefix or namespace binding that
-          satisfies the constraints of XML Namespaces <a href="#xmlns10">[XML Namespaces
-          1.0]</a> may be used that is associated with the specified namespace URI.</p>
-        </div><a id="namespace-vocab-table" name="namespace-vocab-table"></a>
-
-        <table class="common">
-          <caption>
-            Table 1 – Namespaces
-          </caption>
-          <col width="30%" span="1">
-          <col span="1">
-          <col span="1">
-
-          <tbody>
-            <tr>
-              <th>Name</th>
-
-              <th>Prefix</th>
-
-              <th>Value</th>
-            </tr>
-
-            <tr>
-              <td>TT</td>
-
-              <td><code>tt:</code></td>
-
-              <td><code>http://www.w3.org/ns/ttml</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Parameter</td>
-
-              <td><code>ttp:</code></td>
-
-              <td><code>http://www.w3.org/ns/ttml#parameter</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Style</td>
-
-              <td><code>tts:</code></td>
-
-              <td><code>http://www.w3.org/ns/ttml#styling</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Metadata</td>
-
-              <td><code>ttm:</code></td>
-
-              <td><code>http://www.w3.org/ns/ttml#metadata</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Profile</td>
-
-              <td><em>none</em></td>
-
-              <td><code>http://www.w3.org/ns/ttml/profile/</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Feature</td>
-
-              <td><em>none</em></td>
-
-              <td><code>http://www.w3.org/ns/ttml/feature/</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Extension</td>
-
-              <td><em>none</em></td>
-
-              <td><code>http://www.w3.org/ns/ttml/extension/</code></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>If a reference to an element type is used in this specification and the name
-          of the element type is not namespace qualified, then the TT Namespace
-          applies.</p>
-
-          <p>For certain namespaces defined above, the default prefix is specified as
-          <em>none</em> if no XML vocabulary is defined in the namespace by this
-          specification (nor expected to be defined in a future version of this
-          specification). In such cases, the use of the namespace URI is for purposes
-          other than defining XML vocabulary, e.g., for designating profiles, features,
-          extensions and for dereferencing standard profile definitions.</p>
-        </div>
-
-        <p>All TTML Namespaces are <a href=
-        "http://www.w3.org/2001/tag/doc/namespaceState#namespacedef"><em>mutable</em></a>
-        <a href="#nsstate">[NSState]</a>; all undefined names in these namespaces are
-        reserved for future standardization by the W3C.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="vocabulary-profiles" name="vocabulary-profiles"></a>5.2 Profiles</h3>
-
-        <p>The Timed Text Markup Language (TTML) employs a number of standard, predefined
-        profiles of its vocabulary and associated semantics. The following table
-        specifies this set of profiles, indicating a normative name and designator for
-        each predefined profile, and where each of these profiles is formally elaborated
-        in <a href="#profiles"><b>F Profiles</b></a>.</p><a id="profile-vocab-table"
-        name="profile-vocab-table"></a>
-
-        <table class="common">
-          <caption>
-            Table 2 – Profiles
-          </caption>
-          <col width="25%" span="1">
-          <col span="1">
-
-          <tbody>
-            <tr>
-              <th>Name</th>
-
-              <th>Designator</th>
-            </tr>
-
-            <tr>
-              <td>DFXP Transformation</td>
-
-              <td><code>http://www.w3.org/ns/ttml/profile/dfxp-transformation</code></td>
-            </tr>
-
-            <tr>
-              <td>DFXP Presentation</td>
-
-              <td><code>http://www.w3.org/ns/ttml/profile/dfxp-presentation</code></td>
-            </tr>
-
-            <tr>
-              <td>DFXP Full</td>
-
-              <td><code>http://www.w3.org/ns/ttml/profile/dfxp-full</code></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>A profile designator must adhere to the <code>xsd:anyURI</code> data type
-        defined by <a href="#xsd-2">[XML Schema Part 2]</a>, §3.2.17. If the profile
-        designator is expressed as a relative URI, then it must be absolutized by using
-        the TT Profile Namespace value as the base URI.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>For example, if a profile designator is expressed as
-          <code>dfxp-presentation</code>, then the absolutized profile designator would
-          be <code>http://www.w3.org/ns/ttml/profile/dfxp-presentation</code>.</p>
-        </div>
-
-        <p>A profile designator is not restricted to the set of designators enumerated in
-        <a href="#profile-vocab-table"><b>Table 2 – Profiles</b></a>, but may be any URI
-        that feasibly dereferences a TTML <em>Profile Definition Document</em>.</p>
-
-        <p>The profile of TTML that must be supported by a TTML <em>Content
-        Processor</em> in order to process a <em>Document Instance</em> is determined
-        either (1) by specifying a <code>ttp:profile</code> attribute on the root
-        <code>tt</code> element, as defined by <a href=
-        "#parameter-attribute-profile"><b>6.2.8 ttp:profile</b></a>, or (2) by including
-        one or more <code>ttp:profile</code> elements in the <code>head</code> element,
-        in accordance with <a href="#parameter-vocabulary-profile"><b>6.1.1
-        ttp:profile</b></a>.</p>
-
-        <p>If a <code>ttp:profile</code> element appears as a descendant of the
-        <code>tt</code> element, then the <a href=
-        "#parameter-attribute-profile"><code>ttp:profile</code></a> attribute should not
-        be specified on the <code>tt</code> element. If both a <code>ttp:profile</code>
-        element and a <code>ttp:profile</code> attribute are present (in a given
-        <em>Document Instance</em>), then the <code>ttp:profile</code> attribute must be
-        ignored for the purpose of determining the declared profile requirements.</p>
-
-        <p>If more than one <code>ttp:profile</code> element appears in a <em>Document
-        Instance</em>, then all specified profiles apply simultaneously. In such a case,
-        if some feature or some extension is specified by one profile to be used
-        (mandatory and enabled) and by another profile to be required (mandatory) or
-        optional (voluntary), then that feature or extension must be considered to be
-        used (mandatory and enabled); if some feature or some extension is specified by
-        one profile to be merely required (mandatory) and by another profile to be
-        optional (voluntary), then that feature or extension must be considered to be
-        required (mandatory).</p>
-
-        <p>If neither <a href="#parameter-attribute-profile"><code>ttp:profile</code></a>
-        attribute nor <a href=
-        "#parameter-vocabulary-profile"><code>ttp:profile</code></a> element is present
-        in a <em>Document Instance</em>, and if the <em>Document Interchange Context</em>
-        does not make an implicit or explicit reference to a pre-defined Content Profile
-        or does not specify a <em>Profile Definition Document</em> or another equivalent
-        set of feature designations, then the DFXP Transformation profile applies.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>It is not a requirement on a conformant <em>Document Instance</em> that a
-          <em>Content Profile</em> be internally defined by use of a
-          <code>ttp:profile</code> element or internally referenced by a
-          <code>ttp:profile</code> attribute. More specifically, it is permitted that the
-          <em>Document Interchange Context</em> determines the applicable <em>Content
-          Profile</em> through private agreement, out-of-band protocol, or common use
-          (between sender and receiver) of a profile defined by an external
-          specification.</p>
-        </div>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>It is intended that the <code>ttp:profile</code> attribute be used when the
-          author wishes to reference one of the standard, predefined profiles of TTML
-          Content, and does not wish to modify (by supersetting or subsetting) that
-          profile. This attribute may also be used by an author to indicate the use of a
-          non-standard profile, in which case the specified profile designator expresses
-          a URI that denotes an externally defined <em>Profile Definition Document</em>.
-          However, it is not required that a conformant TTML Content processor be able to
-          dereference such an externally specified profile definition.</p>
-
-          <p>In contrast, it is intended that the <code>ttp:profile</code> element be
-          used when the author wishes to make use of a modified predefined profile or
-          wishes to include in the <em>Document Instance</em> a non-standard profile
-          definition not based upon one of the predefined profiles.</p>
-
-          <p>A predefined profile is supersetted by specifying some feature or extension
-          to be required (mandatory) that was either not specified in the underlying,
-          baseline profile or was specified as optional (voluntary) in the baseline
-          profile. A predefined profile is subsetted by specifying some feature or
-          extension to be optional (voluntary) that was specified as required in the
-          underlying, baseline profile.</p>
-
-          <p>When a baseline profile is modified by subsetting, the resulting, derived
-          profile is referred to as a <em>subtractive</em> profile; when modified by
-          supersetting, the result is referred to as an <em>additive</em> profile. It is
-          also possible to define a derived profile that is simultaneously subtractive
-          and additive.</p>
-        </div>
-
-        <p>If a <em>Document Instance</em> makes use of a feature defined by <a href=
-        "#feature-designations"><b>D.1 Feature Designations</b></a> and if the intended
-        use of the document requires the recognition and processing of that feature, then
-        the document must include a <em>required feature</em> or a <em>used feature</em>
-        specification in one of its declared or referenced profiles. If a <em>Document
-        Instance</em> makes use of an extension designatable by <a href=
-        "#extension-designations"><b>E.1 Extension Designations</b></a> and if the
-        intended use of the document requires the recognition and processing of that
-        extension, then the document must include a <em>required extension</em> or a
-        <em>used extension</em> specification in one of its declared or referenced
-        profiles.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>A required or used feature specification is expressed directly (or
-          indirectly by referring to a profile) by means of a <a href=
-          "#parameter-vocabulary-feature"><code>ttp:feature</code></a> element where the
-          value of its <code>value</code> attribute is <code>required</code> or
-          <code>use</code>, respectively. A required or used extension specification is
-          expressed directly (or indirectly by referring to a profile) by means of a
-          <a href="#parameter-vocabulary-extension"><code>ttp:extension</code></a>
-          element where the value of its <code>value</code> attribute is
-          <code>required</code> or <code>use</code>, respectively.</p>
-        </div>
-
-        <p>An example of an author defined additive, derived profile of the DFXP
-        Presentation profile is shown below in <a href=
-        "#ttml-example-sub-profile"><b>Example Fragment – DFXP Additive
-        Profile</b></a>.</p><a id="ttml-example-sub-profile" name=
-        "ttml-example-sub-profile"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – DFXP Additive Profile
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
- &lt;head&gt;
-   &lt;profile use="dfxp-presentation" xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
-     &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-       &lt;feature value="required"&gt;#fontStyle-italic&lt;/feature&gt;
-     &lt;/features&gt;
-   &lt;/profile&gt;
- &lt;/head&gt;
- &lt;body/&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>In the above example, the baseline profile is declared to be the DFXP
-          Presentation profile, which is then additively modified by making the
-          <code>#fontStyle-italic</code> feature required (rather than optional as it is
-          defined in <a href="#profile-dfxp-presentation"><b>F.2 DFXP Presentation
-          Profile</b></a>). Note also the resetting of the default XMLNS binding on the
-          <code>profile</code> element to the TT Parameter Namespace.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="vocabulary-overview" name="vocabulary-overview"></a>5.3 Catalog</h3>
-
-        <p>The vocabulary of the Timed Text Markup Language (TTML) is defined in the
-        following major catalogs (divisions of vocabulary):</p>
-
-        <ul>
-          <li>
-            <p><a href="#core-vocabulary-overview"><b>5.3.1 Core Catalog</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#extension-vocabulary-overview"><b>5.3.2 Extension
-            Catalog</b></a></p>
-          </li>
-        </ul>
-
-        <p>The core catalog defines the baseline, core vocabulary of TTML, and, in
-        particular, the vocabulary of TTML Content. The extension catalog serves as a
-        placeholder for extensions to the core vocabulary defined by TTML.</p>
-
-        <div class="div3">
-          <h4><a id="core-vocabulary-overview" name="core-vocabulary-overview"></a>5.3.1
-          Core Catalog</h4>
-
-          <p>The core vocabulary catalog is intended to satisfy the needs of TTML while
-          providing a baseline vocabulary for future profiles. This vocabulary is divided
-          into distinct categories, specified in detail in the following sections:</p>
-
-          <ul>
-            <li>
-              <p><a href="#parameters"><b>6 Parameters</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content"><b>7 Content</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#styling"><b>8 Styling</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#layout"><b>9 Layout</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing"><b>10 Timing</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#animation"><b>11 Animation</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata"><b>12 Metadata</b></a></p>
-            </li>
-          </ul>
-
-          <p>The core element vocabulary specified for use with a <em>Document
-          Instance</em> is enumerated in <a href="#element-vocab-table"><b>Table 3 –
-          Element Vocabulary</b></a>.</p><a id="element-vocab-table" name=
-          "element-vocab-table"></a>
-
-          <table class="common">
-            <caption>
-              Table 3 – Element Vocabulary
-            </caption>
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <th>Module</th>
-
-                <th>Elements</th>
-              </tr>
-
-              <tr>
-                <td>Animation</td>
-
-                <td><a href="#animation-vocabulary-set">set</a></td>
-              </tr>
-
-              <tr>
-                <td>Content</td>
-
-                <td><a href="#document-structure-vocabulary-body">body</a>, <a href=
-                "#content-vocabulary-div">div</a>, <a href="#content-vocabulary-p">p</a>,
-                <a href="#content-vocabulary-span">span</a>, <a href=
-                "#content-vocabulary-br">br</a></td>
-              </tr>
-
-              <tr>
-                <td>Document</td>
-
-                <td><a href="#document-structure-vocabulary-tt">tt</a></td>
-              </tr>
-
-              <tr>
-                <td>Head</td>
-
-                <td><a href="#document-structure-vocabulary-head">head</a></td>
-              </tr>
-
-              <tr>
-                <td>Layout</td>
-
-                <td><a href="#layout-vocabulary-layout">layout</a>, <a href=
-                "#layout-vocabulary-region">region</a></td>
-              </tr>
-
-              <tr>
-                <td>Metadata</td>
-
-                <td><a href="#metadata-vocabulary-metadata">metadata</a></td>
-              </tr>
-
-              <tr>
-                <td>Metadata Items</td>
-
-                <td><a href="#metadata-vocabulary-actor">ttm:actor</a>, <a href=
-                "#metadata-vocabulary-agent">ttm:agent</a>, <a href=
-                "#metadata-vocabulary-copyright">ttm:copyright</a>, <a href=
-                "#metadata-vocabulary-desc">ttm:desc</a>, <a href=
-                "#metadata-vocabulary-name">ttm:name</a>, <a href=
-                "#metadata-vocabulary-title">ttm:title</a></td>
-              </tr>
-
-              <tr>
-                <td>Parameter Items</td>
-
-                <td><a href="#parameter-vocabulary-profile">ttp:profile</a>, <a href=
-                "#parameter-vocabulary-features">ttp:features</a>, <a href=
-                "#parameter-vocabulary-feature">ttp:feature</a>, <a href=
-                "#parameter-vocabulary-extensions">ttp:extensions</a>, <a href=
-                "#parameter-vocabulary-extension">ttp:extension</a></td>
-              </tr>
-
-              <tr>
-                <td>Styling</td>
-
-                <td><a href="#styling-vocabulary-styling">styling</a>, <a href=
-                "#styling-vocabulary-style">style</a></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>Element vocabulary groups that are used in defining content models for TTML
-          element types are enumerated in <a href="#element-vocab-group-table"><b>Table 4
-          – Element Vocabulary Groups</b></a>.</p><a id="element-vocab-group-table" name=
-          "element-vocab-group-table"></a>
-
-          <table class="common">
-            <caption>
-              Table 4 – Element Vocabulary Groups
-            </caption>
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <th>Group</th>
-
-                <th>Elements</th>
-              </tr>
-
-              <tr>
-                <td>Animation.class</td>
-
-                <td><a href="#animation-vocabulary-set">set</a></td>
-              </tr>
-
-              <tr>
-                <td>Block.class</td>
-
-                <td><a href="#content-vocabulary-div">div</a> | <a href=
-                "#content-vocabulary-p">p</a></td>
-              </tr>
-
-              <tr>
-                <td>Inline.class</td>
-
-                <td><a href="#content-vocabulary-span">span</a> | <a href=
-                "#content-vocabulary-span">br</a> | <code>#PCDATA</code></td>
-              </tr>
-
-              <tr>
-                <td>Metadata.class</td>
-
-                <td><a href="#metadata-vocabulary-metadata">metadata</a> | <a href=
-                "#metadata-vocabulary-copyright">ttm:agent</a> | <a href=
-                "#metadata-vocabulary-copyright">ttm:copyright</a> | <a href=
-                "#metadata-vocabulary-desc">ttm:desc</a> | <a href=
-                "#metadata-vocabulary-title">ttm:title</a></td>
-              </tr>
-
-              <tr>
-                <td>Parameters.class</td>
-
-                <td><a href="#parameter-vocabulary-profile">ttp:profile</a></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The attribute vocabulary specified for use with the core vocabulary catalog
-          is enumerated in <a href="#attribute-vocab-table"><b>Table 5 – Attribute
-          Vocabulary</b></a>.</p><a id="attribute-vocab-table" name=
-          "attribute-vocab-table"></a>
-
-          <table class="common">
-            <caption>
-              Table 5 – Attribute Vocabulary
-            </caption>
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <th>Module</th>
-
-                <th>Attributes</th>
-              </tr>
-
-              <tr>
-                <td>Core Attributes</td>
-
-                <td><a href="#content-attribute-id">xml:id</a>, <a href=
-                "#content-attribute-lang">xml:lang</a>, <a href=
-                "#content-attribute-space">xml:space</a></td>
-              </tr>
-
-              <tr>
-                <td>Layout</td>
-
-                <td><a href="#layout-attribute-region">region</a></td>
-              </tr>
-
-              <tr>
-                <td>Metadata Attributes</td>
-
-                <td><a href="#metadata-attribute-agent">ttm:agent</a>, <a href=
-                "#metadata-attribute-role">ttm:role</a></td>
-              </tr>
-
-              <tr>
-                <td>Parameter Attributes</td>
-
-                <td><a href="#parameter-attribute-cellResolution">ttp:cellResolution</a>,
-                <a href="#parameter-attribute-clockMode">ttp:clockMode</a>, <a href=
-                "#parameter-attribute-dropMode">ttp:dropMode</a>, <a href=
-                "#parameter-attribute-frameRate">ttp:frameRate</a>, <a href=
-                "#parameter-attribute-frameRateMultiplier">ttp:frameRateMultipler</a>,
-                <a href="#parameter-attribute-markerMode">ttp:markerMode</a>, <a href=
-                "#parameter-attribute-pixelAspectRatio">ttp:pixelAspectRatio</a>,
-                <a href="#parameter-attribute-profile">ttp:profile</a>, <a href=
-                "#parameter-attribute-subFrameRate">ttp:subFrameRate</a>, <a href=
-                "#parameter-attribute-tickRate">ttp:tickRate</a>, <a href=
-                "#parameter-attribute-timeBase">ttp:timeBase</a></td>
-              </tr>
-
-              <tr>
-                <td>Styling</td>
-
-                <td><a href="#style-attribute-style">style</a></td>
-              </tr>
-
-              <tr>
-                <td>Styling Attributes</td>
-
-                <td><a href="#style-attribute-backgroundColor">tts:backgroundColor</a>,
-                <a href="#style-attribute-color">tts:color</a>, <a href=
-                "#style-attribute-direction">tts:direction</a>, <a href=
-                "#style-attribute-display">tts:display</a>, <a href=
-                "#style-attribute-displayAlign">tts:displayAlign</a>, <a href=
-                "#style-attribute-extent">tts:extent</a>, <a href=
-                "#style-attribute-fontFamily">tts:fontFamily</a>, <a href=
-                "#style-attribute-fontSize">tts:fontSize</a>, <a href=
-                "#style-attribute-fontStyle">tts:fontStyle</a>, <a href=
-                "#style-attribute-fontWeight">tts:fontWeight</a>, <a href=
-                "#style-attribute-lineHeight">tts:lineHeight</a>, <a href=
-                "#style-attribute-opacity">tts:opacity</a>, <a href=
-                "#style-attribute-origin">tts:origin</a>, <a href=
-                "#style-attribute-overflow">tts:overflow</a>, <a href=
-                "#style-attribute-padding">tts:padding</a>, <a href=
-                "#style-attribute-showBackground">tts:showBackground</a>, <a href=
-                "#style-attribute-textAlign">tts:textAlign</a>, <a href=
-                "#style-attribute-textDecoration">tts:textDecoration</a>, <a href=
-                "#style-attribute-textOutline">tts:textOutline</a>, <a href=
-                "#style-attribute-unicodeBidi">tts:unicodeBidi</a>, <a href=
-                "#style-attribute-visibility">tts:visibility</a>, <a href=
-                "#style-attribute-wrapOption">tts:wrapOption</a>, <a href=
-                "#style-attribute-writingMode">tts:writingMode</a>, <a href=
-                "#style-attribute-zIndex">tts:zIndex</a></td>
-              </tr>
-
-              <tr>
-                <td>Timing Attributes</td>
-
-                <td><a href="#timing-attribute-begin">begin</a>, <a href=
-                "#timing-attribute-dur">dur</a>, <a href="#timing-attribute-end">end</a>,
-                <a href="#timing-attribute-timeContainer">timeContainer</a></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Only those attributes defined as either (1) global, i.e., namespace
-            qualified, or (2) shared element-specific, i.e., not namespace qualified but
-            shared across multiple element types, are listed in <a href=
-            "#attribute-vocab-table"><b>Table 5 – Attribute Vocabulary</b></a> above.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>All vocabulary defined by TTML consistently makes use of the so-called
-            <em>lowerCamelCase</em> naming convention. In some cases, this results in the
-            change of a name when the name was based upon another specification that used
-            a different naming convention.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="extension-vocabulary-overview" name=
-          "extension-vocabulary-overview"></a>5.3.2 Extension Catalog</h4>
-
-          <p>The extension vocabulary catalog is intended for use by future profiles of
-          TTML, and is not further defined by this version of this specification.</p>
-
-          <p>In addition to standardized extension vocabulary, a conforming <em>Document
-          Instance</em> may contain arbitrary namespace qualified elements that reside in
-          any namespace other than those namespaces defined for use with this
-          specification. Furthermore, a conforming <em>Document Instance</em> may contain
-          arbitrary namespace qualified attributes on TTML defined vocabulary where such
-          attributes reside in any namespace other than those defined for use with this
-          specification.</p>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="parameters" name="parameters"></a>6 Parameters</h2>
-
-      <p>This section specifies the <em>parameters</em> matter of the core vocabulary
-      catalog, where parameters are to be understood as information that is either (1)
-      essential or (2) of significant importance for the purpose of interpreting the
-      semantics of other types of information expressed by core vocabulary items or for
-      establishing a <em>Document Processing Context</em> by means of which TTML Content
-      can be related to an external environment.</p>
-
-      <div class="div2">
-        <h3><a id="parameter-element-vocabulary" name=
-        "parameter-element-vocabulary"></a>6.1 Parameter Element Vocabulary</h3>
-
-        <p>The following elements, all defined in the TT Parameter Namespace, specify
-        parametric information that applies to a <em>Document Instance</em> or
-        <em>Content Processor</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#parameter-vocabulary-profile"><b>6.1.1 ttp:profile</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-vocabulary-features"><b>6.1.2 ttp:features</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-vocabulary-feature"><b>6.1.3 ttp:feature</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-vocabulary-extensions"><b>6.1.4
-            ttp:extensions</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-vocabulary-extension"><b>6.1.5
-            ttp:extension</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-profile" name=
-          "parameter-vocabulary-profile"></a>6.1.1 ttp:profile</h4>
-
-          <p>The <code>ttp:profile</code> element is used to specify a collection of used
-          (mandatory and enabled), required (mandatory), and optional (voluntary)
-          features and extensions that must or may be supported by a <em>Content
-          Processor</em> in order to process a <em>Document Instance</em> that makes (or
-          may make) use of such features and extensions.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The difference between a <em>feature</em> and an <em>extension</em> is
-            where it is defined and how it is labeled: if defined in this specification
-            (or a future revision thereof) and labeled with a feature designation in
-            <a href="#features"><b>D Features</b></a>, then it is considered to be a
-            feature; if defined in another specification and labeled there with an
-            extension designation, then it is considered to be an extension. In general,
-            features are expected to be defined by the W3C standards process, while
-            extensions are expected to be defined by third parties.</p>
-          </div>
-
-          <p>This specification defines two distinct uses of the <code>ttp:profile</code>
-          element:</p>
-
-          <ul>
-            <li>
-              <p>as a child of the <code>head</code> element within a TTML <em>Document
-              Instance</em>;</p>
-            </li>
-
-            <li>
-              <p>as the root element of a TTML <em>Profile Definition Document</em>
-              instance;</p>
-            </li>
-          </ul>
-
-          <p>When a <code>tt:profile</code> element appears within a TTML <em>Document
-          Instance</em>, its purpose is to express authorial intentions about which
-          features and extensions must or may be supported by a recipient content
-          processor. In addition, the element indirectly expresses information about the
-          set of features or extensions that are (or may expected to be) used by the
-          <em>Document Instance</em>.</p>
-
-          <p>When a <code>tt:profile</code> element is used by a TTML <em>Profile
-          Definition Document</em> instance, it serves to publish a machine readable
-          specification of a specific TTML Content profile, of which this specification
-          defines three such <em>Profile Definition Documents</em> in <a href=
-          "#profiles"><b>F Profiles</b></a>.</p>
-
-          <p>The <code>ttp:profile</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed by zero or
-          more <code>ttp:features</code> elements, followed by zero or more
-          <code>ttp:extensions</code> elements.</p><a id="elt-syntax-parameter-profile"
-          name="elt-syntax-parameter-profile"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:profile
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:profile
-  use = string
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#parameter-vocabulary-features">ttp:features</a>*, <a href=
-"#parameter-vocabulary-extensions">ttp:extensions</a>*
-&lt;/ttp:profile&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If specified, the <code>use</code> attribute must adhere to the
-          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
-          2]</a>, §3.2.17, and, furthermore, must denote a profile designator in
-          accordance with <a href="#vocabulary-profiles"><b>5.2 Profiles</b></a>. In this
-          case, the profile designator must refer to (1) a standard, predefined
-          <em>Profile Definition Document</em> as defined by <a href="#profiles"><b>F
-          Profiles</b></a>, or (2) a feasibly dereferenceable resource representing a
-          valid <em>Profile Definition Document</em> instance. In either case, the
-          referenced profile serves as the baseline profile of the specifying
-          <code>ttp:profile</code> element.</p>
-
-          <p>If the <code>use</code> attribute is not specified, then the baseline
-          profile of the <code>ttp:profile</code> element must be considered to be the
-          empty (null) profile, i.e., a profile definition containing no feature or
-          extension specifications.</p>
-
-          <p>The collection of features and extensions of a profile are determined
-          according to the following ordered rules:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>initialize the features and extensions of the profile to the empty
-              set;</p>
-            </li>
-
-            <li>
-              <p>if a <code>use</code> attribute is present, then augment the profile
-              with the set of features and extensions specified by the referenced
-              baseline profile;</p>
-            </li>
-
-            <li>
-              <p>for each <code>ttp:feature</code> and <code>ttp:extension</code> element
-              descendant of the <code>ttp:profile</code> element, using a post-order
-              traversal, merge the specified feature or extension with the features and
-              extensions of the profile, where merging a feature or extension entails
-              replacing an existing feature or extension specification, if it already
-              exists, or adding a new feature or extension specification, if it does not
-              yet exist in the profile;</p>
-            </li>
-          </ol>
-
-          <p>A conformant TTML processor is not required to be able to dereference a
-          <em>Profile Definition Document</em> that is not one of the standard,
-          predefined profiles defined by <a href="#profiles"><b>F Profiles</b></a>.
-          Furthermore, a conformant TTML processor may make use of a built-in, static
-          form of each standard, predefined profile so as not to require dereferencing a
-          network resource.</p>
-
-          <p>If a TTML processor is unable to dereference a non-standard <em>Profile
-          Definition Document</em>, then it must not further process the document without
-          the presence of an explicit override from an end-user or some implementation
-          specific parameter traceable to an end-user or to a user or system
-          configuration setting. If a TTML processor aborts processing of a <em>Document
-          Instance</em> due to the inability to reference a non-standard <em>Profile
-          Definition Document</em>, then some end-user notification should be given
-          unless the end-user or system has disabled such a notification, or if the
-          processor does not permit or entail the intervention of an end-user.</p>
-
-          <p>The <code>ttp:profile</code> element is illustrated by the following
-          example.</p><a id="parameter-vocabulary-profile-example-1" name=
-          "parameter-vocabulary-profile-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – ttp:profile
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:profile use="dfxp-presentation"&gt;
-  &lt;ttp:features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    &lt;ttp:feature&gt;#text-outline&lt;/ttp:feature&gt;
-  &lt;/ttp:features&gt;
-&lt;/ttp:profile&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the DFXP presentation profile is used as the
-            baseline profile. This baseline profile is then supersetted (thus creating an
-            additive derived profile) by requiring support for <code>#text-outline</code>
-            feature.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-features" name=
-          "parameter-vocabulary-features"></a>6.1.2 ttp:features</h4>
-
-          <p>The <code>ttp:features</code> element is a container element used to group
-          infomation about feature support requirements.</p>
-
-          <p>The <code>ttp:features</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed by zero or
-          more <code>ttp:feature</code> elements.</p><a id=
-          "elt-syntax-parameter-features" name="elt-syntax-parameter-features"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:features
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:features
-  xml:base = string : <em>TT Feature Namespace</em>
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#parameter-vocabulary-feature">ttp:feature</a>*
-&lt;/ttp:features&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If specified, the <code>xml:base</code> attribute must (1) adhere to the
-          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
-          2]</a>, §3.2.17, (2) express an absolute URI that adheres to <a href=
-          "#xmlbase">[XML Base]</a> and, (3) express a feature namespace as defined by
-          <a href="#feature-designations"><b>D.1 Feature Designations</b></a>. If not
-          specified, the <code>xml:base</code> attribute's default value applies, which
-          is the TT Feature Namespace.</p>
-
-          <p>The <code>xml:base</code> attribute is used to permit the abbreviation of
-          feature designation URIs expressed by child <code>ttp:feature</code>
-          elements.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-feature" name=
-          "parameter-vocabulary-feature"></a>6.1.3 ttp:feature</h4>
-
-          <p>The <code>ttp:feature</code> element is used to specify infomation about
-          support requirements for a particular feature.</p>
-
-          <p>The children of the <code>ttp:feature</code> element must express a
-          non-empty sequence of character information items that adheres to the
-          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
-          2]</a>, §3.2.17.</p><a id="elt-syntax-parameter-feature" name=
-          "elt-syntax-parameter-feature"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:feature
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:feature
-  value = (optional|required|use) : required
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttp:feature&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the URI expressed by the content of the <code>ttp:feature</code> element
-          is a relative URI, then, when combined with the feature namespace value
-          expressed by the <code>xml:base</code> attribute of the nearest ancestor
-          <code>ttp:features</code> element, it must express an absolute URI. In either
-          case (original absolute URI or resulting absolutized URI), the URI expressed by
-          the <code>ttp:feature</code> element must further adhere to the syntax of a
-          feature designation as defined by <a href="#feature-designations"><b>D.1
-          Feature Designations</b></a>.</p>
-
-          <p>If the URI expressed by the content of the <code>ttp:feature</code> element
-          is a relative URI, then an <code>xml:base</code> attribute should be specified
-          on the nearest ancestor <code>ttp:features</code> element.</p>
-
-          <p>The <code>value</code> attribute specifies whether a conforming TTML
-          processor must or may implement the designated feature in order to process the
-          document. If the value of the <code>value</code> attribute is
-          <code>optional</code>, then the processor need not implement or otherwise
-          support the feature in order to process the document; if the value is
-          <code>required</code>, then the processor must implement or otherwise support
-          the feature, irrespective of whether the feature is enabled or disabled, in
-          order to process the document; if the value is <code>use</code>, then the
-          processor must both (1) implement or otherwise support the feature and (2) have
-          enabled (activated) use of the feature.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The default value of the <code>value</code> attribute is
-            <code>required</code>, as indicated in the above element information item
-            definition. Therefore, if a <code>value</code> attribute is not specified on
-            a <code>ttp:feature</code> element, it is equivalent to specifying that
-            support for the feature is required.</p>
-          </div>
-
-          <p>If the value of the <code>value</code> attribute is <code>required</code> or
-          <code>use</code> and the TTML processor implementation does not support the
-          feature, or if the <code>value</code> attribute is <code>use</code> and the
-          TTML processor implementation supports but has disabled that feature, then it
-          must not further process the document without the presence of an explicit
-          override from an end-user or some implementation specific parameter traceable
-          to an end-user or to a user or system configuration setting. If a TTML
-          processor aborts processing of a <em>Document Instance</em> due to the
-          specification of a required, but unsupported feature by this element, then some
-          end-user notification should be given unless the end-user or system has
-          disabled such a notification, or if the processor does not permit or entail the
-          intervention of an end-user.</p>
-
-          <p>If the value of the <code>value</code> attribute is <code>optional</code>,
-          and if the TTML processor implementation does not support the feature, then it
-          may further process the document even in the case that some use of the feature
-          is present in the document. In the case of actual use of a feature designated
-          as optional, the default semantics associated with that feature apply; that is,
-          the processor may behave as if the feature were not actually used or referenced
-          by the document. Notwithstanding the above, the syntactic presence or reference
-          to an optional feature by a document must not be considered to be a violation
-          of document validity or a barrier to further processing if the syntactic
-          expression is well-formed and valid.</p>
-
-          <p>If some defined (i.e., standardized) or otherwise well known feature is not
-          specified by a <code>ttp:feature</code> element in a given profile, then it
-          must be interpreted as if the feature were specified with the
-          <code>value</code> attribute equal to <code>optional</code>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In particular, if some feature is not present in a profile definition,
-            then it is not to be interpreted as meaning the use of that feature (in a
-            <em>Document Instance</em>) is disallowed or otherwise prohibited.</p>
-          </div>
-
-          <p>The <code>ttp:feature</code> element is illustrated by the following
-          example.</p><a id="parameter-vocabulary-feature-example-1" name=
-          "parameter-vocabulary-feature-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – ttp:feature
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-presentation"&gt;
-  &lt;ttp:features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    <span class=
-"strong">&lt;ttp:feature value="required"&gt;#fontStyle-italic&lt;/ttp:feature&gt;</span>
-    <span class=
-"strong">&lt;ttp:feature value="required"&gt;#textDecoration-under&lt;/ttp:feature&gt;</span>
-  &lt;/ttp:features&gt;
-&lt;/ttp:profile&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the DFXP presentation profile is used as the
-            baseline profile. This baseline profile is then modified by two
-            <code>ttp:feature</code> elements in order to superset the baseline profile
-            (since neither <code>#fontStyle-italic</code> nor
-            <code>#textDecoration-under</code> are required by the DFXP presentation
-            profile).</p>
-
-            <p>The effect of this example is to express authorial intentions that italic
-            font style and text underlining must be supported.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-extensions" name=
-          "parameter-vocabulary-extensions"></a>6.1.4 ttp:extensions</h4>
-
-          <p>The <code>ttp:extensions</code> element is a container element used to group
-          infomation about extension support requirements.</p>
-
-          <p>The <code>ttp:extensions</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed by zero or
-          more <code>ttp:extension</code> elements.</p><a id=
-          "elt-syntax-parameter-extensions" name="elt-syntax-parameter-extensions"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:extensions
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:extensions
-  xml:base = string : <em>TT Extension Namespace</em>
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#parameter-vocabulary-extension">ttp:extension</a>*
-&lt;/ttp:extensions&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If specified, the <code>xml:base</code> attribute must (1) adhere to the
-          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
-          2]</a>, §3.2.17, (2) express an absolute URI that adheres to <a href=
-          "#xmlbase">[XML Base]</a> and, (3) express an extension namespace as defined by
-          <a href="#extension-designations"><b>E.1 Extension Designations</b></a>. If not
-          specified, the <code>xml:base</code> attribute's default value applies, which
-          is the TT Extension Namespace.</p>
-
-          <p>The <code>xml:base</code> attribute is used to permit the abbreviation of
-          feature designation URIs expressed by child <code>ttp:extension</code>
-          elements.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-extension" name=
-          "parameter-vocabulary-extension"></a>6.1.5 ttp:extension</h4>
-
-          <p>The <code>ttp:extension</code> element is used to specify infomation about
-          support requirements for a particular extension.</p>
-
-          <p>The children of the <code>ttp:extension</code> element must express a
-          non-empty sequence of character information items that adheres to the
-          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
-          2]</a>, §3.2.17.</p><a id="elt-syntax-parameter-extension" name=
-          "elt-syntax-parameter-extension"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:extension
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:extension
-  value = (optional|required|use) : required
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttp:extension&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the URI expressed by the content of the <code>ttp:extension</code>
-          element is a relative URI, then, when combined with the extension namespace
-          value expressed by the <code>xml:base</code> attribute of the nearest ancestor
-          <code>ttp:extensions</code> element, it must express an absolute URI. In either
-          case (original absolute URI or resulting absolutized URI), the URI expressed by
-          the <code>ttp:extension</code> element must further adhere to the syntax of an
-          extension designation as defined by <a href="#extension-designations"><b>E.1
-          Extension Designations</b></a>.</p>
-
-          <p>If the URI expressed by the content of the <code>ttp:feature</code> element
-          is a relative URI, then an <code>xml:base</code> attribute should be specified
-          on the nearest ancestor <code>ttp:extensions</code> element.</p>
-
-          <p>The <code>value</code> attribute specifies whether a conforming TTML
-          processor must or may implement the designated extension in order to process
-          the document. If the value of the <code>value</code> attribute is
-          <code>optional</code>, then the processor need not implement or otherwise
-          support the extension in order to process the document; if the value is
-          <code>required</code>, then the processor must implement or otherwise support
-          the extension in order to process the document; if the value is
-          <code>use</code>, then the processor must both (1) implement or otherwise
-          support the extension and (2) enable (activate) use of the extension.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The default value of the <code>value</code> attribute is
-            <code>required</code>, as indicated in the above element information item
-            definition. Therefore, if a <code>value</code> attribute is not specified on
-            a <code>ttp:extension</code> element, it is equivalent to specifying that
-            support for the extension is required.</p>
-          </div>
-
-          <p>If the value of the <code>value</code> attribute is <code>required</code> or
-          <code>use</code> and the TTML processor implementation does not support the
-          extension, or if the <code>value</code> attribute is <code>use</code> and the
-          TTML processor implementation supports but has disabled that extension, then it
-          must not further process the document without the presence of an explicit
-          override from an end-user or some implementation specific parameter traceable
-          to an end-user or to a user or system configuration setting. If a TTML
-          processor aborts processing of a <em>Document Instance</em> due to the
-          specification of a required, but unsupported extension by this element, then
-          some end-user notification should be given unless the end-user or system has
-          disabled such a notification, or if the processor does not permit or entail the
-          intervention of an end-user.</p>
-
-          <p>If the value of the <code>value</code> attribute is <code>optional</code>,
-          and if the TTML processor implementation does not support the extension, then
-          it may further process the document even in the case that some use of the
-          extension is present in the document. In the case of actual use of an extension
-          designated as optional, the default semantics associated with that extension
-          apply; that is, the processor may behave as if the extension were not actually
-          used or referenced by the document. Notwithstanding the above, the syntactic
-          presence or reference to an optional extension by a document must not be
-          considered to be a violation of document validity or a barrier to further
-          processing if the syntactic expression is well-formed and valid.</p>
-
-          <p>If some well known extension is not specified by a
-          <code>ttp:extension</code> element in a given profile, then it must be
-          interpreted as if the extension were specified with the <code>value</code>
-          attribute equal to <code>optional</code>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In particular, if some extension is not present in a profile definition,
-            then it is not to be interpreted as meaning the use of that extension (in a
-            <em>Document Instance</em>) is disallowed or otherwise prohibited.</p>
-          </div>
-
-          <p>The <code>ttp:extension</code> element is illustrated by the following
-          example.</p><a id="parameter-vocabulary-extension-example-1" name=
-          "parameter-vocabulary-extension-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – ttp:extension
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-transformation"&gt;
-  &lt;ttp:extensions xml:base="http://example.org/ttaf1/extension/"&gt;
-    <span class=
-"strong">&lt;ttp:extension value="use"&gt;#prefilter-by-language&lt;/ttp:extension&gt;</span>
-  &lt;/ttp:extensions&gt;
-&lt;/ttp:profile&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the DFXP transformation profile is used as the
-            baseline profile. This baseline profile is then supersetted by specifying
-            that support and use is required for a private extension defined in a third
-            party namespace.</p>
-
-            <p>The effect of this example is to express authorial intentions that a
-            recipient processor must support the DFXP transformation profile and must
-            also support and enable an extension defined by a third party.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="parameter-attribute-vocabulary" name=
-        "parameter-attribute-vocabulary"></a>6.2 Parameter Attribute Vocabulary</h3>
-
-        <p>The following attributes are defined in the TT Parameter Namespace.</p>
-
-        <ul>
-          <li>
-            <p><a href="#parameter-attribute-cellResolution"><b>6.2.1
-            ttp:cellResolution</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-clockMode"><b>6.2.2
-            ttp:clockMode</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-dropMode"><b>6.2.3 ttp:dropMode</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-frameRate"><b>6.2.4
-            ttp:frameRate</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-frameRateMultiplier"><b>6.2.5
-            ttp:frameRateMultiplier</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-markerMode"><b>6.2.6
-            ttp:markerMode</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-pixelAspectRatio"><b>6.2.7
-            ttp:pixelAspectRatio</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-profile"><b>6.2.8 ttp:profile</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-subFrameRate"><b>6.2.9
-            ttp:subFrameRate</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-tickRate"><b>6.2.10 ttp:tickRate</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a></p>
-          </li>
-        </ul>
-
-        <p>Unless explicitly stated otherwise, linear white-space (LWSP) must appear
-        between adjacent non-terminal components of a TT Parameter value unless some
-        other delimiter is permitted and used.</p>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-cellResolution" name=
-          "parameter-attribute-cellResolution"></a>6.2.1 ttp:cellResolution</h4>
-
-          <p>The <code>ttp:cellResolution</code> attribute may be used by an author to
-          express the number of horizontal and vertical cells into which the root
-          container region area is divided for the purpose of expressing presentation
-          semantics in terms of a uniform grid.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-cellResolution-syntax" name=
-          "parameter-attribute-cellResolution-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:cellResolution
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:cellResolution
-  : columns rows                            // <em>columns</em> != 0; <em>rows</em> != 0
-
-columns | rows
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If not specified, the number of columns and rows must be considered to be 32
-          and 15, respectively. If specified, then columns or rows must not be zero
-          (0).</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The choice of values 32 and 15 are based on this being the maximum number
-            of columns and rows defined by <a href="#cea608c">[CEA-608-C]</a>.</p>
-          </div>
-
-          <p>A <code>ttp:cellResolution</code> attribute is considered to be significant
-          only when specified on the <code>tt</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The use of a uniform grid is employed only for the purpose of measuring
-            lengths and expressing coordinates. In particular, it is not assumed that the
-            presentation of text or the alignment of individual glyph areas is
-            coordinated with this grid. Such alignment is possible, but requires the use
-            of a monospaced font and a font size whose EM square exactly matches the cell
-            size.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Except where indicated otherwise, when a <a href=
-            "#style-value-length">&lt;length&gt;</a> expressed in cells expresses a
-            dimension parallel to the inline or block progression dimension, the cell's
-            dimension in the inline or block progression dimension applies, respectively.
-            For example, if padding (on all four edges) is specified as 0.1c, the cell
-            resolution is 20 by 10, and the root container extent is 640 by 480, then,
-            assuming top to bottom, left to right writing mode, the start and end padding
-            will be 640 / 20 * 0.1 pixels and the before and after padding will be 480 /
-            10 * 0.1 pixels.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-clockMode" name=
-          "parameter-attribute-clockMode"></a>6.2.2 ttp:clockMode</h4>
-
-          <p>The <code>ttp:clockMode</code> attribute is used to specify the
-          interpretation of time expressions as real-time time coordinates when operating
-          with time base of <code>clock</code> as defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#timing-time-value-expressions"><b>10.3 Time Value
-            Expressions</b></a> for the specification of time expression syntax and
-            semantics.</p>
-          </div>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-clockMode-syntax" name=
-          "parameter-attribute-clockMode-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:clockMode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:clockMode
-  : "local"
-  | "gps"
-  | "utc"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the time base, defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is designated
-          as <code>clock</code>, then this parameter applies as follows: if the
-          parameter's value is <code>local</code>, then time expressions are interpreted
-          as local wall-clock time coordinates; if <code>utc</code>, then time
-          expressions are interpreted as UTC time coordinates <a href="#utc">[UTC]</a>;
-          if <code>gps</code>, then time expressions are interpreted as GPS time
-          coordinates <a href="#gps">[GPS]</a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The primary difference between GPS time and UTC time is that GPS time is
-            not adjusted for leap seconds, while UTC time is adjusted as follows: UTC =
-            TAI (<em>Temp Atomique International</em>) + <em>leap seconds accumulated
-            since 1972</em>. TAI is maintained by the <em>Bureau International des Poids
-            et Mesures</em> (BIPM) in Sevres, France. The GPS system time is steered to a
-            Master Clock (MC) at the US Naval Observatory which is kept within a close
-            but unspecified tolerance of TAI.</p>
-          </div>
-
-          <p>If not specified, the value of this parameter must be considered to be
-          <code>utc</code>.</p>
-
-          <p>A <code>ttp:clockMode</code> attribute is considered to be significant only
-          when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-dropMode" name=
-          "parameter-attribute-dropMode"></a>6.2.3 ttp:dropMode</h4>
-
-          <p>The <code>ttp:dropMode</code> attribute is used to specify constraints on
-          the interpretation and use of frame counts that correspond with <a href=
-          "#smpte12m">[SMPTE 12M]</a> time coordinates when operating with time base of
-          <code>smpte</code> as defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-dropMode-syntax" name=
-          "parameter-attribute-dropMode-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:dropMode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:dropMode
-  : "dropNTSC"
-  | "dropPAL"
-  | "nonDrop"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the time base, defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is designated
-          as <code>smpte</code>, then this parameter applies as follows: if the
-          parameter's value is <code>nonDrop</code>, then, within any given second of a
-          time expression, frames count from 0 to <em>N−1</em>, where <em>N</em> is the
-          value specified by the <code>ttp:frameRate</code> parameter, but while ignoring
-          any value specified by the <code>ttp:frameRateMultiplier</code> parameter.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When operating in <code>nonDrop</code> mode, a second of a time expression
-            may or may not be equal to a second of real time during normal (1x speed)
-            forward playback. If the <code>ttp:frameRateMultiplier</code> parameter is
-            specified and is not equal to 1:1, then a second of a time expression will
-            either be shorter or longer than a second of elapsed play in real time.</p>
-          </div>
-
-          <p>If this parameter's value is <code>dropNTSC</code>, then, within any given
-          second of a time expression except the second <code>00</code>, frames count
-          from 0 to <em>N−1</em>, where <em>N</em> is the value specified by the
-          <code>ttp:frameRate</code> parameter, but while ignoring any value specified by
-          the <code>ttp:frameRateMultiplier</code> parameter. If the second of a time
-          expression is <code>00</code> and the minute of the time expression is not
-          <code>00</code>, <code>10</code>, <code>20</code>, <code>30</code>,
-          <code>40</code>, or <code>50</code>, then frame codes <code>00</code> and
-          <code>01</code> are dropped during that second; otherwise, these frame codes
-          are not dropped.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>For example, when operating in <code>dropNTSC</code> mode with
-            <code>ttp:frameRate</code> of <code>30</code>, a discontinuity in frame count
-            occurs between consecutive frames as shown in the following sequence of time
-            expressions: <code>01:08:59:28</code>, <code>01:08:59:29</code>,
-            <code>01:09:00:02</code>, <code>01:09:00:03</code>.</p>
-          </div>
-
-          <p>If this parameter's value is <code>dropPAL</code>, then, within any given
-          second of a time expression except the second <code>00</code>, frames count
-          from 0 to <em>N−1</em>, where <em>N</em> is the value specified by the
-          <code>ttp:frameRate</code> parameter, but while ignoring any value specified by
-          the <code>ttp:frameRateMultiplier</code> parameter. If the second of a time
-          expression is <code>00</code> and the minute of the time expression is even but
-          not <code>00</code>, <code>20</code>, or <code>40</code>, then frame codes
-          <code>00</code> through <code>03</code> are dropped during that second;
-          otherwise, these frame codes are not dropped.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>For example, when operating in <code>dropPAL</code> mode with
-            <code>ttp:frameRate</code> of <code>30</code>, a discontinuity in frame count
-            occurs between consecutive frames as shown in the following sequence of time
-            expressions: <code>01:09:59:28</code>, <code>01:09:59:29</code>,
-            <code>01:10:00:04</code>, <code>01:10:00:05</code>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The <code>dropPAL</code> mode is also known as the <em>M/PAL</em> or
-            <em>PAL (M)</em> drop-frame code, which uses PAL modulation with the NTSC
-            frame rate of ~29.97 frames/second. The M/PAL system is used primarily in
-            Brazil.</p>
-          </div>
-
-          <p>If not specified, then <code>nonDrop</code> must be assumed to apply.</p>
-
-          <p>A <code>ttp:dropMode</code> attribute is considered to be significant only
-          when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-frameRate" name=
-          "parameter-attribute-frameRate"></a>6.2.4 ttp:frameRate</h4>
-
-          <p>The <code>ttp:frameRate</code> attribute is used to specify the frame rate
-          of a related media object or the intrinsic frame rate of a <em>Document
-          Instance</em> in case it is intended to function as an independent media
-          object.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-frameRate-syntax" name=
-          "parameter-attribute-frameRate-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:frameRate
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:frameRate
-  : <a href=
-"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The frame rate that applies to a <em>Document Instance</em> is used to
-          interpret time expressions that are expressed in <em>frames</em> as defined by
-          <a href="#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>If the <code>media</code> time base applies and the effective frame rate is
-          integral, then a frame is interpreted as a division of a second of media time,
-          such that if the frame rate is specified as <em>F</em>, then a second of media
-          time is divided into <em>F</em> intervals of equal duration, where each
-          interval is labeled as frame <em>f</em>, with <em>f</em> ∈
-          [0…<em>F−1</em>].</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
-            Base</b></a> for further details on the interpretation of time expressions
-            for the <code>media</code> time base.</p>
-          </div>
-
-          <p>If not specified, the frame rate must be considered to be equal to some
-          application defined frame rate, or if no application defined frame rate
-          applies, then thirty (30) frames per second. If specified, then the frame rate
-          must be greater than zero (0).</p>
-
-          <p>A <code>ttp:frameRate</code> attribute is considered to be significant only
-          when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-frameRateMultiplier" name=
-          "parameter-attribute-frameRateMultiplier"></a>6.2.5
-          ttp:frameRateMultiplier</h4>
-
-          <p>The <code>ttp:frameRateMultiplier</code> attribute is used to specify a
-          multiplier to be applied to the frame rate specified by a
-          <code>ttp:frameRate</code> attribute in order to compute the effective frame
-          rate.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-frameRateMultiplier-syntax" name=
-          "parameter-attribute-frameRateMultiplier-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:frameRateMultiplier
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:frameRateMultiplier
-  : numerator denominator                   // <em>numerator</em> != 0; <em>denominator</em> != 0
-
-numerator | denominator
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>A frame rate multiplier is used when the desired frame rate cannot be
-          expressed as an integral number of frames per second.</p>
-
-          <p>If not specified, the frame rate multiplier must be considered to be equal
-          to one (1:1). Both numerator and denominator must be non-zero.</p>
-
-          <p>A <code>ttp:frameRateMultiplier</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The frame rate multiplier used for synchronizing with NTSC <a href=
-            "#smpte170m">[SMPTE 170M]</a> formatted video objects at 30 frames per second
-            is nominally 1000:1001. The nominal frame rate of NTSC video is defined as
-            the chrominance sub-carrier frequency of 3,579,545.45…Hz (= 5.0MHz × 63/88)
-            times the ratio 2/455 divided by the number of horizontal lines per frame of
-            525, which yields a frame rate of 29.970029970029… (= 30 × 1000/1001) frames
-            per second. Other frame rate multipliers apply to different regions of usage
-            and video format standards.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Except in the case of PAL/M, the frame rate multiplier used for
-            synchronizing with PAL formatted video objects at 25 frames per second is
-            nominally 1:1.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-markerMode" name=
-          "parameter-attribute-markerMode"></a>6.2.6 ttp:markerMode</h4>
-
-          <p>The <code>ttp:markerMode</code> attribute is used to specify constraints on
-          the interpretation and use of time expressions that correspond with <a href=
-          "#smpte12m">[SMPTE 12M]</a> time coordinates when operating with time base of
-          <code>smpte</code> as defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-markerMode-syntax" name=
-          "parameter-attribute-markerMode-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:markerMode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:markerMode
-  : "continuous"
-  | "discontinuous"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the time base, defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is designated
-          as <code>smpte</code>, then this parameter applies as follows: if the
-          parameter's value is <code>continuous</code>, then <a href="#smpte12m">[SMPTE
-          12M]</a> time coordinates may be assumed to be linear and either monotonically
-          increasing or decreasing; however, if <code>discontinuous</code>, then any
-          assumption must not be made regarding linearity or monotonicity of time
-          coordinates.</p>
-
-          <p>If not specified, the value of this parameter must be considered to be
-          <code>discontinuous</code>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The default value for this parameter was originally specified (in <a href=
-            "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">TTML 1.0 First
-            Edition</a>) as <code>continuous</code>; however, further evaluation of the
-            state of the industry indicates this choice was incorrect, and that the most
-            common default is <code>discontinuous</code>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Due to lack of industry consensus on the utility and interpretation of the
-            <code>continuous</code> marker mode, authors are advised to avoid its use.
-            Furthermore, the <code>ttp:markerMode</code> is being considered for
-            deprecation in the next revision of this specification.</p>
-          </div>
-
-          <p>A <code>ttp:markerMode</code> attribute is considered to be significant only
-          when specified on the <code>tt</code> element.</p>
-
-          <p>If a value of <code>continuous</code> applies, then time expressions may be
-          converted to real time coordinates by taking into account the computed frame
-          rate and drop mode as expressed by the <code>ttp:dropMode</code> parameter. In
-          this case, the <em>Content Processor</em> must create and maintain a
-          <em>Synthetic SMPTE Document Syncbase</em> within which these time expressions
-          are interpreted as further described in <a href=
-          "#timing-time-intervals"><b>10.4 Time Intervals</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When operating with <code>smpte</code> time base and
-            <code>continuous</code> marker mode, there is an implied time coordinate
-            space, the <em>Synthetic SMPTE Document Syncbase</em>, defined by the
-            monotonically increasing (or decreasing) <a href="#smpte12m">[SMPTE 12M]</a>
-            time coordinates, while taking into account the computed frame rate and drop
-            mode. All time expressions are interpreted in relationship to this time
-            coordinate space based upon <em>SMPTE Time Code</em> synchronization events
-            (markers), where the <em>Document Processing Context</em> emits these events
-            with implied constraints regarding time coordinate monoticity and
-            resynchronization in the presence of dropped frames.</p>
-
-            <p>Use of <code>continuous</code> marker mode with the <code>smpte</code>
-            time base is different from using the <code>media</code> time base because
-            (1) the semantics of the <code>ttp:dropMode</code> parameter apply to the
-            former, but not the latter, and (2) <a href="#smpte12m">[SMPTE 12M]</a> time
-            coordinates may be applied monotonically to media which has been subjected to
-            dilation in time, constriction in time, or reversal in time.</p>
-          </div>
-
-          <p>If a value of <code>discontinuous</code> applies, then time expressions must
-          not be converted to real time coordinates, arithmetical operators (addition,
-          multiplication) are not defined on time expressions, and, consequently, any
-          expression of a duration must be considered to be invalid.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When operating with <code>smpte</code> time base and
-            <code>discontinuous</code> marker mode, there is no effective time coordinate
-            space; rather, all time expressions are interpreted as labeled
-            synchronization events (markers), where the <em>Document Processing
-            Context</em> emits these events, which, when they correspond with time
-            expressions that denote the same label, cause a temporal interval to begin or
-            end accordingly.</p>
-
-            <p>An additional side-effect of operating in <code>discontinuous</code> mode
-            is that time expressions of children have no necessary relationship with time
-            expressions of their temporal container; that is, temporal containers and
-            children of these containers are temporally activated and inactivated
-            independently based on the occurrence of a labeled synchronization (marker)
-            event.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The notion of marker discontinuity as captured by this parameter is
-            logically independent from the method used to count frames as expressed by
-            the <code>ttp:dropMode</code> parameter. In particular, even if the
-            <code>ttp:dropMode</code> parameter is specified as <code>dropNTSC</code> or
-            <code>dropPAL</code>, the marker mode may be specified as
-            <code>continuous</code>, even in the presence of frame count discontinuities
-            induced by the frame counting method, unless there were some other
-            non-linearity or discontinuity in marker labeling, for example, two
-            consecutive frames labeled as <code>10:00:00:00</code> and
-            <code>10:00:01:00</code>.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-pixelAspectRatio" name=
-          "parameter-attribute-pixelAspectRatio"></a>6.2.7 ttp:pixelAspectRatio</h4>
-
-          <p>The <code>ttp:pixelAspectRatio</code> attribute may be used by a content
-          author to express the aspect ratio of non-square pixels in the production of
-          content that makes use of pixel coordinates.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-pixelAspectRatio-syntax" name=
-          "parameter-attribute-pixelAspectRatio-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:pixelAspectRatio
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:pixelAspectRatio
-  : width height                            // <em>width</em> != 0; <em>height</em> != 0
-
-width | height
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If not specified, then square pixels (i.e., aspect ratio 1:1) must be
-          assumed to apply. If specified, then both width and height must be
-          non-zero.</p>
-
-          <p>A <code>ttp:pixelAspectRatio</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>This parameter may be used by a content transcoder or translator in order
-            to convert pixel measurements between different pixel aspect ratios while
-            still maintaining authorial layout intentions.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-profile" name=
-          "parameter-attribute-profile"></a>6.2.8 ttp:profile</h4>
-
-          <p>The <code>ttp:profile</code> attribute may be used by a content author to
-          express the profile of the Timed Text Markup Language (TTML) used in a
-          <em>Document Instance</em>.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
-          2]</a>, §3.2.17, and, further, must specify a profile designator in accordance
-          with <a href="#vocabulary-profiles"><b>5.2 Profiles</b></a>.</p>
-
-          <p>A <code>ttp:profile</code> attribute is considered to be significant only
-          when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-subFrameRate" name=
-          "parameter-attribute-subFrameRate"></a>6.2.9 ttp:subFrameRate</h4>
-
-          <p>The <code>ttp:subFrameRate</code> attribute is used to specify the sub-frame
-          rate of a related media object or the intrinsic sub-frame rate of a
-          <em>Document Instance</em> in case it is intended to function as an independent
-          media object.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-subFrameRate-syntax" name=
-          "parameter-attribute-subFrameRate-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:subFrameRate
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:subFrameRate
-  : <a href=
-"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The sub-frame rate that applies to a <em>Document Instance</em> is used to
-          interpret time expressions that are expressed in <em>sub-frames</em> as defined
-          by <a href="#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>If the <code>media</code> time base applies and the effective frame rate is
-          integral, a sub-frame is interpreted as a division of a frame of media time,
-          such that if the sub-frame rate is specified as <em>S</em>, then a frame of
-          media time is divided into <em>S</em> intervals of equal duration, where each
-          interval is labeled as sub-frame <em>s</em>, with <em>s</em> ∈
-          [0…<em>S−1</em>].</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
-            Base</b></a> for further details on the interpretation of time expressions
-            for the <code>media</code> time base.</p>
-          </div>
-
-          <p>If not specified, the sub-frame rate must be considered to be equal to one
-          (1). If specified, then the sub-frame rate must be greater than zero (0).</p>
-
-          <p>A <code>ttp:subFrameRate</code> attribute is considered to be significant
-          only when specified on the <code>tt</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The sub-frame is sometimes referred to as a <em>field</em> in the context
-            of synchronization with an interlaced video media object.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-tickRate" name=
-          "parameter-attribute-tickRate"></a>6.2.10 ttp:tickRate</h4>
-
-          <p>The <code>ttp:tickRate</code> attribute is used to specify the tick rate of
-          a related media object or the intrinsic tick rate of content of a <em>Document
-          Instance</em> in case it is intended to function as an independent media
-          object.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-tickRate-syntax" name=
-          "parameter-attribute-tickRate-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:tickRate
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:tickRate
-  : <a href=
-"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The tick rate that applies to a <em>Document Instance</em> is used to
-          interpret time expressions that are expressed in <em>ticks</em> by using the
-          <code>t</code> metric as defined by <a href=
-          "#timing-value-timeExpression"><b>10.3.1 &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>If the <code>media</code> time base applies, a tick is interpreted as an
-          integral division of a second of media time, such that if the tick rate is
-          specified as <em>T</em>, then a second of media time is divided into <em>T</em>
-          intervals of equal duration, where each interval is labeled as tick <em>t</em>,
-          with <em>t</em> ∈ [0…<em>T−1</em>].</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
-            Base</b></a> for further details on the interpretation of time expressions
-            for the <code>media</code> time base.</p>
-          </div>
-
-          <p>If not specified, then if a frame rate is specified, the tick rate must be
-          considered to be the effective frame rate multiplied by the sub-frame rate
-          (i.e., ticks are interpreted as sub-frames); or, if no frame rate is specified,
-          the tick rate must be considered to be one (1) tick per second of media time.
-          If specified, then the tick rate must not be zero (0).</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>There is no predefined relationship between ticks and frames or
-            sub-frames. Ticks are an arbitrary division of seconds that permit use of
-            fixed point arithmetic rather than fractional (and potentially inexact)
-            expressions of seconds.</p>
-          </div>
-
-          <p>A <code>ttp:tickRate</code> attribute is considered to be significant only
-          when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-timeBase" name=
-          "parameter-attribute-timeBase"></a>6.2.11 ttp:timeBase</h4>
-
-          <p>The <code>ttp:timeBase</code> attribute is used to specify the temporal
-          coordinate system by means of which time expressions are interpreted in a
-          <em>Document Instance</em>.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax:</p><a id="parameter-attribute-timeBase-syntax" name=
-          "parameter-attribute-timeBase-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:timeBase
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:timeBase
-  : "media"
-  | "smpte"
-  | "clock"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the time base is designated as <code>media</code>, then a time expression
-          denotes a coordinate in some media object's time line, where the media object
-          may be an external media object with which the content of a <em>Document
-          Instance</em> is to be synchronized, or it may be the content of a <em>Document
-          Instance</em> itself in a case where the timed text content is intended to
-          establish an independent time line.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When using a media time base, if that time base is paused or scaled
-            positively or negatively, i.e., the media play rate is not unity, then it is
-            expected that the presentation of associated Timed Text content will be
-            similarly paused, accelerated, or decelerated, respectively. The means for
-            controlling an external media time base is outside the scope of this
-            specification.</p>
-          </div>
-
-          <p>If the time base is designated as <code>smpte</code>, then a time expression
-          denotes a <a href="#smpte12m">[SMPTE 12M]</a> time coordinate with which the
-          content of a <em>Document Instance</em> is to be synchronized. In this case,
-          the value of the <code>ttp:markerMode</code> and <code>ttp:dropMode</code>
-          parameters apply, as defined by <a href=
-          "#parameter-attribute-markerMode"><b>6.2.6 ttp:markerMode</b></a> and <a href=
-          "#parameter-attribute-dropMode"><b>6.2.3 ttp:dropMode</b></a>,
-          respectively.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When the time base is designated as <code>smpte</code>, every time
-            expression denotes a media marker value akin to that defined by <a href=
-            "#smil21">[SMIL 2.1]</a>, § 10.4.1, except instead of using an opaque marker
-            name, a structured <a href="#smpte12m">[SMPTE 12M]</a> time coordinate serves
-            as the marker name.</p>
-          </div>
-
-          <p>If the time base is designated as <code>clock</code>, then the time
-          expression denotes a coordinate in some real-world time line as established by
-          some real-time clock, such as the local wall-clock time or UTC (Coordinated
-          Universal Time) or GPS (Global Positioning System) time lines.</p>
-
-          <p>If not specified, the default time base must be considered to be
-          <code>media</code>.</p>
-
-          <p>A <code>ttp:timeBase</code> attribute is considered to be significant only
-          when specified on the <code>tt</code> element.</p>
-
-          <p>When operating with either <code>media</code> or <code>smpte</code> time
-          bases, a diachronic presentation of a <em>Document Instance</em> may be subject
-          to transformations of the controlling time line, such as temporal reversal,
-          dilation (expansion), or constriction (compression); however, when operating
-          with the <code>clock</code> time base, no transformations are permitted, and
-          diachronic presentation proceeds on a linear, monotonically increasing time
-          line based on the passage of real time.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Due to there being only one time base parameter that applies to a given
-            <em>Document Instance</em>, the interpretation of time expressions is uniform
-            throughout the <em>Document Instance</em>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#time-expression-semantics"><b>N Time Expression
-            Semantics</b></a> for further details on the interpretation of time
-            expressions according to the designated time base.</p>
-          </div>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="content" name="content"></a>7 Content</h2>
-
-      <p>This section specifies the <em>content</em> matter of the core vocabulary
-      catalog.</p>
-
-      <div class="div2">
-        <h3><a id="content-element-vocabulary" name="content-element-vocabulary"></a>7.1
-        Content Element Vocabulary</h3>
-
-        <p>The following elements specify the structure and principal content aspects of
-        a <em>Document Instance</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#document-structure-vocabulary-tt"><b>7.1.1 tt</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#document-structure-vocabulary-head"><b>7.1.2 head</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#document-structure-vocabulary-body"><b>7.1.3 body</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-vocabulary-div"><b>7.1.4 div</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-vocabulary-p"><b>7.1.5 p</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-vocabulary-span"><b>7.1.6 span</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-vocabulary-br"><b>7.1.7 br</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="document-structure-vocabulary-tt" name=
-          "document-structure-vocabulary-tt"></a>7.1.1 tt</h4>
-
-          <p>The <code>tt</code> element serves as the root document element of a
-          <em>Document Instance</em>.</p>
-
-          <p>The <code>tt</code> element accepts as its children zero or one
-          <code>head</code> element followed by zero or one <code>body</code>
-          element.</p><a id="elt-syntax-tt" name="elt-syntax-tt"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: tt
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt
-  <a href="#style-attribute-extent">tts:extent</a> = string
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang"><span class="reqattr">xml:lang</span></a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>) : default
-  {<em>any attribute in TT Parameter namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#document-structure-vocabulary-head">head</a>?, <a href=
-"#document-structure-vocabulary-body">body</a>?
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The <em>Root Temporal Extent</em>, i.e., the time interval over which a
-          <em>Document Instance</em> is active, has an implicit duration that is equal to
-          the implicit duration of the <code>body</code> element of the document, if the
-          <code>body</code> element is present, or zero, if the <code>body</code> element
-          is absent.</p>
-
-          <p>If the <code>tts:extent</code> attribute is specified on the <code>tt</code>
-          element, then it must adhere to <a href="#style-attribute-extent"><b>8.2.7
-          tts:extent</b></a>, in which case it specifies the spatial extent of the
-          <em>Root Container Region</em> in which content regions are located and
-          presented. If no <code>tts:extent</code> attribute is specified, then the
-          spatial extent of the <em>Root Container Region</em> is considered to be
-          determined by the <em>Document Processing Context</em>. The origin of the
-          <em>Root Container Region</em> is determined by the <em>Document Processing
-          Context</em>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>If an author desires to signal the (storage or image) aspect ratio of the
-            <em>Root Container Region</em> without specifying its resolution, then this
-            may be accomplished by using metadata specified in an external namespace,
-            such as <code>m708:aspectRatio</code> as defined in <a href=
-            "#smpte2052">[SMPTE 2052-11]</a>, §5.4.4. This would permit, for example, the
-            interchange of information that reflects the the semantics of <a href=
-            "#cea708d">[CEA-708-D]</a> , §4.5 “Caption Service Metadata”, “ASPECT
-            RATIO”.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the absence of other requirements, and if a <em>Related Media
-            Object</em> exists, then it is recommended that the origin of the <em>Root
-            Container Region</em> be established so that it is centered in the region
-            within which the <em>Related Media Object</em> is presented.</p>
-          </div>
-
-          <p>An <code>xml:lang</code> attribute must be specified on the <code>tt</code>
-          element. If the attribute value is empty, it signifies that there is no default
-          language that applies to the text contained within the <em>Document
-          Instance</em>.</p>
-
-          <p>If no <code>xml:space</code> attribute is specified upon the <code>tt</code>
-          element, then it must be considered as if the attribute had been specified with
-          a value of <code>default</code>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="document-structure-vocabulary-head" name=
-          "document-structure-vocabulary-head"></a>7.1.2 head</h4>
-
-          <p>The <code>head</code> element is a container element used to group header
-          matter, including metadata, profile, styling, and layout information.</p>
-
-          <p>The <code>head</code> element accepts as its children zero or more elements
-          in the <code>Metadata.class</code> element group, followed by zero or more
-          elements in the <code>Parameters.class</code> element group, followed by zero
-          or one <code>styling</code> element, followed by zero or one
-          <code>layout</code> element.</p>
-
-          <p>Any metadata specified by children in the <code>Metadata.class</code>
-          element group applies semantically to the <em>Document Instance</em> as a
-          whole, and not just the <code>head</code> element.</p>
-
-          <p>Any parameters specified by children in the <code>Parameters.class</code>
-          element group applies semantically to the <em>Document Instance</em> as a
-          whole, and not just the <code>head</code> element.</p>
-
-          <p>A <code>styling</code> child element is used to specify style constructs
-          that are referenced from other style constructs, by layout constructs, and by
-          content elements.</p>
-
-          <p>A <code>layout</code> child element is used to specify layout constructs
-          that are referenced by content elements.</p><a id="elt-syntax-head" name=
-          "elt-syntax-head"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: head
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;head
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Parameters.class</a>*, <a href=
-"#styling-vocabulary-styling">styling</a>?, <a href=
-"#layout-vocabulary-layout">layout</a>?
-&lt;/head&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>To the extent that time semantics apply to the content of the
-          <code>head</code> element, the implied time interval of this element is defined
-          to be coterminous with the <em>Root Temporal Extent</em>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="document-structure-vocabulary-body" name=
-          "document-structure-vocabulary-body"></a>7.1.3 body</h4>
-
-          <p>The <code>body</code> element functions as a logical container and a
-          temporal structuring element for a sequence of textual content units
-          represented as logical divisions.</p>
-
-          <p>The <code>body</code> element accepts as its children zero or more elements
-          in the <code>Metadata.class</code> element group, followed by zero or more
-          elements in the <code>Animation.class</code> element group, followed by zero or
-          more <code>div</code> elements.</p>
-
-          <p>Any metadata specified by children in the <code>Metadata.class</code>
-          element group applies semantically to the <code>body</code> element and its
-          descendants as a whole.</p>
-
-          <p>Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>body</code> element.</p><a id="elt-syntax-body" name=
-          "elt-syntax-body"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: body
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;body
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#layout-attribute-region">region</a> = IDREF
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#content-vocabulary-div">div</a>*
-&lt;/body&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An author may specify a temporal interval for a <code>body</code> element
-          using the <code>begin</code>, <code>dur</code>, and <code>end</code>
-          attributes. If the begin point of this interval remains unspecified, then the
-          begin point is interpreted as the beginning point of the <em>Root Temporal
-          Extent</em>. Similarly, if the end point of this interval remains unspecified,
-          then the end point is interpreted as the ending point of the <em>Root Temporal
-          Extent</em>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>A <em>Document Instance</em> referenced from a SMIL presentation is
-            expected to follow the same timing rules as apply to other SMIL media
-            objects.</p>
-          </div>
-
-          <p>If relative begin or end times are specified on the <code>body</code>
-          element, then these times are resolved by reference to the beginning and ending
-          time of the <em>Root Temporal Extent</em>.</p>
-
-          <p>If the <em>Root Temporal Extent</em> is shorter than the computed duration
-          of the <code>body</code> element, then the active time interval of a
-          <code>body</code> element is truncated to the active end point of the <em>Root
-          Temporal Extent</em>.</p>
-
-          <p>An author may associate a set of style properties with a <code>body</code>
-          element by means of either the <code>style</code> attribute or inline style
-          attributes or a combination thereof.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Style properties that are associated with a <code>body</code> element in a
-            <em>Document Instance</em> are available for style inheritance by descendant
-            content elements such as <code>div</code>, <code>p</code>, <code>span</code>
-            and <code>br</code>.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>body</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-vocabulary-div" name="content-vocabulary-div"></a>7.1.4
-          div</h4>
-
-          <p>The <code>div</code> element functions as a logical container and a temporal
-          structuring element for a sequence of textual content units represented as
-          logical sub-divisions or paragraphs.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When rendered on a continuous (non-paged) visual presentation medium, a
-            <code>div</code> element is expected to generate one or more block areas that
-            contain zero or more child block areas generated by the <code>div</code>
-            element's descendant <code>p</code> elements.</p>
-
-            <p>If some block area generated by a <code>div</code> element does not
-            contain any child areas, then it is not expected to be presented.</p>
-          </div>
-
-          <p>The <code>div</code> element accepts as its children zero or more elements
-          in the <code>Metadata.class</code> element group, followed by zero or more
-          elements in the <code>Animation.class</code> element group, followed by zero or
-          more <code>div</code> or <code>p</code> elements.</p>
-
-          <p>Any metadata specified by children in the <code>Metadata.class</code>
-          element group applies semantically to the <code>div</code> element and its
-          descendants as a whole.</p>
-
-          <p>Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>div</code> element.</p><a id="elt-syntax-div" name="elt-syntax-div"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: div
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;div
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#layout-attribute-region">region</a> = IDREF
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#element-vocab-group-table">Block.class</a>*
-&lt;/div&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An author may associate a set of style properties with a <code>div</code>
-          element by means of either the <code>style</code> attribute or inline style
-          attributes or a combination thereof.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Style properties that are associated with a <code>div</code> element in a
-            <em>Document Instance</em> are available for style inheritance by descendant
-            content elements such as <code>div</code>, <code>p</code>, <code>span</code>,
-            and <code>br</code>.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>div</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-vocabulary-p" name="content-vocabulary-p"></a>7.1.5 p</h4>
-
-          <p>A <code>p</code> element represents a logical paragraph, serving as a
-          transition between block level and inline level formatting semantics.</p>
-
-          <p>The <code>p</code> element accepts as its children zero or more elements in
-          the <code>Metadata.class</code> element group, followed by zero or more
-          elements in the <code>Animation.class</code> element group, followed by zero or
-          more intermixed <code>span</code> elements, <code>br</code> elements, or text
-          nodes interpreted as an anonymous spans.</p>
-
-          <p>Any metadata specified by children in the <code>Metadata.class</code>
-          element group applies semantically to the <code>p</code> element and its
-          descendants as a whole.</p>
-
-          <p>Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>p</code> element.</p><a id="elt-syntax-p" name="elt-syntax-p"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: p
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;p
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#layout-attribute-region">region</a> = IDREF
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#element-vocab-group-table">Inline.class</a>*
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An author may associate a set of style properties with a <code>p</code>
-          element by means of either the <code>style</code> attribute or inline style
-          attributes or a combination thereof.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Style properties that are associated with a <code>p</code> element in a
-            <em>Document Instance</em> are available for style inheritance by descendant
-            content elements such as <code>span</code> and <code>br</code>.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a <code>p</code>
-          element, then it must be interpreted as having <em>parallel</em> time
-          containment semantics.</p>
-
-          <p>If a sequence of children of a <code>p</code> element consists solely of
-          character information items, then that sequence must be considered to be an
-          <em>anonymous span</em> for the purpose of applying style properties that apply
-          to <code>span</code> elements.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The presentation semantics of TTML effectively implies that a
-            <code>p</code> element constitutes a line break. In particular, it is
-            associated with a block-stacking constraint both before the first generated
-            line area and after the last generated line area. See <a href=
-            "#semantics-region-layout-step-2"><b>9.3.3 Synchronic Flow Processing</b></a>
-            for further details.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-vocabulary-span" name="content-vocabulary-span"></a>7.1.6
-          span</h4>
-
-          <p>The <code>span</code> element functions as a logical container and a
-          temporal structuring element for a sequence of textual content units having
-          inline level formatting semantics.</p>
-
-          <p>When presented on a visual medium, a <code>span</code> element is intended
-          to generate a sequence of inline areas, each containing one or more glyph
-          areas.</p>
-
-          <p>The <code>span</code> element accepts as its children zero or more elements
-          in the <code>Metadata.class</code> element group, followed by zero or more
-          elements in the <code>Animation.class</code> element group, followed by zero or
-          more intermixed <code>span</code> elements, <code>br</code> elements, or text
-          nodes interpreted as anonymous spans.</p>
-
-          <p>Any metadata specified by children in the <code>Metadata.class</code>
-          element group applies semantically to the <code>span</code> element and its
-          descendants as a whole.</p>
-
-          <p>Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>span</code> element.</p><a id="elt-syntax-span" name=
-          "elt-syntax-span"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: span
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;span
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#layout-attribute-region">region</a> = IDREF
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#element-vocab-group-table">Inline.class</a>*
-&lt;/span&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An author may associate a set of style properties with a <code>span</code>
-          element by means of either the <code>style</code> attribute or inline style
-          attributes or a combination thereof.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Style properties that are associated with a <code>span</code> element in a
-            <em>Document Instance</em> are available for style inheritance by descendant
-            content elements such as <code>span</code> and <code>br</code>.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>span</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-vocabulary-br" name="content-vocabulary-br"></a>7.1.7
-          br</h4>
-
-          <p>The <code>br</code> element denotes an explicit line break.</p><a id=
-          "elt-syntax-br" name="elt-syntax-br"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: br
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;br
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*
-&lt;/br&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>When presented on a visual medium, the presence of a <code>br</code> element
-          must be interpreted as a forced line break.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The visual presentation of a <code>br</code> element is intended to
-            produce the same effect as the control character <code>CR</code> (U+000D)
-            followed by the control code <code>LF</code> (U+000A) when presented on a
-            teletype device. Therefore, two <code>br</code> elements in sequence will
-            produce a different effect than a single <code>br</code> element.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="content-attribute-vocabulary" name=
-        "content-attribute-vocabulary"></a>7.2 Content Attribute Vocabulary</h3>
-
-        <p>This section defines the following common attributes used with many or all
-        element types in the core vocabulary catalog:</p>
-
-        <ul>
-          <li>
-            <p><a href="#content-attribute-id"><b>7.2.1 xml:id</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-attribute-lang"><b>7.2.2 xml:lang</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-attribute-space"><b>7.2.3 xml:space</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="content-attribute-id" name="content-attribute-id"></a>7.2.1
-          xml:id</h4>
-
-          <p>The <code>xml:id</code> attribute is used as defined by <a href=
-          "#xmlid">[XML ID]</a>.</p>
-
-          <p>The <code>xml:id</code> attribute may be used with any element in the core
-          vocabulary catalog.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-attribute-lang" name="content-attribute-lang"></a>7.2.2
-          xml:lang</h4>
-
-          <p>The <code>xml:lang</code> attribute is used as defined by <a href=
-          "#xml10">[XML 1.0]</a>, §2.12, <em>Language Identification</em>.</p>
-
-          <p>The <code>xml:lang</code> attribute must be specified on the <code>tt</code>
-          element and may be specified by an instance of any other element type in the
-          core vocabulary catalog.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-attribute-space" name="content-attribute-space"></a>7.2.3
-          xml:space</h4>
-
-          <p>The <code>xml:space</code> attribute is used as defined by <a href=
-          "#xml10">[XML 1.0]</a>, §2.10, <em>White Space Handling</em>.</p>
-
-          <p>The <code>xml:space</code> attribute may be used with any element in the
-          core vocabulary catalog.</p>
-
-          <p>The semantics of the value <code>default</code> are fixed to mean that when
-          performing presentation processing of a <em>Document Instance</em> as described
-          by <a href="#semantics-region-layout-step-2"><b>9.3.3 Synchronic Flow
-          Processing</b></a>, processing must occur as if the following properties were
-          specified on the affected elements of an equivalent intermediate XSL-FO
-          document:</p>
-
-          <ul>
-            <li>
-              <p><code>suppress-at-line-break="auto"</code></p>
-            </li>
-
-            <li>
-              <p><code>linefeed-treatment="treat-as-space"</code></p>
-            </li>
-
-            <li>
-              <p><code>white-space-collapse="true"</code></p>
-            </li>
-
-            <li>
-              <p><code>white-space-treatment="ignore-if-surrounding-linefeed"</code></p>
-            </li>
-          </ul>
-
-          <p>Similarly, the semantics of the value <code>preserve</code> are fixed to
-          mean that when performing presentation processing, processing must occur as if
-          the following properties were specified on the affected elements of an
-          equivalent intermediate XSL-FO document:</p>
-
-          <ul>
-            <li>
-              <p><code>suppress-at-line-break="retain"</code></p>
-            </li>
-
-            <li>
-              <p><code>linefeed-treatment="preserve"</code></p>
-            </li>
-
-            <li>
-              <p><code>white-space-collapse="false"</code></p>
-            </li>
-
-            <li>
-              <p><code>white-space-treatment="preserve"</code></p>
-            </li>
-          </ul>
-
-          <p>When performing other types of processing intended to eventually result in a
-          visual presentation by means other than those described in this specification,
-          the semantics of space collapsing and preservation as described above should be
-          respected. For other types of processing, the treatment of the
-          <code>xml:space</code> attribute is processor dependent, but should respect the
-          semantics described above if possible.</p>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="styling" name="styling"></a>8 Styling</h2>
-
-      <p>This section specifies the <em>styling</em> matter of the core vocabulary
-      catalog, where styling is to be understood as a separable layer of information that
-      applies to content and that denotes authorial intentions about the presentation of
-      that content.</p>
-
-      <p>Styling attributes are included in TTML to enable authorial intent of
-      presentation to be included within a self-contained document. This section
-      describes the semantics of style presentation in terms of a standard processing
-      model. TTML Processors are not required to present <em>Document Instances</em> in
-      any particular way; but an implementation of this model by a TTML Presentation
-      Processor that provides externally observable results that are consistent with this
-      model is likely to lead to a user experience that closely resembles the experience
-      intended by the documents' authors.</p>
-
-      <p>The semantics of TTML style presentation are described in terms of the model in
-      <a href="#xsl11">[XSL 1.1]</a>. The intended effect of the attributes in this
-      section are to be compatible with the layout model of XSL. Presentation agents may
-      however use any technology to satisfy the authorial intent of the document. In
-      particular since <a href="#css2">[CSS2]</a> is a subset of this model, a CSS
-      processor may be used for the features that the models have in common.</p>
-
-      <p>No normative use of an <code>&lt;?xml-stylesheet ... ?&gt;</code> processing
-      instruction is defined by this specification.</p>
-
-      <div class="div2">
-        <h3><a id="styling-element-vocabulary" name="styling-element-vocabulary"></a>8.1
-        Styling Element Vocabulary</h3>
-
-        <p>The following elements specify the structure and principal styling aspects of
-        a <em>Document Instance</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#styling-vocabulary-styling"><b>8.1.1 styling</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#styling-vocabulary-style"><b>8.1.2 style</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="styling-vocabulary-styling" name=
-          "styling-vocabulary-styling"></a>8.1.1 styling</h4>
-
-          <p>The <code>styling</code> element is a container element used to group
-          styling matter, including metadata that applies to styling matter.</p>
-
-          <p>The <code>styling</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed by zero or
-          more <code>style</code> elements.</p><a id="elt-syntax-styling" name=
-          "elt-syntax-styling"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: styling
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;styling
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#styling-vocabulary-style">style</a>*
-&lt;/styling&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>To the extent that time semantics apply to the content of the
-          <code>styling</code> element, the implied time interval of this element is
-          defined to be coterminous with the <em>Root Temporal Extent</em>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="styling-vocabulary-style" name="styling-vocabulary-style"></a>8.1.2
-          style</h4>
-
-          <p>The <code>style</code> element is used to define a set of style
-          specifications expressed as a specified style set in accordance with <a href=
-          "#semantics-style-resolution-processing-sss"><b>8.4.4.2 Specified Style Set
-          Processing</b></a>.</p>
-
-          <p>The <code>style</code> element accepts as its children zero or more
-          <code>metadata</code> elements.</p><a id="elt-syntax-style" name=
-          "elt-syntax-style"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: style
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;style
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
- <em>Content:</em> EMPTY
-&lt;/style&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a <code>style</code> element appears as a descendant of a
-          <code>region</code> element, then the <code>style</code> element must be
-          ignored for the purpose of computing referential styles as defined by <a href=
-          "#semantics-style-association-referential"><b>8.4.1.2 Referential
-          Styling</b></a> and <a href=
-          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
-          Referential Styling</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>That is to say, when referential styling is used by an element to refer to
-            a <code>style</code> element, then the referenced <code>style</code> element
-            must appear as a descendant of the <code>styling</code> element, and not in
-            any other context.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In this version of this specification, the <code>style</code> element is
-            the only non-metadata element that is not defined to accept
-            <code>Metadata.class</code> children. It is expected that this asymmetry will
-            be corrected in the next revision of this specification.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="styling-attribute-vocabulary" name=
-        "styling-attribute-vocabulary"></a>8.2 Styling Attribute Vocabulary</h3>
-
-        <p>This section defines the <a href="#style-attribute-style"><b>8.2.1
-        style</b></a> attribute used with both style definition elements as well as
-        content elements.</p>
-
-        <p>In addition, this section specifies the following attributes in the TT Style
-        Namespace for use with style definition elements, certain layout elements, and
-        content elements that support inline style specifications:</p>
-
-        <ul>
-          <li>
-            <p><a href="#style-attribute-backgroundColor"><b>8.2.2
-            tts:backgroundColor</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-color"><b>8.2.3 tts:color</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-direction"><b>8.2.4 tts:direction</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-display"><b>8.2.5 tts:display</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-displayAlign"><b>8.2.6
-            tts:displayAlign</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-extent"><b>8.2.7 tts:extent</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-fontFamily"><b>8.2.8 tts:fontFamily</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-fontSize"><b>8.2.9 tts:fontSize</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-fontStyle"><b>8.2.10 tts:fontStyle</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-fontWeight"><b>8.2.11 tts:fontWeight</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-lineHeight"><b>8.2.12 tts:lineHeight</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-opacity"><b>8.2.13 tts:opacity</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-origin"><b>8.2.14 tts:origin</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-overflow"><b>8.2.15 tts:overflow</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-padding"><b>8.2.16 tts:padding</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-showBackground"><b>8.2.17
-            tts:showBackground</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-textAlign"><b>8.2.18 tts:textAlign</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-textDecoration"><b>8.2.19
-            tts:textDecoration</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-textOutline"><b>8.2.20
-            tts:textOutline</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-unicodeBidi"><b>8.2.21
-            tts:unicodeBidi</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-visibility"><b>8.2.22 tts:visibility</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-wrapOption"><b>8.2.23 tts:wrapOption</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-writingMode"><b>8.2.24
-            tts:writingMode</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-zIndex"><b>8.2.25 tts:zIndex</b></a></p>
-          </li>
-        </ul>
-
-        <p>Unless explicitly stated otherwise, linear white-space (LWSP) must appear
-        between adjacent non-terminal components of a value of a TT Style or TT Style
-        Extension Property value unless some other delimiter is permitted and used.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>This specification makes use of <em>lowerCamelCased</em> local names for
-          style attributes that are based upon like-named properties defined by <a href=
-          "#xsl11">[XSL 1.1]</a>. This convention is likewise extended to token values of
-          such properties.</p>
-        </div>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>A style property may be expressed as a specified attribute on any content
-          element type independently of whether the property applies to that element
-          type. This capability permits the expression of an inheritable style property
-          on ancestor elements to which the property does not apply.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-style" name="style-attribute-style"></a>8.2.1
-          style</h4>
-
-          <p>The <code>style</code> attribute is used by referential style association to
-          reference one or more <code>style</code> elements each of which define a
-          specified style set.</p>
-
-          <p>The <code>style</code> attribute may be specified by an instance of the
-          following element types:</p>
-
-          <ul>
-            <li>
-              <p><a href="#document-structure-vocabulary-body"><code>body</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#layout-vocabulary-region"><code>region</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#styling-vocabulary-style"><code>style</code></a></p>
-            </li>
-          </ul>
-
-          <p>If specified, the value of a <code>style</code> attribute must adhere to the
-          <code>IDREFS</code> data type defined by <a href="#xsd-2">[XML Schema Part
-          2]</a>, § 3.3.10.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See the specific element type definitions that permit use of the
-            <code>style</code> attribute, as well as <a href=
-            "#semantics-style-association-referential"><b>8.4.1.2 Referential
-            Styling</b></a> and <a href=
-            "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
-            Referential Styling</b></a>, for further information on its semantics.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-backgroundColor" name=
-          "style-attribute-backgroundColor"></a>8.2.2 tts:backgroundColor</h4>
-
-          <p>The <code>tts:backgroundColor</code> attribute is used to specify a style
-          property that defines the background color of a region or an area generated by
-          content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-backgroundColor" name=
-          "style-property-details-backgroundColor"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-color">&lt;color&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>transparent</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
-                <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
-                "#content-vocabulary-p"><code>p</code></a>, <a href=
-                "#layout-vocabulary-region"><code>region</code></a>, <a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>The <code>tts:backgroundColor</code> style is illustrated by the following
-          example.</p><a id="style-attribute-backgroundColor-example-1" name=
-          "style-attribute-backgroundColor-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Background Color
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="306px 114px"/&gt;
-  &lt;style <span class="strong">tts:backgroundColor="red"</span>/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:padding="3px 40px"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1" <span class=
-"strong">tts:backgroundColor="purple"</span> tts:textAlign="center"&gt;
-  Twinkle, twinkle, little bat!&lt;br/&gt;
-  How &lt;span <span class=
-"strong">tts:backgroundColor="green"</span>&gt;I wonder&lt;/span&gt; where you're at!
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-backgroundColor-example-1-images" name=
-          "style-attribute-backgroundColor-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Background Color
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/backgroundColor.png" alt=
-                "TTML backgroundColor style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-color" name="style-attribute-color"></a>8.2.3
-          tts:color</h4>
-
-          <p>The <code>tts:color</code> attribute is used to specify a style property
-          that defines the foreground color of marks associated with an area generated by
-          content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-color" name=
-          "style-property-details-color"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-color">&lt;color&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td>see prose</td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>The initial value of the <code>tts:color</code> property is considered to be
-          implementation dependent. In the absence of end-user preference information, a
-          conformant presentation processor should use an initial value that is highly
-          contrastive to the background color of the root container region.</p>
-
-          <p>The <code>tts:color</code> style is illustrated by the following
-          example.</p><a id="style-attribute-color-example-1" name=
-          "style-attribute-color-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Color
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style <span class="strong">tts:color="white"</span>/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  In spring, when woods are &lt;span <span class=
-"strong">tts:color="green"</span>&gt;getting green&lt;/span&gt;,&lt;br/&gt;
-  I'll try and tell you what I mean.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-color-example-1-images" name=
-          "style-attribute-color-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Color
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/color.png" alt="TTML color style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-direction" name=
-          "style-attribute-direction"></a>8.2.4 tts:direction</h4>
-
-          <p>The <code>tts:direction</code> attribute is used to specify a style property
-          that defines the directionality of an embedding or override according to the
-          Unicode bidirectional algorithm.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-direction" name=
-          "style-property-details-direction"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>ltr</code> | <code>rtl</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>ltr</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-p"><code>p</code></a>, <a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must ignore the attribute.</p>
-
-          <p>The <code>tts:direction</code> style is illustrated by the following
-          example.</p><a id="style-attribute-direction-example-1" name=
-          "style-attribute-direction-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Direction
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="265px 84px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  Little birds are playing&lt;br/&gt;
-  Bagpipes on the shore,&lt;br/&gt;
-  &lt;span tts:unicodeBidi="bidiOverride" <span class=
-"strong">tts:direction="rtl"</span>&gt;where the tourists snore.&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-direction-example-1-images" name=
-          "style-attribute-direction-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Direction
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/direction.png" alt=
-                "TTML direction style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-display" name="style-attribute-display"></a>8.2.5
-          tts:display</h4>
-
-          <p>The <code>tts:display</code> attribute is used to specify a style property
-          that defines whether an element is a candidate for layout and composition in a
-          region.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-display" name=
-          "style-property-details-display"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>auto</code> | <code>none</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>auto</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
-                <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
-                "#content-vocabulary-p"><code>p</code></a>, <a href=
-                "#layout-vocabulary-region"><code>region</code></a>, <a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>If the value of this attribute is <code>auto</code>, then the affected
-          element is a candidate for region layout and presentation; however, if the
-          value is <code>none</code>, then the affected element and its descendants must
-          be considered ineligible for region layout and presentation.</p>
-
-          <p>The <code>tts:display</code> style is illustrated by the following
-          example.</p><a id="style-attribute-display-example-1" name=
-          "style-attribute-display-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Display
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="369px 119px"
-            tts:backgroundColor="black"
-            tts:color="white"
-            tts:displayAlign="before"
-            tts:textAlign="start"/&gt;
-&lt;/region&gt;
-...
-&lt;div region="r1"&gt;
-  &lt;p dur="5s"&gt;
-    [[[
-    &lt;span <span class="strong">tts:display="none"</span>&gt;
-      &lt;set begin="1s" dur="1s" <span class="strong">tts:display="auto"</span>/&gt;
-      Beautiful soup,
-    &lt;/span&gt;
-    &lt;span <span class="strong">tts:display="none"</span>&gt;
-      &lt;set begin="2s" dur="1s" <span class="strong">tts:display="auto"</span>/&gt;
-      so rich and green,
-    &lt;/span&gt;
-    &lt;span <span class="strong">tts:display="none"</span>&gt;
-      &lt;set begin="3s" dur="1s" <span class="strong">tts:display="auto"</span>/&gt;
-      waiting in a hot tureen!
-    &lt;/span&gt;
-    ]]]
-  &lt;/p&gt;
-&lt;/div&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-display-example-1-images" name=
-          "style-attribute-display-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Display
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/display_0.png" alt=
-                "TTML display style property - [0,1)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/display_1.png" alt=
-                "TTML display style property - [1,2)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/display_2.png" alt=
-                "TTML display style property - [2,3)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/display_3.png" alt=
-                "TTML display style property - [3,4)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/display_4.png" alt=
-                "TTML display style property - [4,5)"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-displayAlign" name=
-          "style-attribute-displayAlign"></a>8.2.6 tts:displayAlign</h4>
-
-          <p>The <code>tts:displayAlign</code> attribute is used to specify a style
-          property that defines the alignment of block areas in the block progression
-          direction.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-displayAlign" name=
-          "style-property-details-displayAlign"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>before</code> | <code>center</code> | <code>after</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>before</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>before</code> were
-          specified.</p>
-
-          <p>The <code>tts:displayAlign</code> style is illustrated by the following
-          example.</p><a id="style-attribute-displayAlign-example-1" name=
-          "style-attribute-displayAlign-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Display Align
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="128px 66px" tts:origin="0px 0px"
-       tts:backgroundColor="black" tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:displayAlign="before"</span>/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:extent="192px 66px" tts:origin="128px 66px"/&gt;
-       tts:backgroundColor="green" tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:displayAlign="after"</span>/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r3"&gt;
-  &lt;style tts:extent="128px 66px"/&gt; style tts:origin="0px 132px"
-       tts:backgroundColor="black" tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:displayAlign="before"</span>/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r4"&gt;
-  &lt;style tts:extent="192px 66px" tts:origin="128px 198px"/&gt;
-       tts:backgroundColor="green" tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:displayAlign="after"</span>/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-...
-&lt;div&gt;
-  &lt;p region="r1"&gt;I sent a message to the fish:&lt;/p&gt;
-  &lt;p region="r2"&gt;I told them&lt;br/&gt; "This is what I wish."&lt;/p&gt;
-  &lt;p region="r3"&gt;The little fishes of the sea,&lt;/p&gt;
-  &lt;p region="r4"&gt;They sent an&lt;br/&gt; answer back to me.&lt;/p&gt;
-&lt;/div&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-displayAlign-example-1-images" name=
-          "style-attribute-displayAlign-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Display Align
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/displayAlign.png" alt=
-                "TTML displayAlign style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-extent" name="style-attribute-extent"></a>8.2.7
-          tts:extent</h4>
-
-          <p>The <code>tts:extent</code> attribute is used to specify the <em>width</em>
-          and <em>height</em> of a region area (which may be the root container
-          region).</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-extent" name=
-          "style-property-details-extent"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>auto</code> | <a href="#style-value-length">&lt;length&gt;</a>
-                <a href="#style-value-length">&lt;length&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>auto</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#document-structure-vocabulary-tt"><code>tt</code></a>,
-                <a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to width and height of root container region</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute consists of two <a href=
-          "#style-value-length">&lt;length&gt;</a> specifications, then they must be
-          interpreted as <em>width</em> and <em>height</em>, where the first
-          specification is the <em>width</em>, and the second specification is the
-          <em>height</em>, where, if either <em>width</em> or <em>height</em> is negative
-          or zero, then extent must be considered zero in both inline and block
-          progression dimensions.</p>
-
-          <p>If the value of this attribute is <code>auto</code>, then the initial value
-          of the style property must be considered to be the same as the root container
-          extent.</p>
-
-          <p>The root container extent is determined either by a <code>tts:extent</code>
-          specified on the <code>tt</code> element, if present, or by the external
-          authoring context, if not present. If <code>tts:extent</code> is specified on
-          the <code>tt</code> element, then the width and height must be expressed in
-          terms of two <a href="#style-value-length">&lt;length&gt;</a> specifications,
-          and these specifications must be expressed as non-percentage, definite lengths
-          using pixel units.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>auto</code> were
-          specified.</p>
-
-          <p>The <code>tts:extent</code> style is illustrated by the following
-          example.</p><a id="style-attribute-extent-example-1" name=
-          "style-attribute-extent-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Extent
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style <span class="strong">tts:extent="330px 122px"</span>/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  'Tis the voice of the Lobster:&lt;br/&gt;
-  I heard him declare,&lt;br/&gt;
-  "You have baked me too brown,&lt;br/&gt;
-  I must sugar my hair."
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-extent-example-1-images" name=
-          "style-attribute-extent-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Extent
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/extent.png" alt="TTML extent style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-fontFamily" name=
-          "style-attribute-fontFamily"></a>8.2.8 tts:fontFamily</h4>
-
-          <p>The <code>tts:fontFamily</code> attribute is used to specify a style
-          property that defines the font family from which glyphs are selected for glyph
-          areas generated by content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-fontFamily" name=
-          "style-property-details-fontFamily"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td>(<a href="#style-value-familyName">&lt;familyName&gt;</a> | <a href=
-                "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a>)
-                (<code>","</code> &nbsp;(<a href=
-                "#style-value-familyName">&lt;familyName&gt;</a> | <a href=
-                "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a>))*</td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>default</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The initial value, <code>default</code>, is a generic font family name,
-            and is further described in <a href="#style-value-genericFamilyName"><b>8.3.6
-            &lt;genericFamilyName&gt;</b></a> below.</p>
-          </div>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>If a specified font family is not available, then a presentation processor
-          must attempt to map the specified font family to an available font family that
-          has similar typographic characteristics, or, in the absence of such a mapping,
-          it must interpret the font family as if the value <code>default</code> were
-          specified.</p>
-
-          <p>The <code>tts:fontFamily</code> style is illustrated by the following
-          example.</p><a id="style-attribute-fontFamily-example-1" name=
-          "style-attribute-fontFamily-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Font Family
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="474px 146px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-  &lt;style <span class="strong">tts:fontFamily="proportionalSansSerif"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;div region="r1"&gt;
-  &lt;p&gt;
-    "The time has come," the Walrus said,&lt;br/&gt;
-    "to talk of many things:
-  &lt;/p&gt;
-  &lt;p tts:textAlign="end" <span class=
-"strong">tts:fontFamily="monospaceSerif"</span>&gt;
-    Of shoes, and ships, and sealing wax,&lt;br/&gt;
-    Of cabbages and kings,
-  &lt;/p&gt;
-  &lt;p&gt;
-    And why the sea is boiling hot,&lt;br/&gt;
-    and whether pigs have wings."
-  &lt;/p&gt;
-&lt;/div&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-fontFamily-example-1-images" name=
-          "style-attribute-fontFamily-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Font Family
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/fontFamily.png" alt=
-                "TTML fontFamily style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-fontSize" name="style-attribute-fontSize"></a>8.2.9
-          tts:fontSize</h4>
-
-          <p>The <code>tts:fontSize</code> attribute is used to specify a style property
-          that defines the font size for glyphs that are selected for glyph areas
-          generated by content flowed into a region, where font size is interpreted as a
-          scaling transform to the font's design EM square.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-fontSize" name=
-          "style-property-details-fontSize"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a>?</td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>1c</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to parent element's font size</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a single <a href="#style-value-length">&lt;length&gt;</a> value is
-          specified, then this length applies equally to horizontal and vertical scaling
-          of a glyph's EM square; if two <a href="#style-value-length">&lt;length&gt;</a>
-          values are specified, then the first expresses the horizontal scaling and the
-          second expresses vertical scaling.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Use of independent horizontal and vertical font sizes is expected to be
-            used with cell based units in order to denote fonts that are two rows in
-            height and one column in width.</p>
-          </div>
-
-          <p>If horizontal and vertical sizes are expressed independently, then the units
-          of the <a href="#style-value-length">&lt;length&gt;</a> values must be the
-          same.</p>
-
-          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used to
-          express font size must be non-negative.</p>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>1c</code> were
-          specified.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The expression <code>1c</code> means one cell, where <code>'c'</code>
-            expresses the <em>cell</em> length unit as defined by <a href=
-            "#style-value-length"><b>8.3.9 &lt;length&gt;</b></a>.</p>
-          </div>
-
-          <p>The <code>tts:fontSize</code> style is illustrated by the following
-          example.</p><a id="style-attribute-fontSize-example-1" name=
-          "style-attribute-fontSize-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Font Size
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="299px 97px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style <span class="strong">tts:fontSize="18px"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  Then fill up the glasses&lt;br/&gt;
-  with treacle and ink,&lt;br/&gt;
-  Or anything else&lt;br/&gt;
-  that is &lt;span <span class=
-"strong">tts:fontSize="24px"</span>&gt;pleasant&lt;/span&gt; to drink.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-fontSize-example-1-images" name=
-          "style-attribute-fontSize-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Font Size
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/fontSize.png" alt=
-                "TTML fontSize style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-fontStyle" name=
-          "style-attribute-fontStyle"></a>8.2.10 tts:fontStyle</h4>
-
-          <p>The <code>tts:fontStyle</code> attribute is used to specify a style property
-          that defines the font style to apply to glyphs that are selected for glyph
-          areas generated by content flowed into a region, where the mapping from font
-          style value to specific font face or style parameterization is not determined
-          by this specification.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-fontStyle" name=
-          "style-property-details-fontStyle"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>normal</code> | <code>italic</code> | <code>oblique</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>normal</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>Use of the value <code>oblique</code> denote a shear transformation (at an
-          unspecified angle) in the inline progression dimension.</p>
-
-          <p>If a specified font style is not available, then a presentation processor
-          must attempt to map the specified font style to an available font style that
-          has similar typographic characteristics, or, in the absence of such a mapping,
-          it must interpret the font style as if the value <code>normal</code> were
-          specified.</p>
-
-          <p>The <code>tts:fontStyle</code> style is illustrated by the following
-          example.</p><a id="style-attribute-fontStyle-example-1" name=
-          "style-attribute-fontStyle-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Font Style
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="331px 84px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  In autumn, when the leaves are brown,&lt;br/&gt;
-  Take pen and ink, and &lt;span <span class=
-"strong">tts:fontStyle="italic"</span>&gt;write it down.&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-fontStyle-example-1-images" name=
-          "style-attribute-fontStyle-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Font Style
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/fontStyle.png" alt=
-                "TTML fontStyle style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-fontWeight" name=
-          "style-attribute-fontWeight"></a>8.2.11 tts:fontWeight</h4>
-
-          <p>The <code>tts:fontWeight</code> attribute is used to specify a style
-          property that defines the font weight to apply to glyphs that are selected for
-          glyph areas generated by content flowed into a region, where the mapping from
-          font weight value to specific font face or weight parameterization is not
-          determined by this specification.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-fontWeight" name=
-          "style-property-details-fontWeight"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>normal</code> | <code>bold</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>normal</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>If a specified font weight is not available, then a presentation processor
-          must attempt to map the specified font weight to an available font weight that
-          has similar typographic characteristics, or, in the absence of such a mapping,
-          it must interpret the font weight as if the value <code>normal</code> were
-          specified.</p>
-
-          <p>The <code>tts:fontWeight</code> style is illustrated by the following
-          example.</p><a id="style-attribute-fontWeight-example-1" name=
-          "style-attribute-fontWeight-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Font Weight
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="376px 95px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  They told me you had been to her,&lt;br/&gt;
-  &lt;span <span class=
-"strong">tts:fontWeight="bold"</span>&gt;and mentioned me to him:&lt;/span&gt;&lt;br/&gt;
-  She gave me a good character&lt;br/&gt;
-  &lt;span <span class=
-"strong">tts:fontWeight="bold"</span>&gt;but said I could not swim.&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-fontWeight-example-1-images" name=
-          "style-attribute-fontWeight-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Font Weight
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/fontWeight.png" alt=
-                "TTML fontWeight style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-lineHeight" name=
-          "style-attribute-lineHeight"></a>8.2.12 tts:lineHeight</h4>
-
-          <p>The <code>tts:lineHeight</code> attribute is used to specify a style
-          property that defines the inter-baseline separation between line areas
-          generated by content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-lineHeight" name=
-          "style-property-details-lineHeight"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>normal</code> | <a href=
-                "#style-value-length">&lt;length&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>normal</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-p"><code>p</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to this element's font size</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute is <code>normal</code>, then the initial
-          value of the style property must be considered to be the same as the largest
-          font size that applies to any descendant element.</p>
-
-          <p>If specified as a <a href="#style-value-length">&lt;length&gt;</a>, then the
-          length must be non-negative.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>normal</code> were
-          specified.</p>
-
-          <p>The <code>tts:lineHeight</code> style is illustrated by the following
-          example.</p><a id="style-attribute-lineHeight-example-1" name=
-          "style-attribute-lineHeight-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Line Height
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="255px 190px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style tts:fontSize="16px"/&gt;
-  &lt;style <span class="strong">tts:lineHeight="32px"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  He thought he saw an elephant,&lt;br/&gt;
-  That practised on a fife:&lt;br/&gt;
-  He looked again, and found it was&lt;br/&gt;
-  A letter from his wife.&lt;br/&gt;
-  "At length I realise," he said,&lt;br/&gt;
-  "The bitterness of Life.
-"&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-lineHeight-example-1-images" name=
-          "style-attribute-lineHeight-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Line Height
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/lineHeight.png" alt=
-                "TTML lineHeight style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-opacity" name="style-attribute-opacity"></a>8.2.13
-          tts:opacity</h4>
-
-          <p>The <code>tts:opacity</code> attribute is used to specify a style property
-          that defines the opacity (or conversely, the transparency) of marks associated
-          with a region.</p>
-
-          <p>When presented onto a visual medium, the opacity of the region is applied
-          uniformly and on a linear scale to all marks produced by content targeted to
-          the region.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-opacity" name=
-          "style-property-details-opacity"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-alpha">&lt;alpha&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>1.0</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An <a href="#style-value-alpha">&lt;alpha&gt;</a> value greater than 1.0
-          must be considered equivalent to an <a href=
-          "#style-value-alpha">&lt;alpha&gt;</a> value of 1.0.</p>
-
-          <p>The <code>tts:opacity</code> style is illustrated by the following
-          example.</p><a id="style-attribute-opacity-example-1" name=
-          "style-attribute-opacity-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Opacity
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1" dur="5s"&gt;
-  &lt;set begin="0s" dur="1s" <span class="strong">tts:opacity="1.00"</span>/&gt;
-  &lt;set begin="1s" dur="1s" <span class="strong">tts:opacity="0.75"</span>/&gt;
-  &lt;set begin="2s" dur="1s" <span class="strong">tts:opacity="0.50"</span>/&gt;
-  &lt;set begin="3s" dur="1s" <span class="strong">tts:opacity="0.25"</span>/&gt;
-  &lt;set begin="4s" dur="1s" <span class="strong">tts:opacity="0.00"</span>/&gt;
-  &lt;style tts:extent="304px 77px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  The sun was shining on the sea
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-opacity-example-1-images" name=
-          "style-attribute-opacity-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Opacity
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/opacity_0.png" alt=
-                "TTML opacity style property - [0,1)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/opacity_1.png" alt=
-                "TTML opacity style property - [1,2)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/opacity_2.png" alt=
-                "TTML opacity style property - [2,3)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/opacity_3.png" alt=
-                "TTML opacity style property - [3,4)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/opacity_4.png" alt=
-                "TTML opacity style property - [4,5)"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-origin" name="style-attribute-origin"></a>8.2.14
-          tts:origin</h4>
-
-          <p>The <code>tts:origin</code> attribute is used to specify the <em>x</em> and
-          <em>y</em> coordinates of the origin of a region area with respect to the
-          origin of the root container extent, if specified, or the external authoring
-          context, if not specified.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-origin" name=
-          "style-property-details-origin"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>auto</code> | <a href="#style-value-length">&lt;length&gt;</a>
-                <a href="#style-value-length">&lt;length&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>auto</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to width and height of root container region</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute consists of two <a href=
-          "#style-value-length">&lt;length&gt;</a> specifications, then they must be
-          interpreted as <em>x</em> and <em>y</em> coordinates, where the first
-          specification is the <em>x</em> coordinate, and the second specification is the
-          <em>y</em> coordinate.</p>
-
-          <p>If the value of this attribute is <code>auto</code>, then the initial value
-          of the style property must be considered to be the same as the root container
-          origin.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>auto</code> were
-          specified.</p>
-
-          <p>The <code>tts:origin</code> style is illustrated by the following
-          example.</p><a id="style-attribute-origin-example-1" name=
-          "style-attribute-origin-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Origin
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style <span class="strong">tts:origin="40px 40px"</span>/&gt;
-  &lt;style tts:extent="308px 92px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  "To dine!" she shrieked in dragon-wrath.&lt;br/&gt;
-  "To swallow wines all foam and froth!&lt;br/&gt;
-   To simper at a table-cloth!"
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-origin-example-1-images" name=
-          "style-attribute-origin-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Origin
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/origin.png" alt="TTML origin style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-overflow" name="style-attribute-overflow"></a>8.2.15
-          tts:overflow</h4>
-
-          <p>The <code>tts:overflow</code> attribute is used to specify a style property
-          that defines whether a region area is clipped or not if the descendant areas of
-          the region overflow its extent.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-overflow" name=
-          "style-property-details-overflow"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>visible</code> | <code>hidden</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>hidden</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute is <code>visible</code>, then content should
-          not be clipped outside of the affected region, and region composition and
-          layout must be performed as if the region's width and height were
-          unconstrained, but with a well-defined origin. If the value is
-          <code>hidden</code>, then content should be clipped outside of the affected
-          region.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Unless a manual line break element <code>br</code> is used by the content
-            author, a paragraph of a given region will generate no more than one line
-            area in that region if the value of the <code>tts:overflow</code> style that
-            applies to the region is <code>visible</code> and if the applicable
-            <code>tts:wrapOption</code> style is <code>noWrap</code>.</p>
-          </div>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>hidden</code> were
-          specified.</p>
-
-          <p>The <code>tts:overflow</code> style is illustrated by the following
-          example.</p><a id="style-attribute-overflow-example-1" name=
-          "style-attribute-overflow-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Overflow
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="232px 40px"/&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="red"/&gt;
-  &lt;style tts:displayAlign="before"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style tts:fontSize="18px"/&gt;
-  &lt;style tts:wrapOption="noWrap"/&gt;
-  &lt;style <span class="strong">tts:overflow="visible"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:extent="232px 40px"/&gt;
-  &lt;style tts:origin="0px 43px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="red"/&gt;
-  &lt;style tts:displayAlign="before"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style tts:fontSize="18px"/&gt;
-  &lt;style tts:wrapOption="noWrap"/&gt;
-  &lt;style <span class="strong">tts:overflow="hidden"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  "But wait a bit," the Oysters cried,&lt;br/&gt;
-  "Before we have our chat;
-&lt;/p&gt;
-&lt;p region="r2"&gt;
-  For some of us are out of breath,&lt;br/&gt;
-  And all of us are fat!"
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-overflow-example-1-images" name=
-          "style-attribute-overflow-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Overflow
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/overflow.png" alt=
-                "TTML overflow style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the <code>tts:noWrap</code> is set to
-            <code>noWrap</code> to prevent automatic line wrapping (breaking); if this
-            were not specified, then overflow would occur in the block progression
-            direction as opposed to the inline progression direction.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-padding" name="style-attribute-padding"></a>8.2.16
-          tts:padding</h4>
-
-          <p>The <code>tts:padding</code> attribute is used to specify padding (or inset)
-          space on all sides of a region area.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-padding" name=
-          "style-property-details-padding"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-length">&lt;length&gt;</a> | <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> | <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> | <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>0px</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to width and height of region</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute consists of one <a href=
-          "#style-value-length">&lt;length&gt;</a> specification, then that length
-          applies to all edges of the affected areas. If the value consists of two
-          <a href="#style-value-length">&lt;length&gt;</a> specifications, then the first
-          applies to the before and after edges, and the second applies to the start and
-          end edges. If three <a href="#style-value-length">&lt;length&gt;</a>
-          specifications are provided, then the first applies to the before edge, the
-          second applies to the start and end edges, and the third applies to the after
-          edge. If four <a href="#style-value-length">&lt;length&gt;</a> specifications
-          are provided, then they apply to before, end, after, and start edges,
-          respectively.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>0px</code> were
-          specified.</p>
-
-          <p>The <code>tts:padding</code> style is illustrated by the following
-          example.</p><a id="style-attribute-padding-example-1" name=
-          "style-attribute-padding-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Padding
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="446px 104px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-  &lt;style <span class="strong">tts:padding="10px 40px"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1" tts:backgroundColor="red"&gt;
-  Just the place for a Snark! I have said it twice:&lt;br/&gt;
-  That alone should encourage the crew.&lt;br/&gt;
-  Just the place for a Snark! I have said it thrice:&lt;br/&gt;
-  What I tell you three times is true.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>When rendering an area to which padding applies, the background color that
-          applies to the area is rendered into the padded portion of the area.</p><a id=
-          "style-attribute-padding-example-1-images" name=
-          "style-attribute-padding-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Padding
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/padding.png" alt="TTML padding style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-showBackground" name=
-          "style-attribute-showBackground"></a>8.2.17 tts:showBackground</h4>
-
-          <p>The <code>tts:showBackground</code> attribute is used to specify constraints
-          on when the background color of a region is intended to be presented.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-showBackground" name=
-          "style-property-details-showBackground"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>always</code> | <code>whenActive</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>always</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute is <code>always</code>, then the background
-          color of a region is always rendered when performing presentation processing on
-          a visual medium; if the value is <code>whenActive</code>, then the background
-          color of a region is rendered only when some content is selected into the
-          region.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>always</code> were
-          specified.</p>
-
-          <p>The <code>tts:showBackground</code> style is illustrated by the following
-          example.</p><a id="style-attribute-showBackground-example-1" name=
-          "style-attribute-showBackground-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Show Background
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:extent="265px 100px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style <span class="strong">tts:showBackground="always"</span>/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="before"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:origin="205px 60px"/&gt;
-  &lt;style tts:extent="290px 100px"/&gt;
-  &lt;style tts:backgroundColor="red"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="before"/&gt;
-  &lt;style tts:textAlign="end"/&gt;
-  &lt;style <span class="strong">tts:showBackground="whenActive"</span>/&gt;
-&lt;/region&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-textAlign" name=
-          "style-attribute-textAlign"></a>8.2.18 tts:textAlign</h4>
-
-          <p>The <code>tts:textAlign</code> attribute is used to specify a style property
-          that defines how inline areas are aligned within a containing block area in the
-          inline progression direction.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-textAlign" name=
-          "style-property-details-textAlign"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>left</code> | <code>center</code> | <code>right</code> |
-                <code>start</code> | <code>end</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>start</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-p"><code>p</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>start</code> were
-          specified.</p>
-
-          <p>The <code>tts:textAlign</code> style is illustrated by the following
-          example.</p><a id="style-attribute-textAlign-example-1" name=
-          "style-attribute-textAlign-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Text Align
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="355px 43px"/&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:textAlign="start"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:extent="355px 43px"/&gt;
-  &lt;style tts:origin="0px 47px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:textAlign="end"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  Beware the Jabberwock, my son!&lt;br/&gt;
-  The jaws that bite, the claws that catch!
-&lt;/p&gt;
-&lt;p region="r2"&gt;
-  Beware the Jubjub bird, and shun&lt;br/&gt;
-  The frumious Bandersnatch!
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-textAlign-example-1-images" name=
-          "style-attribute-textAlign-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Text Align
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/textAlign.png" alt=
-                "TTML textAlign style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-textDecoration" name=
-          "style-attribute-textDecoration"></a>8.2.19 tts:textDecoration</h4>
-
-          <p>The <code>tts:textDecoration</code> attribute is used to specify a style
-          property that defines a text decoration effect to apply to glyph areas or other
-          inline areas that are generated by content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-textDecoration" name=
-          "style-property-details-textDecoration"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>none</code> | [ [ <code>underline</code> |
-                <code>noUnderline</code> ] || [ <code>lineThrough</code> |
-                <code>noLineThrough</code> ] || [ <code>overline</code> |
-                <code>noOverline</code> ] ]</td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>none</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>none</code> were
-          specified.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The syntax used above in defining the value of this property is based on
-            the value component syntax defined in <a href="#css2">[CSS2]</a>, § 1.4.2.1.
-            In essence, one or more of the values separated by <code>||</code> may appear
-            in the property value in any order, such as <code>"noUnderline overline
-            lineThrough"</code>.</p>
-          </div>
-
-          <p>The <code>tts:textDecoration</code> style is illustrated by the following
-          example.</p><a id="style-attribute-textDecoration-example-1" name=
-          "style-attribute-textDecoration-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Text Decoration
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="385px 82px"/&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:padding="5px 2px"/&gt;
-  &lt;style <span class="strong">tts:textDecoration="underline"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  The sea was wet&lt;span <span class=
-"strong">tts:textDecoration="noUnderline"</span>&gt; as &lt;/span&gt;wet
-  &lt;span <span class="strong">tts:textDecoration="noUnderline"</span>&gt;
-    could be,&lt;br/&gt;
-    The sand was dry as dry.&lt;br/&gt;
-    &lt;span <span class=
-"strong">tts:textDecoration="lineThrough"</span>&gt;There weren't any&lt;/span&gt;
-    You &lt;span <span class=
-"strong">tts:textDecoration="lineThrough"</span>&gt;couldn't&lt;/span&gt;
-    could not see a cloud&lt;br/&gt;
-    Because no cloud was in the sky.
-  &lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-textDecoration-example-1-images" name=
-          "style-attribute-textDecoration-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Text Decoration
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/textDecoration.png" alt=
-                "TTML textDecoration style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-textOutline" name=
-          "style-attribute-textOutline"></a>8.2.20 tts:textOutline</h4>
-
-          <p>The <code>tts:textOutline</code> attribute is used to specify a style
-          property that defines a text outline effect to apply to glyphs that are
-          selected for glyph areas generated by content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-textOutline" name=
-          "style-property-details-textOutline"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>none</code> | <a href="#style-value-color">&lt;color&gt;</a>?
-                <a href="#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a>?</td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>none</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to this element's font size</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>The value of this attribute consists of an optional <a href=
-          "#style-value-color">&lt;color&gt;</a> term followed by one or two <a href=
-          "#style-value-length">&lt;length&gt;</a> terms. If a <em>color</em> term is
-          present, then it denotes the outline color; if no <em>color</em> term is
-          present, the computed value of the <code>tts:color</code> applies. The first
-          <em>length</em> term denotes the outline thickness and the second length term,
-          if present, indicates the blur radius.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When a <a href="#style-value-length">&lt;length&gt;</a> expressed in cells
-            is used in a <code>tts:textOutline</code> value, the cell's dimension in the
-            block progression dimension applies. For example, if text outline thickness
-            is specified as 0.1c, the cell resolution is 20 by 10, and the root container
-            extent is 640 by 480, then the outline thickness will be a nominal 480 / 10 *
-            0.1 pixels, i.e., 4.8px, without taking into account rasterization
-            effects.</p>
-          </div>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>none</code> were
-          specified.</p>
-
-          <p>The <code>tts:textOutline</code> style is illustrated by the following
-          example.</p><a id="style-attribute-textOutline-example-1" name=
-          "style-attribute-textOutline-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Text Outline
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:backgroundColor="transparent"/&gt;
-  &lt;style tts:color="yellow"/&gt;
-  &lt;style <span class="strong">tts:textOutline="black 2px 0px"</span>/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style tts:fontSize="24px"/&gt;
-&lt;/region&gt;
-...
-&lt;p&gt;
-  How doth the little crocodile&lt;br/&gt;
-  Improve its shining tail,&lt;br/&gt;
-  And pour the waters of the Nile&lt;br/&gt;
-  On every golden scale!&lt;br/&gt;
-  How cheerfully he seems to grin,&lt;br/&gt;
-  How neatly spreads his claws,&lt;br/&gt;
-  And welcomes little fishes in,&lt;br/&gt;
-  With gently smiling jaws!
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-textOutline-example-1-images" name=
-          "style-attribute-textOutline-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Text Outline
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/textOutline.png" alt=
-                "backgroundColor style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-unicodeBidi" name=
-          "style-attribute-unicodeBidi"></a>8.2.21 tts:unicodeBidi</h4>
-
-          <p>The <code>tts:unicodeBidi</code> attribute is used to specify a style
-          property that defines a directional embedding or override according to the
-          Unicode bidirectional algorithm.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-unicodeBidi" name=
-          "style-property-details-unicodeBidi"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>normal</code> | <code>embed</code> |
-                <code>bidiOverride</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>normal</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-p"><code>p</code></a>, <a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>normal</code> were
-          specified.</p>
-
-          <p>The <code>tts:unicodeBidi</code> style is illustrated by the following
-          example.</p><a id="style-attribute-unicodeBidi-example-1" name=
-          "style-attribute-unicodeBidi-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Unicode Bidirectionality
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="265px 84px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  Little birds are playing&lt;br/&gt;
-  Bagpipes on the shore,&lt;br/&gt;
-  &lt;span <span class=
-"strong">tts:unicodeBidi="bidiOverride"</span> tts:direction="rtl"&gt;where the tourists snore.&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-unicodeBidi-example-1-images" name=
-          "style-attribute-unicodeBidi-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Unicode Bidirectionality
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/unicodeBidi.png" alt=
-                "TTML unicodeBidi style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-visibility" name=
-          "style-attribute-visibility"></a>8.2.22 tts:visibility</h4>
-
-          <p>The <code>tts:visibility</code> attribute is used to specify a style
-          property that defines whether generated areas are visible or not when rendered
-          on a visual presentation medium.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-visibility" name=
-          "style-property-details-visibility"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>visible</code> | <code>hidden</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>visible</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
-                <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
-                "#content-vocabulary-p"><code>p</code></a>, <a href=
-                "#layout-vocabulary-region"><code>region</code></a>, <a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>The <code>tts:visibility</code> style has no affect on content layout or
-          composition, but merely determines whether composed content is visible or
-          not.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>visible</code>
-          were specified.</p>
-
-          <p>The <code>tts:visibility</code> style is illustrated by the following
-          example.</p><a id="style-attribute-visibility-example-1" name=
-          "style-attribute-visibility-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Visibility
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="398px 121px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1" dur="4s"&gt;
-  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
-    &lt;set begin="1s" <span class="strong">tts:visibility="visible"</span>/&gt;
-    Curiouser
-  &lt;/span&gt;
-  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
-    &lt;set begin="2s" <span class="strong">tts:visibility="visible"</span>/&gt;
-    and
-  &lt;/span&gt;
-  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
-    &lt;set begin="3s" <span class="strong">tts:visibility="visible"</span>/&gt;
-    curiouser!
-  &lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-visibility-example-1-images" name=
-          "style-attribute-visibility-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Visibility
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/visibility_0.png" alt=
-                "TTML visibility style property - [0,1)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/visibility_1.png" alt=
-                "TTML visibility style property - [1,2)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/visibility_2.png" alt=
-                "TTML visibility style property - [2,3)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/visibility_3.png" alt=
-                "TTML visibility style property - [3,4)"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-wrapOption" name=
-          "style-attribute-wrapOption"></a>8.2.23 tts:wrapOption</h4>
-
-          <p>The <code>tts:wrapOption</code> attribute is used to specify a style
-          property that defines whether or not automatic line wrapping (breaking) applies
-          within the context of the affected element.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-wrapOption" name=
-          "style-property-details-wrapOption"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>wrap</code> | <code>noWrap</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>wrap</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style property, each
-          character child of a <code>p</code> element is considered to be enclosed in an
-          anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>wrap</code> were
-          specified.</p>
-
-          <p>The <code>tts:wrapOption</code> style is illustrated by the following
-          example.</p><a id="style-attribute-wrapOption-example-1" name=
-          "style-attribute-wrapOption-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Wrap Option
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="192px 117px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:overflow="hidden"/&gt;
-  &lt;style <span class="strong">tts:wrapOption="noWrap"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p&gt;
-  I'll tell thee everything I can:&lt;br/&gt;
-  There's little to relate.&lt;br/&gt;
-  I saw an aged aged man,&lt;br/&gt;
-  A-sitting on a gate.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-wrapOption-example-1-images" name=
-          "style-attribute-wrapOption-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Wrap Option
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/wrapOption.png" alt=
-                "TTML wrapOption style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-writingMode" name=
-          "style-attribute-writingMode"></a>8.2.24 tts:writingMode</h4>
-
-          <p>The <code>tts:writingMode</code> attribute is used to specify a style
-          property that defines the block and inline progression directions to be used
-          for the purpose of stacking block and inline areas within a region area.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-writingMode" name=
-          "style-property-details-writingMode"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>lrtb</code> | <code>rltb</code> | <code>tbrl</code> |
-                <code>tblr</code> | <code>lr</code> | <code>rl</code> |
-                <code>tb</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>lrtb</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>lrtb</code> were
-          specified.</p>
-
-          <p>The <code>tts:writingMode</code> style is illustrated by the following
-          example.</p><a id="style-attribute-writingMode-example-1" name=
-          "style-attribute-writingMode-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Writing Mode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="50px 570px"/&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:padding="10px 3px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:writingMode="tbrl"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:extent="310px 50px"/&gt;
-  &lt;style tts:origin="70px 120px"/&gt;
-  &lt;style tts:padding="10px 3px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:writingMode="rltb"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  I sometimes dig for buttered rolls,&lt;br/&gt;
-  Or set limed twigs for crabs:
-&lt;/p&gt;
-&lt;p region="r2" tts:direction="rtl" tts:unicodeBidi="bidiOverride"&gt;
-  I sometimes search the grassy knolls for the wheels of Hansom-cabs.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-writingMode-example-1-images" name=
-          "style-attribute-writingMode-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Writing Mode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/writingMode.png" alt=
-                "TTML writingMode style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the second paragraph in the above example that targets region
-            <code>r2</code>, the <code>tts:unicodeBidi</code> and
-            <code>tts:direction</code> properties are set to <code>bidiOverride</code>
-            and <code>rtl</code>, respectively, in order to override the normally
-            left-to-right directionality of characters in the Latin script.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-zIndex" name="style-attribute-zIndex"></a>8.2.25
-          tts:zIndex</h4>
-
-          <p>The <code>tts:zIndex</code> attribute is used to specify a style property
-          that defines the front-to-back ordering of region areas in the case that they
-          overlap.</p>
-
-          <p>This attribute may be specified by any element type that permits use of
-          attributes in the TT Style Namespace; however, this attribute applies as a
-          style property only to those element types indicated in the following
-          table.</p><a id="style-property-details-zIndex" name=
-          "style-property-details-zIndex"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>auto</code> | <a href=
-                "#style-value-integer">&lt;integer&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>auto</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If two areas are associated with the same Z-index value, then, if those
-          areas overlap in space, the area(s) generated by lexically subsequent elements
-          must be rendered over area(s) generated by lexically prior elements, where
-          lexical order is defined as the postorder traversal of a <em>Document
-          Instance</em>.</p>
-
-          <p>The semantics of the value <code>auto</code> are those defined by <a href=
-          "#xsl11">[XSL 1.1]</a>, § 7.30.18, where the <code>tt</code> element is
-          considered to establish the root stacking context.</p>
-
-          <p>If a specified value of this attribute is not supported, then a presentation
-          processor must interpret the attribute as if the value <code>auto</code> were
-          specified.</p>
-
-          <p>The <code>tts:zIndex</code> style is illustrated by the following
-          example.</p><a id="style-attribute-zIndex-example-1" name=
-          "style-attribute-zIndex-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Z Index
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:extent="400px 100px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:zIndex="0"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:origin="100px 60px"/&gt;
-  &lt;style tts:extent="400px 100px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="red"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:textAlign="end"/&gt;
-  &lt;style <span class="strong">tts:zIndex="1"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r3"&gt;
-  &lt;style tts:origin="0px 120px"/&gt;
-  &lt;style tts:extent="400px 100px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:zIndex="2"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r4"&gt;
-  &lt;style tts:origin="100px 180px"/&gt;
-  &lt;style tts:extent="400px 100px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="red"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:textAlign="end"/&gt;
-  &lt;style <span class="strong">tts:zIndex="3"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  I passed by his garden, and marked, with one eye,&lt;br/&gt;
-  How the Owl and the Panther were sharing a pie.
-&lt;/p&gt;
-&lt;p region="r2"&gt;
-  The Panther took pie-crust, and gravy, and meat,&lt;br/&gt;
-  While the Owl had the dish as its share of the treat.
-&lt;/p&gt;
-&lt;p region="r3"&gt;
-  When the pie was all finished, the Owl, as a boon,&lt;br/&gt;
-  Was kindly permitted to pocket the spoon:
-&lt;/p&gt;
-&lt;p region="r4"&gt;
-  While the Panther received knife and fork&lt;br/&gt;
-  with a growl,&lt;br/&gt;
-  And concluded the banquet by...
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-zIndex-example-1-images" name=
-          "style-attribute-zIndex-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Z Index
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/zIndex.png" alt="TTML zIndex style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="styling-style-value-expressions" name=
-        "styling-style-value-expressions"></a>8.3 Style Value Expressions</h3>
-
-        <p>Style property values include the use of the following expressions:</p>
-
-        <ul>
-          <li>
-            <p><a href="#style-value-alpha"><b>8.3.1 &lt;alpha&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-color"><b>8.3.2 &lt;color&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-digit"><b>8.3.3 &lt;digit&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-duration"><b>8.3.4 &lt;duration&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-familyName"><b>8.3.5 &lt;familyName&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-genericFamilyName"><b>8.3.6
-            &lt;genericFamilyName&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-hexDigit"><b>8.3.7 &lt;hexDigit&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-integer"><b>8.3.8 &lt;integer&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-length"><b>8.3.9 &lt;length&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-namedColor"><b>8.3.10 &lt;namedColor&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-quotedString"><b>8.3.11
-            &lt;quotedString&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-string"><b>8.3.12 &lt;string&gt;</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="style-value-alpha" name="style-value-alpha"></a>8.3.1
-          &lt;alpha&gt;</h4>
-
-          <p>An &lt;alpha&gt; expression is used to express an opacity value, where 0
-          means fully transparent and 1 means fully opaque.</p><a id=
-          "alpha-style-expression-syntax" name="alpha-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;alpha&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;alpha&gt;
-  : <em>float</em>
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>In the above syntax representation, the syntactic element
-          <em><code>float</code></em> must adhere to the lexical representation defined
-          by <a href="#xsd-2">[XML Schema Part 2]</a>&nbsp;§ 3.2.4.1. If the value
-          represented is less than 0.0, then it must be interpreted as equal to 0.0;
-          similarly, if the value represented is greater than 1.0, then it must be
-          interpreted as 1.0. The value NaN must be interpreted as 0.0.</p>
-
-          <p>If a presentation processor does not support a specific, valid opacity
-          value, then it must interpret it as being equal to the closest supported
-          value.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-color" name="style-value-color"></a>8.3.2
-          &lt;color&gt;</h4>
-
-          <p>A &lt;color&gt; expression is used to specify a named color, exact RGB color
-          triple, or exact RGBA color tuple, where the alpha component, if expressed, is
-          maximum (255) at 100% opacity and minimum (0) at 0% opacity, and where the
-          applicable color space is defined by <a href="#srgb">[SRGB]</a>.</p><a id=
-          "color-style-expression-syntax" name="color-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;color&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;color&gt;
-  : "#" rrggbb
-  | "#" rrggbbaa
-  | "rgb" "(" r-value "," g-value "," b-value ")"
-  | "rgba" "(" r-value "," g-value "," b-value "," a-value ")"
-  | <a href="#style-value-namedColor">&lt;namedColor&gt;</a>
-
-rrggbb
-  :  <a href="#style-value-hexDigit">&lt;hexDigit&gt;</a>{6}
-
-rrggbbaa
-  :  <a href="#style-value-hexDigit">&lt;hexDigit&gt;</a>{8}
-
-r-value | g-value | b-value | a-value
-  : component-value
-
-component-value
-  : non-negative-integer                    // valid range: [0,255]
-
-non-negative-integer
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>When expressing RGB component values, these values are considered to
-          <span class="strong">not</span> be premultiplied by alpha.</p>
-
-          <p>For the purpose of performing presentation processing such that non-opaque
-          or non-transparent alpha or opacity values apply, then the semantics of
-          compositing functions are defined with respect to the use of the <a href=
-          "#srgb">[SRGB]</a> color space for both inputs and outputs of the composition
-          function.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The use of <a href="#srgb">[SRGB]</a> for the stated semantics of
-            composition is not meant to prevent an actual processor from using some other
-            color space either for internal or external purposes. For example, a
-            presentation processor may ultimately convert the SRGB values used here to
-            the YUV color space for rendition on a television device.</p>
-          </div>
-
-          <p>If a presentation processor does not support a specific, valid color or
-          alpha value, then it must interpret it as being equal to the closest supported
-          value.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-digit" name="style-value-digit"></a>8.3.3
-          &lt;digit&gt;</h4>
-
-          <p>A &lt;digit&gt; is used to express integers and other types of numbers or
-          tokens.</p><a id="digit-style-expression-syntax" name=
-          "digit-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;digit&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;digit&gt;
-  : "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-duration" name="style-value-duration"></a>8.3.4
-          &lt;duration&gt;</h4>
-
-          <p>A &lt;duration&gt; expression is used to express a temporal duration
-          value.</p><a id="duration-style-expression-syntax" name=
-          "duration-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;duration&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;duration&gt;
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+ ( "." <a href=
-"#style-value-digit">&lt;digit&gt;</a>+ )? metric
-
-metric
-  : "s"                 // seconds
-  | "ms"                // milliseconds
-  | "f"                 // frames
-  | "t"                 // ticks
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>It is an error to omit the metric component of a duration.</p>
-
-          <p>When operating with <code>smpte</code> time base and
-          <code>discontinuous</code> mode, a duration expression must be considered to
-          denote a duration in (local) real-time, independently of the governing time
-          base.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-familyName" name="style-value-familyName"></a>8.3.5
-          &lt;familyName&gt;</h4>
-
-          <p>A &lt;familyName&gt; expression specifies a font family name.</p>
-
-          <p>If the name contains a quotation delimiter character, then it must be
-          expressed as a &lt;quotedString&gt;. If the name contains a whitespace
-          character, then it should be expressed as a &lt;quotedString&gt;; however, if
-          it is expressed as a &lt;string&gt;, then it must not contain a
-          <code>COMMA</code> ',' character.</p><a id="familyName-style-expression-syntax"
-          name="familyName-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;familyName&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;familyName&gt;
-  : <a href="#style-value-string">&lt;string&gt;</a>
-  | <a href="#style-value-quotedString">&lt;quotedString&gt;</a>
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-genericFamilyName" name=
-          "style-value-genericFamilyName"></a>8.3.6 &lt;genericFamilyName&gt;</h4>
-
-          <p>A &lt;genericFamilyName&gt; expression specifies a font family using a
-          general token that indicates a class of font families.</p>
-
-          <p>The resolution of a generic family name to a concrete font instance is
-          considered to be implementation dependent, both in the case of content
-          authoring and content interpretation.</p><a id=
-          "genericFamilyName-style-expression-syntax" name=
-          "genericFamilyName-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;genericFamilyName&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;genericFamilyName&gt;
-  : "default"
-  | "monospace"
-  | "sansSerif"
-  | "serif"
-  | "monospaceSansSerif"
-  | "monospaceSerif"
-  | "proportionalSansSerif"
-  | "proportionalSerif"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The mapping between a generic (font) family name and an actual font is not
-          determined by this specification; however, the distinction of monospace versus
-          proportional and serif versus sans-serif should be maintained if possible when
-          performing presentation.</p>
-
-          <p>If a generic (font) family name of <code>monospace</code> is specified, then
-          it may be interpreted as equivalent to either <code>monospaceSansSerif</code>
-          or <code>monospaceSerif</code>. The generic family names <code>sansSerif</code>
-          and <code>serif</code> are to be interpreted as equivalent to
-          <code>proportionalSansSerif</code> and <code>proportionalSerif</code>,
-          respectively.</p>
-
-          <p>If the generic family name <code>default</code> is specified (or implied by
-          an initial value), then its typographic characteristics is considered to be
-          implementation dependent; however, it is recommended that this default font
-          family be mapped to an monospaced, sans-serif font.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-hexDigit" name="style-value-hexDigit"></a>8.3.7
-          &lt;hexDigit&gt;</h4>
-
-          <p>A &lt;hexDigit&gt; is used to express integers and other types of numbers or
-          tokens that employ base 16 arithmetic.</p>
-
-          <p>For the purpose of parsing, no distinction must be made between lower and
-          upper case.</p><a id="hexDigit-style-expression-syntax" name=
-          "hexDigit-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;hexDigit&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;hexDigit&gt;
-  : <a href="#style-value-digit">&lt;digit&gt;</a>
-  | "a" | "b" | "c" | "d" | "e" | "f"
-  | "A" | "B" | "C" | "D" | "E" | "F"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-integer" name="style-value-integer"></a>8.3.8
-          &lt;integer&gt;</h4>
-
-          <p>An &lt;integer&gt; expression is used to express an arbitrary, signed
-          integral value.</p><a id="integer-style-expression-syntax" name=
-          "integer-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;integer&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;integer&gt;
-  : ( "+" | "-" )? <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-length" name="style-value-length"></a>8.3.9
-          &lt;length&gt;</h4>
-
-          <p>A &lt;length&gt; expression is used to express either a coordinate component
-          of point in a cartesian space or a distance between two points in a cartesian
-          space.</p><a id="length-style-expression-syntax" name=
-          "length-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;length&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;length&gt;
-  : scalar
-  | percentage
-
-scalar
-  : number units
-
-percentage
-  : number "%"
-
-sign
-  : "+" | "-"
-
-number
-  : sign? non-negative-number
-
-non-negative-number
-  : non-negative-integer
-  | non-negative-real
-
-non-negative-integer
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-non-negative-real
-  : <a href="#style-value-digit">&lt;digit&gt;</a>* "." <a href=
-"#style-value-digit">&lt;digit&gt;</a>+
-
-units
-  : "px"
-  | "em"
-  | "c"                                     // abbreviation of "cell"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>It is an error to omit the units component of a scalar length value.</p>
-
-          <p>The semantics of the unit of measure <code>px</code> (pixel) are as defined
-          by <a href="#xsl11">[XSL 1.1]</a>, § 5.9.13.</p>
-
-          <p>When specified relative to a font whose size is expressed as a single length
-          measure or as two length measures of equal length, the unit of measure
-          <code>em</code> is considered to be identical to that defined by <a href=
-          "#xsl11">[XSL 1.1]</a>, § 5.9.13; however, when specified relative to a font
-          whose size is expressed as two length measures of non-equal lengths, then one
-          <code>em</code> is equal to the inline progression dimension of the
-          anamorphically scaled font when used to specify lengths in the inline
-          progression direction and equal to the block progression dimension of the
-          scaled font when used to specify lengths in the block progression
-          direction.</p>
-
-          <p>The semantics of the unit of measure <code>c</code> (cell) are defined by
-          the parameter <a href="#parameter-attribute-cellResolution"><b>6.2.1
-          ttp:cellResolution</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-namedColor" name="style-value-namedColor"></a>8.3.10
-          &lt;namedColor&gt;</h4>
-
-          <p>A &lt;namedColor&gt; is used to express an RGBA color with a convenient
-          name, and where the applicable color space is defined by <a href=
-          "#srgb">[SRGB]</a>.</p>
-
-          <p>For the purpose of parsing, no distinction must be made between lower and
-          upper case.</p><a id="namedColor-style-expression-syntax" name=
-          "namedColor-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;namedColor&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;namedColor&gt;
-  : "transparent"                           // #00000000
-  | "black"                                 // #000000ff
-  | "silver"                                // #c0c0c0ff
-  | "gray"                                  // #808080ff
-  | "white"                                 // #ffffffff
-  | "maroon"                                // #800000ff
-  | "red"                                   // #ff0000ff
-  | "purple"                                // #800080ff
-  | "fuchsia"                               // #ff00ffff
-  | "magenta"                               // #ff00ffff (= fuchsia)
-  | "green"                                 // #008000ff
-  | "lime"                                  // #00ff00ff
-  | "olive"                                 // #808000ff
-  | "yellow"                                // #ffff00ff
-  | "navy"                                  // #000080ff
-  | "blue"                                  // #0000ffff
-  | "teal"                                  // #008080ff
-  | "aqua"                                  // #00ffffff
-  | "cyan"                                  // #00ffffff (= aqua)
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Except for <code>transparent</code>, the set of named colors specified
-            above constitutes a proper subset of the set of named colors specified by
-            <a href="#svg11">[SVG 1.1]</a>, § 4.2.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-quotedString" name="style-value-quotedString"></a>8.3.11
-          &lt;quotedString&gt;</h4>
-
-          <p>A &lt;quotedString&gt; is used to express a delimited string that may
-          contain a whitespace or a quotation delimiter character. Two types of quotation
-          delimiters are provided in order to accommodate strings that contain the other
-          delimiter.</p><a id="quotedString-style-expression-syntax" name=
-          "quotedString-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;quotedString&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;quotedString&gt;
-  : "\"" ( <em>char</em> - { "\"" } )* "\""
-  | "\'" ( <em>char</em> - { "\'" } )* "\'"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>In the above syntax representation, the syntactic element
-          <em><code>char</code></em> must adhere to production [2] <code>Char</code> as
-          defined by <a href="#xml10">[XML 1.0]</a>&nbsp;§ 2.2.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-string" name="style-value-string"></a>8.3.12
-          &lt;string&gt;</h4>
-
-          <p>A &lt;string&gt; expression consists of a sequence of characters where no
-          character is a quotation delimiter character.</p><a id=
-          "string-style-expression-syntax" name="string-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;string&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;string&gt;
-  : ( <em>char</em> - { "\"" | "\'" } )+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>In the above syntax representation, the syntactic element
-          <em><code>char</code></em> must adhere to production [2] <code>Char</code> as
-          defined by <a href="#xml10">[XML 1.0]</a>&nbsp;§ 2.2.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="semantics-style-resolution" name="semantics-style-resolution"></a>8.4
-        Style Resolution</h3>
-
-        <p>This section defines the semantics of style resolution in terms of a standard
-        processing model as follows:</p>
-
-        <ul>
-          <li>
-            <p><a href="#semantics-style-association"><b>8.4.1 Style
-            Association</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-style-inheritance"><b>8.4.2 Style
-            Inheritance</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-style-resolution-value-categories"><b>8.4.3 Style
-            Resolution Value Categories</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-style-resolution-processing"><b>8.4.4 Style Resolution
-            Processing</b></a></p>
-          </li>
-        </ul>
-
-        <p>Any implementation of this model is permitted provided that the externally
-        observable results are consistent with the results produced by this model.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The semantics of style resolution employed here are based upon <a href=
-          "#xsl11">[XSL 1.1]</a>, § 5.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-style-association" name=
-          "semantics-style-association"></a>8.4.1 Style Association</h4>
-
-          <p>Style association is a sub-process of <a href=
-          "#semantics-style-resolution-processing"><b>8.4.4 Style Resolution
-          Processing</b></a> used to determine the specified style set of each content
-          and layout element.</p>
-
-          <p>Style matter may be associated with content and layout matter in a number of
-          ways:</p>
-
-          <ul>
-            <li>
-              <p><a href="#semantics-style-association-inline">inline styling</a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-association-referential">referential
-              styling</a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-association-chained-referential">chained
-              referential styling</a></p>
-            </li>
-          </ul>
-
-          <p>In addition to the above, style matter may be associated with layout matter
-          using:</p>
-
-          <ul>
-            <li>
-              <p><a href="#semantics-style-association-nested">nested styling</a></p>
-            </li>
-          </ul>
-
-          <div class="div4">
-            <h5><a id="semantics-style-association-inline" name=
-            "semantics-style-association-inline"></a>8.4.1.1 Inline Styling</h5>
-
-            <p>Style properties may be expressed in an inline manner by direct
-            specification of an attribute from the TT Style Namespace on the affected
-            element. When expressed in this manner, the association of style information
-            is referred to as <em>inline styling</em>.</p>
-
-            <p>Style properties associated by inline styling are afforded a higher
-            priority than all other forms of style association.</p><a id=
-            "style-association-example-1" name="style-association-example-1"></a>
-
-            <table class="example">
-              <caption>
-                Example – Inline Styling
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;p <span class="strong">tts:color="white"</span>&gt;White 1 &lt;span <span class=
-"strong">tts:color="yellow"</span>&gt;Yellow&lt;/span&gt; White 2&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In the above example, the two text fragments <code>"White 1 "</code> and
-              <code>" White 2"</code>, which are interpreted as anonymous spans, are not
-              associated with a color style property; rather, they inherit their color
-              style from their parent <code>p</code> element as described in <a href=
-              "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
-              Inheritance</b></a> below.</p>
-            </div>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-association-referential" name=
-            "semantics-style-association-referential"></a>8.4.1.2 Referential
-            Styling</h5>
-
-            <p>Style properties may be expressed in an out-of-line manner and referenced
-            by the affected element using the <code>style</code> attribute. When
-            expressed in this manner, the association of style information is referred to
-            as <em>referential styling</em>.</p>
-
-            <p>If a <code>style</code> attribute specifies multiple references, then
-            those references are evaluated in the specified order, and that order applies
-            to resolution of the value of a style property in the case that it is
-            specified along multiple reference paths.</p>
-
-            <p>The use of referential styling is restricted to making reference to
-            <code>style</code> element descendants of a <code>styling</code> element. It
-            is considered an error to reference a <code>style</code> element that is a
-            descendant of a <code>layout</code> element.</p>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>The use of referential styling encourages the reuse of style
-              specifications while sacrificing locality of reference.</p>
-            </div>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>A single content element may be associated with style properties by a
-              hybrid mixture of inline and referential styling, in which case inline
-              styling is given priority as described above by <a href=
-              "#semantics-style-association-inline"><b>8.4.1.1 Inline
-              Styling</b></a>.</p>
-            </div><a id="style-association-example-2" name=
-            "style-association-example-2"></a>
-
-            <table class="example">
-              <caption>
-                Example – Referential Styling
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;style <span class="strong">xml:id="s1"</span> tts:color="white"/&gt;
-&lt;style <span class="strong">xml:id="s2"</span> tts:color="yellow"/&gt;
-...
-&lt;p <span class="strong">style="s1"</span>&gt;White 1 &lt;span <span class=
-"strong">style="s2"</span>&gt;Yellow&lt;/span&gt; White 2&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In the above example, the two text fragments <code>"White 1 "</code> and
-              <code>" White 2"</code>, which are interpreted as anonymous spans, are not
-              associated with a color style property; rather, they inherit their color
-              style from their parent <code>p</code> element as described in <a href=
-              "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
-              Inheritance</b></a> below.</p>
-            </div>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-association-chained-referential" name=
-            "semantics-style-association-chained-referential"></a>8.4.1.3 Chained
-            Referential Styling</h5>
-
-            <p>Style properties may be expressed in an out-of-line manner and may
-            themselves reference other out-of-line style properties, thus creating a
-            chain of references starting at the affected element. When expressed in this
-            manner, the association of style information is referred to as <em>chained
-            referential styling</em>.</p>
-
-            <p>If the same style property is specified in more than one referenced style
-            set, then the last referenced style set applies, where the order of
-            application starts from the affected element and proceeds to referenced style
-            sets, and, in turn, to subsequent, recursively referenced style sets.</p>
-
-            <p>A loop in a sequence of chained style references must be considered an
-            error.</p>
-
-            <p>The use of referential styling is restricted to making reference to
-            <code>style</code> element descendants of a <code>styling</code> element. It
-            is considered an error to reference a <code>style</code> element that is a
-            descendant of a <code>layout</code> element.</p>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>The use of chained referential styling encourages the grouping of style
-              specifications into general and specific sets, which further aids in style
-              specification reuse.</p>
-            </div>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>A single content element may be associated with style properties by a
-              hybrid mixture of inline, referential styling, and chained referential
-              styling, in which case inline styling is given priority as described above
-              by <a href="#semantics-style-association-inline"><b>8.4.1.1 Inline
-              Styling</b></a>.</p>
-            </div><a id="style-association-example-3" name=
-            "style-association-example-3"></a>
-
-            <table class="example">
-              <caption>
-                Example – Chained Referential Styling
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;style <span class=
-"strong">xml:id="s1"</span> tts:color="white" tts:fontFamily="monospaceSerif"/&gt;
-&lt;style <span class="strong">xml:id="s2"</span> <span class=
-"strong">style="s1"</span> tts:color="yellow"/&gt;
-...
-&lt;p <span class="strong">style="s1"</span>&gt;White Monospace&lt;/p&gt;
-&lt;p <span class="strong">style="s2"</span>&gt;Yellow Monospace&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-association-nested" name=
-            "semantics-style-association-nested"></a>8.4.1.4 Nested Styling</h5>
-
-            <p>Style properties may be expressed in an nested manner by direct
-            specification of one or more <code>style</code> element children of the
-            affected element. When expressed in this manner, the association of style
-            information is referred to as <em>nested styling</em>.</p>
-
-            <p>Style properties associated by nested styling are afforded a lower
-            priority than inline styling but with higher priority than referential
-            styling.</p><a id="style-association-example-4" name=
-            "style-association-example-4"></a>
-
-            <table class="example">
-              <caption>
-                Example – Nested Styling
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;region xml:id="r1"&gt;
-  <span class="strong">&lt;style tts:extent="128px 66px"/&gt;</span>
-  <span class="strong">&lt;style tts:origin="0px 0px"/&gt;</span>
-  <span class="strong">&lt;style tts:displayAlign="center"/&gt;</span>
-&lt;/region&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In this version of this specification, nested styling applies only to
-              the <code>region</code> element.</p>
-            </div>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-style-inheritance" name=
-          "semantics-style-inheritance"></a>8.4.2 Style Inheritance</h4>
-
-          <p>Style inheritance is a sub-process of <a href=
-          "#semantics-style-resolution-processing"><b>8.4.4 Style Resolution
-          Processing</b></a> used to determine the specified style set of each content
-          and layout element.</p>
-
-          <p>Styles are further propagated to content matter using:</p>
-
-          <ul>
-            <li>
-              <p><a href="#semantics-style-inheritance-content">content style
-              inheritance</a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-inheritance-content">region style
-              inheritance</a></p>
-            </li>
-          </ul>
-
-          <p>For the purpose of determining inherited styles, the element hierarchy of an
-          intermediate synchronic document form of a <em>Document Instance</em> must be
-          used, where such intermediate forms are defined by <a href=
-          "#semantics-region-layout-step-1"><b>9.3.2 Intermediate Synchronic Document
-          Construction</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The intermediate synchronic document form is utilized rather than the
-            original form in order to facilitate region inheritance processing.</p>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-inheritance-content" name=
-            "semantics-style-inheritance-content"></a>8.4.2.1 Content Style
-            Inheritance</h5>
-
-            <p>Style properties are inherited from ancestor content elements within an
-            intermediate synchronic document if a style property is not associated with a
-            content element (or an anonymous span) and the style property is designated
-            as inheritable.</p>
-
-            <p>If a style property is determined to require inheritance, then the
-            inherited value must be the value of the same named style property in the
-            computed style set of the element's immediate ancestor element within the
-            applicable intermediate synchronic document.</p><a id=
-            "style-inheritance-example-2" name="style-inheritance-example-2"></a>
-
-            <table class="example">
-              <caption>
-                Example – Content Style Inheritance
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;p <span class="strong">tts:fontFamily="monospaceSansSerif"</span>&gt;
-  &lt;span tts:color="yellow"&gt;Yellow Monospace&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In the above example, the <code>span</code> element that encloses the
-              character items <code>Yellow Monospace</code> is not associated with a
-              <code>tts:fontFamily</code> style property and this property is
-              inheritable; therefore, the value of the <code>tts:fontFamily</code> style
-              is inherited from the computed style set of the ancestor <code>p</code>
-              element, and is added to the specified style set of the <code>span</code>
-              element.</p>
-            </div>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-inheritance-region" name=
-            "semantics-style-inheritance-region"></a>8.4.2.2 Region Style
-            Inheritance</h5>
-
-            <p>Style properties are inherited from a region element in the following
-            case:</p>
-
-            <ol class="enumar">
-              <li>
-                <p>if a style property <em>P</em> is not associated with a content
-                element or an anonymous span <em>E</em> and the style property is
-                designated as inheritable, and</p>
-              </li>
-
-              <li>
-                <p>if that style property <em>P</em> is in the computed style set of
-                region <em>R</em>, and</p>
-              </li>
-
-              <li>
-                <p>if that element <em>E</em> is flowed into (presented within) region
-                <em>R</em>.</p>
-              </li>
-            </ol><a id="style-inheritance-example-3" name=
-            "style-inheritance-example-3"></a>
-
-            <table class="example">
-              <caption>
-                Example – Region Style Inheritance
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;region <span class="strong">xml:id="r1"</span>&gt;
-  &lt;style tts:color="yellow"/&gt;
-  &lt;style tts:fontFamily="monospaceSerif"/&gt;
-&lt;/region&gt;
-...
-&lt;p <span class="strong">region="r1"</span>&gt;Yellow Monospace&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In the above example, the anonymous span that encloses the character
-              items <code>Yellow Monospace</code> effectively inherits the
-              <code>tts:color</code> and <code>tts:fontFamily</code> styles specified on
-              the <code>region</code> element into which the <code>p</code> element is
-              flowed (presented).</p>
-            </div>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-style-resolution-value-categories" name=
-          "semantics-style-resolution-value-categories"></a>8.4.3 Style Resolution Value
-          Categories</h4>
-
-          <p>During style resolution, layout, and presentation processing, three
-          categories of style property values are distinguished as follows:</p>
-
-          <ul>
-            <li>
-              <p><a href="#semantics-style-resolved-value-category-specified">specified
-              values</a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-resolved-value-category-computed">computed
-              values</a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-resolved-value-category-actual">actual
-              values</a></p>
-            </li>
-          </ul>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolved-value-category-specified" name=
-            "semantics-style-resolved-value-category-specified"></a>8.4.3.1 Specified
-            Values</h5>
-
-            <p>Values of style properties that are associated with or inherited by an
-            element or anonymous span are referred to as <em>specified values</em>. The
-            set of all specified style properties of a given element is referred to as
-            the <em>specified style set</em> of that element.</p>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolved-value-category-computed" name=
-            "semantics-style-resolved-value-category-computed"></a>8.4.3.2 Computed
-            Values</h5>
-
-            <p>When style properties are specified using relative value expressions, such
-            as a named color, a relative unit (e.g., cell), or a percentage, then they
-            need to be further resolved into absolute units, such as an RGB triple,
-            pixels, etc.</p>
-
-            <p>During the style resolution process, all specified style values are
-            reinterpreted (or recalculated) in absolute terms, and then recorded as
-            <em>computed values</em>. The set of all computed style properties of a given
-            element is referred to as the <em>computed style set</em> of that
-            element.</p>
-
-            <p>When a style value is inherited, either explicitly or implicitly, it is
-            the computed value of the style that is inherited from an ancestor element.
-            This is required since the resolution of certain relative units, such as
-            percentage, require evaluating the expression in the immediate (local)
-            context of reference, and not in a distant (remote) context of reference
-            where the related (resolving) expression is not available.</p>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolved-value-category-actual" name=
-            "semantics-style-resolved-value-category-actual"></a>8.4.3.3 Actual
-            Values</h5>
-
-            <p>During the actual presentation process, other transformations occur that
-            map some value expressions to concrete, physical values. For example, the
-            colors of computed style values are further subjected to closest color
-            approximation and gamma correction during the display process. In addition,
-            length value expressions that use pixels in computed style values are
-            considered to express logical rather than physical (device) pixels.
-            Consequently, these logical pixels are subject to being further transformed
-            or mapped to physical (device) pixels during presentation.</p>
-
-            <p>The final values that result from the logical to device mapping process
-            are referred to as <em>actual values</em>. The set of all actual style
-            properties of a given element is referred to as the <em>actual style set</em>
-            of that element.</p>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>More than one set of actual values may be produced during the process of
-              presentation. For example, a TTML presentation processor device may output
-              an RGBA component video signal which is then further transformed by an NTSC
-              or PAL television to produce a final image. In this case, both color and
-              dimensions may further be modified prior to presentation.</p>
-            </div>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In general, a TTML presentation processor will not have access to actual
-              style set values; as a consequence, no further use or reference to actual
-              values is made below when formally describing the style resolution
-              process.</p>
-            </div>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-style-resolution-processing" name=
-          "semantics-style-resolution-processing"></a>8.4.4 Style Resolution
-          Processing</h4>
-
-          <p>The process of style resolution is defined herein as the procedure (and
-          results thereof) for resolving (determining) the computed values of all style
-          properties that apply to content and layout elements:</p>
-
-          <ul>
-            <li>
-              <p><a href="#semantics-style-resolution-processing-definitions"><b>8.4.4.1
-              Conceptual Definitions</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-resolution-processing-sss"><b>8.4.4.2
-              Specified Style Set Processing</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-resolution-processing-css"><b>8.4.4.3 Computed
-              Style Set Processing</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-resolution-process-overall"><b>8.4.4.4 Style
-              Resolution Process</b></a></p>
-            </li>
-          </ul>
-
-          <p>The process described here forms an integral sub-process of <a href=
-          "#semantics-region-layout"><b>9.3 Region Layout and Presentation</b></a>.</p>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolution-processing-definitions" name=
-            "semantics-style-resolution-processing-definitions"></a>8.4.4.1 Conceptual
-            Definitions</h5>
-
-            <p>For the purpose of interpreting the style resolution processing model
-            specified below, the following conceptual definitions apply:</p>
-
-            <dl>
-              <dt class="label">[style property]</dt>
-
-              <dd>
-                <p>a style property, <em>P</em>, is considered to consist of a tuple
-                <code>[name, value]</code>, where the name of the property is a tuple
-                <code>[namespace value, unqualified name]</code> and the value of the
-                property is a tuple <code>[category, type, value
-                expression]</code></p><a id=
-                "conceptual-definition-example-style-property" name=
-                "conceptual-definition-example-style-property"></a>
-
-                <table class="example">
-                  <caption>
-                    Example – conceptual style property
-                  </caption>
-
-                  <tbody>
-                    <tr>
-                      <td>
-                        <div class="exampleInner">
-                          <pre>
-[
-  ["http://www.w3.org/ns/ttml#styling", "color"],
-  ["specified", <em>color</em>, "red"]
-]
-</pre>
-                        </div>
-                      </td>
-                    </tr>
-                  </tbody>
-                </table>
-              </dd>
-
-              <dt class="label">[style (property) set]</dt>
-
-              <dd>
-                <p>a style (property) set consists of an unordered collection of style
-                properties, where no two style properties within the set have an
-                identical name, where by "identical name" is meant equality of namespace
-                value of name tuple and unqualified name of name tuple;</p>
-
-                <p>in a specified style (property) set, the category of each style
-                property is "specified"; a specified style (property) set of an element
-                <em>E</em> is referred to as <em>SSS(E)</em>;</p><a id=
-                "conceptual-definition-example-specified-style-set" name=
-                "conceptual-definition-example-specified-style-set"></a>
-
-                <table class="example">
-                  <caption>
-                    Example – conceptual (specified) style (property) set
-                  </caption>
-
-                  <tbody>
-                    <tr>
-                      <td>
-                        <div class="exampleInner">
-                          <pre>
-{
-  [
-    ["http://www.w3.org/ns/ttml#styling", "backgroundColor"],
-    ["specified", <em>color</em>, 0x00FF00 ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "color"],
-    ["specified", <em>color</em>, "red" ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "fontSize"],
-    ["specified", <em>length</em>, "1c" ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "lineHeight"],
-    ["specified", <em>length</em>, "117%" ]
-  ]
-}
-</pre>
-                        </div>
-                      </td>
-                    </tr>
-                  </tbody>
-                </table>
-
-                <p>in a computed style (property) set, the category of each style
-                property is either "specified" or "computed"; a computed style (property)
-                set of an element <em>E</em> is referred to as <em>CSS(E)</em>;</p><a id=
-                "conceptual-definition-example-computed-style-set" name=
-                "conceptual-definition-example-computed-style-set"></a>
-
-                <table class="example">
-                  <caption>
-                    Example – conceptual (computed) style (property) set
-                  </caption>
-
-                  <tbody>
-                    <tr>
-                      <td>
-                        <div class="exampleInner">
-                          <pre>
-{
-  [
-    ["http://www.w3.org/ns/ttml#styling", "backgroundColor"],
-    ["specified", <em>color</em>, 0x00FF00 ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "color"],
-    ["computed", <em>color</em>, 0xFF0000 ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "fontSize"],
-    ["computed", <em>length</em>, "24px" ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "lineHeight"],
-    ["computed", <em>length</em>, "28px" ]
-  ]
-}
-</pre>
-                        </div>
-                      </td>
-                    </tr>
-                  </tbody>
-                </table>
-              </dd>
-
-              <dt class="label">[style (property) merging]</dt>
-
-              <dd>
-                <p>a style property <em>P<sub>new</sub></em> is merged into a style
-                (property) set, <em>SS</em>, as follows: if a style property
-                <em>P<sub>old</sub></em> is already present in <em>SS</em> where the name
-                of <em>P<sub>new</sub></em> is identical to the name of
-                <em>P<sub>old</sub></em>, then replace <em>P<sub>old</sub></em> in
-                <em>SS</em> with <em>P<sub>new</sub></em>; otherwise, add
-                <em>P<sub>new</sub></em> to <em>SS</em>;</p>
-              </dd>
-
-              <dt class="label">[style (property) set merging]</dt>
-
-              <dd>
-                <p>a style (property) set <em>SS<sub>new</sub></em> is merged into an
-                existing style (property) set <em>SS<sub>old</sub></em> as follows: for
-                each style property <em>P<sub>new</sub></em> in
-                <em>SS<sub>new</sub></em>, merge <em>P<sub>new</sub></em> into
-                <em>SS<sub>old</sub></em>;</p>
-              </dd>
-            </dl>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolution-processing-sss" name=
-            "semantics-style-resolution-processing-sss"></a>8.4.4.2 Specified Style Set
-            Processing</h5>
-
-            <p>The specified style set <em>SSS</em> of an element or anonymous span
-            <em>E</em>, <em>SSS(E)</em>, is determined according to the following ordered
-            rules:</p>
-
-            <ol class="enumar">
-              <li>
-                <p><span class="strong">[initialization]</span> initialize the specified
-                style set <em>SSS</em> of <em>E</em> to the empty set;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[referential and chained referential
-                styling]</span> for each <code>style</code> element
-                <em>S<sub>REF</sub></em> referenced by a <code>style</code> attribute
-                specified on <em>E</em>, and in the order specified in the
-                <code>style</code> attribute, then, if <em>S<sub>REF</sub></em> is a
-                descendant of a <code>styling</code> element, merge the specified style
-                set of <em>S<sub>REF</sub></em>, <em>SSS(S<sub>REF</sub>)</em>, into the
-                specified style set of <em>E</em>, <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[nested styling]</span> for each nested
-                <code>style</code> element child <em>S<sub>NEST</sub></em> of <em>E</em>,
-                and in the specified order of child elements, merge the specified style
-                set of <em>S<sub>NEST</sub></em>, <em>SSS(S<sub>NEST</sub>)</em>, into
-                the specified style set of <em>E</em>, <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[inline styling]</span> for each style property
-                <em>P</em> expressed as a specified styling attribute of <em>E</em>,
-                merge <em>P</em> into the specified style set of <em>E</em>,
-                <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[animation styling]</span> for each style
-                property <em>P</em> expressed as a specified styling attribute of an
-                immediate animation (<code>set</code>) element child of element
-                <em>E</em>, merge <em>P</em> into the specified style set of <em>E</em>,
-                <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[implicit inheritance]</span> if the element type
-                of <em>E</em> is not the styling element type <code>style</code>, then
-                for each inheritable style property <em>P<sub>INH</sub></em> in the set
-                of style properties defined above in <a href=
-                "#styling-attribute-vocabulary"><b>8.2 Styling Attribute
-                Vocabulary</b></a>, perform the following ordered sub-steps:</p>
-
-                <ol class="enumla">
-                  <li>
-                    <p>if <em>P<sub>INH</sub></em> is present in the specified style set
-                    of <em>E</em>, <em>SSS(E)</em>, then continue to the next inheritable
-                    style property;</p>
-                  </li>
-
-                  <li>
-                    <p>if the element type of <em>E</em> is the layout element type
-                    <code>region</code>, then set <em>P′</em> to the initial value of
-                    property <em>P</em>, where the initial value of a property is
-                    determined according to the specific property definition found above
-                    in <a href="#styling-attribute-vocabulary"><b>8.2 Styling Attribute
-                    Vocabulary</b></a>;</p>
-                  </li>
-
-                  <li>
-                    <p>if the element type of <em>E</em> is a content element type or
-                    anonymous span, then set <em>P′</em> to the result of looking up the
-                    value of <em>P</em> in the computed style set of the immediate
-                    ancestor element of <em>E</em>, i.e., <em>CSS(PARENT(E))</em>;</p>
-                  </li>
-
-                  <li>
-                    <p>if the value of <em>P′</em> is not undefined, then merge
-                    <em>P′</em> into the specified style set of <em>E</em>,
-                    <em>SSS(E)</em>.</p>
-                  </li>
-                </ol>
-              </li>
-            </ol>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolution-processing-css" name=
-            "semantics-style-resolution-processing-css"></a>8.4.4.3 Computed Style Set
-            Processing</h5>
-
-            <p>The computed style set <em>CSS</em> of an element or anonymous span
-            <em>E</em>, <em>CSS(E)</em>, is determined according to the following ordered
-            rules:</p>
-
-            <ol class="enumar">
-              <li>
-                <p><span class="strong">[resolve specified styles]</span> determine
-                (obtain) the specified style set <em>SSS</em> of <em>E</em>, namely,
-                <em>SSS(E)</em>, in accordance with <a href=
-                "#semantics-style-resolution-processing-sss"><b>8.4.4.2 Specified Style
-                Set Processing</b></a>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[initialization]</span> initialize
-                <em>CSS(E)</em> to a (deep) copy of <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[filter]</span> if <em>E</em> is a
-                <code>style</code> element, then return <em>CSS(E)</em> as the resulting
-                computed style set without further resolution; otherwise, continue with
-                the next rule;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[relative value resolution]</span> for each style
-                property <em>P</em> in <em>CSS(E)</em>, where the value type of
-                <em>P</em> is relative, perform the following ordered sub-steps:</p>
-
-                <ol class="enumla">
-                  <li>
-                    <p>replace the relative value of <em>P</em> with an equivalent,
-                    non-relative (computed) value;</p>
-                  </li>
-
-                  <li>
-                    <p>set the category of <em>P</em> to "computed";</p>
-                  </li>
-                </ol>
-              </li>
-            </ol>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>As a result of the filtering rule above, the computed style set of a
-              <code>style</code> element includes only specified values, in which case
-              relative value expressions remain relative; consequently, the resolution of
-              relative value expressions (that may be assigned by means of referential
-              style association) always takes place in the context of a layout or content
-              element which has a presentation context, and not in the non-presentation,
-              declaration context of a referentiable <code>style</code> element.</p>
-            </div>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolution-process-overall" name=
-            "semantics-style-resolution-process-overall"></a>8.4.4.4 Style Resolution
-            Process</h5>
-
-            <p>The top-level style resolution process is defined as follows: using a
-            preorder traversal of each element and anonymous span, <em>E</em>, of an
-            intermediate synchronic document, <em>DOC<sub>inter</sub></em>, perform the
-            following ordered sub-steps:</p>
-
-            <ol class="enumar">
-              <li>
-                <p><span class="strong">[filter]</span> if the element type of <em>E</em>
-                is not the styling element type <code>style</code>, is not the layout
-                element type <code>region</code>, and is not one of the content element
-                types <code>body</code>, <code>div</code>, <code>p</code>,
-                <code>span</code>, <code>br</code>, or anonymous span, then continue to
-                the next element in the preorder traversal;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[resolve computed styles]</span> determine
-                (obtain) the computed style set <em>CSS</em> of <em>E</em>, namely,
-                <em>CSS(E)</em>, in accordance with <a href=
-                "#semantics-style-resolution-processing-css"><b>8.4.4.3 Computed Style
-                Set Processing</b></a>.</p>
-              </li>
-            </ol>
-          </div>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="layout" name="layout"></a>9 Layout</h2>
-
-      <p>This section specifies the <em>layout</em> matter of the core vocabulary
-      catalog, where layout is to be understood as a separable layer of information that
-      applies to content and that denotes authorial intentions about the presentation of
-      that content.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>The two layers of layout and style matter are considered to be independently
-        separable. Layout matter specifies one or more spaces or areas into which content
-        is intended to be presented, while style matter specifies the manner in which
-        presentation occurs within the layout.</p>
-
-        <p>In certain cases, a content author may choose to embed (inline) style matter
-        directly into layout or content matter. In such cases, an alternative exists –
-        use of referential styling – in which the style matter is not embedded
-        (inlined).</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="layout-element-vocabulary" name="layout-element-vocabulary"></a>9.1
-        Layout Element Vocabulary</h3>
-
-        <p>The following elements specify the structure and principal layout aspects of a
-        <em>Document Instance</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#layout-vocabulary-layout"><b>9.1.1 layout</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#layout-vocabulary-region"><b>9.1.2 region</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="layout-vocabulary-layout" name="layout-vocabulary-layout"></a>9.1.1
-          layout</h4>
-
-          <p>The <code>layout</code> element is a container element used to group layout
-          matter, including metadata that applies to layout matter.</p>
-
-          <p>The <code>layout</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed by zero or
-          more <code>region</code> elements.</p><a id="elt-syntax-layout" name=
-          "elt-syntax-layout"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: layout
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;layout
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#layout-vocabulary-region">region</a>*
-&lt;/layout&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>To the extent that time semantics apply to the content of the
-          <code>layout</code> element, the implied time interval of this element is
-          defined to be coterminous with the <em>Root Temporal Extent</em>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="layout-vocabulary-region" name="layout-vocabulary-region"></a>9.1.2
-          region</h4>
-
-          <p>The <code>region</code> element is used to define a space or area into which
-          content is to be flowed for the purpose of presentation.</p>
-
-          <p>In addition, and in accordance with <a href=
-          "#semantics-style-inheritance-region"><b>8.4.2.2 Region Style
-          Inheritance</b></a>, the <code>region</code> element may be used to specify
-          inheritable style properties to be inherited by content that is flowed into
-          it.</p>
-
-          <p>The <code>region</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed by zero or
-          more elements in the <code>Animation.class</code> element group, followed by
-          zero or more <code>style</code> elements.</p>
-
-          <p>Any metadata specified by children in the <code>Metadata.class</code>
-          element group applies semantically to the <code>region</code> element and its
-          descendants as a whole. Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>region</code> element. Any <code>style</code> child element must be
-          considered a local style definition that applies only to the containing
-          <code>region</code> element, i.e., does not apply for resolving referential
-          styling.</p><a id="elt-syntax-region" name="elt-syntax-region"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: region
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#metadata-attribute-role">ttm:role</a> = string
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#styling-vocabulary-style">style</a>*
-&lt;/region&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If <code>begin</code> and (or) <code>end</code> attributes are specified on
-          a <code>region</code> element, then they specify the beginning and (or) ending
-          points of a time interval during which the region is eligible for activation
-          and with respect to which animation child elements of the region are timed. If
-          specified, these begin and end points are relative to the time interval of the
-          nearest ancestor element associated with a time interval, irregardless of
-          whether that interval is explicit or implied.</p>
-
-          <p>The nearest ancestor element of a <code>region</code> element that is
-          associated with a time interval is the <em>Document Instance</em>'s root
-          <code>tt</code> element.</p>
-
-          <p>If a <code>dur</code> attribute is specified on the <code>region</code>
-          element, then it specifies the simple duration of the region.</p>
-
-          <p>For the purpose of determining the semantics of presentation processing, a
-          region that is temporally inactive must not produce any visible marks when
-          presented on a visual medium.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>A <code>region</code> element may be associated with a time interval for
-            two purposes: (1) in order to temporally bound the presentation of the region
-            and its content, and (2) to provide a temporal context in which animations of
-            region styles may be effected.</p>
-
-            <p>For example, an author may wish a region that is otherwise empty, but may
-            have a visible background color to be presented starting at some time and
-            continuing over the region's duration. The simple duration of the region
-            serves additionally to scope the presentation effects of content that is
-            targeted to the region. An author may also wish to move a region within the
-            root container extent or change a region's background color by means of
-            animation effects. In both of these cases, it is necessary to posit an active
-            time interval for a region.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>region</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-
-          <p>If a <a href="#metadata-attribute-role"><code>ttm:role</code></a> attribute
-          is specified on a <code>region</code> element, then it must adhere to the value
-          syntax defined by <a href="#metadata-attribute-role-syntax"><b>Syntax
-          Representation – ttm:role</b></a>, and where the role(s) identified by this
-          attribute expresses the semantic role(s) of the region independently from the
-          semantic role(s) of any content targeted to (associated with) the region.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="layout-attribute-vocabulary" name=
-        "layout-attribute-vocabulary"></a>9.2 Layout Attribute Vocabulary</h3>
-
-        <p>This section defines the <a href="#layout-attribute-region"><b>9.2.1
-        region</b></a> attribute used with content elements.</p>
-
-        <div class="div3">
-          <h4><a id="layout-attribute-region" name="layout-attribute-region"></a>9.2.1
-          region</h4>
-
-          <p>The <code>region</code> attribute is used to reference a <code>region</code>
-          element which defines a space or area into which a content element is intended
-          to be flowed.</p>
-
-          <p>The <code>region</code> attribute may be specified by an instance of the
-          following element types:</p>
-
-          <ul>
-            <li>
-              <p><a href="#document-structure-vocabulary-body"><code>body</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
-            </li>
-          </ul>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#semantics-region-layout"><b>9.3 Region Layout and
-            Presentation</b></a> below for further information on content flow in a
-            region.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="semantics-region-layout" name="semantics-region-layout"></a>9.3 Region
-        Layout and Presentation</h3>
-
-        <p>This section defines the semantics of region layout and presentation in terms
-        of a standard processing model as follows:</p>
-
-        <ul>
-          <li>
-            <p><a href="#semantics-default-region"><b>9.3.1 Default Region</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-region-layout-step-1"><b>9.3.2 Intermediate Synchronic
-            Document Construction</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-region-layout-step-2"><b>9.3.3 Synchronic Flow
-            Processing</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-region-layout-example"><b>9.3.4 Elaborated Example
-            (Informative)</b></a></p>
-          </li>
-        </ul>
-
-        <p>Any implementation is permitted provided that the externally observable
-        results are consistent with the results produced by this model.</p>
-
-        <div class="div3">
-          <h4><a id="semantics-default-region" name="semantics-default-region"></a>9.3.1
-          Default Region</h4>
-
-          <p>If a <em>Document Instance</em> does not specify a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element, then a <em>default
-          region</em> is implied with the following characteristics:</p>
-
-          <ul>
-            <li>
-              <p>the identity of the default region is considered to be anonymous;</p>
-            </li>
-
-            <li>
-              <p>the extent of the default region is the same as the root container
-              region;</p>
-            </li>
-
-            <li>
-              <p>the temporal interval of the default region is the same as temporal
-              interval of the <em>Document Instance</em>;</p>
-            </li>
-          </ul>
-
-          <p>Furthermore, if no <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element was specified, then
-          the <a href="#layout-attribute-region"><code>region</code></a> attribute must
-          not be specified on any content element in the <em>Document Instance</em>.</p>
-
-          <p>If a default region is implied for a given <em>Document Instance</em>, then
-          the <a href="#document-structure-vocabulary-body"><code>body</code></a> element
-          is implicitly targeted to (associated with) the default region.</p>
-
-          <p>When implying a default region, the <em>Document Instance</em> is to be
-          treated as if a <a href="#layout-vocabulary-region"><code>region</code></a>
-          element and its parent <a href=
-          "#layout-vocabulary-layout"><code>layout</code></a> element were specified in a
-          <a href="#document-structure-vocabulary-head"><code>head</code></a> element,
-          and a matching <a href="#layout-attribute-region"><code>region</code></a>
-          attribute were specified on the <a href=
-          "#document-structure-vocabulary-body"><code>body</code></a> element as shown in
-          the following example:</p><a id="semantics-default-region-example" name=
-          "semantics-default-region-example"></a>
-
-          <table class="example">
-            <caption>
-              Example – Implied Default Region
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
-  &lt;head&gt;
-    <span class="strong">&lt;layout&gt;
-      &lt;region xml:id="anonymous"/&gt;
-    &lt;/layout&gt;</span>
-  &lt;/head&gt;
-  &lt;body <span class="strong">region="anonymous"</span>/&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, a default <code>region</code> element and
-            <code>region</code> attribute are implied. In addition, a <code>layout</code>
-            container element is implied for the implied <code>region</code> element.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-region-layout-step-1" name=
-          "semantics-region-layout-step-1"></a>9.3.2 Intermediate Synchronic Document
-          Construction</h4>
-
-          <p>For the purposes of performing presentation processing, the active time
-          duration of a <em>Document Instance</em> is divided into a sequence of time
-          coordinates where at each time coordinate, some element becomes temporally
-          active or inactive, then, at each such time coordinate, a <em>Document
-          Instance</em> is mapped from its original, source form,
-          <em>DOC<sub>source</sub></em> , to an intermediate synchronic document form,
-          <em>DOC<sub>inter</sub></em> , as follows:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>for each temporally active region <em>R</em>, replicate the sub-tree of
-              <em>DOC<sub>source</sub></em> headed by the <code>body</code> element;</p>
-            </li>
-
-            <li>
-              <p>evaluating this sub-tree in a postorder traversal, prune elements if
-              they are not a content element, if they are temporally inactive, if they
-              are empty, or if they aren't associated with region <em>R</em>;</p>
-            </li>
-
-            <li>
-              <p>if the pruned sub-tree is non-empty, then reparent it to the <em>R</em>
-              element;</p>
-            </li>
-
-            <li>
-              <p>finally, after completing the above steps, prune the original
-              <code>body</code> element from the intermediate document, then prune all
-              <code>region</code>, <code>begin</code>, <code>end</code>, and
-              <code>dur</code> attributes, which are no longer semantically relevant;</p>
-            </li>
-          </ol>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In this section, the term <em>prune</em>, when used in reference to an
-            element, means that the element is to be removed from its parent's children,
-            which, in turn, implies that the descendants of the pruned element will no
-            longer be descendants of the element's parent. When <em>prune</em> is used in
-            reference to an attribute, it means that attribute is to be removed from its
-            associated (owning) element node.</p>
-          </div>
-
-          <p>A content element is associated with a region according to the following
-          ordered rules, where the first rule satisfied is used and remaining rules are
-          skipped:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>if the element specifies a <a href=
-              "#layout-attribute-region"><code>region</code></a> attribute, then the
-              element is associated with the region referenced by that attribute;</p>
-            </li>
-
-            <li>
-              <p>if some ancestor of that element specifies a <a href=
-              "#layout-attribute-region"><code>region</code></a> attribute, then the
-              element is associated with the region referenced by the most immediate
-              ancestor that specifies this attribute;</p>
-            </li>
-
-            <li>
-              <p>if the element contains a descendant element that specifies a <a href=
-              "#layout-attribute-region"><code>region</code></a> attribute, then the
-              element is associated with the region referenced by that attribute;</p>
-            </li>
-
-            <li>
-              <p>if a default region was implied (due to the absence of any <a href=
-              "#layout-vocabulary-region"><code>region</code></a> element), then the
-              element is associated with the default region;</p>
-            </li>
-
-            <li>
-              <p>the element is not associated with any region.</p>
-            </li>
-          </ol>
-
-          <p>The result of performing the processing described above will be a sequence
-          of <em>N</em> intermediate synchronic <em>Document Instances</em>,
-          <em>DOC<sub><span>inter<sub>0</sub></span></sub></em> …
-          <em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>.</p>
-
-          <div class="note" id="semantics-smooth-scrolling-recommendation">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Where an implementation is able to detect significant similarity between
-            two adjacent synchronic <em>Document Instances</em>,
-            <em>DOC<sub><span>inter<sub>N</sub></span></sub></em>
-            <em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>, then it is preferred
-            that the implementation make the transition between presenting the two
-            instances as smooth as possible, e.g., as described by <a href=
-            "#cea608c">[CEA-608-C]</a>, § C.3.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-region-layout-step-2" name=
-          "semantics-region-layout-step-2"></a>9.3.3 Synchronic Flow Processing</h4>
-
-          <p>Subsequent to performing a temporal (synchronic) slice and subsequent
-          remapping of regionally selected content hierarchy, the resulting intermediate
-          synchronic document is subjected to a flow transformation step that produces a
-          rooted flow object tree represented as an XSL FO document instance as defined
-          by <a href="#xsl11">[XSL 1.1]</a>, and semantically extended by TTML specific
-          style properties that have no XSL FO counterpart.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In this section, the use of XSL FO is intended to be conceptual only,
-            employed solely for the purpose of defining the normative presentation
-            semantics of TTML. An actual implementation of this algorithm is not required
-            to create or process XSL-FO representations. In particular, it is possible to
-            implement these semantics using alternative presentation models, such as
-            Cascading Style Sheets (CSS).</p>
-          </div>
-
-          <p>Each intermediate synchronic document produced by <a href=
-          "#semantics-region-layout-step-1"><b>9.3.2 Intermediate Synchronic Document
-          Construction</b></a> is mapped to an XSL FO document instance, <em>F</em>, as
-          follows:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>perform the following ordered sub-steps to create anonymous spans:</p>
-
-              <ol class="enumla">
-                <li>
-                  <p>for each significant text node in a content element, synthesize an
-                  anonymous span to enclose the text node, substituting the new anonymous
-                  span for the original text node child in its sibling and parent
-                  hierarchy;</p>
-                </li>
-
-                <li>
-                  <p>for each contiguous sequence of anonymous spans, replace the
-                  sequence with a single anonymous span which contains a sequence of text
-                  nodes representing the individual text node children of the original
-                  sequence of anonymous spans;</p>
-                </li>
-
-                <li>
-                  <p>for each span element whose child is a single anonymous span,
-                  replace the anonymous span with its sequence of child text nodes;</p>
-                </li>
-              </ol>
-            </li>
-
-            <li>
-              <p>resolve styles according to <a href=
-              "#semantics-style-resolution-process-overall"><b>8.4.4.4 Style Resolution
-              Process</b></a>;</p>
-            </li>
-
-            <li>
-              <p>map the <code>tt</code> element to an <code>fo:root</code> element,
-              populated initially with an <code>fo:layout-master-set</code> element that
-              contains a valid <code>fo:simple-page-master</code> that, in turn, contains
-              an <code>fo:region-body</code> child, where the root container extent
-              expressed on the <code>tt</code> element is mapped to
-              <code>page-width</code> and <code>page-height</code> attributes on the
-              <code>fo:simple-page-master</code> element;</p>
-            </li>
-
-            <li>
-              <p>map the <code>layout</code> element to an <code>fo:page-sequence</code>
-              element and a child <code>fo:flow</code> element that reference the page
-              master and page region defined by the simple page master produced
-              above;</p>
-            </li>
-
-            <li>
-              <p>map each non-empty <code>region</code> element to an
-              <code>fo:block-container</code> element with an
-              <code>absolute-position</code> attribute with value <code>absolute</code>,
-              and where the region's position and extent are mapped to equivalent
-              <code>top</code>, <code>left</code>, <code>width</code>, and
-              <code>height</code> attributes;</p>
-            </li>
-
-            <li>
-              <p>for each <code>body</code>, <code>div</code>, and <code>p</code> element
-              that is not associated with a <code>tts:display</code> style property with
-              the value <code>none</code>, map the element to a distinct
-              <code>fo:block</code> element, populating the style properties of
-              <code>fo:block</code> by using the computed style set associated with each
-              original TTML Content element;</p>
-            </li>
-
-            <li>
-              <p>for the resulting <code>fo:block</code> formatting object produced in
-              the previous step that corresponds to the <code>body</code> element,
-              perform the following ordered sub-steps:</p>
-
-              <ol class="enumla">
-                <li>
-                  <p>if the <code>display-align</code> style property of this
-                  <code>fo:block</code> has the value <code>center</code> or
-                  <code>after</code>, then synthesize and insert as the first child of
-                  this <code>fo:block</code> an empty <code>fo:block</code> with the
-                  following attributes: <code>space-after.optimum</code>,
-                  <code>space-after.maximum</code>, and
-                  <code>space-after.conditionality</code>, where the value of the former
-                  two attributes is the height or width of the containing
-                  <code>fo:block-container</code> element, whichever of these is
-                  designated as the block progression dimension, and where the value of
-                  the last is <code>retain</code>;</p>
-                </li>
-
-                <li>
-                  <p>if the <code>display-align</code> style property of this
-                  <code>fo:block</code> has the value <code>center</code> or
-                  <code>before</code>, then synthesize and insert as the last child of
-                  this <code>fo:block</code> an empty <code>fo:block</code> with the
-                  following attributes: <code>space-after.optimum</code>,
-                  <code>space-after.maximum</code>, and
-                  <code>space-after.conditionality</code>, where the value of the former
-                  two attributes is the height or width of the containing
-                  <code>fo:block-container</code> element, whichever of these is
-                  designated as the block progression dimension, and where the value of
-                  the last is <code>retain</code>;</p>
-                </li>
-              </ol>
-            </li>
-
-            <li>
-              <p>for each <code>span</code> element that is not associated with a
-              <code>tts:display</code> style property with the value <code>none</code>
-              and for each anonymous span that is a child of a <code>p</code> or
-              <code>span</code> element, map the element or sequence of character items
-              to a distinct <code>fo:inline</code> element, populating the style
-              properties of <code>fo:inline</code> by using the computed style set
-              associated with each original TTML Content element or anonymous span;</p>
-            </li>
-
-            <li>
-              <p>for each <code>br</code> element that is not associated with a
-              <code>tts:display</code> style property with the value <code>none</code>,
-              map the element to a distinct <code>fo:character</code> element having the
-              following properties:</p>
-
-              <ul>
-                <li>
-                  <p><code>character="&amp;#x000A;"</code></p>
-                </li>
-
-                <li>
-                  <p><code>suppress-at-line-break="retain"</code></p>
-                </li>
-              </ul>
-            </li>
-
-            <li>
-              <p>for each TTML style property attribute in some computed style set that
-              has no counterpart in <a href="#xsl11">[XSL 1.1]</a>, map that attribute
-              directly through to the relevant formatting object produced by the input
-              TTML Content element to which the style property applies;</p>
-            </li>
-
-            <li>
-              <p>optionally, synthesize a unique <code>id</code> attribute on each
-              resulting formatting object element that relates that element to the input
-              element that resulted in that formatting object element;</p>
-            </li>
-          </ol>
-
-          <p>For each resulting document instance F, if processing requires presentation
-          on a visual medium, then apply formatting and rendering semantics consistent
-          with that prescribed by <a href="#xsl11">[XSL 1.1]</a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In an XSL FO area tree produced by formatting <em>F</em> using an <a href=
-            "#xsl11">[XSL 1.1]</a> formatting processor, the
-            <code>page-viewport-area</code>, which is generated by
-            <code>fo:page-sequence</code> element by reference to the sole generated
-            <code>fo:simple-page-master</code> element, would correspond to the <em>root
-            container region</em> defined above in <a href="#definitions"><b>2
-            Definitions</b></a>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Due to the possible presence of TTML style properties or style property
-            values in a given <em>Document Instance</em> for which there is no <a href=
-            "#xsl11">[XSL 1.1]</a> counterpart, Implementors should recognize that it is
-            the layout model of <a href="#xsl11">[XSL 1.1]</a> that is being referenced
-            by this specification, not the requirement to use a compliant <a href=
-            "#xsl11">[XSL 1.1]</a> formatting processor, since such would not necessarily
-            be sufficient to satisfy the full presentation semantics defined by this
-            specification, and would contain a large number of features not needed to
-            implement the presentation semantics of TTML.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The purpose of inserting additional, collapsible space in the block
-            progression dimension of the <code>fo:block</code> that corresponds with the
-            <code>body</code> element is to ensure that the before and after edges of
-            this <code>fo:block</code> are coincident with the before and after edges of
-            the <code>fo:block-container</code> that corresponds to the containing
-            <code>region</code>, while simultaneously taking into account the needs to
-            satisfy alignment in the block progression dimension. For example, this
-            assures that the background color associated with the <code>body</code>
-            element, if not <code>transparent</code>, will fill the containing region
-            wholly.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-region-layout-example" name=
-          "semantics-region-layout-example"></a>9.3.4 Elaborated Example
-          (Informative)</h4>
-
-          <p>An example of the processing steps described above is elaborated below,
-          starting with <a href="#region-mapping-example-1-s"><b>Example – Sample Source
-          Document</b></a>.</p><a id="region-mapping-example-1-s" name=
-          "region-mapping-example-1-s"></a>
-
-          <table class="example">
-            <caption>
-              Example – Sample Source Document
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt tts:extent="640px 480px" xml:lang="en"
-  xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1"&gt;
-        &lt;style tts:origin="10px 100px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="red"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-      &lt;/region&gt;
-      &lt;region xml:id="r2"&gt;
-        &lt;style tts:origin="10px 300px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="yellow"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-      &lt;/region&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-  &lt;body xml:id="b1"&gt;
-    &lt;div xml:id="d1" begin="0s" dur="2s"&gt;
-      &lt;p xml:id="p1" region="r1"&gt;Text 1&lt;/p&gt;
-      &lt;p xml:id="p2" region="r2"&gt;Text 2&lt;/p&gt;
-    &lt;/div&gt;
-    &lt;div xml:id="d2" begin="1s" dur="2s"&gt;
-      &lt;p xml:id="p3" region="r2"&gt;Text 3&lt;/p&gt;
-      &lt;p xml:id="p4" region="r1"&gt;Text 4&lt;/p&gt;
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>In the above document, the content hierarchy consists of two divisions, each
-          containing two paragraphs. This content is targeted (selected into) one of two
-          non-overlapping regions that are styled identically except for their position
-          and their foreground colors, the latter of which is inherited by and applies to
-          the (and, in this case, anonymous) spans reparented into the regions.</p>
-
-          <p>The following, first intermediate document shows the synchronic state at
-          time interval [0,1), during which time only division <code>d1</code> is
-          temporally active, and where paragraphs <code>p1</code> and <code>p2</code>
-          (and their ancestors) are selected into regions <code>r1</code> and
-          <code>r2</code>, respectively.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The intermediate documents shown below are not valid <em>Document
-            Instances</em>, but rather, are representations of possible internal
-            processing states used for didactic purposes.</p>
-          </div><a id="region-mapping-example-1-i0" name=
-          "region-mapping-example-1-i0"></a>
-
-          <table class="example">
-            <caption>
-              Example – Intermediate Document – [0s,1s)
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt tts:extent="640px 480px" xml:lang="en"
-  xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1"&gt;
-        &lt;style tts:origin="10px 100px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="red"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-1"&gt;
-          &lt;div xml:id="d1-1"&gt;
-            &lt;p xml:id="p1"&gt;Text 1&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-      &lt;region xml:id="r2"&gt;
-        &lt;style tts:origin="10px 300px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="yellow"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-2"&gt;
-          &lt;div xml:id="d1-2"&gt;
-            &lt;p xml:id="p2"&gt;Text 2&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An XSL FO document instance that would yield rendering consistent with TTML,
-          and which may be produced by performing flow processing upon the first
-          intermediate document is illustrated below.</p><a id=
-          "region-mapping-example-1-f0" name="region-mapping-example-1-f0"></a>
-
-          <table class="example">
-            <caption>
-              Example – XSL FO Document – [0s,1s)
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format"&gt;
-  &lt;fo:layout-master-set&gt;
-    &lt;fo:simple-page-master master-name="m1"
-      page-width="640px" page-height="480px"&gt;
-      &lt;fo:region-body/&gt;
-    &lt;/fo:simple-page-master&gt;
-  &lt;/fo:layout-master-set&gt;
-  &lt;fo:page-sequence master-reference="m1"&gt;
-    &lt;fo:flow flow-name="xsl-region-body"&gt;
-      &lt;!-- region (r1) --&gt;
-      &lt;fo:block-container id="r1" absolute-position="absolute"
-        left="10px" top="100px" width="620px" height="96px"
-        background-color="black" display-align="center"&gt;
-        &lt;!-- body (b1) --&gt;
-        &lt;fo:block id="b1-1"&gt;
-          &lt;!-- body's space (before) filler --&gt;
-          &lt;fo:block
-            space-after.optimum="96px"
-            space-after.maximum="96px"
-            space-after.conditionality="retain"/&gt;
-          &lt;!-- div (d1) --&gt;
-          &lt;fo:block id="d1-1"&gt;
-            &lt;!-- p (p1) --&gt;
-            &lt;fo:block id="p1" text-align="center"&gt;
-              &lt;fo:inline font-size="40px" font-weight="bold"
-              color="red"&gt;Text 1&lt;/fo:inline&gt;
-            &lt;/fo:block&gt;
-          &lt;/fo:block&gt;
-          &lt;!-- body's space (after) filler --&gt;
-          &lt;fo:block
-            space-after.optimum="96px"
-            space-after.maximum="96px"
-            space-after.conditionality="retain"/&gt;
-        &lt;/fo:block&gt;
-      &lt;/fo:block-container&gt;
-      &lt;!-- region (r2) --&gt;
-      &lt;fo:block-container id="r2" absolute-position="absolute"
-        left="10px" top="300px" width="620px" height="96px"
-        background-color="black" display-align="center"&gt;
-        &lt;!-- body (b1) --&gt;
-        &lt;fo:block id="b1-2"&gt;
-          &lt;!-- body's space (before) filler --&gt;
-          &lt;fo:block
-            space-after.optimum="96px"
-            space-after.maximum="96px"
-            space-after.conditionality="retain"/&gt;
-          &lt;!-- div (d1) --&gt;
-          &lt;fo:block id="d1-2"&gt;
-            &lt;!-- p (p2) --&gt;
-            &lt;fo:block id="p2" text-align="center"&gt;
-              &lt;fo:inline font-size="40px" font-weight="bold"
-              color="yellow"&gt;Text 2&lt;/fo:inline&gt;
-            &lt;/fo:block&gt;
-          &lt;/fo:block&gt;
-          &lt;!-- body's space (after) filler --&gt;
-          &lt;fo:block
-            space-after.optimum="96px"
-            space-after.maximum="96px"
-            space-after.conditionality="retain"/&gt;
-        &lt;/fo:block&gt;
-      &lt;/fo:block-container&gt;
-    &lt;/fo:flow&gt;
-  &lt;/fo:page-sequence&gt;
-&lt;/fo:root&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The following, second intermediate document shows the synchronic state at
-          time interval [1,2), at which time both divisions <code>d1</code> and
-          <code>d2</code> are temporally active, and where paragraphs <code>p1</code> and
-          <code>p4</code> (and their ancestors) are selected into region <code>r1</code>
-          and paragraphs <code>p2</code> and <code>p3</code> (and their ancestors) are
-          selected into region <code>r2</code>.</p><a id="region-mapping-example-1-i1"
-          name="region-mapping-example-1-i1"></a>
-
-          <table class="example">
-            <caption>
-              Example – Intermediate Document – [1s,2s)
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt tts:extent="640px 480px" xml:lang="en"
-  xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1"&gt;
-        &lt;style tts:origin="10px 100px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="red"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-1"&gt;
-          &lt;div xml:id="d1-1"&gt;
-            &lt;p xml:id="p1"&gt;Text 1&lt;/p&gt;
-          &lt;/div&gt;
-          &lt;div xml:id="d2-1"&gt;
-            &lt;p xml:id="p4"&gt;Text 4&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-      &lt;region xml:id="r2"&gt;
-        &lt;style tts:origin="10px 300px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="yellow"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-2"&gt;
-          &lt;div xml:id="d1-2"&gt;
-            &lt;p xml:id="p2"&gt;Text 2&lt;/p&gt;
-          &lt;/div&gt;
-          &lt;div xml:id="d2-2"&gt;
-            &lt;p xml:id="p3"&gt;Text 3&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The following, third intermediate document shows the synchronic state at
-          time interval [2,3), at which time only division <code>d2</code> is temporally
-          active, and where paragraphs <code>p4</code> and <code>p3</code> (and their
-          ancestors) are selected into regions <code>r1</code> and <code>r2</code>,
-          respectively.</p><a id="region-mapping-example-1-i2" name=
-          "region-mapping-example-1-i2"></a>
-
-          <table class="example">
-            <caption>
-              Example – Intermediate Document – [2s,3s)
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt tts:extent="640px 480px" xml:lang="en"
-  xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1"&gt;
-        &lt;style tts:origin="10px 100px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="red"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-1"&gt;
-          &lt;div xml:id="d2-1"&gt;
-            &lt;p xml:id="p4"&gt;Text 4&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-      &lt;region xml:id="r2"&gt;
-        &lt;style tts:origin="10px 300px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="yellow"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-2"&gt;
-          &lt;div xml:id="d2-2"&gt;
-            &lt;p xml:id="p3"&gt;Text 3&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="semantics-line-layout" name="semantics-line-layout"></a>9.4 Line
-        Layout</h3>
-
-        <p>If a profile that applies to a <em>Document Instance</em> requires use of the
-        <a href="#feature-lineBreak-uax14">#lineBreak-uax14</a> feature (i.e., the value
-        attribute for the feature is specified as <code>use</code>), then the
-        recommendations defined by <a href=
-        "http://www.unicode.org/reports/tr14/#Algorithm">Line Breaking Algorithm</a>
-        <a href="#uax14">[UAX14]</a> apply when performing line layout on the content of
-        the <em>Document Instance</em>.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="timing" name="timing"></a>10 Timing</h2>
-
-      <p>This section specifies the <em>timing</em> matter of the core vocabulary
-      catalog, where timing is to be understood as a separable layer of information that
-      applies to content and that denotes authorial intentions about the temporal
-      presentation of that content.</p>
-
-      <div class="div2">
-        <h3><a id="timing-element-vocabulary" name="timing-element-vocabulary"></a>10.1
-        Timing Element Vocabulary</h3>
-
-        <p>No timing related element vocabulary is defined for use in the core vocabulary
-        catalog.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="timing-attribute-vocabulary" name=
-        "timing-attribute-vocabulary"></a>10.2 Timing Attribute Vocabulary</h3>
-
-        <p>This section defines the following basic timing attributes for use with timed
-        elements:</p>
-
-        <ul>
-          <li>
-            <p><a href="#timing-attribute-begin"><b>10.2.1 begin</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#timing-attribute-end"><b>10.2.2 end</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#timing-attribute-dur"><b>10.2.3 dur</b></a></p>
-          </li>
-        </ul>
-
-        <p>In addition, this section defines the <a href=
-        "#timing-attribute-timeContainer"><b>10.2.4 timeContainer</b></a> attribute for
-        use with timed elements that serve simultaneously as timing containers.</p>
-
-        <div class="div3">
-          <h4><a id="timing-attribute-begin" name="timing-attribute-begin"></a>10.2.1
-          begin</h4>
-
-          <p>The <code>begin</code> attribute is used to specify the begin point of a
-          temporal interval associated with a timed element. If specified, the value of a
-          <code>begin</code> attribute must adhere to a &lt;timeExpression&gt;
-          specification as defined by <a href="#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>The begin point of a temporal interval is included in the interval; i.e.,
-          the interval is left-wise closed.</p>
-
-          <p>The semantics of the <code>begin</code> attribute are those defined by
-          <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking into account any
-          overriding semantics defined by this specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="timing-attribute-end" name="timing-attribute-end"></a>10.2.2
-          end</h4>
-
-          <p>The <code>end</code> attribute is used to specify the ending point of a
-          temporal interval associated with a timed element. If specified, the value of
-          an <code>end</code> attribute must adhere to a &lt;timeExpression&gt;
-          specification as defined by <a href="#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>The ending point of a temporal interval is not included in the interval;
-          i.e., the interval is right-wise open.</p>
-
-          <p>The presentation effects of a non-empty active temporal interval include the
-          frame immediately prior to the frame (or tick) equal to or immediately
-          following the time specified by the ending point, but do not extend into this
-          latter frame (or tick).</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>For example, if an active interval is [10s,10.33333s), and the frame rate
-            is 30 frames per second, then the presentation effects of the interval are
-            limited to frames 300 through 309 only (assuming that 0s corresponds with
-            frame 0). The same holds if the active interval is specified as
-            [300f,310f).</p>
-          </div>
-
-          <p>The semantics of the <code>end</code> attribute are those defined by
-          <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking into account any
-          overriding semantics defined by this specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="timing-attribute-dur" name="timing-attribute-dur"></a>10.2.3
-          dur</h4>
-
-          <p>The <code>dur</code> attribute is used to specify the duration of a temporal
-          interval associated with a timed element. If specified, the value of a
-          <code>dur</code> attribute must adhere to a &lt;timeExpression&gt;
-          specification as defined by <a href="#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When the <code>clock-time</code> form of a &lt;timeExpression&gt;
-            specification is used with a <code>dur</code> attribute, it is intended to be
-            interpreted as a difference between two implied clock time expressions.</p>
-          </div>
-
-          <p>When a <em>Document Instance</em> specifies the use of the
-          <code>smpte</code> time base and <code>discontinuous</code> marker mode, the
-          <code>dur</code> attribute must not be specified on any element.</p>
-
-          <p>The semantics of the <code>dur</code> attribute are those defined by
-          <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking into account any
-          overriding semantics defined by this specification.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the context of the subset of <a href="#smil21">[SMIL 2.1]</a> semantics
-            supported by this specification, the active duration of an element that
-            specifies both <code>end</code> and <code>dur</code> attributes is equal to
-            the lesser of the value of the <code>dur</code> attribute and the difference
-            between the value of the <code>end</code> attribute and the element's begin
-            time.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="timing-attribute-timeContainer" name=
-          "timing-attribute-timeContainer"></a>10.2.4 timeContainer</h4>
-
-          <p>The <code>timeContainer</code> attribute is used to specify a local temporal
-          context by means of which timed child elements are temporally situated.</p>
-
-          <p>If specified, the value of a <code>timeContainer</code> attribute must be
-          one of the following:</p>
-
-          <ul>
-            <li>
-              <p><code>par</code></p>
-            </li>
-
-            <li>
-              <p><code>seq</code></p>
-            </li>
-          </ul>
-
-          <p>If the time container semantics of an element instance is <code>par</code>,
-          then the temporal intervals of child elements are considered to apply in
-          parallel, i.e., simultaneously in time. Furthermore, the specification of the
-          time interval of each child element is considered to be relative to the
-          temporal interval of the container element instance. For the purpose of
-          determining the <a href="#smil21">[SMIL 2.1]</a> <code>endsync</code> semantics
-          of a <code>par</code> time container, a default value of <code>all</code>
-          applies.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The use of a default value of <code>all</code> for the
-            <code>endsync</code> behavior is distinct from <a href="#smil21">[SMIL
-            2.1]</a> which uses a default value of <code>last</code>.</p>
-          </div>
-
-          <p>If the time container semantics of an element instance is <code>seq</code>,
-          then the temporal intervals of child elements are considered to apply in
-          sequence, i.e., sequentially in time. Furthermore, the specification of the
-          time interval of each child element is considered to be relative to the
-          temporal interval of its sibling elements, unless it is the first child
-          element, in which case it is considered to be relative to the temporal interval
-          of the container element instance.</p>
-
-          <p>Each time container is considered to constitute an independent time base,
-          i.e., time coordinate system.</p>
-
-          <p>If a <code>timeContainer</code> attribute is not specified on an element
-          that has time container semantics, then <code>par</code> time container
-          semantics must apply.</p>
-
-          <p>Time container semantics applies only to the following element types:</p>
-
-          <ul>
-            <li>
-              <p><a href="#document-structure-vocabulary-body"><code>body</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#layout-vocabulary-region"><code>region</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
-            </li>
-          </ul>
-
-          <p>The semantics of parallel and sequential time containment are those defined
-          by <a href="#smil21">[SMIL 2.1]</a>, § 10.4.2, while taking into account any
-          overriding semantics defined by this specification.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="timing-time-value-expressions" name=
-        "timing-time-value-expressions"></a>10.3 Time Value Expressions</h3>
-
-        <p>Timing attribute values include the use of the following expressions:</p>
-
-        <ul>
-          <li>
-            <p><a href="#timing-value-timeExpression"><b>10.3.1
-            &lt;timeExpression&gt;</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="timing-value-timeExpression" name=
-          "timing-value-timeExpression"></a>10.3.1 &lt;timeExpression&gt;</h4>
-
-          <p>A &lt;timeExpression&gt; is used to specify a coordinate within some time
-          base, where the applicable time base is determined by the
-          <code>ttp:timeBase</code> parameter, and where the semantics defined by
-          <a href="#time-expression-semantics"><b>N Time Expression Semantics</b></a>
-          apply.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#parameter-attribute-frameRate"><b>6.2.4
-            ttp:frameRate</b></a>, <a href="#parameter-attribute-subFrameRate"><b>6.2.9
-            ttp:subFrameRate</b></a>, <a href="#parameter-attribute-tickRate"><b>6.2.10
-            ttp:tickRate</b></a>, and <a href="#parameter-attribute-timeBase"><b>6.2.11
-            ttp:timeBase</b></a> for further information on explicit specification of
-            frame rate, sub-frame rate, tick rate, and time base.</p>
-          </div><a id="timeExpression-syntax" name="timeExpression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;timeExpression&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;timeExpression&gt;
-  : clock-time
-  | offset-time
-
-clock-time
-  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?
-
-offset-time
-  : time-count fraction? metric
-
-hours
-  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a>
-  | <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a> <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-minutes | seconds
-  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a>
-
-frames
-  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a>
-  | <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a> <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-sub-frames
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-fraction
-  : "." <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-time-count
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-metric
-  : "h"                 // hours
-  | "m"                 // minutes
-  | "s"                 // seconds
-  | "ms"                // milliseconds
-  | "f"                 // frames
-  | "t"                 // ticks
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a &lt;timeExpression&gt; is expressed in terms of a <em>clock-time</em>,
-          then leading zeroes are used when expressing hours, minutes, seconds, and
-          frames less than 10. Minutes are constrained to the range [0…59], while seconds
-          are constrained to [0…60], where the value 60 applies only to leap seconds.</p>
-
-          <p>If a &lt;timeExpression&gt; is expressed in terms of a <em>clock-time</em>
-          and a <em>frames</em> term is specified, then the value of this term must be
-          constrained to the interval [0…<em>F-1</em>], where <em>F</em> is the frame
-          rate determined by the <code>ttp:frameRate</code> parameter as defined by
-          <a href="#parameter-attribute-frameRate"><b>6.2.4 ttp:frameRate</b></a>. It is
-          considered an error if a <em>frames</em> term or <code>f</code> (frames) metric
-          is specified when the <code>clock</code> time base applies.</p>
-
-          <p>If a &lt;timeExpression&gt; is expressed in terms of a <em>clock-time</em>
-          and a <em>sub-frames</em> term is specified, then the value of this term must
-          be constrained to the interval [0…<em>S-1</em>], where <em>S</em> is the
-          sub-frame rate determined by the <code>ttp:subFrameRate</code> parameter as
-          defined by <a href="#parameter-attribute-subFrameRate"><b>6.2.9
-          ttp:subFrameRate</b></a>. It is considered an error if a <em>sub-frames</em>
-          term is specified when the <code>clock</code> time base applies.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="timing-time-intervals" name="timing-time-intervals"></a>10.4 Time
-        Intervals</h3>
-
-        <p>The semantics of time containment, durations, and intervals defined by
-        <a href="#smil21">[SMIL 2.1]</a> apply to the interpretation of like-named timed
-        elements and timing vocabulary defined by this specification, given the following
-        constraints:</p>
-
-        <ul>
-          <li>
-            <p>The implicit duration of an anonymous span is defined as follows: if the
-            anonymous span's parent time container is a parallel time container, then the
-            implicit duration is equivalent to the <code>indefinite</code> duration value
-            as defined by <a href="#smil21">[SMIL 2.1]</a>; if the anonymous span's
-            parent time container is a sequential time container, then the implicit
-            duration is equivalent to zero.</p>
-          </li>
-
-          <li>
-            <p>The implicit duration of a <code>body</code>, <code>div</code>,
-            <code>p</code>, or <code>span</code> element is determined in accordance to
-            (1) whether the element is a parallel or sequential time container, (2) the
-            default <code>endsync</code> semantics defined above by <a href=
-            "#timing-attribute-timeContainer"><b>10.2.4 timeContainer</b></a>, and (3)
-            the semantics of <a href="#smil21">[SMIL 2.1]</a> as applied to these time
-            containers.</p>
-          </li>
-
-          <li>
-            <p>The implicit duration of the <code>region</code> element is defined to be
-            equivalent to the <code>indefinite</code> duration value as defined by
-            <a href="#smil21">[SMIL 2.1]</a>.</p>
-          </li>
-
-          <li>
-            <p>If the governing time base is <code>clock</code>, then time expressions
-            are considered to be equivalent to wall-clock based timing in <a href=
-            "#smil21">[SMIL 2.1]</a>, where the specific semantics of <a href=
-            "#time-expression-semantics-clock"><b>N.1 Clock Time Base</b></a> apply.</p>
-          </li>
-
-          <li>
-            <p>If the governing time base is <code>media</code>, then time expressions
-            are considered to be equivalent to offset based timing in <a href=
-            "#smil21">[SMIL 2.1]</a>, where the specific semantics of <a href=
-            "#time-expression-semantics-media"><b>N.2 Media Time Base</b></a> apply.</p>
-          </li>
-
-          <li>
-            <p>If the governing time base is <code>smpte</code>, then time expressions
-            are considered to be equivalent to either offset based timing or event based
-            timing in <a href="#smil21">[SMIL 2.1]</a>, where the specific semantics of
-            <a href="#time-expression-semantics-smpte"><b>N.3 SMPTE Time Base</b></a>
-            apply.</p>
-          </li>
-        </ul>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="animation" name="animation"></a>11 Animation</h2>
-
-      <p>This section specifies the <em>animation</em> matter of the core vocabulary
-      catalog, where animation is to be understood as a separable layer of information
-      that combines timing and styling in order to denote authorial intention about
-      (temporally) dynamic styling of content.</p>
-
-      <div class="div2">
-        <h3><a id="animation-element-vocabulary" name=
-        "animation-element-vocabulary"></a>11.1 Animation Element Vocabulary</h3>
-
-        <p>The following elements specify the structure and principal animation aspects
-        of a <em>Document Instance</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#animation-vocabulary-set"><b>11.1.1 set</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="animation-vocabulary-set" name="animation-vocabulary-set"></a>11.1.1
-          set</h4>
-
-          <p>The <code>set</code> element is used as a child element of a content element
-          or a <code>region</code> element in order to express a discrete change of some
-          style parameter value that applies over some time interval.</p>
-
-          <p>The <code>set</code> element accepts as its children zero or more elements
-          in the <code>Metadata.class</code> element group.</p><a id="elt-syntax-set"
-          name="elt-syntax-set"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: set
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;set
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>a single attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*
-&lt;/set&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The use of multiple <code>set</code> element children may be used to
-            effect fade and position transitions.</p>
-          </div>
-
-          <p>An example of using the <code>set</code> element to animate content styling
-          is illustrated below:</p><a id="animation-vocabulary-set-example-1" name=
-          "animation-vocabulary-set-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Content Style Animation
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;p dur="5s" tts:color="yellow"&gt;
-<span class="strong">&lt;set begin="1s" dur="1s" tts:color="red"/&gt;</span>
-<span class="strong">&lt;set begin="2s" dur="1s" tts:color="green"/&gt;</span>
-<span class="strong">&lt;set begin="3s" dur="1s" tts:color="red"/&gt;</span>
-Text with Flashing Colors!
-&lt;/p&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the foreground color of the content "Text with
-            Flashing Colors" is animated from yellow, to red, to green, to red, then back
-            to yellow over a 5 second period.</p>
-          </div>
-
-          <p>An example of using the <code>set</code> element to animate region styling
-          is illustrated below:</p><a id="animation-vocabulary-set-example-2" name=
-          "animation-vocabulary-set-example-2"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Region Style Animation
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"
-    xmlns:ttp="http://www.w3.org/ns/ttml#parameter"
-    xmlns:tts="http://www.w3.org/ns/ttml#styling"
-    ttp:cellResolution="40 16"&gt;
-    &lt;head&gt;
-      &lt;layout&gt;
-        &lt;region xml:id="r1" timeContainer="seq"&gt;
-          <span class="strong">&lt;set dur="10s" tts:origin=" 8c 14c"/&gt;</span>
-          <span class="strong">&lt;set dur="2s"  tts:origin=" 2c  2c"/&gt;</span>
-          <span class="strong">&lt;set dur="3s"  tts:origin=" 8c 14c"/&gt;</span>
-          <span class="strong">&lt;set dur="2s"  tts:origin="14c  4c"/&gt;</span>
-          <span class="strong">&lt;set dur="10s" tts:origin=" 8c 14c"/&gt;</span>
-          &lt;style tts:extent="24c 2c"/&gt;
-        &lt;/region&gt;
-      &lt;/layout&gt;
-    &lt;/head&gt;
-    &lt;body region="r1"&gt;...&lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the root container region is divided into a cell
-            grid of 40 columns and 16 rows. A region, <code>r1</code>, with dimensions of
-            24 columns and 2 rows is then positioned within the root container region,
-            with its position varying over time in order to create an effect of moving
-            the region, which may be desirable so as to avoid obscuring characters in an
-            underlying video with captions.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the <code>set</code> element are based upon that defined
-            by <a href="#smil21">[SMIL 2.1]</a>, § 3.6.2.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="animation-attribute-vocabulary" name=
-        "animation-attribute-vocabulary"></a>11.2 Animation Attribute Vocabulary</h3>
-
-        <p>No animation related attribute vocabulary is defined for use in the core
-        vocabulary catalog.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="metadata" name="metadata"></a>12 Metadata</h2>
-
-      <p>This section specifies the <em>metadata</em> matter of the core vocabulary
-      catalog, where metadata is to be understood as a separable layer of information
-      that applies to parameters, content, style, layout, timing, and even metadata
-      itself, where the information represented by metadata takes one of two forms: (1)
-      metadata defined by this specification for standardized use in a <em>Document
-      Instance</em>, and (2) arbitrary metadata defined outside of the scope of this
-      specification, whose use and semantics depend entirely upon an application's use of
-      TTML Content.</p>
-
-      <div class="div2">
-        <h3><a id="metadata-element-vocabulary" name=
-        "metadata-element-vocabulary"></a>12.1 Metadata Element Vocabulary</h3>
-
-        <p>The <a href="#metadata-vocabulary-metadata"><b>12.1.1 metadata</b></a> element
-        serves as a generic container element for grouping metadata information.</p>
-
-        <p>In addition, the following elements, all defined in the TT Metadata Namespace,
-        provide standard representations for common metadata that is expected to be
-        commonly used in a <em>Document Instances</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#metadata-vocabulary-title"><b>12.1.2 ttm:title</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-desc"><b>12.1.3 ttm:desc</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-copyright"><b>12.1.4
-            ttm:copyright</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-agent"><b>12.1.5 ttm:agent</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-name"><b>12.1.6 ttm:name</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-actor"><b>12.1.7 ttm:actor</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-metadata" name=
-          "metadata-vocabulary-metadata"></a>12.1.1 metadata</h4>
-
-          <p>The <code>metadata</code> element functions as a generic container for
-          metadata information.</p>
-
-          <p>Metadata information may be expressed by a <code>metadata</code> element in
-          one of two (non-mutually exclusive) manners: (1) by specifying one or more
-          metadata attributes on the <code>metadata</code> element, and (2) by specifying
-          one or more child elements in the <code>metadata</code> element that express
-          metadata. Both types of metadata are referred to in this document as
-          <em>metadata items</em>.</p><a id="elt-syntax-metadata" name=
-          "elt-syntax-metadata"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;metadata
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> ({<em>any element in TT Metadata namespace</em>}|{<em>any element not in any TT namespace</em>})*
-&lt;/metadata&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The meaning of a specific metadata item must be evaluated in the context
-            of where it appears. The core vocabulary catalog permits an arbitrary number
-            of <code>metadata</code> element children of any content element type except
-            for the <code>tt</code> element. See specific element vocabulary definitions
-            for any constraints that apply to such usage.</p>
-          </div>
-
-          <p>The use of document metadata is illustrated by the following
-          example.</p><a id="metadata-vocabulary-metadata-example-1" name=
-          "metadata-vocabulary-metadata-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Document Metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;head&gt;
-  &lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
-    &lt;ttm:title&gt;Document Metadata Example&lt;/ttm:title&gt;
-    &lt;ttm:desc&gt;This document employs document metadata.&lt;/ttm:desc&gt;
-  &lt;/metadata&gt;
-&lt;/head&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The use of element metadata is illustrated by the following
-          example.</p><a id="metadata-vocabulary-metadata-example-2" name=
-          "metadata-vocabulary-metadata-example-2"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Element Metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;div&gt;
-  &lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
-    &lt;ttm:title&gt;Chapter 6 – Sherlock Holmes Gives a Demonstration&lt;/ttm:title&gt;
-    &lt;ttm:desc&gt;Holmes shows Watson how the murderer entered the window.&lt;/ttm:desc&gt;
-  &lt;/metadata&gt;
-&lt;/div&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The use of metadata attribute items is illustrated by the following
-          example.</p><a id="metadata-vocabulary-metadata-example-3" name=
-          "metadata-vocabulary-metadata-example-3"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Foreign Metadata Attribute Items
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;div xmlns:ext="http://example.org/ttaf1#metadata"&gt;
-  &lt;metadata ext:ednote="remove this division prior to publishing"/&gt;
-&lt;/div&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, a global attribute from a foreign (external)
-            namespace is used to express a metadata attribute that applies semantically
-            to the containing <code>div</code> element. Note that the attribute may also
-            be expressed directly on the <code>div</code> element; however, in this case
-            the author wishes to segregate certain metadata attributes by expressing them
-            indirectly on <code>metadata</code> elements.</p>
-          </div>
-
-          <p>The use of foreign element metadata is illustrated by the following
-          example.</p><a id="metadata-vocabulary-metadata-example-4" name=
-          "metadata-vocabulary-metadata-example-4"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Foreign Element Metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;metadata
-  xmlns:dc="http://purl.org/dc/elements/1.1/"
-  xmlns:dcterms="http://purl.org/dc/terms/"
-  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"&gt;
-  &lt;dc:title&gt;Foreign Element Metadata Example&lt;/dc:title&gt;
-  &lt;dc:description&gt;Express metadata using elements in foreign namespace.&lt;/dc:description&gt;
-  &lt;dc:format xsi:type="dcterms:IMT"&gt;application/ttml+xml&lt;/dc:format&gt;
-&lt;/metadata&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, a number of elements defined by the Dublin Core
-            metadata vocabulary are used to express document level metadata.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-title" name=
-          "metadata-vocabulary-title"></a>12.1.2 ttm:title</h4>
-
-          <p>The <code>ttm:title</code> element is used to express a human-readable title
-          of a specific element instance.</p><a id="elt-syntax-metadata-title" name=
-          "elt-syntax-metadata-title"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:title
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:title
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttm:title&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>No specific use of the <code>ttm:title</code> element is defined by this
-            specification.</p>
-          </div>
-
-          <p>Examples of the <code>ttm:title</code> element are shown above in <a href=
-          "#metadata-vocabulary-metadata-example-1"><b>Example Fragment – Document
-          Metadata</b></a> and <a href=
-          "#metadata-vocabulary-metadata-example-2"><b>Example Fragment – Element
-          Metadata</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-desc" name="metadata-vocabulary-desc"></a>12.1.3
-          ttm:desc</h4>
-
-          <p>The <code>ttm:desc</code> element is used to express a human-readable
-          description of a specific element instance.</p><a id="elt-syntax-metadata-desc"
-          name="elt-syntax-metadata-desc"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:desc
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:desc
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttm:desc&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>No specific use of the <code>ttm:desc</code> element is defined by this
-            specification.</p>
-          </div>
-
-          <p>Examples of the <code>ttm:desc</code> element are shown above in <a href=
-          "#metadata-vocabulary-metadata-example-1"><b>Example Fragment – Document
-          Metadata</b></a> and <a href=
-          "#metadata-vocabulary-metadata-example-2"><b>Example Fragment – Element
-          Metadata</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-copyright" name=
-          "metadata-vocabulary-copyright"></a>12.1.4 ttm:copyright</h4>
-
-          <p>The <code>ttm:copyright</code> element is used to express a human-readable
-          copyright that applies to some scoping level.</p>
-
-          <p>A copyright statement that applies to a document as a whole should appear as
-          a child of the <code>head</code> element.</p><a id=
-          "elt-syntax-metadata-copyright" name="elt-syntax-metadata-copyright"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:copyright
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:copyright
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttm:copyright&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>No specific use of the <code>ttm:copyright</code> element is defined by
-            this specification.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-agent" name=
-          "metadata-vocabulary-agent"></a>12.1.5 ttm:agent</h4>
-
-          <p>The <code>ttm:agent</code> element is used to define an agent for the
-          purpose of associating content information with an agent who is involved in the
-          production or expression of that content.</p>
-
-          <p>The <code>ttm:agent</code> element accepts as its children zero or more
-          <code>ttm:name</code> elements followed by zero or one <code>ttm:actor</code>
-          element.</p>
-
-          <p>At least one <code>ttm:name</code> element child should be specified that
-          expresses a name for the agent, whether it be the name of a person, character,
-          group, or organization.</p><a id="elt-syntax-metadata-agent" name=
-          "elt-syntax-metadata-agent"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:agent
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:agent
-  <span class=
-"reqattr">type</span> = (<em>person</em>|<em>character</em>|<em>group</em>|<em>organization</em>|<em>other</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#metadata-vocabulary-name">ttm:name</a>*, <a href=
-"#metadata-vocabulary-actor">ttm:actor</a>?
-&lt;/ttm:agent&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>A <code>type</code> attribute must be specified on each
-          <code>ttm:agent</code> element, and, if specified, must have one of the
-          following values:</p>
-
-          <ul>
-            <li>
-              <p><code>person</code></p>
-            </li>
-
-            <li>
-              <p><code>character</code></p>
-            </li>
-
-            <li>
-              <p><code>group</code></p>
-            </li>
-
-            <li>
-              <p><code>organization</code></p>
-            </li>
-
-            <li>
-              <p><code>other</code></p>
-            </li>
-          </ul>
-
-          <p>If the value of the <code>type</code> attribute is <code>character</code>,
-          then the <code>ttm:agent</code> element instance should specify a
-          <code>ttm:actor</code> child that specifies the agent that plays the role of
-          the actor.</p>
-
-          <p>A <code>ttm:agent</code> metadata item is considered to be significant only
-          when specified as a child of the <code>head</code> element or as a child of a
-          <code>metadata</code> element child of the <code>head</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>A <code>ttm:agent</code> element instance is typically referenced using a
-            <code>ttm:agent</code> attribute on a content element.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>If a character agent is played by multiple actors, then multiple character
-            agents may be specified (and referenced) wherein different definitions of the
-            character specify different actors.</p>
-          </div>
-
-          <p>The use of agent metadata is illustrated by the following example.</p><a id=
-          "metadata-vocabulary-agent-example-1" name=
-          "metadata-vocabulary-agent-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Agent Metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-
-&lt;tt xml:lang="en" xmlns="http://www.w3.org/ns/ttml" xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
-  &lt;head&gt;
-    <span class="strong">&lt;ttm:agent xml:id="connery" type="person"&gt;</span>
-      &lt;ttm:name type="family"&gt;Connery&lt;/ttm:name&gt;
-      &lt;ttm:name type="given"&gt;Thomas Sean&lt;/ttm:name&gt;
-      &lt;ttm:name type="alias"&gt;Sean&lt;/ttm:name&gt;
-      &lt;ttm:name type="full"&gt;Sir Thomas Sean Connery&lt;/ttm:name&gt;
-    <span class="strong">&lt;/ttm:agent&gt;</span>
-    <span class="strong">&lt;ttm:agent xml:id="bond" type="character"&gt;</span>
-      &lt;ttm:name type="family"&gt;Bond&lt;/ttm:name&gt;
-      &lt;ttm:name type="given"&gt;James&lt;/ttm:name&gt;
-      &lt;ttm:name type="alias"&gt;007&lt;/ttm:name&gt;
-      &lt;ttm:actor agent="connery"/&gt;
-    <span class="strong">&lt;/ttm:agent&gt;</span>
-  &lt;/head&gt;
-  &lt;body&gt;
-    &lt;div&gt;
-      ...  
-      &lt;p <span class=
-"strong">ttm:agent="bond"</span>&gt;I travel, a sort of licensed troubleshooter.&lt;/p&gt;
-      ...  
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, two agents, a real (person) agent, Sean Connery, and
-            a fictitious (character) agent, James Bond, are defined, where the latter is
-            linked to the former by means of the a <code>ttm:actor</code> element. A
-            reference is then made from content (the <code>p</code> element) to the
-            character agent associated with (responsible for producing) that content.
-            Note that in this example the <code>ttm:agent</code> metadata items are
-            specified as immediate children of the document's <code>head</code> element
-            rather than being placed in a container <code>metadata</code> element.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-name" name="metadata-vocabulary-name"></a>12.1.6
-          ttm:name</h4>
-
-          <p>The <code>ttm:name</code> element is used to specify a name of a person,
-          character, group, or organization.</p><a id="elt-syntax-metadata-name" name=
-          "elt-syntax-metadata-name"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:name
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:name
-  <span class=
-"reqattr">type</span> = (<em>full</em>|<em>family</em>|<em>given</em>|<em>alias</em>|<em>other</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttm:name&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>A <code>type</code> attribute must be specified on each
-          <code>ttm:name</code> element, and, if specified, must have one of the
-          following values:</p>
-
-          <ul>
-            <li>
-              <p><code>full</code></p>
-            </li>
-
-            <li>
-              <p><code>family</code></p>
-            </li>
-
-            <li>
-              <p><code>given</code></p>
-            </li>
-
-            <li>
-              <p><code>alias</code></p>
-            </li>
-
-            <li>
-              <p><code>other</code></p>
-            </li>
-          </ul>
-
-          <p>The relationship between the type of a name and the syntactic expression of
-          the name is not defined by this specification.</p>
-
-          <p>Two examples of the <code>ttm:name</code> element are shown above in
-          <a href="#metadata-vocabulary-agent-example-1"><b>Example Fragment – Agent
-          Metadata</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-actor" name=
-          "metadata-vocabulary-actor"></a>12.1.7 ttm:actor</h4>
-
-          <p>The <code>ttm:actor</code> element is used to link the definition of a
-          (role-based) character agent with another agent that portrays the
-          character.</p><a id="elt-syntax-metadata-actor" name=
-          "elt-syntax-metadata-actor"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:actor
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:actor
-  <span class="reqattr">agent</span> = IDREF
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> EMPTY
-&lt;/ttm:actor&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The <code>agent</code> attribute of a <code>ttm:actor</code> element must
-          reference a <code>ttm:agent</code> element that denotes the person, group, or
-          organization acting the part of a character.</p>
-
-          <p>An example of the <code>ttm:actor</code> element is shown above in <a href=
-          "#metadata-vocabulary-agent-example-1"><b>Example Fragment – Agent
-          Metadata</b></a>.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="metadata-attribute-vocabulary" name=
-        "metadata-attribute-vocabulary"></a>12.2 Metadata Attribute Vocabulary</h3>
-
-        <p>This section specifies the following attributes in the TT Metadata Namespace
-        for use with the <code>metadata</code> element and with certain content
-        elements:</p>
-
-        <ul>
-          <li>
-            <p><a href="#metadata-attribute-agent"><b>12.2.1 ttm:agent</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-attribute-role"><b>12.2.2 ttm:role</b></a></p>
-          </li>
-        </ul>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>Only certain metadata item attributes may be used with content elements. See
-          the definitions of content elements to determine permissible usage.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-attribute-agent" name="metadata-attribute-agent"></a>12.2.1
-          ttm:agent</h4>
-
-          <p>The <code>ttm:agent</code> attribute takes an <code>IDREFS</code> value, and
-          is used with certain content elements to designate the agents that perform or
-          are involved in the performance of the content.</p>
-
-          <p>If specified, a <code>ttm:agent</code> attribute must reference
-          <code>ttm:agent</code> element instances that appear as a descendent of the
-          same <em>Document Instance</em> as that of the referring element.</p>
-
-          <p>An example of the <code>ttm:agent</code> attribute is shown above in
-          <a href="#metadata-vocabulary-agent-example-1"><b>Example Fragment – Agent
-          Metadata</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-attribute-role" name="metadata-attribute-role"></a>12.2.2
-          ttm:role</h4>
-
-          <p>The <code>ttm:role</code> attribute may be used by a content author to
-          express the roles, functions, or characteristics of some content element that
-          is so labeled.</p>
-
-          <p>If specified, the value of this attribute must adhere to the following
-          syntax, where the syntactic element <em>S</em> must adhere to production [3]
-          <code>S</code> as defined by <a href="#xml10">[XML 1.0]</a>&nbsp;§
-          2.3:</p><a id="metadata-attribute-role-syntax" name=
-          "metadata-attribute-role-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttm:role
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttm:role
-  role ( <em>S</em> role )*
-
-role
-  : "action"
-  | "caption"
-  | "description"
-  | "dialog"
-  | "expletive"
-  | "kinesic"
-  | "lyrics"
-  | "music"
-  | "narration"
-  | "quality"
-  | "sound"
-  | "source"
-  | "suppressed"
-  | "reproduction"
-  | "thought"
-  | "title"
-  | "transcription"
-  | extension-role
-
-extension-role
-  : "x-" token-char+
-
-token-char
-  : { XML NameChar }    // XML 1.1 Production [4a]
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>All values of <code>ttm:role</code> that do not start with the prefix
-            <code>x-</code> are reserved for future standardization.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>If using a custom <code>x-</code> prefixed form of <code>ttm:role</code>,
-            it is recommended that an organization unique infix be used as well in order
-            to prevent collisions. For example, <code>x-example-org-custom-role</code>.
-            Furthermore, a registry for role values is available at <a href=
-            "http://www.w3.org/wiki/TTML/RoleRegistry">http://www.w3.org/wiki/TTML/RoleRegistry</a>
-            in order to promote interoperability and collision avoidance.</p>
-          </div>
-        </div>
-      </div>
-    </div>
-  </div>
-
-  <div class="back">
-    <div class="div1">
-      <h2><a id="reduced-infoset" name="reduced-infoset"></a>A Reduced XML Infoset</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>For the purposes of this specification, a <em>Reduced XML Infoset</em> is an XML
-      Information Set <a href="#infoset">[XML InfoSet]</a> that consists of only the
-      following information items and information item properties:</p>
-
-      <div class="div2">
-        <h3><a id="reduced-infoset-document" name="reduced-infoset-document"></a>A.1
-        Document Information Item</h3>
-
-        <ul>
-          <li>
-            <p><code>[document element]</code></p>
-          </li>
-        </ul>
-      </div>
-
-      <div class="div2">
-        <h3><a id="reduced-infoset-element" name="reduced-infoset-element"></a>A.2
-        Element Information Item</h3>
-
-        <ul>
-          <li>
-            <p><code>[namespace URI]</code></p>
-          </li>
-
-          <li>
-            <p><code>[local name]</code></p>
-          </li>
-
-          <li>
-            <p><code>[children]</code></p>
-          </li>
-
-          <li>
-            <p><code>[attributes]</code></p>
-          </li>
-        </ul>
-
-        <p>Child information items <code>[children]</code> are reduced to only element
-        and character information items.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="reduced-infoset-attribute" name="reduced-infoset-attribute"></a>A.3
-        Attribute Information Item</h3>
-
-        <ul>
-          <li>
-            <p><code>[namespace URI]</code></p>
-          </li>
-
-          <li>
-            <p><code>[local name]</code></p>
-          </li>
-
-          <li>
-            <p><code>[normalized value]</code></p>
-          </li>
-        </ul>
-      </div>
-
-      <div class="div2">
-        <h3><a id="reduced-infoset-character" name="reduced-infoset-character"></a>A.4
-        Character Information Item</h3>
-
-        <ul>
-          <li>
-            <p><code>[character code]</code></p>
-          </li>
-        </ul>
-
-        <p>Contiguous character information items are not required to be represented
-        distinctly, but may be aggregated (chunked) into a sequence of character codes
-        (i.e., a character string).</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="schemas" name="schemas"></a>B Schemas</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix specifies the following schemas for use with <em>Document
-      Instances</em>:</p>
-
-      <ul>
-        <li>
-          <p>Relax NG, Compact Syntax (RNC) Schema</p>
-        </li>
-
-        <li>
-          <p>XML Schema Definition (XSD) Schema</p>
-        </li>
-      </ul>
-
-      <p>In any case where a schema specified by this appendix differs from the normative
-      definitions of document type, element type, or attribute type as defined by the
-      body of this specification, then the body of this specification takes
-      precedence.</p>
-
-      <div class="div2">
-        <h3><a id="ttml-schema-rnc" name="ttml-schema-rnc"></a>B.1 Relax NG Compact (RNC)
-        Schema</h3>
-
-        <p>A Relax NG Compact Syntax (RNC) <a href="#rng">[RELAX NG]</a> based schema for
-        TTML Content is available at <a href="rnc/schema.zip">ZIP Archive</a>. This
-        schema does not normatively define the validity of Timed Text Markup Language
-        content as defined by this specification. In particular, the formal validity of
-        TTML Content is defined by <a href="#conformance-content"><b>3.1 Content
-        Conformance</b></a>.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="ttml-schema-xsd" name="ttml-schema-xsd"></a>B.2 XML Schema Definition
-        (XSD) Schema</h3>
-
-        <p>A W3C XML Schema Definition (XSD) <a href="#xsd-1">[XML Schema Part 1]</a>
-        based schema for TTML Content is available at <a href="xsd/schema.zip">ZIP
-        Archive</a>. This schema does not normatively define the validity of Timed Text
-        Markup Language content as defined by this specification. In particular, the
-        formal validity of TTML Content is defined by <a href=
-        "#conformance-content"><b>3.1 Content Conformance</b></a>.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="media-types-registration" name="media-types-registration"></a>C Media
-      Type Registration</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix registers a new media type, "application/ttml+xml" in conformance
-      with <a href="http://www.ietf.org/rfc/rfc4288.txt">BCP 13</a> and <a href=
-      "http://www.w3.org/2002/06/registering-mediatype.html">W3CRegMedia</a>. The
-      information in this appendix is being submitted to the Internet Engineering
-      Steering Group (IESG) for review, approval, and registration with the Internet
-      Assigned Numbers Authority (IANA).</p>
-
-      <dl>
-        <dt class="label">Type name:</dt>
-
-        <dd>
-          <p>application</p>
-        </dd>
-
-        <dt class="label">Subtype name:</dt>
-
-        <dd>
-          <p>ttml+xml</p>
-        </dd>
-
-        <dt class="label">Required parameters:</dt>
-
-        <dd>
-          <p>None.</p>
-        </dd>
-
-        <dt class="label">Optional parameters:</dt>
-
-        <dd>
-          <dl>
-            <dt class="label">charset</dt>
-
-            <dd>
-              <p>If specified, the <code>charset</code> parameter must match the XML
-              encoding declaration, or if absent, the actual encoding.</p>
-            </dd>
-
-            <dt class="label">profile</dt>
-
-            <dd>
-              <p>The document profile of a <em>Document Instance</em> may be specified
-              using an optional <code>profile</code> parameter, which, if specified, the
-              value of which must adhere to the syntax and semantics of
-              <code>ttp:profile</code> parameter defined by Section <a href=
-              "#parameter-attribute-profile"><b>6.2.8 ttp:profile</b></a> of the
-              published specification.</p>
-            </dd>
-          </dl>
-        </dd>
-
-        <dt class="label">Encoding considerations:</dt>
-
-        <dd>
-          <p>Same for application/xml, except constrained to either UTF-8 or UTF-16. See
-          <a href="#xml-media">[XML Media]</a>, Section 3.2.</p>
-        </dd>
-
-        <dt class="label">Security considerations:</dt>
-
-        <dd>
-          <p>As with other XML types and as noted in <a href="#xml-media">[XML Media]</a>
-          Section 10, repeated expansion of maliciously constructed XML entities can be
-          used to consume large amounts of memory, which may cause XML processors in
-          constrained environments to fail.</p>
-
-          <p>In addition, because of the extensibility features for TTML and of XML in
-          general, it is possible that "application/ttml+xml" may describe content that
-          has security implications beyond those described here. However, TTML does not
-          provide for any sort of active or executable content, and if the processor
-          follows only the normative semantics of the published specification, this
-          content will be outside TTML namespaces and may be ignored. Only in the case
-          where the processor recognizes and processes the additional content, or where
-          further processing of that content is dispatched to other processors, would
-          security issues potentially arise. And in that case, they would fall outside
-          the domain of this registration document.</p>
-
-          <p>Although not prohibited, there are no expectations that XML signatures or
-          encryption would normally be employed.</p>
-        </dd>
-
-        <dt class="label">Interoperability considerations:</dt>
-
-        <dd>
-          <p>The published specification describes processing semantics that dictate
-          behavior that must be followed when dealing with, among other things,
-          unrecognized elements and attributes, both in TTML namespaces and in other
-          namespaces.</p>
-
-          <p>Because TTML is extensible, conformant "application/ttml+xml" processors
-          must expect that content received is well-formed XML, but it cannot be
-          guaranteed that the content is valid to a particular DTD or Schema or that the
-          processor will recognize all of the elements and attributes in the
-          document.</p>
-        </dd>
-
-        <dt class="label">Published specification:</dt>
-
-        <dd>
-          <p>This media type registration is extracted from Appendix C Media Type
-          Registration of the Timed Text Markup Language (TTML) 1.0 specification:
-          <a href="http://www.w3.org/TR/ttaf1-dfxp/">Timed Text Markup Language (TTML)
-          1.0</a>.</p>
-        </dd>
-
-        <dt class="label">Applications that use this media type:</dt>
-
-        <dd>
-          <p>TTML is used in the television industry for the purpose of authoring,
-          transcoding and exchanging timed text information and for delivering captions
-          for television material repurposed for the internet.</p>
-
-          <p>There is partial and full support of TTML in components used by several Web
-          browsers plugins, and in a number of caption authoring tools.</p>
-        </dd>
-
-        <dt class="label">Additional information:</dt>
-
-        <dd>
-          <dl>
-            <dt class="label">Magic number(s):</dt>
-
-            <dt class="label">File extension(s):</dt>
-
-            <dd>
-              <p>.ttml</p>
-            </dd>
-
-            <dt class="label">Macintosh file type code(s):</dt>
-
-            <dd>
-              <p>"TTML"</p>
-            </dd>
-
-            <dt class="label">Fragment identifiers:</dt>
-
-            <dd>
-              <p>For documents labeled as application/ttml+xml, the fragment identifier
-              notation is intended to be used with xml:id attributes, as described in
-              section 7.2.1 of the <a href="http://www.w3.org/TR/ttaf1-dfxp/">Timed Text
-              Markup Language (TTML) 1.0</a> specification.</p>
-            </dd>
-          </dl>
-        </dd>
-
-        <dt class="label">Person &amp; email address to contact for further
-        information:</dt>
-
-        <dd>
-          <p>Timed Text Working Group (public-tt@w3.org)</p>
-        </dd>
-
-        <dt class="label">Intended usage:</dt>
-
-        <dd>
-          <p>COMMON</p>
-        </dd>
-
-        <dt class="label">Restrictions on usage:</dt>
-
-        <dd>
-          <p>None</p>
-        </dd>
-
-        <dt class="label">Author:</dt>
-
-        <dd>
-          <p>The published specification is a work product of the World Wide Web
-          Consortium's Timed Text (TT) Working Group.</p>
-        </dd>
-
-        <dt class="label">Change controller:</dt>
-
-        <dd>
-          <p>The W3C has change control over this specification.</p>
-        </dd>
-      </dl>
-    </div>
-
-    <div class="div1">
-      <h2><a id="features" name="features"></a>D Features</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix specifies (1) a set of feature designations, each of which labels
-      one or more syntactic and/or semantic features defined by this specification, and
-      (2) for each designated feature, whether the feature is mandatory or optional for a
-      transformation or presentation processor.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>A TTML processor is said to <em>implement the transformation semantics</em> or
-        <em>implement the presentation semantics</em> of feature designation <em>F</em>
-        if it satisfies the requirements of this appendix with respect to the definition
-        of feature designation <em>F</em> as pertains to transformation or presentation
-        processing, respectively.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="feature-designations" name="feature-designations"></a>D.1 Feature
-        Designations</h3>
-
-        <p>A feature designation is expressed as a string that adheres to the following
-        form:</p>
-
-        <div class="exampleInner">
-          <pre>
-feature-designation
-  : feature-namespace designation
-
-feature-namespace
-  : <em>TT Feature Namespace</em>                    // http://www.w3.org/ns/ttml/feature/
-
-designation
-  : "#" token-char+
-
-token-char
-  : { XML NameChar }                        // XML 1.1 Production [4a]
-</pre>
-        </div>
-
-        <p>All values of <code>feature-designation</code> not defined by this
-        specification are reserved for future standardization.</p>
-
-        <p>The following sub-sections define all feature designations, expressed as
-        relative URIs (fragment identifiers) with respect to the TT Feature Namespace
-        base URI.</p>
-
-        <div class="div3">
-          <h4><a id="feature-animation" name="feature-animation"></a>D.1.1
-          #animation</h4>
-
-          <p>A TTML transformation processor supports the <code>#animation</code> feature
-          if it recognizes and is capable of transforming the following vocabulary
-          defined by <a href="#animation"><b>11 Animation</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#animation-vocabulary-set"><code>set</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#animation</code> feature
-          if it implements presentation semantic support for the same vocabulary
-          enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-backgroundColor" name="feature-backgroundColor"></a>D.1.2
-          #backgroundColor</h4>
-
-          <p>A TTML transformation processor supports the <code>#backgroundColor</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#backgroundColor</code>
-          feature if it (1) implements presentation semantic support for the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute and (2) is capable of displaying or generating an output display
-          signal that distinguishes between at least sixteen (16) values of color,
-          including all primary and secondary colors of the SRGB color space.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-backgroundColor-block" name=
-          "feature-backgroundColor-block"></a>D.1.3 #backgroundColor-block</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#backgroundColor-block</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a content element that would generate a block area
-          during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#backgroundColor-block</code> feature if it (1) implements presentation
-          semantic support for the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a content element that generates a block area and (2)
-          is capable of displaying or generating an output display signal that
-          distinguishes between at least sixteen (16) values of color, including all
-          primary and secondary colors of the SRGB color space.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-backgroundColor-inline" name=
-          "feature-backgroundColor-inline"></a>D.1.4 #backgroundColor-inline</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#backgroundColor-inline</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a content element that would generate an inline area
-          during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#backgroundColor-inline</code> feature if it (1) implements presentation
-          semantic support for the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a content element that generates an inline area and
-          (2) is capable of displaying or generating an output display signal that
-          distinguishes between at least sixteen (16) values of color, including all
-          primary and secondary colors of the SRGB color space.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-backgroundColor-region" name=
-          "feature-backgroundColor-region"></a>D.1.5 #backgroundColor-region</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#backgroundColor-region</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#backgroundColor-region</code> feature if it (1) implements presentation
-          semantic support for the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element and (2) is capable
-          of displaying or generating an output display signal that distinguishes between
-          at least sixteen (16) values of color, including all primary and secondary
-          colors of the SRGB color space .</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-bidi" name="feature-bidi"></a>D.1.6 #bidi</h4>
-
-          <p>A TTML processor supports the <code>#bidi</code> feature if it supports the
-          following features:</p>
-
-          <ul>
-            <li>
-              <p><a href="#feature-direction"><code>#direction</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-unicodeBidi"><code>#unicodeBidi</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#feature-writingMode-horizontal"><code>#writingMode-horizontal</code></a></p>
-            </li>
-          </ul>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-cellResolution" name="feature-cellResolution"></a>D.1.7
-          #cellResolution</h4>
-
-          <p>A TTML transformation processor supports the <code>#cellResolution</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#cellResolution</code>
-          feature if it implements presentation semantic support for the <a href=
-          "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-clockMode" name="feature-clockMode"></a>D.1.8
-          #clockMode</h4>
-
-          <p>A TTML transformation processor supports the <code>#clockMode</code> feature
-          if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#clockMode</code> feature
-          if it implements presentation semantic support for the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-clockMode-gps" name="feature-clockMode-gps"></a>D.1.9
-          #clockMode-gps</h4>
-
-          <p>A TTML transformation processor supports the <code>#clockMode-gps</code>
-          feature if it recognizes and is capable of transforming the <code>gps</code>
-          value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#clockMode-gps</code>
-          feature if it implements presentation semantic support for the <code>gps</code>
-          value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-clockMode-local" name="feature-clockMode-local"></a>D.1.10
-          #clockMode-local</h4>
-
-          <p>A TTML transformation processor supports the <code>#clockMode-local</code>
-          feature if it recognizes and is capable of transforming the <code>local</code>
-          value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#clockMode-local</code>
-          feature if it implements presentation semantic support for the
-          <code>local</code> value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-clockMode-utc" name="feature-clockMode-utc"></a>D.1.11
-          #clockMode-utc</h4>
-
-          <p>A TTML transformation processor supports the <code>#clockMode-utc</code>
-          feature if it recognizes and is capable of transforming the <code>utc</code>
-          value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#clockMode-utc</code>
-          feature if it implements presentation semantic support for the <code>utc</code>
-          value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-color" name="feature-color"></a>D.1.12 #color</h4>
-
-          <p>A TTML transformation processor supports the <code>#color</code> feature if
-          it recognizes and is capable of transforming the <a href=
-          "#style-attribute-color"><code>tts:color</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#color</code> feature if it
-          (1) implements presentation semantic support for the <a href=
-          "#style-attribute-color"><code>tts:color</code></a> attribute and (2) is
-          capable of displaying or generating an output display signal that distinguishes
-          between at least sixteen (16) values of color, including all primary and
-          secondary colors of the SRGB color space.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-content" name="feature-content"></a>D.1.13 #content</h4>
-
-          <p>A TTML transformation processor supports the <code>#content</code> feature
-          if it recognizes and is capable of transforming the following vocabulary
-          defined by <a href="#content"><b>7 Content</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#document-structure-vocabulary-body"><code>body</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-br"><code>br</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#content</code> feature if
-          it implements presentation semantic support for the same vocabulary enumerated
-          above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-core" name="feature-core"></a>D.1.14 #core</h4>
-
-          <p>A TTML transformation processor supports the <code>#core</code> feature if
-          it recognizes and is capable of transforming the following core attributes
-          vocabulary defined by <a href="#content"><b>7 Content</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#content-attribute-id">@<code>xml:id</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-attribute-id">@<code>xml:lang</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-attribute-id">@<code>xml:space</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#core</code> feature if it
-          implements presentation semantic support for the same vocabulary enumerated
-          above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-direction" name="feature-direction"></a>D.1.15
-          #direction</h4>
-
-          <p>A TTML transformation processor supports the <code>#direction</code> feature
-          if it recognizes and is capable of transforming all defined values of the
-          <a href="#style-attribute-direction"><code>tts:direction</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#direction</code> feature
-          if it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-direction"><code>tts:direction</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-display" name="feature-display"></a>D.1.16 #display</h4>
-
-          <p>A TTML transformation processor supports the <code>#display</code> feature
-          if it recognizes and is capable of transforming all defined values of the
-          <a href="#style-attribute-display"><code>tts:display</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#display</code> feature if
-          it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-display"><code>tts:display</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-display-block" name="feature-display-block"></a>D.1.17
-          #display-block</h4>
-
-          <p>A TTML transformation processor supports the <code>#display-block</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a content element that would generate a block area during
-          presentation processing.</p>
-
-          <p>A TTML presentation processor supports the <code>#display-block</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href="#style-attribute-display"><code>tts:display</code></a>
-          attribute when applied to a content element that generates a block area.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-display-inline" name="feature-display-inline"></a>D.1.18
-          #display-inline</h4>
-
-          <p>A TTML transformation processor supports the <code>#display-inline</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a content element that would generate an inline area during
-          presentation processing.</p>
-
-          <p>A TTML presentation processor supports the <code>#display-inline</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href="#style-attribute-display"><code>tts:display</code></a>
-          attribute when applied to a content element that generates an inline area.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-display-region" name="feature-display-region"></a>D.1.19
-          #display-region</h4>
-
-          <p>A TTML transformation processor supports the <code>#display-region</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a <a href="#layout-vocabulary-region"><code>region</code></a>
-          element.</p>
-
-          <p>A TTML presentation processor supports the <code>#display-region</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href="#style-attribute-display"><code>tts:display</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-displayAlign" name="feature-displayAlign"></a>D.1.20
-          #displayAlign</h4>
-
-          <p>A TTML transformation processor supports the <code>#displayAlign</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-displayAlign"><code>tts:displayAlign</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#displayAlign</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href=
-          "#style-attribute-displayAlign"><code>tts:displayAlign</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-dropMode" name="feature-dropMode"></a>D.1.21 #dropMode</h4>
-
-          <p>A TTML transformation processor supports the <code>#dropMode</code> feature
-          if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#dropMode</code> feature if
-          it implements presentation semantic support for the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-dropMode-dropNTSC" name=
-          "feature-dropMode-dropNTSC"></a>D.1.22 #dropMode-dropNTSC</h4>
-
-          <p>A TTML transformation processor supports the <code>#dropMode-dropNTSC</code>
-          feature if it recognizes and is capable of transforming the
-          <code>dropNTSC</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#dropMode-dropNTSC</code>
-          feature if it implements presentation semantic support for the
-          <code>dropNTSC</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-dropMode-dropPAL" name="feature-dropMode-dropPAL"></a>D.1.23
-          #dropMode-dropPAL</h4>
-
-          <p>A TTML transformation processor supports the <code>#dropMode-dropPAL</code>
-          feature if it recognizes and is capable of transforming the
-          <code>dropPAL</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#dropMode-dropPAL</code>
-          feature if it implements presentation semantic support for the
-          <code>dropPAL</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-dropMode-nonDrop" name="feature-dropMode-nonDrop"></a>D.1.24
-          #dropMode-nonDrop</h4>
-
-          <p>A TTML transformation processor supports the <code>#dropMode-nonDrop</code>
-          feature if it recognizes and is capable of transforming the
-          <code>nonDrop</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#dropMode-nonDrop</code>
-          feature if it implements presentation semantic support for the
-          <code>nonDrop</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-extent" name="feature-extent"></a>D.1.25 #extent</h4>
-
-          <p>A TTML transformation processor supports the <code>#extent</code> feature if
-          it recognizes and is capable of transforming the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#extent</code> feature if
-          it implements presentation semantic support for the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-extent-region" name="feature-extent-region"></a>D.1.26
-          #extent-region</h4>
-
-          <p>A TTML transformation processor supports the <code>#extent-region</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute when applied to
-          a <a href="#layout-vocabulary-region"><code>region</code></a> element.</p>
-
-          <p>A TTML presentation processor supports the <code>#extent-region</code>
-          feature if it implements presentation semantic support for the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute when applied to
-          a <a href="#layout-vocabulary-region"><code>region</code></a> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-extent-root" name="feature-extent-root"></a>D.1.27
-          #extent-root</h4>
-
-          <p>A TTML transformation processor supports the <code>#extent-root</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute when applied to
-          the <a href="#document-structure-vocabulary-tt"><code>tt</code></a>
-          element.</p>
-
-          <p>A TTML presentation processor supports the <code>#extent-root</code> feature
-          if it implements presentation semantic support for the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute when applied to
-          a <a href="#document-structure-vocabulary-tt"><code>tt</code></a> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontFamily" name="feature-fontFamily"></a>D.1.28
-          #fontFamily</h4>
-
-          <p>A TTML transformation processor supports the <code>#fontFamily</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontFamily</code> feature
-          if it implements presentation semantic support for the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontFamily-generic" name=
-          "feature-fontFamily-generic"></a>D.1.29 #fontFamily-generic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontFamily-generic</code> feature if it recognizes and is capable of
-          transforming <a href=
-          "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a> values when used
-          with the <a href="#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontFamily-generic</code>
-          feature if it implements presentation semantic support for <a href=
-          "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a> values when used
-          with the <a href="#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontFamily-non-generic" name=
-          "feature-fontFamily-non-generic"></a>D.1.30 #fontFamily-non-generic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontFamily-non-generic</code> feature if it recognizes and is capable of
-          transforming <a href="#style-value-familyName">&lt;familyName&gt;</a> values
-          when used with the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontFamily-non-generic</code> feature if it implements presentation
-          semantic support for <a href="#style-value-familyName">&lt;familyName&gt;</a>
-          values when used with the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontSize" name="feature-fontSize"></a>D.1.31 #fontSize</h4>
-
-          <p>A TTML transformation processor supports the <code>#fontSize</code> feature
-          if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontSize</code> feature if
-          it implements presentation semantic support for the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontSize-anamorphic" name=
-          "feature-fontSize-anamorphic"></a>D.1.32 #fontSize-anamorphic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontSize-anamorphic</code> feature if it recognizes and is capable of
-          transforming values of the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute that
-          consist of two <a href="#style-value-length">&lt;length&gt;</a>
-          specifications.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontSize-anamorphic</code>
-          feature if it implements presentation semantic support for defined values of
-          the <a href="#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute
-          that consist of two <a href="#style-value-length">&lt;length&gt;</a>
-          specifications.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontSize-isomorphic" name=
-          "feature-fontSize-isomorphic"></a>D.1.33 #fontSize-isomorphic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontSize-isomorphic</code> feature if it recognizes and is capable of
-          transforming values of the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute that
-          consist of a single <a href="#style-value-length">&lt;length&gt;</a>
-          specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontSize-isomorphic</code>
-          feature if it implements presentation semantic support for defined values of
-          the <a href="#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute
-          that consist of a single <a href="#style-value-length">&lt;length&gt;</a>
-          specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontStyle" name="feature-fontStyle"></a>D.1.34
-          #fontStyle</h4>
-
-          <p>A TTML transformation processor supports the <code>#fontStyle</code> feature
-          if it recognizes and is capable of transforming all defined values of the
-          <a href="#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontStyle</code> feature
-          if it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontStyle-italic" name="feature-fontStyle-italic"></a>D.1.35
-          #fontStyle-italic</h4>
-
-          <p>A TTML transformation processor supports the <code>#fontStyle-italic</code>
-          feature if it recognizes and is capable of transforming the <code>italic</code>
-          value of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontStyle-italic</code>
-          feature if it implements presentation semantic support for the
-          <code>italic</code> of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontStyle-oblique" name=
-          "feature-fontStyle-oblique"></a>D.1.36 #fontStyle-oblique</h4>
-
-          <p>A TTML transformation processor supports the <code>#fontStyle-oblique</code>
-          feature if it recognizes and is capable of transforming the
-          <code>oblique</code> value of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontStyle-oblique</code>
-          feature if it implements presentation semantic support for the
-          <code>oblique</code> of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontWeight" name="feature-fontWeight"></a>D.1.37
-          #fontWeight</h4>
-
-          <p>A TTML transformation processor supports the <code>#fontWeight</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontWeight</code> feature
-          if it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontWeight-bold" name="feature-fontWeight-bold"></a>D.1.38
-          #fontWeight-bold</h4>
-
-          <p>A TTML transformation processor supports the <code>#fontWeight-bold</code>
-          feature if it recognizes and is capable of transforming <code>bold</code> value
-          of the <a href="#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontWeight-bold</code>
-          feature if it implements presentation semantic support for the
-          <code>bold</code> of the <a href=
-          "#style-attribute-fontWeight"><code>tts:fontWeight</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-frameRate" name="feature-frameRate"></a>D.1.39
-          #frameRate</h4>
-
-          <p>A TTML transformation processor supports the <code>#frameRate</code> feature
-          if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#frameRate</code> feature
-          if it implements presentation semantic support for the <a href=
-          "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-frameRateMultiplier" name=
-          "feature-frameRateMultiplier"></a>D.1.40 #frameRateMultiplier</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#frameRateMultiplier</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#frameRateMultiplier</code>
-          feature if it implements presentation semantic support for the <a href=
-          "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-layout" name="feature-layout"></a>D.1.41 #layout</h4>
-
-          <p>A TTML transformation processor supports the <code>#layout</code> feature if
-          it (1) recognizes and is capable of transforming the following vocabulary
-          defined by <a href="#layout"><b>9 Layout</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#layout-vocabulary-layout"><code>layout</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#layout-vocabulary-region"><code>region</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#layout-attribute-region">@<code>region</code></a></p>
-            </li>
-          </ul>
-
-          <p>and (2) supports the following attributes when applied to the <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element:</p>
-
-          <ul>
-            <li>
-              <p><a href="#style-attribute-extent"><code>tts:extent</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#style-attribute-origin"><code>tts:origin</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#layout</code> feature if
-          it implements presentation semantic support for the same vocabulary and
-          features enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length" name="feature-length"></a>D.1.42 #length</h4>
-
-          <p>A TTML transformation processor supports the <code>#length</code> feature if
-          it recognizes and is capable of transforming all defined values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the <code>#length</code> feature if
-          it implements presentation semantic support for all defined values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length</code> is intended to imply support for the
-            following features: <code>#length-integer</code>, <code>#length-real</code>,
-            <code>#length-positive</code>, <code>#length-negative</code>,
-            <code>#length-cell</code>, <code>#length-em</code>,
-            <code>#length-percentage</code>, and <code>#length-pixel</code>.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-cell" name="feature-length-cell"></a>D.1.43
-          #length-cell</h4>
-
-          <p>A TTML transformation processor supports the <code>#length-cell</code>
-          feature if it recognizes and is capable of transforming scalar values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>c</code> (cell) units.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-cell</code> feature
-          if it implements presentation semantic support for scalar values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>c</code> (cell) units.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-cell</code> does not, by itself, imply support
-            for <code>#length-integer</code>, <code>#length-real</code>,
-            <code>#length-positive</code>, or <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-em" name="feature-length-em"></a>D.1.44
-          #length-em</h4>
-
-          <p>A TTML transformation processor supports the <code>#length-em</code> feature
-          if it recognizes and is capable of transforming scalar values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression that use
-          <code>em</code> (EM) units.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-em</code> feature
-          if it implements presentation semantic support for scalar values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>em</code> (EM) units.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-em</code> does not, by itself, imply support for
-            <code>#length-integer</code>, <code>#length-real</code>,
-            <code>#length-positive</code>, or <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-integer" name="feature-length-integer"></a>D.1.45
-          #length-integer</h4>
-
-          <p>A TTML transformation processor supports the <code>#length-integer</code>
-          feature if it recognizes and is capable of transforming integer values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-integer</code>
-          feature if it implements presentation semantic support for integer values of
-          the <a href="#style-value-length">&lt;length&gt;</a> style value
-          expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-integer</code> does not, by itself, imply
-            support for <code>#length-positive</code> or <code>#length-negative</code>
-            features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-negative" name="feature-length-negative"></a>D.1.46
-          #length-negative</h4>
-
-          <p>A TTML transformation processor supports the <code>#length-negative</code>
-          feature if it recognizes and is capable of transforming negative values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-negative</code>
-          feature if it implements presentation semantic support for negative values of
-          the <a href="#style-value-length">&lt;length&gt;</a> style value
-          expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-negative</code> does not, by itself, imply
-            support for <code>#length-integer</code> or <code>#length-real</code>
-            features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-percentage" name=
-          "feature-length-percentage"></a>D.1.47 #length-percentage</h4>
-
-          <p>A TTML transformation processor supports the <code>#length-percentage</code>
-          feature if it recognizes and is capable of transforming percentage values of
-          the <a href="#style-value-length">&lt;length&gt;</a> style value
-          expression.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-percentage</code>
-          feature if it implements presentation semantic support for percentage values of
-          the <a href="#style-value-length">&lt;length&gt;</a> style value
-          expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-percentage</code> does not, by itself, imply
-            support for <code>#length-integer</code>, <code>#length-real</code>,
-            <code>#length-positive</code>, or <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-pixel" name="feature-length-pixel"></a>D.1.48
-          #length-pixel</h4>
-
-          <p>A TTML transformation processor supports the <code>#length-pixel</code>
-          feature if it recognizes and is capable of transforming scalar values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>px</code> (pixel) units.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-pixel</code>
-          feature if it implements presentation semantic support for scalar values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>px</code> (pixel) units.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-pixel</code> does not, by itself, imply support
-            for <code>#length-integer</code>, <code>#length-real</code>,
-            <code>#length-positive</code>, or <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-positive" name="feature-length-positive"></a>D.1.49
-          #length-positive</h4>
-
-          <p>A TTML transformation processor supports the <code>#length-positive</code>
-          feature if it recognizes and is capable of transforming positive values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-positive</code>
-          feature if it implements presentation semantic support for positive values of
-          the <a href="#style-value-length">&lt;length&gt;</a> style value
-          expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-positive</code> is intended to imply support for
-            zero valued <a href="#style-value-length">&lt;length&gt;</a> style value
-            expressions.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-positive</code> does not, by itself, imply
-            support for <code>#length-integer</code> or <code>#length-real</code>
-            features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-real" name="feature-length-real"></a>D.1.50
-          #length-real</h4>
-
-          <p>A TTML transformation processor supports the <code>#length-real</code>
-          feature if it recognizes and is capable of transforming real values of the
-          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-real</code> feature
-          if it implements presentation semantic support for real values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-real</code> is intended to imply support for
-            integer valued <a href="#style-value-length">&lt;length&gt;</a> style value
-            expressions as well as real valued expressions.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-real</code> does not, by itself, imply support
-            for <code>#length-positive</code> or <code>#length-negative</code>
-            features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-lineBreak-uax14" name="feature-lineBreak-uax14"></a>D.1.51
-          #lineBreak-uax14</h4>
-
-          <p>A TTML transformation processor supports the <code>#lineBreak-uax14</code>
-          feature if it recognizes and is capable of transforming requirements expressed
-          by <a href="#uax14">[UAX14]</a> into its target document space.</p>
-
-          <p>A TTML presentation processor supports the <code>#lineBreak-uax14</code>
-          feature if it implements presentation semantic support for <a href=
-          "#uax14">[UAX14]</a> as applies to line breaking.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-lineHeight" name="feature-lineHeight"></a>D.1.52
-          #lineHeight</h4>
-
-          <p>A TTML transformation processor supports the <code>#lineHeight</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-lineHeight"><code>tts:lineHeight</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#lineHeight</code> feature
-          if it implements presentation semantic support for the <a href=
-          "#style-attribute-lineHeight"><code>tts:lineHeight</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-markerMode" name="feature-markerMode"></a>D.1.53
-          #markerMode</h4>
-
-          <p>A TTML transformation processor supports the <code>#markerMode</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#markerMode</code> feature
-          if it implements presentation semantic support for the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-markerMode-continuous" name=
-          "feature-markerMode-continuous"></a>D.1.54 #markerMode-continuous</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#markerMode-continuous</code> feature if it recognizes and is capable of
-          transforming the <code>continuous</code> value of the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#markerMode-continuous</code> feature if it implements presentation
-          semantic support for the <code>continuous</code> value of the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-markerMode-discontinuous" name=
-          "feature-markerMode-discontinuous"></a>D.1.55 #markerMode-discontinuous</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#markerMode-discontinuous</code> feature if it recognizes and is capable
-          of transforming the <code>discontinuous</code> value of the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#markerMode-discontinuous</code> feature if it implements presentation
-          semantic support for the <code>discontinuous</code> value of the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-metadata" name="feature-metadata"></a>D.1.56 #metadata</h4>
-
-          <p>A TTML transformation processor supports the <code>#metadata</code> feature
-          if it recognizes and is capable of transforming the following vocabulary
-          defined by <a href="#metadata"><b>12 Metadata</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#metadata-vocabulary-metadata"><code>metadata</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata-vocabulary-title"><code>ttm:title</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata-vocabulary-title"><code>ttm:desc</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata-vocabulary-title"><code>ttm:copyright</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata-vocabulary-title"><code>ttm:agent</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata-vocabulary-title"><code>ttm:name</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata-vocabulary-title"><code>ttm:actor</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata-attribute-agent">@<code>ttm:agent</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata-attribute-role">@<code>ttm:role</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#metadata</code> feature if
-          it recognizes and is capable of presenting the information expressed by the
-          same vocabulary enumerated above.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>This specification does not define a standardized form for the
-            presentation of metadata information. The presentation or ability to present
-            metadata information is considered to be implementation dependent.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-nested-div" name="feature-nested-div"></a>D.1.57
-          #nested-div</h4>
-
-          <p>A TTML transformation processor supports the <code>#nested-div</code>
-          feature if it recognizes and is capable of transforming nested <a href=
-          "#content-vocabulary-div"><code>div</code></a> elements.</p>
-
-          <p>A TTML presentation processor supports the <code>#nested-div</code> feature
-          if it implements presentation semantic support for nested <a href=
-          "#content-vocabulary-div"><code>div</code></a> elements.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-nested-span" name="feature-nested-span"></a>D.1.58
-          #nested-span</h4>
-
-          <p>A TTML transformation processor supports the <code>#nested-span</code>
-          feature if it recognizes and is capable of transforming nested <a href=
-          "#content-vocabulary-span"><code>span</code></a> elements.</p>
-
-          <p>A TTML presentation processor supports the <code>#nested-span</code> feature
-          if it implements presentation semantic support for nested <a href=
-          "#content-vocabulary-span"><code>span</code></a> elements.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-opacity" name="feature-opacity"></a>D.1.59 #opacity</h4>
-
-          <p>A TTML transformation processor supports the <code>#opacity</code> feature
-          if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-opacity"><code>tts:opacity</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#opacity</code> feature if
-          it (1) implements presentation semantic support for the <a href=
-          "#style-attribute-opacity"><code>tts:opacity</code></a> attribute and (2) is
-          capable of displaying or generating an output display signal that distinguishes
-          between at least eight (8) values of opacity.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-origin" name="feature-origin"></a>D.1.60 #origin</h4>
-
-          <p>A TTML transformation processor supports the <code>#origin</code> feature if
-          it recognizes and is capable of transforming the <a href=
-          "#style-attribute-origin"><code>tts:origin</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#origin</code> feature if
-          it implements presentation semantic support for the <a href=
-          "#style-attribute-origin"><code>tts:origin</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-overflow" name="feature-overflow"></a>D.1.61 #overflow</h4>
-
-          <p>A TTML transformation processor supports the <code>#overflow</code> feature
-          if it recognizes and is capable of transforming all defined values of the
-          <a href="#style-attribute-overflow"><code>tts:overflow</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#overflow</code> feature if
-          it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-overflow"><code>tts:overflow</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-overflow-visible" name="feature-overflow-visible"></a>D.1.62
-          #overflow-visible</h4>
-
-          <p>A TTML transformation processor supports the <code>#overflow-visible</code>
-          feature if it recognizes and is capable of transforming the
-          <code>visible</code> value of the <a href=
-          "#style-attribute-overflow"><code>tts:overflow</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#overflow-visible</code>
-          feature if it implements presentation semantic support for the
-          <code>visible</code> value of the <a href=
-          "#style-attribute-overflow"><code>tts:overflow</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding" name="feature-padding"></a>D.1.63 #padding</h4>
-
-          <p>A TTML transformation processor supports the <code>#padding</code> feature
-          if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding</code> feature if
-          it implements presentation semantic support for the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding-1" name="feature-padding-1"></a>D.1.64
-          #padding-1</h4>
-
-          <p>A TTML transformation processor supports the <code>#padding-1</code> feature
-          if it recognizes and is capable of transforming values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
-          of one <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding-1</code> feature
-          if it implements presentation semantic support for values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
-          of one <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding-2" name="feature-padding-2"></a>D.1.65
-          #padding-2</h4>
-
-          <p>A TTML transformation processor supports the <code>#padding-2</code> feature
-          if it recognizes and is capable of transforming values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
-          of two <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding-2</code> feature
-          if it implements presentation semantic support for values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
-          of two <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding-3" name="feature-padding-3"></a>D.1.66
-          #padding-3</h4>
-
-          <p>A TTML transformation processor supports the <code>#padding-3</code> feature
-          if it recognizes and is capable of transforming values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
-          of three <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding-3</code> feature
-          if it implements presentation semantic support for values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
-          of three <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding-4" name="feature-padding-4"></a>D.1.67
-          #padding-4</h4>
-
-          <p>A TTML transformation processor supports the <code>#padding-4</code> feature
-          if it recognizes and is capable of transforming values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
-          of four <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding-4</code> feature
-          if it implements presentation semantic support for values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
-          of four <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-pixelAspectRatio" name="feature-pixelAspectRatio"></a>D.1.68
-          #pixelAspectRatio</h4>
-
-          <p>A TTML transformation processor supports the <code>#pixelAspectRatio</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#pixelAspectRatio</code>
-          feature if it implements presentation semantic support for the <a href=
-          "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-presentation" name="feature-presentation"></a>D.1.69
-          #presentation</h4>
-
-          <p>A TTML processor supports the <code>#presentation</code> feature if it (1)
-          satisfies the generic processor criteria defined by <a href=
-          "#conformance-generic-processor"><b>3.2.1 Generic Processor
-          Conformance</b></a>, (2) implements support for the region and line layout
-          semantics defined by <a href="#semantics-region-layout"><b>9.3 Region Layout
-          and Presentation</b></a> and <a href="#semantics-line-layout"><b>9.4 Line
-          Layout</b></a>, respectively, and (3) implements presentation semantics for the
-          following features:</p>
-
-          <ul>
-            <li>
-              <p><a href="#content"><code>#content</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-core"><code>#core</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-profile"><code>#profile</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-structure"><code>#structure</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-time-offset"><code>#time-offset</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing"><code>#timing</code></a></p>
-            </li>
-          </ul>
-
-          <p>In addition, a TTML processor that supports the <code>#presentation</code>
-          feature should satisfy the user agent accessibility guidelines specified by
-          <a href="#uaag">[UAAG]</a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-profile" name="feature-profile"></a>D.1.70 #profile</h4>
-
-          <p>A TTML transformation processor supports the <code>#profile</code> feature
-          if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-profile"><code>ttp:profile</code></a> attribute on the
-          <a href="#document-structure-vocabulary-tt"><code>tt</code></a> element and
-          transforming the following vocabulary defined by <a href=
-          "#parameter-element-vocabulary"><b>6.1 Parameter Element
-          Vocabulary</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#parameter-vocabulary-profile"><code>ttp:profile</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#parameter-vocabulary-features"><code>ttp:features</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#parameter-vocabulary-feature"><code>ttp:feature</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#parameter-vocabulary-extensions"><code>ttp:extensions</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#parameter-vocabulary-extension"><code>ttp:extension</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#profile</code> feature if
-          it implements presentation semantic support for the same vocabulary specified
-          above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-showBackground" name="feature-showBackground"></a>D.1.71
-          #showBackground</h4>
-
-          <p>A TTML transformation processor supports the <code>#showBackground</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href=
-          "#style-attribute-showBackground"><code>tts:showBackground</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#showBackground</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href=
-          "#style-attribute-showBackground"><code>tts:showBackground</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-structure" name="feature-structure"></a>D.1.72
-          #structure</h4>
-
-          <p>A TTML transformation processor supports the <code>#structure</code> feature
-          if it recognizes and is capable of transforming the following vocabulary
-          defined by <a href="#content"><b>7 Content</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#document-structure-vocabulary-tt"><code>tt</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#document-structure-vocabulary-head"><code>head</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#structure</code> feature
-          if it implements presentation semantic support for the same vocabulary
-          enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling" name="feature-styling"></a>D.1.73 #styling</h4>
-
-          <p>A TTML transformation processor supports the <code>#styling</code> feature
-          if it recognizes and is capable of transforming the following vocabulary
-          defined by <a href="#styling"><b>8 Styling</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#styling-vocabulary-styling"><code>styling</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#styling-vocabulary-style"><code>style</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#style-attribute-style">@<code>style</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#styling</code> feature if
-          it implements presentation semantic support for the same vocabulary enumerated
-          above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-chained" name="feature-styling-chained"></a>D.1.74
-          #styling-chained</h4>
-
-          <p>A TTML transformation processor supports the <code>#styling-chained</code>
-          feature if it recognizes and is capable of transforming chained style
-          association as defined by <a href=
-          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
-          Referential Styling</b></a>.</p>
-
-          <p>A TTML presentation processor supports the <code>#styling-chained</code>
-          feature if it implements presentation semantic support for chained style
-          association as defined by <a href=
-          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
-          Referential Styling</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-inheritance-content" name=
-          "feature-styling-inheritance-content"></a>D.1.75
-          #styling-inheritance-content</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-inheritance</code> feature if it recognizes and is capable of
-          transforming content style inheritance as defined by <a href=
-          "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
-          Inheritance</b></a>.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#styling-inheritance-content</code> feature if it implements presentation
-          semantic support for content style inheritance as defined by <a href=
-          "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
-          Inheritance</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-inheritance-region" name=
-          "feature-styling-inheritance-region"></a>D.1.76
-          #styling-inheritance-region</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-inheritance</code> feature if it recognizes and is capable of
-          transforming region style inheritance as defined by <a href=
-          "#semantics-style-inheritance-region"><b>8.4.2.2 Region Style
-          Inheritance</b></a>.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#styling-inheritance-region</code> feature if it implements presentation
-          semantic support for region style inheritance as defined by <a href=
-          "#semantics-style-inheritance-region"><b>8.4.2.2 Region Style
-          Inheritance</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-inline" name="feature-styling-inline"></a>D.1.77
-          #styling-inline</h4>
-
-          <p>A TTML transformation processor supports the <code>#styling-inline</code>
-          feature if it recognizes and is capable of transforming inline style
-          association as defined by <a href=
-          "#semantics-style-association-inline"><b>8.4.1.1 Inline Styling</b></a>.</p>
-
-          <p>A TTML presentation processor supports the <code>#styling-inline</code>
-          feature if it implements presentation semantic support for inline style
-          association as defined by <a href=
-          "#semantics-style-association-inline"><b>8.4.1.1 Inline Styling</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-nested" name="feature-styling-nested"></a>D.1.78
-          #styling-nested</h4>
-
-          <p>A TTML transformation processor supports the <code>#styling-nested</code>
-          feature if it recognizes and is capable of transforming nested style
-          association as defined by <a href=
-          "#semantics-style-association-nested"><b>8.4.1.4 Nested Styling</b></a>.</p>
-
-          <p>A TTML presentation processor supports the <code>#styling-nested</code>
-          feature if it implements presentation semantic support for nested style
-          association as defined by <a href=
-          "#semantics-style-association-nested"><b>8.4.1.4 Nested Styling</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-referential" name=
-          "feature-styling-referential"></a>D.1.79 #styling-referential</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-referential</code> feature if it recognizes and is capable of
-          transforming referential style association as defined by <a href=
-          "#semantics-style-association-referential"><b>8.4.1.2 Referential
-          Styling</b></a>.</p>
-
-          <p>A TTML presentation processor supports the <code>#styling-referential</code>
-          feature if it implements presentation semantic support for referential style
-          association as defined by <a href=
-          "#semantics-style-association-referential"><b>8.4.1.2 Referential
-          Styling</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-subFrameRate" name="feature-subFrameRate"></a>D.1.80
-          #subFrameRate</h4>
-
-          <p>A TTML transformation processor supports the <code>#subFrameRate</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#subFrameRate</code>
-          feature if it implements presentation semantic support for the <a href=
-          "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textAlign" name="feature-textAlign"></a>D.1.81
-          #textAlign</h4>
-
-          <p>A TTML transformation processor supports the <code>#textAlign</code> feature
-          if it recognizes and is capable of transforming all defined values of the
-          <a href="#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#textAlign</code> feature
-          if it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textAlign-absolute" name=
-          "feature-textAlign-absolute"></a>D.1.82 #textAlign-absolute</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textAlign-absolute</code> feature if it recognizes and is capable of
-          transforming the <code>left</code>, <code>center</code>, and <code>right</code>
-          values of the <a href=
-          "#style-attribute-textAlign"><code>tts:textAlign</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#textAlign-absolute</code>
-          feature if it implements presentation semantic support for the
-          <code>left</code>, <code>center</code>, and <code>right</code> values of the
-          <a href="#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textAlign-relative" name=
-          "feature-textAlign-relative"></a>D.1.83 #textAlign-relative</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textAlign-relative</code> feature if it recognizes and is capable of
-          transforming the <code>start</code>, <code>center</code>, and <code>end</code>
-          values of the <a href=
-          "#style-attribute-textAlign"><code>tts:textAlign</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#textAlign-relative</code>
-          feature if it implements presentation semantic support for the
-          <code>start</code>, <code>center</code>, and <code>end</code> values of the
-          <a href="#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textDecoration" name="feature-textDecoration"></a>D.1.84
-          #textDecoration</h4>
-
-          <p>A TTML transformation processor supports the <code>#textDecoration</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#textDecoration</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textDecoration-over" name=
-          "feature-textDecoration-over"></a>D.1.85 #textDecoration-over</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textDecoration-over</code> feature if it recognizes and is capable of
-          transforming the <code>overline</code> and <code>noOverline</code> values of
-          the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#textDecoration-over</code>
-          feature if it implements presentation semantic support for the
-          <code>overline</code> and <code>noOverline</code> values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textDecoration-through" name=
-          "feature-textDecoration-through"></a>D.1.86 #textDecoration-through</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textDecoration-through</code> feature if it recognizes and is capable of
-          transforming the <code>lineThrough</code> and <code>noLineThrough</code> values
-          of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textDecoration-through</code> feature if it implements presentation
-          semantic support for the <code>lineThrough</code> and
-          <code>noLineThrough</code> values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textDecoration-under" name=
-          "feature-textDecoration-under"></a>D.1.87 #textDecoration-under</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textDecoration-under</code> feature if it recognizes and is capable of
-          transforming the <code>underline</code> and <code>noUnderline</code> values of
-          the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textDecoration-under</code> feature if it implements presentation
-          semantic support for the <code>underline</code> and <code>noUnderline</code>
-          values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textOutline" name="feature-textOutline"></a>D.1.88
-          #textOutline</h4>
-
-          <p>A TTML transformation processor supports the <code>#textOutline</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#textOutline</code> feature
-          if it implements presentation semantic support for the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textOutline-blurred" name=
-          "feature-textOutline-blurred"></a>D.1.89 #textOutline-blurred</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textOutline-blurred</code> feature if it recognizes and is capable of
-          transforming values of the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute that
-          includes a blur radius specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#textOutline-blurred</code>
-          feature if it implements presentation semantic support for values of the
-          <a href="#style-attribute-textOutline"><code>tts:textOutline</code></a>
-          attribute that includes a blur radius specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textOutline-unblurred" name=
-          "feature-textOutline-unblurred"></a>D.1.90 #textOutline-unblurred</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textOutline-unblurred</code> feature if it recognizes and is capable of
-          transforming values of the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute that
-          does not include a blur radius specification.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textOutline-unblurred</code> feature if it implements presentation
-          semantic support for values of the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute that
-          does not include a blur radius specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-tickRate" name="feature-tickRate"></a>D.1.91 #tickRate</h4>
-
-          <p>A TTML transformation processor supports the <code>#tickRate</code> feature
-          if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-tickRate"><code>ttp:tickRate</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#tickRate</code> feature if
-          it implements presentation semantic support for the <a href=
-          "#parameter-attribute-tickRate"><code>ttp:tickRate</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timeBase-clock" name="feature-timeBase-clock"></a>D.1.92
-          #timeBase-clock</h4>
-
-          <p>A TTML transformation processor supports the <code>#timeBase-clock</code>
-          feature if it recognizes and is capable of transforming the <code>clock</code>
-          value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute and if
-          it supports the <a href="#feature-clockMode"><code>#clockMode</code></a>
-          feature.</p>
-
-          <p>A TTML presentation processor supports the <code>#timeBase-clock</code>
-          feature if it implements presentation semantic support for the
-          <code>clock</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute and if
-          it supports the <a href="#feature-clockMode"><code>#clockMode</code></a>
-          feature.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timeBase-media" name="feature-timeBase-media"></a>D.1.93
-          #timeBase-media</h4>
-
-          <p>A TTML transformation processor supports the <code>#timeBase-media</code>
-          feature if it recognizes and is capable of transforming the <code>media</code>
-          value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#timeBase-media</code>
-          feature if it implements presentation semantic support for the
-          <code>media</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timeBase-smpte" name="feature-timeBase-smpte"></a>D.1.94
-          #timeBase-smpte</h4>
-
-          <p>A TTML transformation processor supports the <code>#timeBase-smpte</code>
-          feature if it recognizes and is capable of transforming the <code>smpte</code>
-          value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute and if
-          it supports the <a href="#feature-dropMode"><code>#dropMode</code></a>
-          feature.</p>
-
-          <p>A TTML presentation processor supports the <code>#timeBase-smpte</code>
-          feature if it implements presentation semantic support for the
-          <code>smpte</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute and if
-          it supports the <a href="#feature-dropMode"><code>#dropMode</code></a>
-          feature.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timeContainer" name="feature-timeContainer"></a>D.1.95
-          #timeContainer</h4>
-
-          <p>A TTML transformation processor supports the <code>#timeContainer</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#timing-attribute-timeContainer"><code>timeContainer</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#timeContainer</code>
-          feature if it implements presentation semantic support for the <a href=
-          "#timing-attribute-timeContainer"><code>timeContainer</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-clock" name="feature-time-clock"></a>D.1.96
-          #time-clock</h4>
-
-          <p>A TTML transformation processor supports the <code>#time-clock</code>
-          feature if it recognizes and is capable of transforming all values of the
-          <a href="#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy
-          the following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : hours ":" minutes ":" seconds ( fraction )?
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the <code>#time-clock</code> feature
-          if it implements presentation semantic support for the same syntax specified
-          above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-clock-with-frames" name=
-          "feature-time-clock-with-frames"></a>D.1.97 #time-clock-with-frames</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#time-clock-with-frames</code> feature if it supports the <a href=
-          "#feature-frameRate"><code>#frameRate</code></a>, <a href=
-          "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a>, and
-          <a href="#feature-subFrameRate"><code>#subFrameRate</code></a> features and if
-          it recognizes and is capable of transforming all values of the <a href=
-          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy the
-          following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the
-          <code>#time-clock-with-frames</code> feature if it implements presentation
-          semantic support for the same features and syntax specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-offset" name="feature-time-offset"></a>D.1.98
-          #time-offset</h4>
-
-          <p>A TTML transformation processor supports the <code>#time-offset</code>
-          feature if it recognizes and is capable of transforming all values of the
-          <a href="#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy
-          the following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : time-count fraction? ( "h" | "m" | "s" | "ms" )
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the <code>#time-offset</code> feature
-          if it implements presentation semantic support for the same syntax specified
-          above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-offset-with-frames" name=
-          "feature-time-offset-with-frames"></a>D.1.99 #time-offset-with-frames</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#time-offset-with-frames</code> feature if it supports the <a href=
-          "#feature-frameRate"><code>#frameRate</code></a>, <a href=
-          "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a>, and
-          <a href="#feature-subFrameRate"><code>#subFrameRate</code></a> features and if
-          it recognizes and is capable of transforming all values of the <a href=
-          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy the
-          following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : time-count fraction? "f"
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the
-          <code>#time-offset-with-frames</code> feature if it implements presentation
-          semantic support for the same features and syntax specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-offset-with-ticks" name=
-          "feature-time-offset-with-ticks"></a>D.1.100 #time-offset-with-ticks</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#time-offset-with-ticks</code> feature if it supports the <a href=
-          "#feature-tickRate"><code>#tickRate</code></a> feature and if it recognizes and
-          is capable of transforming all values of the <a href=
-          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy the
-          following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : time-count fraction? "t"
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the
-          <code>#time-offset-with-ticks</code> feature if it implements presentation
-          semantic support for the same features and syntax specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timing" name="feature-timing"></a>D.1.101 #timing</h4>
-
-          <p>A TTML transformation processor supports the <code>#timing</code> feature if
-          it recognizes and is capable of transforming the following vocabulary defined
-          by <a href="#timing"><b>10 Timing</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#timing-attribute-begin">@<code>begin</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing-attribute-dur">@<code>dur</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing-attribute-end">@<code>end</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#timing</code> feature if
-          it implements presentation semantic support for the same vocabulary enumerated
-          above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-transformation" name="feature-transformation"></a>D.1.102
-          #transformation</h4>
-
-          <p>A TTML processor supports the <code>#transformation</code> feature if it (1)
-          satisfies the generic processor criteria defined by <a href=
-          "#conformance-generic-processor"><b>3.2.1 Generic Processor Conformance</b></a>
-          and (2) implements the transformation semantics of the following features:</p>
-
-          <ul>
-            <li>
-              <p><a href="#content"><code>#content</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-core"><code>#core</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-profile"><code>#profile</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-structure"><code>#structure</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-time-offset"><code>#time-offset</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing"><code>#timing</code></a></p>
-            </li>
-          </ul>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-unicodeBidi" name="feature-unicodeBidi"></a>D.1.103
-          #unicodeBidi</h4>
-
-          <p>A TTML transformation processor supports the <code>#unicodeBidi</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#unicodeBidi</code> feature
-          if it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-visibility" name="feature-visibility"></a>D.1.104
-          #visibility</h4>
-
-          <p>A TTML transformation processor supports the <code>#visibility</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#visibility</code> feature
-          if it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-visibility-block" name=
-          "feature-visibility-block"></a>D.1.105 #visibility-block</h4>
-
-          <p>A TTML transformation processor supports the <code>#visibility-block</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a content element that would generate a block area
-          during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the <code>#visibility-block</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a content element that generates a block area.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-visibility-inline" name=
-          "feature-visibility-inline"></a>D.1.106 #visibility-inline</h4>
-
-          <p>A TTML transformation processor supports the <code>#visibility-inline</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a content element that would generate an inline area
-          during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the <code>#visibility-inline</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a content element that generates an inline area.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-visibility-region" name=
-          "feature-visibility-region"></a>D.1.107 #visibility-region</h4>
-
-          <p>A TTML transformation processor supports the <code>#visibility-region</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-
-          <p>A TTML presentation processor supports the <code>#visibility-region</code>
-          feature if it implements presentation semantic support for all defined values
-          of the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-wrapOption" name="feature-wrapOption"></a>D.1.108
-          #wrapOption</h4>
-
-          <p>A TTML transformation processor supports the <code>#wrapOption</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-wrapOption"><code>tts:wrapOption</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#wrapOption</code> feature
-          if it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-wrapOption"><code>tts:wrapOption</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode" name="feature-writingMode"></a>D.1.109
-          #writingMode</h4>
-
-          <p>A TTML transformation processor supports the <code>#writingMode</code>
-          feature if it recognizes and is capable of transforming all defined values of
-          the <a href="#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#writingMode</code> feature
-          if it implements presentation semantic support for all defined values of the
-          <a href="#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode-vertical" name=
-          "feature-writingMode-vertical"></a>D.1.110 #writingMode-vertical</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode-vertical</code> feature if it recognizes and is capable of
-          transforming the <code>tbrl</code>, <code>tblr</code>, and <code>tb</code>
-          values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode-vertical</code> feature if it implements presentation
-          semantic support for the <code>tbrl</code>, <code>tblr</code>, and
-          <code>tb</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode-horizontal" name=
-          "feature-writingMode-horizontal"></a>D.1.111 #writingMode-horizontal</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode-horizontal</code> feature if it recognizes and is capable of
-          transforming the <code>lrtb</code>, <code>rltb</code>, <code>lr</code> and
-          <code>rl</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode-horizontal</code> feature if it implements presentation
-          semantic support for the <code>lrtb</code>, <code>rltb</code>, <code>lr</code>
-          and <code>rl</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode-horizontal-lr" name=
-          "feature-writingMode-horizontal-lr"></a>D.1.112 #writingMode-horizontal-lr</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode-horizontal</code> feature if it recognizes and is capable of
-          transforming the <code>lrtb</code> and <code>lr</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode-horizontal-lr</code> feature if it implements presentation
-          semantic support for the <code>lrtb</code> and <code>lr</code> values of the
-          <a href="#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode-horizontal-rl" name=
-          "feature-writingMode-horizontal-rl"></a>D.1.113 #writingMode-horizontal-rl</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode-horizontal</code> feature if it recognizes and is capable of
-          transforming the <code>rltb</code> and <code>rl</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode-horizontal-rl</code> feature if it implements presentation
-          semantic support for the <code>rltb</code> and <code>rl</code> values of the
-          <a href="#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-zIndex" name="feature-zIndex"></a>D.1.114 #zIndex</h4>
-
-          <p>A TTML transformation processor supports the <code>#zIndex</code> feature if
-          it recognizes and is capable of transforming the <a href=
-          "#style-attribute-zIndex"><code>tts:zIndex</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#zIndex</code> feature if
-          it implements presentation semantic support for the <a href=
-          "#style-attribute-zIndex"><code>tts:zIndex</code></a> attribute.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="feature-support" name="feature-support"></a>D.2 Feature Support</h3>
-
-        <p>The following table, <a href="#feature-support-table"><b>Table D-1 – Feature
-        Support</b></a>, enumerates every defined feature designation (expressed without
-        the TT Feature Namespace), and, for each designated feature, specifies whether
-        the feature must be implemented, i.e., is mandatory (M), or may be implemented,
-        i.e., is optional (O), for transformation and presentation processors.</p><a id=
-        "feature-support-table" name="feature-support-table"></a>
-
-        <table class="common">
-          <caption>
-            Table D-1 – Feature Support
-          </caption>
-          <col width="60%" span="1">
-          <col width="20%" span="1">
-          <col width="20%" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Feature</span></td>
-
-              <td><span class="strong">Transformation</span></td>
-
-              <td><span class="strong">Presentation</span></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-animation"><code>#animation</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-backgroundColor"><code>#backgroundColor</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-backgroundColor-block"><code>#backgroundColor-block</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-backgroundColor-inline"><code>#backgroundColor-inline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-backgroundColor-region"><code>#backgroundColor-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-bidi"><code>#bidi</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-cellResolution"><code>#cellResolution</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-clockMode"><code>#clockMode</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-clockMode-gps"><code>#clockMode-gps</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-clockMode-local"><code>#clockMode-local</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-clockMode-utc"><code>#clockMode-utc</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-color"><code>#color</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-content"><code>#content</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-core"><code>#core</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-direction"><code>#direction</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-display"><code>#display</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-display-block"><code>#display-block</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-display-inline"><code>#display-inline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-display-region"><code>#display-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-displayAlign"><code>#displayAlign</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-dropMode"><code>#dropMode</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-dropMode-dropNTSC"><code>#dropMode-dropNTSC</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-dropMode-dropPAL"><code>#dropMode-dropPAL</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-dropMode-nonDrop"><code>#dropMode-nonDrop</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-extent"><code>#extent</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-extent-region"><code>#extent-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-extent-root"><code>#extent-root</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-fontFamily"><code>#fontFamily</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontFamily-generic"><code>#fontFamily-generic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontFamily-non-generic"><code>#fontFamily-non-generic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-fontSize"><code>#fontSize</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontSize-anamorphic"><code>#fontSize-anamorphic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontSize-isomorphic"><code>#fontSize-isomorphic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-fontStyle"><code>#fontStyle</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontStyle-italic"><code>#fontStyle-italic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontStyle-oblique"><code>#fontStyle-oblique</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-fontWeight"><code>#fontWeight</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontWeight-bold"><code>#fontWeight-bold</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-frameRate"><code>#frameRate</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-layout"><code>#layout</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-length"><code>#length</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-length-cell"><code>#length-cell</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-length-em"><code>#length-em</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-length-integer"><code>#length-integer</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-negative"><code>#length-negative</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-percentage"><code>#length-percentage</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-length-pixel"><code>#length-pixel</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-positive"><code>#length-positive</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-length-real"><code>#length-real</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-lineBreak-uax14"><code>#lineBreak-uax14</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-lineHeight"><code>#lineHeight</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-markerMode"><code>#markerMode</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-markerMode-continuous"><code>#markerMode-continuous</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-markerMode-discontinuous"><code>#markerMode-discontinuous</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-metadata"><code>#metadata</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-nested-div"><code>#nested-div</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-nested-span"><code>#nested-span</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-opacity"><code>#opacity</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-origin"><code>#origin</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-overflow"><code>#overflow</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-overflow-visible"><code>#overflow-visible</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding"><code>#padding</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding-1"><code>#padding-1</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding-2"><code>#padding-2</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding-3"><code>#padding-3</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding-4"><code>#padding-4</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-pixelAspectRatio"><code>#pixelAspectRatio</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-presentation"><code>#presentation</code></a></td>
-
-              <td>O</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-profile"><code>#profile</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-showBackground"><code>#showBackground</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-structure"><code>#structure</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-styling"><code>#styling</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-chained"><code>#styling-chained</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-inheritance-content"><code>#styling-inheritance-content</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-inheritance-region"><code>#styling-inheritance-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-styling-inline"><code>#styling-inline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-styling-nested"><code>#styling-nested</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-referential"><code>#styling-referential</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-subFrameRate"><code>#subFrameRate</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-textAlign"><code>#textAlign</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textAlign-absolute"><code>#textAlign-absolute</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textAlign-relative"><code>#textAlign-relative</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-textDecoration"><code>#textDecoration</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textDecoration-over"><code>#textDecoration-over</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textDecoration-through"><code>#textDecoration-through</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textDecoration-under"><code>#textDecoration-under</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-textOutline"><code>#textOutline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textOutline-blurred"><code>#textOutline-blurred</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textOutline-unblurred"><code>#textOutline-unblurred</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-tickRate"><code>#tickRate</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timeBase-clock"><code>#timeBase-clock</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timeBase-media"><code>#timeBase-media</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timeBase-smpte"><code>#timeBase-smpte</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timeContainer"><code>#timeContainer</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-time-clock"><code>#time-clock</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-clock-with-frames"><code>#time-clock-with-frames</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-time-offset"><code>#time-offset</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-offset-with-frames"><code>#time-offset-with-frames</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-offset-with-ticks"><code>#time-offset-with-ticks</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timing"><code>#timing</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-transformation"><code>#transformation</code></a></td>
-
-              <td>M</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-unicodeBidi"><code>#unicodeBidi</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-visibility"><code>#visibility</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-visibility-block"><code>#visibility-block</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-visibility-inline"><code>#visibility-inline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-visibility-region"><code>#visibility-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-wrapOption"><code>#wrapOption</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-writingMode"><code>#writingMode</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode-vertical"><code>#writingMode-vertical</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode-horizontal"><code>#writingMode-horizontal</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode-horizontal-lr"><code>#writingMode-horizontal-lr</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode-horizontal-rl"><code>#writingMode-horizontal-rl</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-zIndex"><code>#zIndex</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>For the sake of convenience, the following table, <a href=
-        "#feature-transformation-mandatory-table"><b>Table D-2 – Mandatory Features -
-        Transformation</b></a>, enumerates all mandatory features for a TTML
-        Transformation Processor, providing additional comments to summarize the context
-        of usage or the nature of the feature. The <em>Profile Definition Document</em>
-        that defines the corresponding DFXP Transformation Profile is specified in
-        <a href="#profile-dfxp-transformation"><b>F.1 DFXP Transformation
-        Profile</b></a>.</p><a id="feature-transformation-mandatory-table" name=
-        "feature-transformation-mandatory-table"></a>
-
-        <table class="common">
-          <caption>
-            Table D-2 – Mandatory Features - Transformation
-          </caption>
-          <col width="60%" span="1">
-          <col width="40%" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Feature</span></td>
-
-              <td><span class="strong">Comments</span></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-content"><code>#content</code></a></td>
-
-              <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
-              <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
-              "#content-vocabulary-p"><code>p</code></a>, <a href=
-              "#content-vocabulary-span"><code>span</code></a>, <a href=
-              "#content-vocabulary-br"><code>br</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-core"><code>#core</code></a></td>
-
-              <td><a href="#content-attribute-id">@<code>xml:id</code></a>, <a href=
-              "#content-attribute-id">@<code>xml:lang</code></a>, <a href=
-              "#content-attribute-id">@<code>xml:space</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-profile"><code>#profile</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-structure"><code>#structure</code></a></td>
-
-              <td><a href="#document-structure-vocabulary-tt"><code>tt</code></a>,
-              <a href="#document-structure-vocabulary-head"><code>head</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-time-offset"><code>#time-offset</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timing"><code>#timing</code></a></td>
-
-              <td><a href="#timing-attribute-begin">@<code>begin</code></a>, <a href=
-              "#timing-attribute-dur">@<code>dur</code></a>, <a href=
-              "#timing-attribute-end">@<code>end</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-transformation"><code>#transformation</code></a></td>
-
-              <td></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>For the sake of convenience, the following table, <a href=
-        "#feature-presentation-mandatory-table"><b>Table D-3 – Mandatory Features -
-        Presentation</b></a>, enumerates all mandatory features for a TTML Presentation
-        Processor, providing additional comments to summarize the context of usage or the
-        nature of the feature. The <em>Profile Definition Document</em> that defines the
-        corresponding DFXP Presentation Profile is specified in <a href=
-        "#profile-dfxp-presentation"><b>F.2 DFXP Presentation Profile</b></a>.</p><a id=
-        "feature-presentation-mandatory-table" name=
-        "feature-presentation-mandatory-table"></a>
-
-        <table class="common">
-          <caption>
-            Table D-3 – Mandatory Features - Presentation
-          </caption>
-          <col width="60%" span="1">
-          <col width="40%" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Feature</span></td>
-
-              <td><span class="strong">Comments</span></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-content"><code>#content</code></a></td>
-
-              <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
-              <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
-              "#content-vocabulary-p"><code>p</code></a>, <a href=
-              "#content-vocabulary-span"><code>span</code></a>, <a href=
-              "#content-vocabulary-br"><code>br</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-core"><code>#core</code></a></td>
-
-              <td><a href="#content-attribute-id">@<code>xml:id</code></a>, <a href=
-              "#content-attribute-id">@<code>xml:lang</code></a>, <a href=
-              "#content-attribute-id">@<code>xml:space</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-profile"><code>#profile</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-presentation"><code>#presentation</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-structure"><code>#structure</code></a></td>
-
-              <td><a href="#document-structure-vocabulary-tt"><code>tt</code></a>,
-              <a href="#document-structure-vocabulary-head"><code>head</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-time-offset"><code>#time-offset</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timing"><code>#timing</code></a></td>
-
-              <td><a href="#timing-attribute-begin">@<code>begin</code></a>, <a href=
-              "#timing-attribute-dur">@<code>dur</code></a>, <a href=
-              "#timing-attribute-end">@<code>end</code></a></td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="extensions" name="extensions"></a>E Extensions</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix specifies the syntactic form of extension designations, which are
-      used to express authorial intent regarding the support for extension mechanisms in
-      a TTML processor.</p>
-
-      <div class="div2">
-        <h3><a id="extension-designations" name="extension-designations"></a>E.1
-        Extension Designations</h3>
-
-        <p>An extension designation is expressed as a string that adheres to the
-        following form:</p>
-
-        <div class="exampleInner">
-          <pre>
-extension-designation
-  : extension-namespace designation
-
-extension-namespace
-  : <em>TT Extension Namespace</em>                  // http://www.w3.org/ns/ttml/extension/
-  | <em>Other Extension Namespace</em>               // expressed as an absolute URI
-
-designation
-  : "#" token-char+
-
-token-char
-  : { XML NameChar }                        // XML 1.1 Production [4a]
-</pre>
-        </div>
-
-        <p>If the extension namespace of an extension designation is the TT Extension
-        Namespace, then all values of the following <code>designation</code> token are
-        reserved for future standardization.</p>
-
-        <p>If the extension namespace of an extension designation is not the TT Extension
-        Namespace, i.e., is an <em>Other Extension Namespace</em>, then the extension
-        namespace must be expressed as an absolute URI capable of serving as a base URI
-        used in combination with a <code>designation</code> token that takes the form of
-        a fragment identifier.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="profiles" name="profiles"></a>F Profiles</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix specifies the following standard TTML profiles:</p>
-
-      <ul>
-        <li>
-          <p><a href="#profile-dfxp-transformation"><b>F.1 DFXP Transformation
-          Profile</b></a></p>
-        </li>
-
-        <li>
-          <p><a href="#profile-dfxp-presentation"><b>F.2 DFXP Presentation
-          Profile</b></a></p>
-        </li>
-
-        <li>
-          <p><a href="#profile-dfxp-full"><b>F.3 DFXP Full Profile</b></a></p>
-        </li>
-      </ul>
-
-      <p>Each TTML profile is defined in terms of a <em>Profile Definition Document</em>,
-      which is expressed as an XML document wherein the root element adheres to <a href=
-      "#parameter-vocabulary-profile"><b>6.1.1 ttp:profile</b></a>.</p>
-
-      <div class="div2">
-        <h3><a id="profile-dfxp-transformation" name=
-        "profile-dfxp-transformation"></a>F.1 DFXP Transformation Profile</h3>
-
-        <p>The DFXP Transformation Profile is intended to be used to express minimum
-        compliance for transformation processing.</p>
-
-        <div class="exampleInner">
-          <pre>
-&lt;?xml version="1.0" encoding="utf-8"?&gt;
-&lt;!-- this file defines the "dfxp-transformation" profile of ttaf1 --&gt;
-&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
-  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    &lt;!-- required (mandatory) feature support --&gt;
-    &lt;feature value="required"&gt;#content&lt;/feature&gt;
-    &lt;feature value="required"&gt;#core&lt;/feature&gt;
-    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
-    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
-    &lt;feature value="required"&gt;#transformation&lt;/feature&gt;
-    &lt;!-- optional (voluntary) feature support --&gt;
-    &lt;feature value="optional"&gt;#animation&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#bidi&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#cellResolution&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-gps&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-local&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-utc&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#color&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#direction&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#displayAlign&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-dropNTSC&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-dropPAL&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-nonDrop&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent-root&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily-generic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily-non-generic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize-anamorphic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize-isomorphic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle-italic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle-oblique&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontWeight-bold&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontWeight&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#frameRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#frameRateMultiplier&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#layout&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-cell&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-em&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-integer&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-negative&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-percentage&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-pixel&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-positive&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-real&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#lineBreak-uax14&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#lineHeight&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode-continuous&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode-discontinuous&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#metadata&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#nested-div&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#nested-span&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#opacity&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#origin&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#overflow-visible&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#overflow&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-1&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-2&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-3&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-4&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#pixelAspectRatio&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#presentation&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#showBackground&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-chained&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inheritance-content&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inheritance-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-nested&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-referential&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#subFrameRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign-absolute&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign-relative&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-over&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-through&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-under&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline-blurred&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline-unblurred&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#tickRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-clock-with-frames&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-clock&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-offset-with-frames&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-offset-with-ticks&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-clock&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-media&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-smpte&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeContainer&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#unicodeBidi&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#wrapOption&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-vertical&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#zIndex&lt;/feature&gt;
-  &lt;/features&gt;
-  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
-    &lt;!-- required (mandatory) extension support --&gt;
-    &lt;!-- optional (voluntary) extension support --&gt;
-  &lt;/extensions&gt;
-&lt;/profile&gt;
-
-</pre>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="profile-dfxp-presentation" name="profile-dfxp-presentation"></a>F.2
-        DFXP Presentation Profile</h3>
-
-        <p>The DFXP Presentation Profile is intended to be used to express minimum
-        compliance for presentation processing.</p>
-
-        <div class="exampleInner">
-          <pre>
-&lt;?xml version="1.0" encoding="utf-8"?&gt;
-&lt;!-- this file defines the "dfxp-presentation" profile of ttaf1-dfxp --&gt;
-&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
-  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    &lt;!-- required (mandatory) feature support --&gt;
-    &lt;feature value="required"&gt;#content&lt;/feature&gt;
-    &lt;feature value="required"&gt;#core&lt;/feature&gt;
-    &lt;feature value="required"&gt;#presentation&lt;/feature&gt;
-    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
-    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
-    &lt;!-- optional (voluntary) feature support --&gt;
-    &lt;feature value="optional"&gt;#animation&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#bidi&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#cellResolution&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-gps&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-local&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-utc&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#color&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#direction&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#displayAlign&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-dropNTSC&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-dropPAL&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-nonDrop&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent-root&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily-generic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily-non-generic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize-anamorphic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize-isomorphic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle-italic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle-oblique&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontWeight-bold&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontWeight&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#frameRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#frameRateMultiplier&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#layout&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-cell&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-em&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-integer&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-negative&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-percentage&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-pixel&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-positive&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-real&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#lineBreak-uax14&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#lineHeight&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode-continuous&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode-discontinuous&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#metadata&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#nested-div&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#nested-span&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#opacity&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#origin&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#overflow-visible&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#overflow&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-1&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-2&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-3&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-4&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#pixelAspectRatio&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#showBackground&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-chained&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inheritance-content&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inheritance-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-nested&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-referential&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#subFrameRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign-absolute&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign-relative&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-over&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-through&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-under&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline-blurred&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline-unblurred&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#tickRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-clock-with-frames&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-clock&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-offset-with-frames&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-offset-with-ticks&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-clock&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-media&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-smpte&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeContainer&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#transformation&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#unicodeBidi&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#wrapOption&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-vertical&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#zIndex&lt;/feature&gt;
-  &lt;/features&gt;
-  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
-    &lt;!-- required (mandatory) extension support --&gt;
-    &lt;!-- optional (voluntary) extension support --&gt;
-  &lt;/extensions&gt;
-&lt;/profile&gt;
-
-</pre>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="profile-dfxp-full" name="profile-dfxp-full"></a>F.3 DFXP Full
-        Profile</h3>
-
-        <p>The DFXP Full Profile is intended to be used to express maximum compliance for
-        both transformation and presentation processing.</p>
-
-        <div class="exampleInner">
-          <pre>
-&lt;?xml version="1.0" encoding="utf-8"?&gt;
-&lt;!-- this file defines the "dfxp-full" profile of ttaf1-dfxp --&gt;
-&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
-  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    &lt;!-- required (mandatory) feature support --&gt;
-    &lt;feature value="required"&gt;#animation&lt;/feature&gt;
-    &lt;feature value="required"&gt;#backgroundColor-block&lt;/feature&gt;
-    &lt;feature value="required"&gt;#backgroundColor-inline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#backgroundColor-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#backgroundColor&lt;/feature&gt;
-    &lt;feature value="required"&gt;#bidi&lt;/feature&gt;
-    &lt;feature value="required"&gt;#cellResolution&lt;/feature&gt;
-    &lt;feature value="required"&gt;#clockMode-gps&lt;/feature&gt;
-    &lt;feature value="required"&gt;#clockMode-local&lt;/feature&gt;
-    &lt;feature value="required"&gt;#clockMode-utc&lt;/feature&gt;
-    &lt;feature value="required"&gt;#clockMode&lt;/feature&gt;
-    &lt;feature value="required"&gt;#color&lt;/feature&gt;
-    &lt;feature value="required"&gt;#content&lt;/feature&gt;
-    &lt;feature value="required"&gt;#core&lt;/feature&gt;
-    &lt;feature value="required"&gt;#direction&lt;/feature&gt;
-    &lt;feature value="required"&gt;#display-block&lt;/feature&gt;
-    &lt;feature value="required"&gt;#display-inline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#display-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#display&lt;/feature&gt;
-    &lt;feature value="required"&gt;#displayAlign&lt;/feature&gt;
-    &lt;feature value="required"&gt;#dropMode-dropNTSC&lt;/feature&gt;
-    &lt;feature value="required"&gt;#dropMode-dropPAL&lt;/feature&gt;
-    &lt;feature value="required"&gt;#dropMode-nonDrop&lt;/feature&gt;
-    &lt;feature value="required"&gt;#dropMode&lt;/feature&gt;
-    &lt;feature value="required"&gt;#extent-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#extent-root&lt;/feature&gt;
-    &lt;feature value="required"&gt;#extent&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontFamily-generic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontFamily-non-generic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontFamily&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontSize-anamorphic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontSize-isomorphic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontSize&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontStyle-italic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontStyle-oblique&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontStyle&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontWeight-bold&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontWeight&lt;/feature&gt;
-    &lt;feature value="required"&gt;#frameRate&lt;/feature&gt;
-    &lt;feature value="required"&gt;#frameRateMultiplier&lt;/feature&gt;
-    &lt;feature value="required"&gt;#layout&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-cell&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-em&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-integer&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-negative&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-percentage&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-pixel&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-positive&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-real&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length&lt;/feature&gt;
-    &lt;feature value="required"&gt;#lineBreak-uax14&lt;/feature&gt;
-    &lt;feature value="required"&gt;#lineHeight&lt;/feature&gt;
-    &lt;feature value="required"&gt;#markerMode-continuous&lt;/feature&gt;
-    &lt;feature value="required"&gt;#markerMode-discontinuous&lt;/feature&gt;
-    &lt;feature value="required"&gt;#markerMode&lt;/feature&gt;
-    &lt;feature value="required"&gt;#metadata&lt;/feature&gt;
-    &lt;feature value="required"&gt;#nested-div&lt;/feature&gt;
-    &lt;feature value="required"&gt;#nested-span&lt;/feature&gt;
-    &lt;feature value="required"&gt;#opacity&lt;/feature&gt;
-    &lt;feature value="required"&gt;#origin&lt;/feature&gt;
-    &lt;feature value="required"&gt;#overflow-visible&lt;/feature&gt;
-    &lt;feature value="required"&gt;#overflow&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding-1&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding-2&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding-3&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding-4&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding&lt;/feature&gt;
-    &lt;feature value="required"&gt;#pixelAspectRatio&lt;/feature&gt;
-    &lt;feature value="required"&gt;#presentation&lt;/feature&gt;
-    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
-    &lt;feature value="required"&gt;#showBackground&lt;/feature&gt;
-    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-chained&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-inheritance-content&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-inheritance-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-inline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-nested&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-referential&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling&lt;/feature&gt;
-    &lt;feature value="required"&gt;#subFrameRate&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textAlign-absolute&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textAlign-relative&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textAlign&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textDecoration-over&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textDecoration-through&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textDecoration-under&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textDecoration&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textOutline-blurred&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textOutline-unblurred&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textOutline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#tickRate&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-clock-with-frames&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-clock&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset-with-frames&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset-with-ticks&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timeBase-clock&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timeBase-media&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timeBase-smpte&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timeContainer&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
-    &lt;feature value="required"&gt;#transformation&lt;/feature&gt;
-    &lt;feature value="required"&gt;#unicodeBidi&lt;/feature&gt;
-    &lt;feature value="required"&gt;#visibility-block&lt;/feature&gt;
-    &lt;feature value="required"&gt;#visibility-inline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#visibility-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#visibility&lt;/feature&gt;
-    &lt;feature value="required"&gt;#wrapOption&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode-horizontal&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode-vertical&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode&lt;/feature&gt;
-    &lt;feature value="required"&gt;#zIndex&lt;/feature&gt;
-    &lt;!-- optional (voluntary) feature support --&gt;
-  &lt;/features&gt;
-  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
-    &lt;!-- required (mandatory) extension support --&gt;
-    &lt;!-- optional (voluntary) extension support --&gt;
-  &lt;/extensions&gt;
-&lt;/profile&gt;
-
-</pre>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="references" name="references"></a>G References</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <dl>
-        <dt class="label"><a id="css2" name="css2"></a>CSS2</dt>
-
-        <dd>Bert Bos et al., <a href=
-        "http://www.w3.org/TR/1998/REC-CSS2-19980512/"><cite>Cascading Style Sheets,
-        Level 2</cite></a>, W3C Recommendation, 12 May 1998. (See <a href=
-        "http://www.w3.org/TR/1998/REC-CSS2-19980512/">http://www.w3.org/TR/1998/REC-CSS2-19980512/</a>.)</dd>
-
-        <dt class="label"><a id="gps" name="gps"></a>GPS</dt>
-
-        <dd><a href="http://tycho.usno.navy.mil/gpsinfo.html"><cite>Global Positioning
-        System</cite></a>, US Naval Observatory. (See <a href=
-        "http://tycho.usno.navy.mil/gpsinfo.html">http://tycho.usno.navy.mil/gpsinfo.html</a>.)</dd>
-
-        <dt class="label"><a id="media-types" name="media-types"></a>Media Types</dt>
-
-        <dd>Ned Freed and Nathaniel Borenstein, <a href=
-        "http://www.rfc-editor.org/rfc/rfc2046.txt"><cite>Multipurpose Internet Mail
-        Extensions (MIME) Part Two: Media Types</cite></a>, RFC 2046, November 1996,
-        IETF.(See <a href=
-        "http://www.rfc-editor.org/rfc/rfc2046.txt">http://www.rfc-editor.org/rfc/rfc2046.txt</a>.)</dd>
-
-        <dt class="label"><a id="rng" name="rng"></a>RELAX NG</dt>
-
-        <dd>ISO/IEC 19757-2, <a href="http://www.iso.org/"><cite>Information technology –
-        Document Schema Definition Language (DSDL) – Part 2: Regular-grammar-based
-        validation – RELAX NG</cite></a>, International Organization for Standardization
-        (ISO).</dd>
-
-        <dt class="label"><a id="smil21" name="smil21"></a>SMIL 2.1</dt>
-
-        <dd>Dick Bultermann, et al., <a href=
-        "http://www.w3.org/TR/2005/REC-SMIL2-20051213/"><cite>Synchronized Multimedia
-        Integration Language (SMIL 2.1)</cite></a>, W3C Recommendation, 13 December 2005.
-        (See <a href=
-        "http://www.w3.org/TR/2005/REC-SMIL2-20051213/">http://www.w3.org/TR/2005/REC-SMIL2-20051213/</a>.)</dd>
-
-        <dt class="label"><a id="smpte12m" name="smpte12m"></a>SMPTE 12M</dt>
-
-        <dd>ANSI/SMPTE 12M, <a href="https://www.smpte.org/"><cite>Television, Audio and
-        Film – Time and Control Code</cite></a>, SMPTE Standard.</dd>
-
-        <dt class="label"><a id="srgb" name="srgb"></a>SRGB</dt>
-
-        <dd>IEC 61966-2-1, <a href="http://www.iec.ch/"><cite>Multimedia systems and
-        equipment – Colour measurement and management – Part 2-1: Colour management –
-        Default RGB colour space – sRGB</cite></a>, International Electrotechnical
-        Commission (IEC).</dd>
-
-        <dt class="label"><a id="uaag" name="uaag"></a>UAAG</dt>
-
-        <dd>Ian Jacobs, Jon Gunderson, and Eric Hansen, Eds., <a href=
-        "http://www.w3.org/TR/2002/REC-UAAG10-20021217/"><cite>User Agent Accessibility
-        Guidelines 1.0</cite></a>, W3C Recommendation, 17 December 2002. (See <a href=
-        "http://www.w3.org/TR/2002/REC-UAAG10-20021217/">http://www.w3.org/TR/2002/REC-UAAG10-20021217/</a>.)</dd>
-
-        <dt class="label"><a id="utc" name="utc"></a>UTC</dt>
-
-        <dd>Recommendation TF.460, <a href="http://www.itu.int/"><cite>Standard-Frequency
-        and Time-Signal Emissions</cite></a>, International Telecommunciations Union,
-        Radio Sector (ITU-R).</dd>
-
-        <dt class="label"><a id="uax14" name="uax14"></a>UAX14</dt>
-
-        <dd>Asmus Freytag, <a href=
-        "http://www.unicode.org/reports/tr14/tr14-17.html"><cite>Line Breaking
-        Properties</cite></a>, Unicode Consortium, 29 August 2005. (See <a href=
-        "http://www.unicode.org/reports/tr14/tr14-17.html">http://www.unicode.org/reports/tr14/tr14-17.html</a>.)</dd>
-
-        <dt class="label"><a id="wcag" name="wcag"></a>WCAG</dt>
-
-        <dd>Ben Caldwell, et al., Eds., <a href=
-        "http://www.w3.org/TR/2008/REC-WCAG20-20081211/"><cite>Web Content Accessibility
-        Guidelines (WCAG) 2.0</cite></a>, W3C Recommendation, 11 December 2008. (See
-        <a href=
-        "http://www.w3.org/TR/2008/REC-WCAG20-20081211/">http://www.w3.org/TR/2008/REC-WCAG20-20081211/</a>.)</dd>
-
-        <dt class="label"><a id="xml10" name="xml10"></a>XML 1.0</dt>
-
-        <dd>Tim Bray, et al. <a href=
-        "http://www.w3.org/TR/2008/REC-xml-20081126/"><cite>Extensible Markup Language
-        (XML) 1.0 (Fifth Edition)</cite></a>, W3C Recommendation, 26 November 2008. (See
-        <a href=
-        "http://www.w3.org/TR/2008/REC-xml-20081126/">http://www.w3.org/TR/2008/REC-xml-20081126/</a>.)</dd>
-
-        <dt class="label"><a id="xml11" name="xml11"></a>XML 1.1</dt>
-
-        <dd>Tim Bray, et al. <a href=
-        "http://www.w3.org/TR/2006/REC-xml11-20060816/"><cite>Extensible Markup Language
-        (XML) 1.1 (Second Edition)</cite></a>, W3C Recommendation, 16 August 2006, edited
-        in place 29 September 2006. (See <a href=
-        "http://www.w3.org/TR/2006/REC-xml11-20060816/">http://www.w3.org/TR/2006/REC-xml11-20060816/</a>.)</dd>
-
-        <dt class="label"><a id="xmlbase" name="xmlbase"></a>XML Base</dt>
-
-        <dd>Jonathan Marsh and Richard Tobin, Eds., <a href=
-        "http://www.w3.org/TR/2009/REC-xmlbase-20090128/"><cite>XML Base (Second
-        Edition)</cite></a>, W3C Recommendation, 28 January 2009. (See <a href=
-        "http://www.w3.org/TR/2009/REC-xmlbase-20090128/">http://www.w3.org/TR/2009/REC-xmlbase-20090128/</a>.)</dd>
-
-        <dt class="label"><a id="xmlid" name="xmlid"></a>XML ID</dt>
-
-        <dd>Jonathan Marsh, Daniel Veillard, Norman Walsh, Eds., <a href=
-        "http://www.w3.org/TR/2005/REC-xml-id-20050909/"><cite>xml:id Version
-        1.0</cite></a>, W3C Recommendation, 09 September 2005. (See <a href=
-        "http://www.w3.org/TR/2005/REC-xml-id-20050909/">http://www.w3.org/TR/2005/REC-xml-id-20050909/</a>.)</dd>
-
-        <dt class="label"><a id="xml-media" name="xml-media"></a>XML Media</dt>
-
-        <dd>Makato Murata, Simon St. Laurent, Kan Khon, Eds., <a href=
-        "http://www.rfc-editor.org/rfc/rfc3023.txt"><cite>XML Media Types</cite></a>, RFC
-        3023, January 2001, IETF.(See <a href=
-        "http://www.rfc-editor.org/rfc/rfc3023.txt">http://www.rfc-editor.org/rfc/rfc3023.txt</a>.)</dd>
-
-        <dt class="label"><a id="infoset" name="infoset"></a>XML InfoSet</dt>
-
-        <dd>John Cowan and Richard Tobin, Eds., <a href=
-        "http://www.w3.org/TR/2004/REC-xml-infoset-20040204/"><cite>XML Information Set
-        (Second Edition)</cite></a>, W3C Recommendation, 04 February 2004. (See <a href=
-        "http://www.w3.org/TR/2004/REC-xml-infoset-20040204/">http://www.w3.org/TR/2004/REC-xml-infoset-20040204/</a>.)</dd>
-
-        <dt class="label"><a id="rfc3023" name="rfc3023"></a>XML Media Types</dt>
-
-        <dd>Makato Murata, et al., <a href=
-        "http://www.rfc-editor.org/rfc/rfc3023.txt"><cite>XML Media Types</cite></a>, RFC
-        3023, January 2001, IETF.(See <a href=
-        "http://www.rfc-editor.org/rfc/rfc3023.txt">http://www.rfc-editor.org/rfc/rfc3023.txt</a>.)</dd>
-
-        <dt class="label"><a id="xmlns10" name="xmlns10"></a>XML Namespaces 1.0</dt>
-
-        <dd>Tim Bray, et al. <a href=
-        "http://www.w3.org/TR/2009/REC-xml-names-20091208/"><cite>Namespaces in XML 1.0
-        (Third Edition)</cite></a>, W3C Recommendation, 8 December 2009. (See <a href=
-        "http://www.w3.org/TR/2009/REC-xml-names-20091208/">http://www.w3.org/TR/2009/REC-xml-names-20091208/</a>.)</dd>
-
-        <dt class="label"><a id="xsd-1" name="xsd-1"></a>XML Schema Part 1</dt>
-
-        <dd>Henry S. Thompson, David Beech, Murray Maloney, Noah Mendelsohn, Eds.,
-        <a href="http://www.w3.org/TR/xmlschema-1/"><cite>XML Schema Part 1:
-        Structures</cite></a>, W3C Recommendation, 28 October 2004. (See <a href=
-        "http://www.w3.org/TR/xmlschema-1/">http://www.w3.org/TR/xmlschema-1/</a>.)</dd>
-
-        <dt class="label"><a id="xsd-2" name="xsd-2"></a>XML Schema Part 2</dt>
-
-        <dd>Paul Biron and Ashok Malhotra, <a href=
-        "http://www.w3.org/TR/xmlschema-2/"><cite>XML Schema Part 2:
-        Datatypes</cite></a>, W3C Recommendation, 28 October 2004. (See <a href=
-        "http://www.w3.org/TR/xmlschema-2/">http://www.w3.org/TR/xmlschema-2/</a>.)</dd>
-
-        <dt class="label"><a id="xsl11" name="xsl11"></a>XSL 1.1</dt>
-
-        <dd>Anders Berglund, <a href=
-        "http://www.w3.org/TR/2006/REC-xsl11-20061205/"><cite>Extensible Stylesheet
-        Language (XSL) Version 1.1</cite></a>, W3C Recommendation, 05 December 2006. (See
-        <a href=
-        "http://www.w3.org/TR/2006/REC-xsl11-20061205/">http://www.w3.org/TR/2006/REC-xsl11-20061205/</a>.)</dd>
-      </dl>
-    </div>
-
-    <div class="div1">
-      <h2><a id="other-references" name="other-references"></a>H Other References
-      (Non-Normative)</h2>
-
-      <dl>
-        <dt class="label"><a id="ccreq" name="ccreq"></a>CC-DECODER-REQ</dt>
-
-        <dd><a href=
-        "http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml">
-        <cite>Closed Caption Decoder Requirements for Analog Television</cite></a>,
-        United States Code of Federal Regulations, Title 47, Volume 1, Part 15, § 15.119.
-        (See <a href=
-        "http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml">
-        http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml</a>.)</dd>
-
-        <dt class="label"><a id="cea608c" name="cea608c"></a>CEA-608-C</dt>
-
-        <dd>EIA/CEA-608-C, <a href="http://www.ce.org/"><cite>Line 21 Data
-        Services</cite></a>, EIA/CEA Standard, Consumer Electronics Association
-        (CEA).</dd>
-
-        <dt class="label"><a id="cea708d" name="cea708d"></a>CEA-708-D</dt>
-
-        <dd>CEA-708-D, <a href="http://www.ce.org/"><cite>Digital Television (DTV) Closed
-        Captioning</cite></a>, CEA Standard, Consumer Electronics Association (CEA).</dd>
-
-        <dt class="label"><a id="css3-color" name="css3-color"></a>CSS3 Color</dt>
-
-        <dd>Tantek Çelik and Chris Lilley, <a href=
-        "http://www.w3.org/TR/2003/CR-css3-color-20030514/"><cite>CSS3 Color
-        Module</cite></a>, W3C Candidate Recommendation, 14 May 2003. (See <a href=
-        "http://www.w3.org/TR/2003/CR-css3-color-20030514/">http://www.w3.org/TR/2003/CR-css3-color-20030514/</a>.)</dd>
-
-        <dt class="label"><a id="dcmes" name="dcmes"></a>DCMES 1.1</dt>
-
-        <dd>Dublin Core Metadata Initiative, <a href=
-        "http://dublincore.org/documents/dces/"><cite>Dublin Core Metadata Element Set,
-        Version 1.1: Reference Description</cite></a>. (See <a href=
-        "http://dublincore.org/documents/dces/">http://dublincore.org/documents/dces/</a>.)</dd>
-
-        <dt class="label"><a id="mpeg7-5" name="mpeg7-5"></a>MPEG7-5</dt>
-
-        <dd>ISO/IEC 15938-5, <a href="http://www.iso.org/"><cite>Information technology –
-        Multimedia content description interface – Part 5: Multimedia description
-        schemes</cite></a>, International Organization for Standardization (ISO).</dd>
-
-        <dt class="label"><a id="nsstate" name="nsstate"></a>NSState</dt>
-
-        <dd>Norman Walsh, Ed., <a href=
-        "http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09.html"><cite>The
-        Disposition of Names in an XML Namespace</cite></a>, TAG Finding, 9 January 2006.
-        (See <a href=
-        "http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09.html">http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09</a>.)</dd>
-
-        <dt class="label"><a id="qaf-sg" name="qaf-sg"></a>QAF SG</dt>
-
-        <dd>Karl Dubost, et al., <a href=
-        "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/"><cite>QA Framework:
-        Specifications Guidelines</cite></a>, W3C Recommendation, 17 August 2005. (See
-        <a href=
-        "http://www.w3.org/TR/qaframe-spec/">http://www.w3.org/TR/qaframe-spec/</a>.)</dd>
-
-        <dt class="label"><a id="smpte170m" name="smpte170m"></a>SMPTE 170M</dt>
-
-        <dd>ANSI/SMPTE 170M, <a href="http://www.smpte.org/"><cite>Television – Composite
-        Analog Video Signal – NTSC for Studio Applications</cite></a>, SMPTE
-        Standard.</dd>
-
-        <dt class="label"><a id="smpte2052" name="smpte2052"></a>SMPTE 2052-11</dt>
-
-        <dd>SMPTE 2052-11, <a href="http://www.smpte.org/"><cite>Conversion from CEA-708
-        Caption Data to SMPTE-TT</cite></a>, SMPTE Recommended Practice.</dd>
-
-        <dt class="label"><a id="svg11" name="svg11"></a>SVG 1.1</dt>
-
-        <dd>Jon Ferraiolo, Jun Fujisawa, Dean Jackson, Eds., <a href=
-        "http://www.w3.org/TR/2003/REC-SVG11-20030114/"><cite>Scalable Vector Graphics
-        (SVG) 1.1 Specification</cite></a>, W3C Recommendation, 14 January 2003. (See
-        <a href=
-        "http://www.w3.org/TR/2003/REC-SVG11-20030114/">http://www.w3.org/TR/2003/REC-SVG11-20030114/</a>.)</dd>
-
-        <dt class="label"><a id="ttaf1-req" name="ttaf1-req"></a>TTAF1-REQ</dt>
-
-        <dd>Glenn Adams, Ed., <a href=
-        "http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/"><cite>Timed Text (TT)
-        Authoring Format 1.0 Use Cases and Requirements</cite></a>, W3C Working Group
-        Note, 27 April 2006. (See <a href=
-        "http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/">http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/</a>.)</dd>
-
-        <dt class="label"><a id="xhtml10" name="xhtml10"></a>XHTML 1.0</dt>
-
-        <dd>Steven Pemberton, et al., <a href=
-        "http://www.w3.org/TR/2002/REC-xhtml1-20020801/"><cite>XHTML™ 1.0, The Extensible
-        Hypertext Markup Language (Second Edition)</cite></a>, W3C Recommendation, 01
-        August 2002. (See <a href=
-        "http://www.w3.org/TR/2002/REC-xhtml1-20020801/">http://www.w3.org/TR/2002/REC-xhtml1-20020801/</a>.)</dd>
-      </dl>
-    </div>
-
-    <div class="div1">
-      <h2><a id="requirements" name="requirements"></a>I Requirements
-      (Non-Normative)</h2>
-
-      <p>The Distribution Format Exchange Profile (DFXP) of the Timed Text Authoring
-      Format (TTML) satisfies a subset of the requirements established by <a href=
-      "#ttaf1-req">[TTAF1-REQ]</a>. The following table enumerates these requirements and
-      indicates the extent to which they are satisfied by this specification, where
-      <em>S</em> denotes a requirement is satisfied, <em>P</em> denotes a requirement is
-      partially satisfied, and <em>N</em> denotes a requirement is not
-      satisfied.</p><a id="requirements-table" name="requirements-table"></a>
-
-      <table class="common">
-        <caption>
-          Table I-1 – Requirement Satisfaction
-        </caption>
-        <col width="10%" span="1">
-        <col width="40%" span="1">
-        <col width="10%" span="1">
-        <col span="1">
-
-        <tbody>
-          <tr>
-            <th>ID</th>
-
-            <th>Name</th>
-
-            <th>Status</th>
-
-            <th>Comments</th>
-          </tr>
-
-          <tr>
-            <td>R100</td>
-
-            <td>Specification Format</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R101</td>
-
-            <td>Specification Modularity</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R102</td>
-
-            <td>Specification Organization</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R103</td>
-
-            <td>Core and Periphery</td>
-
-            <td>S</td>
-
-            <td>TT extension namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R104</td>
-
-            <td>Evolution of Core</td>
-
-            <td>S</td>
-
-            <td>TT extension namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R105</td>
-
-            <td>Ownership of Core</td>
-
-            <td>S</td>
-
-            <td>TT namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R106</td>
-
-            <td>Surjection of Core</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R107</td>
-
-            <td>Evolution of Periphery</td>
-
-            <td>S</td>
-
-            <td>TT extension namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R108</td>
-
-            <td>Ownership of Periphery</td>
-
-            <td>S</td>
-
-            <td>Non-TT namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R109</td>
-
-            <td>Transformation</td>
-
-            <td>S</td>
-
-            <td>Supports 3GPP, QText, RealText, SAMI</td>
-          </tr>
-
-          <tr>
-            <td>R110</td>
-
-            <td>Streamable Transformation</td>
-
-            <td>S</td>
-
-            <td>Progressive decoding</td>
-          </tr>
-
-          <tr>
-            <td>R111</td>
-
-            <td>Accessibility – Content</td>
-
-            <td>S</td>
-
-            <td>Alternative document instances</td>
-          </tr>
-
-          <tr>
-            <td>R112</td>
-
-            <td>Accessibility – Authoring System</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R200</td>
-
-            <td>Authorability</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R201</td>
-
-            <td>Multiple Natural Languages</td>
-
-            <td>S</td>
-
-            <td>Alternative document instances</td>
-          </tr>
-
-          <tr>
-            <td>R202</td>
-
-            <td>Natural Language Coverage</td>
-
-            <td>S</td>
-
-            <td>Unicode 4.0</td>
-          </tr>
-
-          <tr>
-            <td>R203</td>
-
-            <td>Natural Language Association Granularity</td>
-
-            <td>S</td>
-
-            <td>See <code>xml:lang</code></td>
-          </tr>
-
-          <tr>
-            <td>R204</td>
-
-            <td>Minimum Character Representability</td>
-
-            <td>S</td>
-
-            <td>Unicode 4.0</td>
-          </tr>
-
-          <tr>
-            <td>R205</td>
-
-            <td>Intrinsic and Extrinsic Text Content</td>
-
-            <td>P</td>
-
-            <td>Intrinsic only</td>
-          </tr>
-
-          <tr>
-            <td>R206</td>
-
-            <td>Markup Association</td>
-
-            <td>P</td>
-
-            <td>Intrinsic only</td>
-          </tr>
-
-          <tr>
-            <td>R207</td>
-
-            <td>Conditional Content</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R208</td>
-
-            <td>Flowed Text</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R209</td>
-
-            <td>Logical Flowed Text Vocabulary</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R210</td>
-
-            <td>Presentational Flowed Text Vocabulary</td>
-
-            <td>S</td>
-
-            <td>Implied mapping from logical flowed text.</td>
-          </tr>
-
-          <tr>
-            <td>R211</td>
-
-            <td>Flowed Text Vocabulary Relationship</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R212</td>
-
-            <td>Flowed Text Vocabulary Separation</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R213</td>
-
-            <td>Non-Flowed Text</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R214</td>
-
-            <td>Non-Flowed Text Vocabulary</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R215</td>
-
-            <td>Hybrid Flowed and Non-Flowed Text</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R216</td>
-
-            <td>Hyperlinking</td>
-
-            <td>N</td>
-
-            <td>Can support via XLink</td>
-          </tr>
-
-          <tr>
-            <td>R217</td>
-
-            <td>Embedded Graphics</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R218</td>
-
-            <td>Non-Embedded Graphics</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R219</td>
-
-            <td>Embedded Fonts</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R220</td>
-
-            <td>Non-Embedded Fonts</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R221</td>
-
-            <td>Descriptive Vocabulary</td>
-
-            <td>S</td>
-
-            <td>See <code>ttm:agent</code>, <code>ttm:role</code></td>
-          </tr>
-
-          <tr>
-            <td>R222</td>
-
-            <td>Embedded Audio</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R223</td>
-
-            <td>Non-Embedded Audio</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R290</td>
-
-            <td>Markup Format</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R291</td>
-
-            <td>Markup Format and Unicode Interaction</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R292</td>
-
-            <td>Extrinsic Resource References</td>
-
-            <td>N</td>
-
-            <td>No extrinsic references</td>
-          </tr>
-
-          <tr>
-            <td>R293</td>
-
-            <td>Schema Validity Specification</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R300</td>
-
-            <td>Inline Styling</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R301</td>
-
-            <td>Inline Styling Form</td>
-
-            <td>P</td>
-
-            <td>Inline and referential styling</td>
-          </tr>
-
-          <tr>
-            <td>R301</td>
-
-            <td>Out-of-Line Styling</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R301</td>
-
-            <td>Out-of-Line Styling Form</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R304</td>
-
-            <td>Styling Prioritization</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R305</td>
-
-            <td>Style Parameters – Aural</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R306</td>
-
-            <td>Style Parameters – Visual</td>
-
-            <td>P</td>
-
-            <td>Supports absolute position, background color, color, display none,
-            display alignment, font family, font size, font style, font weight, height,
-            line height, origin, opacity, overflow, padding (before, after, start, end),
-            text alignment, text shadow (as outline), visibility, width, writing mode,
-            z-index</td>
-          </tr>
-
-          <tr>
-            <td>R390</td>
-
-            <td>Style Parameter Symmetry</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R391</td>
-
-            <td>Style Parameter Definitions</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R392</td>
-
-            <td>Style Parameter Shorthands</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R401</td>
-
-            <td>Inline Timing</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R402</td>
-
-            <td>Out-of-Line Timing</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R403</td>
-
-            <td>Synchronization Parameters</td>
-
-            <td>P</td>
-
-            <td>Supports begin, end, dur</td>
-          </tr>
-
-          <tr>
-            <td>R404</td>
-
-            <td>Synchronization Parameter Value Spaces</td>
-
-            <td>P</td>
-
-            <td>Supports offset values, media marker values (SMPTE 12M), wall-clock
-            values</td>
-          </tr>
-
-          <tr>
-            <td>R405</td>
-
-            <td>Time Containment Semantics</td>
-
-            <td>P</td>
-
-            <td>Supports sequential, parallel</td>
-          </tr>
-
-          <tr>
-            <td>R500</td>
-
-            <td>Animation Modes</td>
-
-            <td>P</td>
-
-            <td>Supports discrete</td>
-          </tr>
-
-          <tr>
-            <td>R502</td>
-
-            <td>Highlight Animation</td>
-
-            <td>S</td>
-
-            <td><code>&lt;set tts:backgroundColor="..."/&gt;</code></td>
-          </tr>
-
-          <tr>
-            <td>R503</td>
-
-            <td>Fade Transition Animation</td>
-
-            <td>S</td>
-
-            <td><code>&lt;set tts:opacity="..."/&gt;</code></td>
-          </tr>
-
-          <tr>
-            <td>R504</td>
-
-            <td>Animated Style Parameters – Aural</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R505</td>
-
-            <td>Animated Style Parameters – Visual</td>
-
-            <td>P</td>
-
-            <td>Supports animating background color, color, display, opacity, origin,
-            visibility</td>
-          </tr>
-
-          <tr>
-            <td>N506</td>
-
-            <td>Animated Content</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R600</td>
-
-            <td>Metadata Item Association</td>
-
-            <td>S</td>
-
-            <td>See <code>metadata</code>, <code>Metadata.class</code></td>
-          </tr>
-
-          <tr>
-            <td>R601</td>
-
-            <td>Metadata Item Constituents</td>
-
-            <td>P</td>
-
-            <td>Supports name, value</td>
-          </tr>
-
-          <tr>
-            <td>R602</td>
-
-            <td>Metadata Item Value Representation</td>
-
-            <td>P</td>
-
-            <td>See <code>metadata</code></td>
-          </tr>
-
-          <tr>
-            <td>R603</td>
-
-            <td>Metadata Item Extensibility</td>
-
-            <td>S</td>
-
-            <td>See <code>metadata</code></td>
-          </tr>
-
-          <tr>
-            <td>R604</td>
-
-            <td>Metadata Item Validation</td>
-
-            <td>S</td>
-
-            <td>See <code>metadata</code></td>
-          </tr>
-
-          <tr>
-            <td>R690</td>
-
-            <td>Dublin Core Preference</td>
-
-            <td>N</td>
-
-            <td>Uses <code>ttm:copyright</code>, <code>ttm:desc</code>,
-            <code>ttm:title</code></td>
-          </tr>
-        </tbody>
-      </table>
-    </div>
-
-    <div class="div1">
-      <h2><a id="derivation" name="derivation"></a>J Vocabulary Derivation
-      (Non-Normative)</h2>
-
-      <p>This appendix provides information about the derivation of TTML vocabulary,
-      separately describing derivation of elements and attributes.</p>
-
-      <div class="div2">
-        <h3><a id="d3e18280" name="d3e18280"></a>J.1 Element Derivation</h3>
-
-        <p>The first column of <a href="#element-vocab-derivation-table"><b>Table J-1 –
-        Elements</b></a> specifies a TTML element vocabulary item; the second column
-        specifies the syntactic and/or semantic model on which the vocabulary item is
-        based; the third column specifies the reference that defines the model (if a
-        model is indicated); the fourth column specifies details about the derivation;
-        the last column refers to additional notes describing the nature of the
-        derivation.</p>
-
-        <p>In the fourth column, which describes details of derivation, a notation is use
-        to indicate the addition or removal of an attribute. For example, in the
-        derivation of the <code>tt:div</code> element, the details column includes
-        "-@class", which denotes that the <code>class</code> attribute that is specified
-        for use with the <code>xhtml:div</code> model element is not specified for use
-        with the corresponding TTML element; in contrast, the details column includes
-        "+@begin", which denotes that a <code>begin</code> attribute is added that is not
-        specified for use with the <code>xhtml:div</code> model element.</p><a id=
-        "element-vocab-derivation-table" name="element-vocab-derivation-table"></a>
-
-        <table class="common">
-          <caption>
-            Table J-1 – Elements
-          </caption>
-          <col width="20%" span="1">
-          <col width="17%" span="1">
-          <col width="13%" align="center" span="1">
-          <col width="40%" span="1">
-          <col width="10%" align="center" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Element</span></td>
-
-              <td><span class="strong">Model</span></td>
-
-              <td><span class="strong">Reference</span></td>
-
-              <td><span class="strong">Details</span></td>
-
-              <td><span class="strong">Notes</span></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#document-structure-vocabulary-body"><code>tt:body</code></a></td>
-
-              <td><code>xhtml:body</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end,
-              +@region, +@timeContainer, +@ttm:*, +@tts:*; content model subsetted to
-              zero or more division (div) children, and supersetted by optional metadata
-              and animation children</td>
-
-              <td>1,2</td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-vocabulary-br"><code>tt:br</code></a></td>
-
-              <td><code>xhtml:br</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@title; +@ttm:*, +@tts:*, +@xml:lang, +@xml:space; content
-              model supersetted by optional metadata and animation children for congruity
-              with other content vocabulary</td>
-
-              <td>1,2</td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-vocabulary-div"><code>tt:div</code></a></td>
-
-              <td><code>xhtml:div</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end,
-              +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model
-              subsetted to zero or more paragraph (p) children, and supersetted by
-              optional metadata and animation children</td>
-
-              <td>1,2,3</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#document-structure-vocabulary-head"><code>tt:head</code></a></td>
-
-              <td><code>xhtml:head</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@dir, -@lang, -@profile; +@id, +@xml:space; content model changed to
-              optional metadata children, followed by optional styling child, followed by
-              optional layout child</td>
-
-              <td>1,3</td>
-            </tr>
-
-            <tr>
-              <td><a href="#layout-vocabulary-layout"><code>tt:layout</code></a></td>
-
-              <td><code>fo:simple-page-master</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-metadata"><code>tt:metadata</code></a></td>
-
-              <td><code>svg:metadata</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>-@xml:base; +@ttm:*, +@xml:lang, +@xml:space; content model subsetted
-              to foreign namespace element content only (no #PCDATA)</td>
-
-              <td>3,5</td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-vocabulary-p"><code>tt:p</code></a></td>
-
-              <td><code>xhtml:p</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end,
-              +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model
-              subsetted to zero or more span children, and supersetted by optional
-              metadata and animation children</td>
-
-              <td>1,2,3</td>
-            </tr>
-
-            <tr>
-              <td><a href="#layout-vocabulary-region"><code>tt:region</code></a></td>
-
-              <td><code>fo:region-*</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#animation-vocabulary-set"><code>tt:set</code></a></td>
-
-              <td><code>svg:set</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>-@* except begin, dur, end; +@tts:*, +@xml:lang, +@xml:space</td>
-
-              <td>3,6</td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-vocabulary-span"><code>tt:span</code></a></td>
-
-              <td><code>xhtml:span</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end,
-              +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model
-              subsetted to zero or more #PCDATA or break (br) children, and supersetted
-              by optional metadata and animation children</td>
-
-              <td>1,2,3</td>
-            </tr>
-
-            <tr>
-              <td><a href="#styling-vocabulary-style"><code>tt:style</code></a></td>
-
-              <td><em>style specification</em></td>
-
-              <td><a href="#css2">[CSS2]</a></td>
-
-              <td>XML representation of identified set of pairs of style property name
-              and value, with optional inclusion of other styles by reference to other
-              style elements</td>
-
-              <td>7</td>
-            </tr>
-
-            <tr>
-              <td><a href="#styling-vocabulary-styling"><code>tt:styling</code></a></td>
-
-              <td><code>xhtml:style</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>XML representation of a set of style specifications sets, each
-              represented by a style child element</td>
-
-              <td>1,7</td>
-            </tr>
-
-            <tr>
-              <td><a href="#document-structure-vocabulary-tt"><code>tt:tt</code></a></td>
-
-              <td><code>xhtml:html</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@dir, -@lang; +@id, +@ttp:*, +@xml:space; content model subsetted by
-              permitting body and/or head to be optional</td>
-
-              <td>1,8</td>
-            </tr>
-
-            <tr>
-              <td><a href="#metadata-vocabulary-actor"><code>ttm:actor</code></a></td>
-
-              <td><code>mpeg7:Creator</code></td>
-
-              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#metadata-vocabulary-agent"><code>ttm:agent</code></a></td>
-
-              <td><code>mpeg7:Agent</code></td>
-
-              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-copyright"><code>ttm:copyright</code></a></td>
-
-              <td><code>mpeg7:CopyrightString</code></td>
-
-              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#metadata-vocabulary-desc"><code>ttm:desc</code></a></td>
-
-              <td><code>svg:desc</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>-@class, -@style, -@xml:base</td>
-
-              <td>2,5,9</td>
-            </tr>
-
-            <tr>
-              <td><a href="#metadata-vocabulary-name"><code>ttm:name</code></a></td>
-
-              <td><code>mpeg7:Name</code></td>
-
-              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#metadata-vocabulary-title"><code>ttm:title</code></a></td>
-
-              <td><code>svg:title</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>-@class, -@style, -@xml:base</td>
-
-              <td>2,5,9</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-extension"><code>ttp:extension</code></a></td>
-
-              <td><code>@requiredExtensions</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>10</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-extensions"><code>ttp:extensions</code></a></td>
-
-              <td><code>@requiredExtensions</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>10</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-feature"><code>ttp:feature</code></a></td>
-
-              <td><code>@requiredFeatures</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>10</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-features"><code>ttp:features</code></a></td>
-
-              <td><code>@requiredFeatures</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>10</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-profile"><code>ttp:profile</code></a></td>
-
-              <td><code>@baseProfile</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>11</td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <ol class="enumar">
-            <li>
-              <p>Derivation is indicated with respect to the strict DTD defined by
-              <a href="#xhtml10">[XHTML 1.0]</a>, §A.1.</p>
-            </li>
-
-            <li>
-              <p>The <code>class</code> attribute is effectively replaced by the
-              <code>style</code> attribute, which, instead of specifying an inline style,
-              refers indirectly to one or more <a href=
-              "#styling-vocabulary-style"><code>style</code></a> elements that define a
-              set of style specification sets.</p>
-            </li>
-
-            <li>
-              <p>The <code>xml:lang</code> and <code>xml:space</code> attributes are
-              defined for all element types in order to support their inheritance
-              semantics to operate in the context of foreign namespace elements.</p>
-            </li>
-
-            <li>
-              <p>Derivation is conceptual (notional) only.</p>
-            </li>
-
-            <li>
-              <p>The <code>xml:base</code> attribute is not used since there are no
-              external references from core vocabulary.</p>
-            </li>
-
-            <li>
-              <p>The <code>attributeName</code> and <code>to</code> attributes of
-              <code>svg:set</code> are replaced by the direct expression of the target
-              attribute name and value by use of a <code>tts:*</code> attribute.</p>
-            </li>
-
-            <li>
-              <p>CSS style specification syntax is mapped to XML by use of attributes
-              defined in the TT Style Namespace.</p>
-            </li>
-
-            <li>
-              <p>The <code>xml:id</code> attribute is defined for use on all element
-              types.</p>
-            </li>
-
-            <li>
-              <p>The <code>style</code> attribute is supported only on content
-              elements.</p>
-            </li>
-
-            <li>
-              <p>Derived from the use of <code>@requiredExtensions</code> and
-              <code>@requiredFeatures</code> on the <code>svg:svg</code> element, but
-              extended to support distinct specification of optionality.</p>
-            </li>
-
-            <li>
-              <p>Derived from the use of <code>@baseProfile</code> and
-              <code>@version</code> on the <code>svg:svg</code> element.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="d3e18759" name="d3e18759"></a>J.2 Attribute Derivation</h3>
-
-        <p>The first column of <a href="#attribute-vocab-derivation-table"><b>Table J-2 –
-        Attributes</b></a> specifies a TTML attribute vocabulary item; the second column
-        specifies the syntactic and/or semantic model on which the vocabulary item is
-        based; the third column specifies the reference that defines the model (if a
-        model is indicated); the fourth column specifies details about the derivation;
-        the last column refers to additional notes describing the nature of the
-        derivation.</p>
-
-        <p>In the fourth column, which describes details of derivation, a notation is use
-        to indicate the addition or removal of an attribute value. For example, in the
-        derivation of the <code>timeContainer</code> attribute, the details column
-        includes "-excl", which denotes that the <code>excl</code> value that is
-        specified for use with the <code>timeContainer</code> model attribute is not
-        specified for use with the corresponding TTML attribute; similarly, an
-        "+<em>value</em>" in the details column indicates that the attribute's values
-        have been extended to include <em>value</em>.</p>
-
-        <p>Only those attributes that are specified for use on more than one TTML element
-        type are listed below. Those per-element namespace attributes that are uniquely
-        defined for a specific TTML element type are not listed below, but are considered
-        to be part of the specific element type's derivation described in <a href=
-        "#element-vocab-derivation-table"><b>Table J-1 – Elements</b></a>
-        above.</p><a id="attribute-vocab-derivation-table" name=
-        "attribute-vocab-derivation-table"></a>
-
-        <table class="common">
-          <caption>
-            Table J-2 – Attributes
-          </caption>
-          <col width="20%" span="1">
-          <col width="17%" span="1">
-          <col width="13%" align="center" span="1">
-          <col width="40%" span="1">
-          <col width="10%" align="center" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Attribute</span></td>
-
-              <td><span class="strong">Model</span></td>
-
-              <td><span class="strong">Reference</span></td>
-
-              <td><span class="strong">Details</span></td>
-
-              <td><span class="strong">Notes</span></td>
-            </tr>
-
-            <tr>
-              <td><a href="#timing-attribute-begin"><code>begin</code></a></td>
-
-              <td><code>begin</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td>see notes</td>
-
-              <td>2,3,4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#timing-attribute-dur"><code>dur</code></a></td>
-
-              <td><code>dur</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td>see notes</td>
-
-              <td>2,3,4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#timing-attribute-end"><code>end</code></a></td>
-
-              <td><code>end</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td>see notes</td>
-
-              <td>2,3,4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#layout-attribute-region"><code>region</code></a></td>
-
-              <td><code>master-reference</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-style"><code>style</code></a></td>
-
-              <td><code>class</code></td>
-
-              <td><a href="#css2">[CSS2]</a></td>
-
-              <td>dereferences style specification(s) directly</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#timing-attribute-timeContainer"><code>timeContainer</code></a></td>
-
-              <td><code>timeContainer</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td>-excl, -none; no default attribute value</td>
-
-              <td>5</td>
-            </tr>
-
-            <tr>
-              <td><a href="#metadata-attribute-agent"><code>ttm:agent</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to attribute agent of content</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#metadata-attribute-role"><code>ttm:role</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to attribute role of content</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses uniform grid resolution for cell based coordinates</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>determines how to interpret time expressions</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses integral frame rate</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to express non-integral, rational frame rates</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses marker continuity semantics</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses pixel aspect ratio of related media</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-profile"><code>ttp:profile</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses profile of TTML used by <em>Document Instance</em></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses frame counting (drop) modes</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses sub-frame rate</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-tickRate"><code>ttp:tickRate</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to interpret tick based time expressions</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to interpret semantics of time expressions</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a></td>
-
-              <td><code>background-color</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1,6</td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-color"><code>tts:color</code></a></td>
-
-              <td><code>color</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>6</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-direction"><code>tts:direction</code></a></td>
-
-              <td><code>direction</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-display"><code>tts:display</code></a></td>
-
-              <td><code>display</code></td>
-
-              <td><a href="#css2">[CSS2]</a></td>
-
-              <td>only <code>auto</code>, <code>none</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-displayAlign"><code>tts:displayAlign</code></a></td>
-
-              <td><code>display-align</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-extent"><code>tts:extent</code></a></td>
-
-              <td><code>width</code>, <code>height</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>shorthand property</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-fontFamily"><code>tts:fontFamily</code></a></td>
-
-              <td><code>font-family</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, extends generic family names</td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-fontSize"><code>tts:fontSize</code></a></td>
-
-              <td><code>font-size</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1,7</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-fontWeight"><code>tts:fontWeight</code></a></td>
-
-              <td><code>font-weight</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-bolder</code>, <code>-lighter</code>,
-              <code>-&lt;number&gt;</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-lineHeight"><code>tts:lineHeight</code></a></td>
-
-              <td><code>line-height</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-&lt;number&gt;</code>,
-              <code>-&lt;space&gt;</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-opacity"><code>tts:opacity</code></a></td>
-
-              <td><code>opacity</code></td>
-
-              <td><a href="#css3-color">[CSS3 Color]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-origin"><code>tts:origin</code></a></td>
-
-              <td><code>top</code>, <code>left</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>shorthand property</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-overflow"><code>tts:overflow</code></a></td>
-
-              <td><code>overflow</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-auto</code>,
-              <code>-error-if-overflow</code>;</td>
-
-              <td>8</td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-padding"><code>tts:padding</code></a></td>
-
-              <td><code>padding</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>9</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-showBackground"><code>tts:showBackground</code></a></td>
-
-              <td><code>showBackground</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-textAlign"><code>tts:textAlign</code></a></td>
-
-              <td><code>text-align</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-textDecoration"><code>tts:textDecoration</code></a></td>
-
-              <td><code>text-decoration</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1,10,13</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-textOutline"><code>tts:textOutline</code></a></td>
-
-              <td><code>text-shadow</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>11,13</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a></td>
-
-              <td><code>unicode-bidi</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-visibility"><code>tts:visibility</code></a></td>
-
-              <td><code>visibility</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-collapse</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-wrapOption"><code>tts:wrapOption</code></a></td>
-
-              <td><code>wrap-option</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-writingMode"><code>tts:writingMode</code></a></td>
-
-              <td><code>writing-mode</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>+tblr</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-zIndex"><code>tts:zIndex</code></a></td>
-
-              <td><code>z-index</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-attribute-id"><code>xml:id</code></a></td>
-
-              <td><code>xml:id</code></td>
-
-              <td><a href="#xmlid">[XML ID]</a></td>
-
-              <td>complies with model</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-attribute-lang"><code>xml:lang</code></a></td>
-
-              <td><code>xml:lang</code></td>
-
-              <td><a href="#xml10">[XML 1.0]</a></td>
-
-              <td>complies with model</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-attribute-space"><code>xml:space</code></a></td>
-
-              <td><code>xml:space</code></td>
-
-              <td><a href="#xml10">[XML 1.0]</a></td>
-
-              <td>see notes</td>
-
-              <td>12</td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <ol class="enumar">
-            <li>
-              <p>Attribute name and/or value(s) are normalized to use
-              <em>lowerCamelCase</em> naming convention.</p>
-            </li>
-
-            <li>
-              <p>Restricted to expressing a clock value that denotes one of the following
-              in accordance to whether the parameter expressed by the
-              <code>ttp:timeBase</code> attribute is <code>media</code>,
-              <code>smpte</code>, or <code>clock</code>, respectively: (1) an offset from
-              an implicit syncbase that is linked to a media time line, (2) an event time
-              that represents the occurrence of an implicit media marker, or (3) a
-              wall-clock time.</p>
-            </li>
-
-            <li>
-              <p>Syntactically subsets and supersets the <a href="#smil21">[SMIL
-              2.1]</a>&nbsp;<code>Clock-value</code> syntax as follows: (1) requires
-              non-negative <code>Full-clock-value</code> or <code>Timecount-value</code>;
-              (2) if <code>Full-clock-value</code> then <em>hours</em> must be two or
-              more digits; (3) if <code>Timecount-value</code>, then <em>metric</em> must
-              be specified; (4) uses <code>m</code> as alias for <code>min</code> metric
-              to denote minutes; (5) adds <code>f</code> and <code>t</code> metrics
-              denoting frames and ticks, respectively; (6) adds alternative expression of
-              optional <code>Fraction</code> in <code>Full-clock-value</code> by
-              specifying frame count or frame count with subframe count.</p>
-            </li>
-
-            <li>
-              <p>Interpretation of time expression is further constrained by parameters
-              expressed by <code>ttp:clockMode</code>, <code>ttp:dropMode</code>,
-              <code>ttp:frameRate</code>, <code>ttp:frameRateMultiplier</code>,
-              <code>ttp:markerMode</code>, <code>ttp:subFrameRate</code>,
-              <code>ttp:tickRate</code>, and <code>ttp:timeBase</code> attributes.</p>
-            </li>
-
-            <li>
-              <p>Uses subset of named colors from model to which two aliases are added as
-              follows: <code>magenta</code> as <code>fuchsia</code>, and
-              <code>cyan</code> as <code>aqua</code>.</p>
-            </li>
-
-            <li>
-              <p>If not specified, then parallel (par) container semantics apply to the
-              element types specified by <a href=
-              "#timing-attribute-timeContainer"><b>10.2.4 timeContainer</b></a>.</p>
-            </li>
-
-            <li>
-              <p>Restricts size to length specification which can be a percentage; adds
-              optional second length (or percentage) for specifying separate horizontal
-              and vertical scaling of glyph's EM square.</p>
-            </li>
-
-            <li>
-              <p>Expressed in terms of writing mode relative padding properties rather
-              than absolute padding properties.</p>
-            </li>
-
-            <li>
-              <p>Excludes <code>blink</code> and <code>no-blink</code> values.</p>
-            </li>
-
-            <li>
-              <p>Uses only one length specification instead of two, where one length
-              defines distance of outline effect from nominal edge of glyph contour
-              outline perpendicular to point of glyph contour. Percentage lengths are
-              also added to express outline effect in relative to font size. Outline
-              effects are intended to be drawn both outside of outer closed contours and
-              inside of inner closed contours.</p>
-            </li>
-
-            <li>
-              <p>On root element, default attribute value specified as
-              <code>default</code>, which is defined in terms of whitespace
-              normalization. Semantics of preservation and default normalization are
-              defined in terms of presentation semantics by <a href=
-              "#content-attribute-space"><b>7.2.3 xml:space</b></a>.</p>
-            </li>
-
-            <li>
-              <p>Defined to be inheritable.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="qa" name="qa"></a>K QA Framework Compliance (Non-Normative)</h2>
-
-      <p>This appendix specifies the compliance of this specification with the
-      requirements and guidelines defined by <a href=
-      "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/">QA Framework Specifications
-      Guidelines</a>&nbsp;<a href="#qaf-sg">[QAF SG]</a>.</p>
-
-      <div class="div2">
-        <h3><a id="d3e19629" name="d3e19629"></a>K.1 Requirements</h3><a id=
-        "qa-framework-requirements-table" name="qa-framework-requirements-table"></a>
-
-        <table class="common">
-          <caption>
-            Table K-1 – QA Framework Requirements Checklist
-          </caption>
-          <col width="76%" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Requirement</span></td>
-
-              <td><span class="strong">YES</span></td>
-
-              <td><span class="strong">NO</span></td>
-
-              <td><span class="strong">N/A</span></td>
-
-              <td><span class="strong">Notes</span></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#include-conformance-clause-principle">
-              Requirement 01: Include a conformance clause</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-scope-principle">
-              Requirement 02: Define the scope.</a></td>
-
-              <td><a href="#intro">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#implement-principle">Requirement
-              03: Identify who or what will implement the specification.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-norm-principle">Requirement
-              04: Make a list of normative references.</a></td>
-
-              <td><a href="#references">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-principle">
-              Requirement 05: Define the terms used in the normative parts of the
-              specification.</a></td>
-
-              <td><a href="#definitions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conf-label-principle">
-              Requirement 06: Create conformance labels for each part of the conformance
-              model.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#consistent-style-principle">
-              Requirement 07: Use a consistent style for conformance requirements and
-              explain how to distinguish them.</a></td>
-
-              <td><a href="#conventions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#req-opt-conf-principle">
-              Requirement 08: Indicate which conformance requirements are mandatory,
-              which are recommended, and which are optional.</a></td>
-
-              <td><a href="#conventions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-mandatory-principle">
-              Requirement 09: If the technology is subdivided, then indicate which
-              subdivisions are mandatory for conformance.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdiv-constraints-principle">
-              Requirement 10: If the technology is subdivided, then address subdivision
-              constraints.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#likehood-extension-principle">
-              Requirement 11: Address Extensibility.</a></td>
-
-              <td><a href="#doctypes">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#deprecated-feature-principle">
-              Requirement 12: Identify deprecated features.</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>N/A</td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#degree-support-principle">
-              Requirement 13: Define how each class of product handles each deprecated
-              feature.</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>N/A</td>
-
-              <td>1</td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <ol class="enumar">
-            <li>
-              <p>No feature is deprecated by this version of this specification.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="d3e19793" name="d3e19793"></a>K.2 Guidelines</h3><a id=
-        "qa-framework-guidelines-table" name="qa-framework-guidelines-table"></a>
-
-        <table class="common">
-          <caption>
-            Table K-2 – QA Framework Guidelines Checklist
-          </caption>
-          <col width="76%" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Guideline</span></td>
-
-              <td><span class="strong">YES</span></td>
-
-              <td><span class="strong">NO</span></td>
-
-              <td><span class="strong">N/A</span></td>
-
-              <td><span class="strong">Notes</span></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-model-gp">
-              Good Practice 01: Define the specification's conformance model in the
-              conformance clause.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#norm-informative-gp">Good
-              Practice 02: Specify in the conformance clause how to distinguish normative
-              from informative content.</a></td>
-
-              <td><a href="#conventions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-claim-gp">
-              Good Practice 03: Provide the wording for conformance claims.</a></td>
-
-              <td><a href="#claims">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-gp">Good Practice
-              04: Provide an Implementation Conformance Statement Pro Forma.</a></td>
-
-              <td></td>
-
-              <td>NO</td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-claim-gp">Good
-              Practice 05: Require an Implementation Conformance Statement as part of
-              valid conformance claims.</a></td>
-
-              <td><a href="#claims">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#use-example-gp">Good
-              Practice 06: Provide examples, use cases, and graphics.</a></td>
-
-              <td><a href="#example">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-sample-gp">Good
-              Practice 07: Write sample code or tests.</a></td>
-
-              <td>YES</td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-define-practice">Good
-              Practice 08: When imposing requirements by normative references, address
-              conformance dependencies.</a></td>
-
-              <td><a href="#references">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-inline-gp">
-              Good Practice 09: Define unfamiliar terms in-line and consolidate the
-              definitions in a glossary section.</a></td>
-
-              <td><a href="#definitions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#reuse-terms-gp">Good
-              Practice 10: Use terms already defined without changing their
-              definition.</a></td>
-
-              <td><a href="#definitions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>2</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#formal-language-gp">Good
-              Practice 11: Use formal languages when possible.</a></td>
-
-              <td><a href="#schemas">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-assertion-gp">Good
-              Practice 12: Write Test Assertions.</a></td>
-
-              <td></td>
-
-              <td>NO</td>
-
-              <td></td>
-
-              <td>3</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-foster-gp">Good
-              Practice 13: Create subdivisions of the technology when warranted.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#rules-profiles-gp">Good
-              Practice 14: If the technology is profiled, define rules for creating new
-              profiles.</a></td>
-
-              <td><a href="#vocabulary-profiles">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#need-option-gp">Good
-              Practice 15:Use optional features as warranted.</a></td>
-
-              <td>YES</td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#label-options-gp">Good
-              Practice 16: Clearly identify optional features.</a></td>
-
-              <td>YES</td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#constraints-gp">Good
-              Practice 17: Indicate any limitations or constraints on optional
-              features.</a></td>
-
-              <td>YES</td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#extensions-prohibited-gp">
-              Good Practice 18: If extensibility is allowed, define an extension
-              mechanism.</a></td>
-
-              <td><a href="#extension-vocabulary-overview">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#breaking-conformance-gp">
-              Good Practice 19: Warn extension creators to create extensions that do not
-              interfere with conformance.</a></td>
-
-              <td><a href="#extension-vocabulary-overview">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-error-gp">Good
-              Practice 20: Define error-handling for unknown extensions.</a></td>
-
-              <td><a href="#conformance-processor">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#workaround-gp">Good
-              Practice 21: Explain how to avoid using a deprecated feature.</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>N/A</td>
-
-              <td>5</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#obsolete-gp">Good
-              Practice 22: Identify obsolete features.</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>N/A</td>
-
-              <td>5</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#error-handling-gp">Good
-              Practice 23: Define an error handling mechanism.</a></td>
-
-              <td><a href="#reduced-infoset">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <ol class="enumar">
-            <li>
-              <p>When making normative references to external specifications, specific
-              clauses or sections are cited.</p>
-            </li>
-
-            <li>
-              <p>See also <a href="#derivation"><b>J Vocabulary Derivation</b></a>.</p>
-            </li>
-
-            <li>
-              <p>Test assertions and test suites will be provided prior to entering
-              Proposed Recommendation (PR) phase.</p>
-            </li>
-
-            <li>
-              <p>See criterion #3 in <a href="#conformance-processor"><b>3.2 Processor
-              Conformance</b></a> and definition of TTML <a href="#doctypes">Abstract
-              Document Instance</a>.</p>
-            </li>
-
-            <li>
-              <p>No feature is deprecated or obsoleted by this version of this
-              specification.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="streaming" name="streaming"></a>L Streaming TTML Content
-      (Non-Normative)</h2>
-
-      <p>TTML Content is designed to support streamability by implementing the following
-      properties:</p>
-
-      <ul>
-        <li>
-          <p>can be progressively encoded (i.e., does not require computing subsequent
-          data prior to sending current data);</p>
-        </li>
-
-        <li>
-          <p>can be progressively decoded (i.e., does not require forward references, but
-          uses only reverse references when necessary);</p>
-        </li>
-
-        <li>
-          <p>does not require dereferencing (and subsequent loading) of any resources
-          other than TTML Content (i.e., no embedded URIs);</p>
-        </li>
-
-        <li>
-          <p>does not support alternative content forms (e.g., different language,
-          graphics formats, time bases) in a single document;</p>
-        </li>
-
-        <li>
-          <p>has timing structure compiled into inline format that makes possible a
-          temporal ordering of content that follows temporal presentation order;</p>
-        </li>
-
-        <li>
-          <p>constrains content models to prevent arbitrary nested content
-          structures;</p>
-        </li>
-      </ul>
-
-      <p>One possible means by which TTML Content may be streamed is to partition a
-      <em>Document Instance</em>'s information set into non-overlapping fragments, where
-      one particular fragment, call it the <em>root fragment</em>, represents the front
-      matter (head) of the <em>Document Instance</em> as well as its top level structural
-      elements, and other fragments represent content whose time intervals are expected
-      to be active in parallel.</p>
-
-      <p>In applications that require arbitrary (random) entry into a stream, i.e., the
-      property of being able to start reading data at an arbitrary data access unit, the
-      root fragment will be repetitively transmitted (inserted) into the stream in order
-      to permit a decoder to resynchronize and acquire sufficient structural information
-      in the information set in order to interpret subsequent content fragments.</p>
-
-      <p>An example of such a fragmentation of a <em>Document Instance</em> is shown in
-      <a href="#fragment-streaming-graphic"><b>Figure 3 – Fragment
-      Streaming</b></a>.</p><a id="fragment-streaming-graphic" name=
-      "fragment-streaming-graphic"></a>
-
-      <table class="example-images">
-        <caption>
-          Figure 3 – Fragment Streaming
-        </caption>
-        <col span="1">
-
-        <tbody>
-          <tr>
-            <td><img src="images/streaming.png" alt="Fragment Streaming"></td>
-          </tr>
-        </tbody>
-      </table>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>This specification does not define a transport buffer model or a decoder
-        capabilities model.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="concrete-encoding" name="concrete-encoding"></a>M Concrete Encoding
-      (Non-Normative)</h2>
-
-      <p>In the absence of other requirements, it is recommended that a <em>Document
-      Instance</em> be concretely encoded as a well-formed XML 1.0 <a href="#xml10">[XML
-      1.0]</a> document using the UTF-8 character encoding.</p>
-    </div>
-
-    <div class="div1">
-      <h2><a id="time-expression-semantics" name="time-expression-semantics"></a>N Time
-      Expression Semantics (Non-Normative)</h2>
-
-      <p>This appendix describes the intended semantics for interpreting time expressions
-      in <em>Document Instances</em>.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>It is expected that the information in this appendix will be elevated to
-        normative status in a future revision of this specification.</p>
-      </div>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>The phrase <em>local real time</em> as used below is intended to model a
-        virtual real time clock in the document processing context, where <em>local</em>
-        means in the immediate proximity of the implementation of this processing
-        context. The intent of defining relationships with this virtual clock is to
-        establish a locally valid physical realization of time for didactic purposes.</p>
-      </div>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>The phrase <em>play rate</em> as used below is intended to model a (possibly
-        variable) parameter in the document processing context wherein the rate of
-        playback (or interpretation) of time may artificially dilated or narrowed, for
-        example, when speeding up or slowing down the rate of playback of a <em>Related
-        Media Object</em>. Without loss of generality, the following discussion assumes a
-        fixed play(back) rate. In the case of variable play rates, appropriate
-        adjustments may need to be made to the resulting computations.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="time-expression-semantics-clock" name=
-        "time-expression-semantics-clock"></a>N.1 Clock Time Base</h3>
-
-        <p>When operating with the <code>clock</code> time base, the following semantics
-        should be applied for interpreting time expressions, as defined by <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their relationship
-        to media time and local real time.</p>
-
-        <p>The clock time base <span class="strong"><code>C</code></span> is related to
-        local real time <span class="strong"><code>R</code></span> expressed in an
-        arbitrary (implementation defined) epoch <span class=
-        "strong"><code>E</code></span> as follows:</p><a id="clock-time-and-real-time"
-        name="clock-time-and-real-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Clock Time and Real Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><code>R = C + epochOffset + discontinuityOffset</code><br>
-                  <br>
-                  where <code>C ∈ ℜ</code>, <code>0 ≤ C &lt; ∞</code>, <code>C</code> in
-                  seconds since the most immediately prior midnight of the reference
-                  clock base;<br>
-                  <br>
-                  <code>epochOffset ∈ ℜ</code>, <code>0 ≤ epochOffset &lt; ∞</code>,
-                  <code>epochOffset</code> in seconds, with 0 being the beginning of
-                  epoch <code>E</code>, and where the value of <code>epochOffset</code>
-                  is determined from the computed value of the <code>ttp:clockMode</code>
-                  parameter as follows:<br>
-                  <br>
-                  (1) if <code>local</code>, then the difference between the local real
-                  time at the most immediately prior local midnight and the local real
-                  time at the beginning of epoch <code>E</code>, expressed in
-                  seconds;<br>
-                  <br>
-                  (2) if <code>gps</code>, then the difference between the GPS time at
-                  the most immediately prior GPS midnight and the GPS time at the
-                  beginning of epoch <code>E</code>, expressed in seconds;<br>
-                  <br>
-                  (3) if <code>utc</code>, then the difference between the UTC time at
-                  the most immediately prior UTC midnight and the UTC time at the
-                  beginning of epoch <code>E</code>, expressed in seconds;<br>
-                  <br>
-                  <code>discontinuityOffset ∈ ℜ</code>, <code>−∞ &lt; discontinuityOffset
-                  &lt; ∞</code>, <code>discontinuityOffset</code> in seconds, and where
-                  the value of <code>discontinuityOffset</code> is equal to the sum of
-                  leap seconds (and fractions thereof) that have been added (or
-                  subtracted) since the most immediately prior midnight in the reference
-                  clock base;<br>
-                  <br>
-                  and <code>epochOffset</code> and <code>discontinuityOffset</code> are
-                  determined once and only once prior to the beginning of the <em>Root
-                  Temporal Extent</em> such that during the period between value
-                  determination and the beginning of the <em>Root Temporal Extent</em>
-                  there occurs no local midnight or reference clock base
-                  discontinuity.<br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Time value expressions, as denoted by a <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, are related to clock
-        time <span class="strong"><code>C</code></span> as follows:</p><a id=
-        "time-expressions-and-clock-time" name="time-expressions-and-clock-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Time Expressions and Clock Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p>If a time expression uses the <em>clock-time</em> form or an
-                  <em>offset-time</em> form that doesn't use the ticks (<code>t</code>)
-                  metric, then:<br>
-                  <br>
-                  <code>C = 3600 * hours + 60 * minutes + seconds</code><br>
-                  <br>
-                  where <code>hours</code>, <code>minutes</code>, <code>seconds</code>
-                  components are extracted from time expression if present, or zero if
-                  not present.<br>
-                  <br>
-                  Otherwise, if a time expression uses an <em>offset-time</em> form that
-                  uses the ticks (<code>t</code>) metric, then:<br>
-                  <br>
-                  <code>C = ticks / tickRate</code><br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The <em>frames</em> and <em>sub-frames</em> terms and the frames
-          (<code>f</code>) metric of time expressions do not apply when using the
-          <code>clock</code> time base.</p>
-        </div>
-
-        <p>The clock time base <span class="strong"><code>C</code></span> is independent
-        of media time <span class="strong"><code>M</code></span>:</p><a id=
-        "clock-time-and-media-time" name="clock-time-and-media-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Clock Time and Media Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><code>M ¬∝ C</code><br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>That is to say, timing is disconnected from (not necessarily proportional
-          to) media time when the <code>clock</code> time base is used. For example, if
-          the media play rate is zero (0), media playback is suspended; however, timing
-          coordinates will continue to advance according to the natural progression of
-          clock time in direct proportion to the reference clock base. Furthermore, if
-          the media play rate changes during playback, presentation timing is not
-          affected.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="time-expression-semantics-media" name=
-        "time-expression-semantics-media"></a>N.2 Media Time Base</h3>
-
-        <p>When operating with the <code>media</code> time base, the following semantics
-        should be applied for interpreting time expressions, as defined by <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their relationship
-        to media time and local real time.</p>
-
-        <p>The media time base <span class="strong"><code>M</code></span> is related to
-        local real time <span class="strong"><code>R</code></span> expressed in an
-        arbitrary (implementation defined) epoch <span class=
-        "strong"><code>E</code></span> as follows:</p><a id="media-time-and-real-time"
-        name="media-time-and-real-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Media Time and Real Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><code>R = playRate * M + epochOffset</code><br>
-                  <br>
-                  where <code>M ∈ ℜ</code>, <code>0 ≤ M &lt; ∞</code>, <code>M</code> in
-                  seconds, with 0 corresponding to the beginning of the <em>Root Temporal
-                  Extent</em>;<br>
-                  <br>
-                  <code>playRate ∈ ℜ</code>, <code>−∞ &lt; playRate &lt; ∞</code>,
-                  <code>playRate</code> is unit-less, and where the value of
-                  <code>playRate</code> is determined by the document processing
-                  context;<br>
-                  <br>
-                  and <code>epochOffset ∈ ℜ</code>, <code>0 ≤ epochOffset &lt; ∞</code>,
-                  <code>epochOffset</code> in seconds, with 0 corresponding to the
-                  beginning of an epoch <code>E</code>, and where the value of
-                  <code>epochOffset</code> is the difference between the local real time
-                  at the beginning of the <em>Root Temporal Extent</em> and the local
-                  real time at the the beginning of epoch <code>E</code>, expressed in
-                  seconds.</p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Time value expressions, as denoted by a <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, are related to media
-        time <span class="strong"><code>M</code></span> in accordance to the
-        <code>ttp:frameRate</code>, <code>ttp:subFrameRate</code>, and
-        <code>ttp:frameRateMultipler</code> parameters as follows:</p><a id=
-        "time-expressions-and-media-time" name="time-expressions-and-media-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Time Expressions and Media Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p>If a time expression uses a <em>clock-time</em> form or an
-                  <em>offset-time</em> form that doesn't use the ticks (<code>t</code>)
-                  metric, then:<br>
-                  <br>
-                  <code>M = containerBegin + 3600 * hours + 60 * minutes + seconds +
-                  ((frames + (subFrames / subFrameRate)) / effectiveFrameRate)</code><br>
-                  <br>
-                  where <code>containerBegin</code> is the media time that corresponds to
-                  the beginning of the nearest ancestor time container or zero (0) if
-                  this time container is the <em>Root Temporal Extent</em>;<br>
-                  <br>
-                  the <code>hours</code>, <code>minutes</code>, <code>seconds</code>,
-                  <code>frames</code>, <code>subFrames</code> components are extracted
-                  from time expression if present, or zero if not present;<br>
-                  <br>
-                  <code>subFrameRate</code> is the computed value of the
-                  <code>ttp:subFrameRate</code> parameter;<br>
-                  <br>
-                  and <code>effectiveFrameRate</code> (in frames per second) is
-                  <code>frameRate * frameRateMultipler</code> where
-                  <code>frameRate</code> is the computed value of the
-                  <code>ttp:frameRate</code> parameter and
-                  <code>frameRateMultipler</code> is the computed value of the
-                  <code>ttp:frameRateMultiplier</code> parameter.<br>
-                  <br>
-                  Otherwise, if a time expression uses an <em>offset-time</em> form that
-                  uses the ticks (<code>t</code>) metric, then:<br>
-                  <br>
-                  <code>M = containerBegin + ticks / tickRate</code><br>
-                  <br>
-                  where <code>containerBegin</code> is as described above;<br>
-                  <br>
-                  the <code>ticks</code> component is extracted from time expression;<br>
-                  <br>
-                  and <code>tickRate</code> is the computed value of the
-                  <code>ttp:tickRate</code> parameter;<br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>If the computed <code>frameRateMultipler</code> ratio is not integral, then
-          <code>effectiveFrameRate</code> will be a non-integral rational.</p>
-        </div>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The above formalisms assumes that the <em>Root Temporal Extent</em>
-          corresponds with the beginning of a related media object. If this assumption
-          doesn't hold, then an additional offset that accounts for the difference may be
-          introduced when computing media time <code>M</code>.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="time-expression-semantics-smpte" name=
-        "time-expression-semantics-smpte"></a>N.3 SMPTE Time Base</h3>
-
-        <p>When operating with the <code>smpte</code> time base, the following semantics
-        should be applied for interpreting time expressions, as defined by <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their relationship
-        to media time and local real time.</p>
-
-        <p>If the computed value of the <code>ttp:markerMode</code> parameter is
-        <code>discontinuous</code>, then there is no direct relationship between time
-        expressions and media time <span class="strong"><code>M</code></span> or local
-        real time <span class="strong"><code>R</code></span>. In this case, time
-        expressions refer to synchronization events (markers) emitted by the <em>Document
-        Processing Context</em> when <em>SMPTE Time Codes</em> are encountered in the
-        <em>Related Media Object</em>.</p>
-
-        <p>Otherwise, if the computed value of the <code>ttp:markerMode</code> parameter
-        is <code>continuous</code>, then the relationships between time expressions and
-        local real time and media time are as described below in terms of a <em>Synthetic
-        SMPTE Document Syncbase</em>, here referred to as the SMPTE time base
-        <span class="strong"><code>S</code></span>.</p><a id=
-        "time-expressions-and-smpte-time" name="time-expressions-and-smpte-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Time Expressions and SMPTE Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><code>S = (countedFrames - droppedFrames + (subFrames /
-                  subFrameRate)) / effectiveFrameRate</code><br>
-                  <br>
-                  where<br>
-                  <br>
-                  <code>countedFrames = (3600 * hours + 60 * minutes + seconds) *
-                  frameRate + frames</code><br>
-                  <br>
-                  <code>hours</code>, <code>minutes</code>, <code>seconds</code>,
-                  <code>frames</code>, <code>subFrames</code> components are extracted
-                  from time expression if present, or zero if not present;<br>
-                  <br>
-                  <code>droppedFrames</code> is computed as follows:<br>
-                  <br>
-                  1. let <em>dropMode</em> be the computed value of the
-                  <code>ttp:dropMode</code> parameter;<br>
-                  <br>
-                  2. if <em>dropMode</em> is <code>dropNTSC</code>, let
-                  <code>droppedFrames = (hours * 54 + floor(minutes - minutes/10)) *
-                  2</code>;<br>
-                  <br>
-                  3. otherwise, if <em>dropMode</em> is <code>dropPAL</code>, let
-                  <code>droppedFrames = (hours * 27 + floor(minutes/2 - minutes/20)) *
-                  4</code>;<br>
-                  <br>
-                  4. otherwise, let <code>droppedFrames = 0</code>;<br>
-                  <br>
-                  <code>frameRate</code> is the computed value of the
-                  <code>ttp:frameRate</code> parameter;<br>
-                  <br>
-                  <code>subFrameRate</code> is the computed value of the
-                  <code>ttp:subFrameRate</code> parameter;<br>
-                  <br>
-                  and <code>effectiveFrameRate</code> (in frames per second) is
-                  <code>frameRate * frameRateMultipler</code> where
-                  <code>frameRate</code> is the computed value of the
-                  <code>ttp:frameRate</code> parameter and
-                  <code>frameRateMultipler</code> is the computed value of the
-                  <code>ttp:frameRateMultiplier</code> parameter.<br>
-                  <br>
-                  Notwithstanding the above, if a time expression contains a frame code
-                  that is designated as dropped according to <a href=
-                  "#parameter-attribute-dropMode"><b>6.2.3 ttp:dropMode</b></a>, then
-                  that time expression should be considered to be invalid for purposes of
-                  validation assessment.<br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The SMPTE time base <span class="strong"><code>S</code></span> is related to
-        the media time base <span class="strong"><code>M</code></span> as
-        follows:</p><a id="smpte-time-and-media-time" name=
-        "smpte-time-and-media-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – SMPTE Time and Media Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><code>M = containerBegin + S</code><br>
-                  <br>
-                  where <code>containerBegin</code> is the SMPTE time that corresponds to
-                  the beginning of the nearest ancestor time container or zero (0) if
-                  this time container is the <em>Root Temporal Extent</em>;<br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Given the derived media time base as described above, then media time base
-        <span class="strong"><code>M</code></span> is related to the local real time
-        <span class="strong"><code>R</code></span> as described in <a href=
-        "#time-expression-semantics-media"><b>N.2 Media Time Base</b></a> above.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="common-styling" name="common-styling"></a>O Common Caption Style
-      Examples (Non-Normative)</h2>
-
-      <p>This section provides examples of the following common caption styles using TTML
-      Content to obtain the desired behavior:</p>
-
-      <ul>
-        <li>
-          <p>Pop-On Captions</p>
-        </li>
-
-        <li>
-          <p>Roll-Up Captions</p>
-        </li>
-
-        <li>
-          <p>Paint-On Captions</p>
-        </li>
-      </ul>
-
-      <div class="div2">
-        <h3><a id="pop-on-example" name="pop-on-example"></a>O.1 Pop-On Caption
-        Example</h3>
-
-        <p>An example of paint-on captions. In this example, two regions are targeted
-        with alternating, paint-on content, where content is timed using explicit
-        sequential time containment rules. Each paragraph is non-overlapping in time and
-        appears in the same single row of its targeted region.</p><a id=
-        "pop-on-example-1-s" name="pop-on-example-1-s"></a>
-
-        <table class="example">
-          <caption>
-            Example – Pop-On Captions
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 1c"/&gt;
-      &lt;region xml:id="r2" tts:color="yellow" tts:origin="10c 8c" tts:extent="40c 1c"/&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-  &lt;body&gt;
-    &lt;div timeContainer="seq"&gt;
-      &lt;p region="r1" dur="4s"&gt;Lorem ipsum dolor sit&lt;/p
-      &lt;p region="r2" dur="4s"&gt;Amet consectetur adipiscing elit&lt;/p&gt;
-      &lt;p region="r1" dur="6s"&gt;Sed do eiusmod tempor incididunt labore&lt;/p&gt;
-      &lt;p region="r2" dur="4s"&gt;et dolore magna aliqua&lt;/p&gt;
-      &lt;p region="r1" dur="7s"&gt;Ut enim ad minim veniam quis, nostrud&lt;/p&gt;
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-
-      <div class="div2">
-        <h3><a id="roll-up-example" name="roll-up-example"></a>O.2 Roll-Up Caption
-        Example</h3>
-
-        <p>An example of roll-up captions. Roll-up effects are achieved by using
-        overlapped time intervals, where zero, one, or two paragraphs appear in the
-        region at a given time. Each paragraph consumes a single row (line) of the region
-        since no wrapping occurs. Depending on whether a presentation processor supports
-        <a href="#semantics-smooth-scrolling-recommendation">smooth scrolling between
-        adjacent synchronic intermediate document instances</a>, the transitions, i.e.,
-        moving an old paragraph (line) out and a new paragraph (line) in, will be either
-        smooth or discrete.</p><a id="roll-up-example-1-s" name=
-        "roll-up-example-1-s"></a>
-
-        <table class="example">
-          <caption>
-            Example – Roll-Up Captions
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 2c"/&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-  &lt;body&gt;
-    &lt;div region="r1"&gt;
-      &lt;p begin="0s" end="8s"&gt;Lorem ipsum dolor sit&lt;/p
-      &lt;p begin="4s" end="12s"&gt;Amet consectetur adipiscing elit&lt;/p&gt;
-      &lt;p begin="8s" end="18s"&gt;Sed do eiusmod tempor incididunt labore&lt;/p&gt;
-      &lt;p begin="14s" end="25s"&gt;et dolore magna aliqua&lt;/p&gt;
-      &lt;p begin="18s" end="29s"&gt;Ut enim ad minim veniam quis, nostrud&lt;/p&gt;
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-
-      <div class="div2">
-        <h3><a id="paint-on-example" name="paint-on-example"></a>O.3 Paint-On Caption
-        Example</h3>
-
-        <p>An example of paint-on captions. Paint-on effects are achieved by using timed
-        <code>span</code> elements in order to expose (paint) inline text units, e.g.,
-        words, over some time interval. Here, five paragraphs have their individual words
-        sequentially timed in order to paint one new word every second. The end of the
-        active duration of each inline element coincides with the end of the
-        <code>div</code> element's parallel time container, so that once a word is
-        painted, it remains in the region (on its rendered line) until the
-        <code>div</code> element's active time interval lapses.</p><a id=
-        "paint-on-example-1-s" name="paint-on-example-1-s"></a>
-
-        <table class="example">
-          <caption>
-            Example – Paint-On Captions
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 5c"/&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-  &lt;body&gt;
-    &lt;div begin="0s" end="25s"&gt;
-      &lt;p&gt;
-        &lt;span begin="0s"&gt;Lorem&lt;/span&gt;
-        &lt;span begin="1s"&gt;ipsum&lt;/span&gt;
-        &lt;span begin="2s"&gt;dolor&lt;/span&gt;
-        &lt;span begin="3s"&gt;sit&lt;/span&gt;
-      &lt;/p&gt;
-      &lt;p&gt;
-        &lt;span begin="4s"&gt;Amet&lt;/span&gt;                
-        &lt;span begin="5s"&gt;consectetur&lt;/span&gt;
-        &lt;span begin="6s"&gt;adipiscing&lt;/span&gt;
-        &lt;span begin="7s"&gt;elit&lt;/span&gt;
-      &lt;/p&gt;
-      &lt;p&gt;
-        &lt;span begin="8s"&gt;Sed&lt;/span&gt;
-        &lt;span begin="9s"&gt;do&lt;/span&gt;
-        &lt;span begin="10s"&gt;eiusmod&lt;/span&gt;
-        &lt;span begin="11s"&gt;tempor&lt;/span&gt;
-        &lt;span begin="12s"&gt;incididunt &lt;/span&gt;
-        &lt;span begin="13s"&gt;labore&lt;/span&gt;
-     &lt;/p&gt;
-     &lt;p&gt;
-        &lt;span begin="14s"&gt;et&lt;/span&gt;
-        &lt;span begin="15s"&gt;dolore&lt;/span&gt;
-        &lt;span begin="16s"&gt;magna&lt;/span&gt;
-        &lt;span begin="17s"&gt;aliqua&lt;/span&gt;
-      &lt;/p&gt;
-      &lt;p&gt;
-        &lt;span begin="18s"&gt;Ut&lt;/span&gt;
-        &lt;span begin="19s"&gt;enim&lt;/span&gt;
-        &lt;span begin="20s"&gt;ad&lt;/span&gt;
-        &lt;span begin="21s"&gt;minim&lt;/span&gt;
-        &lt;span begin="22s"&gt;veniam&lt;/span&gt;
-        &lt;span begin="23s"&gt;quis,&lt;/span&gt;
-        &lt;span begin="24s"&gt;nostrud&lt;/span&gt;
-      &lt;/p&gt;
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="acknowledgments" name="acknowledgments"></a>P Acknowledgments
-      (Non-Normative)</h2>
-
-      <p>The editor acknowledges the current and former members of the Timed Text Working
-      Group, the members of other W3C Working Groups, and industry experts in other
-      forums who have contributed directly or indirectly to the process or content of
-      this document as follows:</p>
-
-      <p>Glenn Adams, Thomas Bause-Mason, John Birch, Kees Blom, Bert Bos, Brad Botkin,
-      Dick Bulterman, Frans de Jong, Mike Dolan, Martin Dürst, Donald Evans, Geoff Freed,
-      Al Gilman, Giles Godart-Brown, Markus Gylling, Markku Hakkinen, Sean Hayes, Erik
-      Hodge, Philipp Hoschka, Suzi Hyun, Michael Jordan, Masahiko Kaneko, Courtney
-      Kennedy, George Kerscher, David Kirby, Andrew Kirkpatrick, Philippe Le Hégaret,
-      Chris Lilley, Pierre-Anthony Lemieux, Jason Livingston, Monica Martin, Thierry
-      Michel, Matthew May, Frank Olivier, Soohong Daniel Park, Silvia Pfeiffer, Brian
-      Raymor, David Ronca, Patrick Schmitz, David Singer, Craig Smithpeters, Andreas Tai,
-      and Mohamed Zergaoui.</p>
-
-      <p>The editor wishes to especially acknowledge the following contributions by
-      members: Micheal Dolan (SMPTE time codes, streaming; SMPTE liaison), David Kirby
-      (introductory example document; SMPTE time codes, descriptive metadata; EBU/AAF
-      liaison), Geoff Freed (styling and example images of style properties), Sean Hayes
-      (advanced profile concepts, including applicative timing), Eric Hodge (timing),
-      Thierry Michel (metadata), and Dave Singer (animation, scrolling).</p>
-
-      <p>The Working Group dedicates this specification to our colleague David Kirby.</p>
-    </div>
-  </div>
-</body>
-</html>
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@@ -0,0 +1,20379 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+
+<html lang="en-us">
+<head>
+  <meta name="generator" content=
+  "HTML Tidy for Linux/x86 (vers 25 March 2009), see www.w3.org">
+  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+
+  <title>Timed Text Markup Language (TTML) 1.0 (Second Edition)</title>
+  <style type="text/css">
+code           { font-family: monospace; }
+
+  div.constraint,
+  div.issue,
+  div.note,
+  div.notice     { margin-left: 2em; }
+
+  ol.enumar      { list-style-type: decimal; }
+  ol.enumla      { list-style-type: lower-alpha; }
+  ol.enumlr      { list-style-type: lower-roman; }
+  ol.enumua      { list-style-type: upper-alpha; }
+  ol.enumur      { list-style-type: upper-roman; }
+
+
+  div.exampleInner pre { margin-left: 1em;
+                       margin-top: 0em; margin-bottom: 0em}
+  div.exampleOuter {border: 4px double gray;
+                  margin: 0em; padding: 0em}
+  div.exampleInner { background-color: #d5dee3;
+                   border-top-width: 4px;
+                   border-top-style: double;
+                   border-top-color: #d3d3d3;
+                   border-bottom-width: 4px;
+                   border-bottom-style: double;
+                   border-bottom-color: #d3d3d3;
+                   padding: 4px; margin: 0em }
+  div.exampleWrapper { margin: 4px }
+  div.exampleHeader { font-weight: bold;
+                    margin: 4px}
+
+  li p { margin-top: 0.3em; margin-bottom: 0.3em; }
+  div.issue { border: 2px solid black; background-color: #ffff66; padding: 0em 1em; margin: 0em 0em }
+  table.ednote { border-collapse: collapse; border: 2px solid black; width: 85% }
+  table.ednote td { background-color: #ddaa66; border: 2px solid black }
+  table.acronyms td.label { width: 15% }
+  table.acronyms td.def { width: 65% }
+  table.graphic { border: 0px none black; width: 100%; border-collapse: collapse }
+  table.graphic caption { font-weight: bold; text-align: center; padding-bottom: 0.5em }
+  table.graphic td { border: 0px none black; text-align: center }
+  table.common { border: 2px solid black; width: 85%; border-collapse: collapse }
+  table.common caption { font-weight: bold; text-align: left; padding-bottom: 0.5em }
+  table.common th { padding: 0em 0.5em; border: 2px solid black; text-align: left }
+  table.common td { padding: 0em 0.5em; border: 2px solid black }
+  table.syntax { border: 0px solid black; width: 85%; border-collapse: collapse }
+  table.syntax caption { font-weight: bold; text-align: left; padding-bottom: 0.5em }
+  table.syntax th { border: 0px solid black; text-align: left }
+  table.syntax td { border: 0px solid black }
+  table.syntax div { background-color: #ffffc8 }
+  table.semantics { border: 0px solid black; width: 85%; border-collapse: collapse }
+  table.semantics caption { font-weight: bold; text-align: left; padding-bottom: 0.5em }
+  table.semantics th { border: 0px solid black; text-align: left }
+  table.semantics td {
+  border-left: 0px solid black;
+  border-right: 0px solid black;
+  border-top: 4px double #d3d3d3;
+  border-bottom: 4px double #d3d3d3;
+  background-color: #ccffcc
+  }
+  table.semantics code.formulae {
+  padding: 1em;
+  border: 1px dashed #005a9c;
+  line-height: 1.1em;
+  background-color: #fdfdfd;
+  }
+  table.example { border: 0px solid black; width: 85%; border-collapse: collapse }
+  table.example caption { font-weight: bold; text-align: left; padding-bottom: 0.5em }
+  table.example th { border: 0px solid black; text-align: left }
+  table.example td { border: 0px solid black;  }
+  table.example div { background-color: #c8ffff }
+  table.example-images { text-align: center; border: 0px solid black; width: 85%; border-collapse: collapse }
+  table.example-images caption { font-weight: bold; text-align: center; padding-bottom: 0.5em }
+  table.example-images td { border: 0px solid black; text-align: center }
+  table.example-images-bordered { text-align: center; border: 0px solid black; width: 85%; border-collapse: collapse }
+  table.example-images-bordered caption { font-weight: bold; text-align: center; padding-bottom: 0.5em }
+  table.example-images-bordered td { border: 1px solid red; text-align: left }
+  .tbd { background-color: #ffff33; border: 2px solid black; width: 85% }
+  .strong { font-weight: bold }
+  .reqattr { font-weight: bold }
+  .optattr { font-style: italic }
+  </style>
+  <link rel="stylesheet" type="text/css" href=
+  "http://www.w3.org/StyleSheets/TR/W3C-PER.css">
+</head>
+
+<body>
+  <div class="head">
+    <p><a href="http://www.w3.org/"><img src="http://www.w3.org/Icons/w3c_home" alt="W3C"
+    height="48" width="72"></a></p>
+
+    <h1><a id="title" name="title"></a>Timed Text Markup Language (TTML) 1.0 (Second
+    Edition)</h1>
+
+    <h2><a id="w3c-doctype" name="w3c-doctype"></a>W3C Proposed Edited Recommendation 09
+    July 2013</h2>
+
+    <dl>
+      <dt>This version:</dt>
+
+      <dd><a href=
+      "http://www.w3.org/TR/2013/PER-ttaf1-dfxp-20130709/">http://www.w3.org/TR/2013/PER-ttaf1-dfxp-20130709/</a></dd>
+
+      <dt>Latest version:</dt>
+
+      <dd><a href=
+      "http://www.w3.org/TR/ttaf1-dfxp/">http://www.w3.org/TR/ttaf1-dfxp/</a></dd>
+
+      <dt>Previous version:</dt>
+
+      <dd><a href=
+      "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/</a></dd>
+
+      <dt>Editor:</dt>
+
+      <dd>Glenn Adams, Cox Communications, Inc.</dd>
+
+      <dt>Contributing Authors:</dt>
+
+      <dd>Mike Dolan, Invited Expert</dd>
+
+      <dd>Geoff Freed, WGBH National Center for Accessible Media</dd>
+
+      <dd>Sean Hayes, Microsoft</dd>
+
+      <dd>Erik Hodge, RealNetworks</dd>
+
+      <dd>David Kirby, British Broadcasting Corporation (BBC)</dd>
+
+      <dd>Thierry Michel, W3C</dd>
+
+      <dd>Dave Singer, Apple Computer</dd>
+    </dl>
+
+    <p>Please refer to the <a href=
+    "https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttml-issues.html">errata</a>
+    for this document, which may include normative corrections.</p>
+
+    <p>See also <a href=
+    "http://www.w3.org/2003/03/Translations/byTechnology?technology=ttaf1-dfxp"><strong>translations</strong></a>.</p>
+
+    <p class="copyright"><a href=
+    "http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>&nbsp;©&nbsp;2013&nbsp;<a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup>
+    (<a href="http://www.csail.mit.edu/"><acronym title=
+    "Massachusetts Institute of Technology">MIT</acronym></a>, <a href=
+    "http://www.ercim.eu/"><acronym title=
+    "European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>,
+    <a href="http://www.keio.ac.jp/">Keio</a>, <a href=
+    "http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a href=
+    "http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
+    <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
+    and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a>
+    rules apply.</p>
+  </div>
+  <hr>
+
+  <div>
+    <h2><a id="abstract" name="abstract"></a>Abstract</h2>
+
+    <p>This document specifies the Timed Text Markup Language (TTML) in terms of a
+    vocabulary and semantics thereof.</p>
+
+    <p>The Timed Text Markup Language is a content type that represents timed text media
+    for the purpose of interchange among authoring systems. Timed text is textual
+    information that is intrinsically or extrinsically associated with timing
+    information.</p>
+
+    <p>It is intended to be used for the purpose of transcoding or exchanging timed text
+    information among legacy distribution content formats presently in use for subtitling
+    and captioning functions.</p>
+
+    <p>In addition to being used for interchange among legacy distribution content
+    formats, TTML Content may be used directly as a distribution format, for example,
+    providing a standard content format to reference from a <code>&lt;track&gt;</code>
+    element in an HTML5 document, or a <code>&lt;text&gt;</code> or
+    <code>&lt;textstream&gt;</code> media element in a <a href="#smil21">[SMIL 2.1]</a>
+    document.</p>
+  </div>
+
+  <div>
+    <h2><a id="status" name="status"></a>Status of this Document</h2>
+
+    <p><em>This section describes the status of this document at the time of its
+    publication. Other documents may supersede this document. A list of current W3C
+    publications and the latest revision of this technical report can be found in the
+    <a href="http://www.w3.org/TR/">W3C technical reports index</a> at
+    http://www.w3.org/TR/.</em></p>
+
+    <p>This document, published on 09 July 2013, is a <a href=
+    "http://www.w3.org/2005/10/Process-20051014/tr.html#ProposedEditedRec">Proposed
+    Edited Recommendation</a> of the W3C. This second edition is not a new version of
+    this specification; its purpose is to clarify a number of issues that have become
+    apparent since the first edition was published.</p>
+
+    <p>This document has been produced by the <a href=
+    "http://www.w3.org/AudioVideo/TT/">Timed Text (TT) Working Group</a> as part of the
+    W3C <a href="http://www.w3.org/2008/WebVideo/">Video in the Web Activity</a>,
+    following the procedures set out for the W3C <a href=
+    "http://www.w3.org/Consortium/Process/">Process</a>. The authors of this document are
+    listed in the header of this document, including input and review by liaisons from
+    the <a href="http://www3.ebu.ch/cms/en/home">European Broadcasting Union (EBU)</a>,
+    and the <a href="https://www.smpte.org">Society of Motion Picture &amp; Television
+    Engineers (SMPTE)</a>.</p>
+
+    <p>Publication as a Proposed Edited Recommendation does not imply endorsement by the
+    W3C Membership. This is a draft document and may be updated, replaced or obsoleted by
+    other documents at any time. It is inappropriate to cite this document as other than
+    work in progress.</p>
+
+    <p>W3C Advisory Committee Members are invited to send formal review comments on this
+    Proposed Edited Recommendation to the W3C Team until 06 August 2013. Members of the
+    W3C Advisory Committee will find the appropriate review form for this document by
+    consulting their <a href="http://www.w3.org/2002/09/wbs/myQuestionnaires">list of WBS
+    questionnaires</a>.</p>
+
+    <p>This document incorporates changes made against the <a href=
+    "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">Recommendation</a> of 18
+    November 2010 that resolve all errata known at the date of publication. A list of the
+    errata that have been applied is provided in <a href=
+    "https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttml-changes.html#change-history-rec-to-2e-per">
+    Changes from Recommendation to Proposed Edited Recommendation (2nd Ed.)</a>.</p>
+
+    <p>Please report errors in and submit comments on this document to the W3C Timed Text
+    public comments mailing list, <a href=
+    "mailto:public-tt-comments@w3.org">public-tt-comments@w3.org</a>. Please include the
+    string <code>[ttml10se]</code> at the beginning of the subject line of your report.
+    Each email message should contain only one error report. Archives of the comments and
+    responses are available at <a href=
+    "http://lists.w3.org/Archives/Public/public-tt-comments/">http://lists.w3.org/Archives/Public/public-tt-comments/</a>.</p>
+
+    <p>An updated <a href="http://www.w3.org/2009/05/dfxp-results.html">implementation
+    report</a> will be made available, but the decision of the Director to transition
+    this document to Proposed Edited Recommendation did not depend on the existence of
+    that report.</p>
+
+    <p>The Timed Text Working Group plans to submit this specification for consideration
+    as a W3C Recommendation (Second Edition) as soon as the Working Group has responded
+    formally to all issues raised during the PER review period against this document.</p>
+
+    <p>This document was produced by a group operating under the <a href=
+    "http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent
+    Policy</a>. W3C maintains a <a href=
+    "http://www.w3.org/2004/01/pp-impl/34314/status#disclosures" rel="disclosure">public
+    list of any patent disclosures</a> made in connection with the deliverables of the
+    group; that page also includes instructions for disclosing a patent. An individual
+    who has actual knowledge of a patent which the individual believes contains <a href=
+    "http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
+    Claim(s)</a> must disclose the information in accordance with <a href=
+    "http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of
+    the W3C Patent Policy</a>.</p>
+  </div>
+
+  <div class="toc">
+    <h2><a id="contents" name="contents"></a>Table of Contents</h2>
+
+    <p class="toc">1 <a href="#intro">Introduction</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;1.1 <a href="#model">System Model</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;1.2 <a href="#example">Document Example</a><br>
+    2 <a href="#definitions">Definitions</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;2.1 <a href="#acronyms">Acronyms</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;2.2 <a href="#terms">Terminology</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;2.3 <a href="#conventions">Documentation Conventions</a><br>
+    3 <a href="#conformance">Conformance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;3.1 <a href="#conformance-content">Content
+    Conformance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;3.2 <a href="#conformance-processor">Processor
+    Conformance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.1 <a href=
+    "#conformance-generic-processor">Generic Processor Conformance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.2 <a href=
+    "#conformance-transformation-processor">Transformation Processor Conformance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.3 <a href=
+    "#conformance-presentation-processor">Presentation Processor Conformance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;3.3 <a href="#claims">Claims</a><br>
+    4 <a href="#doctypes">Document Types</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;4.1 <a href="#ttml-content-doctype">TTML Content</a><br>
+    5 <a href="#vocabulary">Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;5.1 <a href="#vocabulary-namespaces">Namespaces</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;5.2 <a href="#vocabulary-profiles">Profiles</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;5.3 <a href="#vocabulary-overview">Catalog</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.3.1 <a href=
+    "#core-vocabulary-overview">Core Catalog</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.3.2 <a href=
+    "#extension-vocabulary-overview">Extension Catalog</a><br>
+    6 <a href="#parameters">Parameters</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;6.1 <a href="#parameter-element-vocabulary">Parameter Element
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.1 <a href=
+    "#parameter-vocabulary-profile">ttp:profile</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.2 <a href=
+    "#parameter-vocabulary-features">ttp:features</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.3 <a href=
+    "#parameter-vocabulary-feature">ttp:feature</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.4 <a href=
+    "#parameter-vocabulary-extensions">ttp:extensions</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.5 <a href=
+    "#parameter-vocabulary-extension">ttp:extension</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;6.2 <a href="#parameter-attribute-vocabulary">Parameter
+    Attribute Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.1 <a href=
+    "#parameter-attribute-cellResolution">ttp:cellResolution</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.2 <a href=
+    "#parameter-attribute-clockMode">ttp:clockMode</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.3 <a href=
+    "#parameter-attribute-dropMode">ttp:dropMode</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.4 <a href=
+    "#parameter-attribute-frameRate">ttp:frameRate</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.5 <a href=
+    "#parameter-attribute-frameRateMultiplier">ttp:frameRateMultiplier</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.6 <a href=
+    "#parameter-attribute-markerMode">ttp:markerMode</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.7 <a href=
+    "#parameter-attribute-pixelAspectRatio">ttp:pixelAspectRatio</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.8 <a href=
+    "#parameter-attribute-profile">ttp:profile</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.9 <a href=
+    "#parameter-attribute-subFrameRate">ttp:subFrameRate</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.10 <a href=
+    "#parameter-attribute-tickRate">ttp:tickRate</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.11 <a href=
+    "#parameter-attribute-timeBase">ttp:timeBase</a><br>
+    7 <a href="#content">Content</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;7.1 <a href="#content-element-vocabulary">Content Element
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.1 <a href=
+    "#document-structure-vocabulary-tt">tt</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.2 <a href=
+    "#document-structure-vocabulary-head">head</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.3 <a href=
+    "#document-structure-vocabulary-body">body</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.4 <a href=
+    "#content-vocabulary-div">div</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.5 <a href=
+    "#content-vocabulary-p">p</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.6 <a href=
+    "#content-vocabulary-span">span</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.7 <a href=
+    "#content-vocabulary-br">br</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;7.2 <a href="#content-attribute-vocabulary">Content Attribute
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.1 <a href=
+    "#content-attribute-id">xml:id</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.2 <a href=
+    "#content-attribute-lang">xml:lang</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.3 <a href=
+    "#content-attribute-space">xml:space</a><br>
+    8 <a href="#styling">Styling</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;8.1 <a href="#styling-element-vocabulary">Styling Element
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.1.1 <a href=
+    "#styling-vocabulary-styling">styling</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.1.2 <a href=
+    "#styling-vocabulary-style">style</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;8.2 <a href="#styling-attribute-vocabulary">Styling Attribute
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.1 <a href=
+    "#style-attribute-style">style</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.2 <a href=
+    "#style-attribute-backgroundColor">tts:backgroundColor</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.3 <a href=
+    "#style-attribute-color">tts:color</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.4 <a href=
+    "#style-attribute-direction">tts:direction</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.5 <a href=
+    "#style-attribute-display">tts:display</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.6 <a href=
+    "#style-attribute-displayAlign">tts:displayAlign</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.7 <a href=
+    "#style-attribute-extent">tts:extent</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.8 <a href=
+    "#style-attribute-fontFamily">tts:fontFamily</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.9 <a href=
+    "#style-attribute-fontSize">tts:fontSize</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.10 <a href=
+    "#style-attribute-fontStyle">tts:fontStyle</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.11 <a href=
+    "#style-attribute-fontWeight">tts:fontWeight</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.12 <a href=
+    "#style-attribute-lineHeight">tts:lineHeight</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.13 <a href=
+    "#style-attribute-opacity">tts:opacity</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.14 <a href=
+    "#style-attribute-origin">tts:origin</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.15 <a href=
+    "#style-attribute-overflow">tts:overflow</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.16 <a href=
+    "#style-attribute-padding">tts:padding</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.17 <a href=
+    "#style-attribute-showBackground">tts:showBackground</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.18 <a href=
+    "#style-attribute-textAlign">tts:textAlign</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.19 <a href=
+    "#style-attribute-textDecoration">tts:textDecoration</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.20 <a href=
+    "#style-attribute-textOutline">tts:textOutline</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.21 <a href=
+    "#style-attribute-unicodeBidi">tts:unicodeBidi</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.22 <a href=
+    "#style-attribute-visibility">tts:visibility</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.23 <a href=
+    "#style-attribute-wrapOption">tts:wrapOption</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.24 <a href=
+    "#style-attribute-writingMode">tts:writingMode</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.25 <a href=
+    "#style-attribute-zIndex">tts:zIndex</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;8.3 <a href="#styling-style-value-expressions">Style Value
+    Expressions</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.1 <a href=
+    "#style-value-alpha">&lt;alpha&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.2 <a href=
+    "#style-value-color">&lt;color&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.3 <a href=
+    "#style-value-digit">&lt;digit&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.4 <a href=
+    "#style-value-duration">Deleted</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.5 <a href=
+    "#style-value-familyName">&lt;familyName&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.6 <a href=
+    "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.7 <a href=
+    "#style-value-hexDigit">&lt;hexDigit&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.8 <a href=
+    "#style-value-integer">&lt;integer&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.9 <a href=
+    "#style-value-length">&lt;length&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.10 <a href=
+    "#style-value-namedColor">&lt;namedColor&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.11 <a href=
+    "#style-value-quotedString">Deleted</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.12 <a href=
+    "#style-value-string">Deleted</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;8.4 <a href="#semantics-style-resolution">Style
+    Resolution</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1 <a href=
+    "#semantics-style-association">Style Association</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.1
+    <a href="#semantics-style-association-inline">Inline Styling</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.2
+    <a href="#semantics-style-association-referential">Referential Styling</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.3
+    <a href="#semantics-style-association-chained-referential">Chained Referential
+    Styling</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.4
+    <a href="#semantics-style-association-nested">Nested Styling</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2 <a href=
+    "#semantics-style-inheritance">Style Inheritance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2.1
+    <a href="#semantics-style-inheritance-content">Content Style Inheritance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2.2
+    <a href="#semantics-style-inheritance-region">Region Style Inheritance</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3 <a href=
+    "#semantics-style-resolution-value-categories">Style Resolution Value
+    Categories</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.1
+    <a href="#semantics-style-resolved-value-category-specified">Specified Values</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.2
+    <a href="#semantics-style-resolved-value-category-computed">Computed Values</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.3
+    <a href="#semantics-style-resolved-value-category-actual">Actual Values</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4 <a href=
+    "#semantics-style-resolution-processing">Style Resolution Processing</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.1
+    <a href="#semantics-style-resolution-processing-definitions">Conceptual
+    Definitions</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.2
+    <a href="#semantics-style-resolution-processing-sss">Specified Style Set
+    Processing</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.3
+    <a href="#semantics-style-resolution-processing-css">Computed Style Set
+    Processing</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.4
+    <a href="#semantics-style-resolution-process-overall">Style Resolution
+    Process</a><br>
+    9 <a href="#layout">Layout</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;9.1 <a href="#layout-element-vocabulary">Layout Element
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.1.1 <a href=
+    "#layout-vocabulary-layout">layout</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.1.2 <a href=
+    "#layout-vocabulary-region">region</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;9.2 <a href="#layout-attribute-vocabulary">Layout Attribute
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.2.1 <a href=
+    "#layout-attribute-region">region</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;9.3 <a href="#semantics-region-layout">Region Layout and
+    Presentation</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.1 <a href=
+    "#semantics-default-region">Default Region</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.2 <a href=
+    "#semantics-region-layout-step-1">Intermediate Synchronic Document
+    Construction</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.3 <a href=
+    "#semantics-region-layout-step-2">Synchronic Flow Processing</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.4 <a href=
+    "#semantics-region-layout-example">Elaborated Example (Informative)</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;9.4 <a href="#semantics-line-layout">Line Layout</a><br>
+    10 <a href="#timing">Timing</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;10.1 <a href="#timing-element-vocabulary">Timing Element
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;10.2 <a href="#timing-attribute-vocabulary">Timing Attribute
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.1 <a href=
+    "#timing-attribute-begin">begin</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.2 <a href=
+    "#timing-attribute-end">end</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.3 <a href=
+    "#timing-attribute-dur">dur</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.4 <a href=
+    "#timing-attribute-timeContainer">timeContainer</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;10.3 <a href="#timing-time-value-expressions">Time Value
+    Expressions</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.3.1 <a href=
+    "#timing-value-timeExpression">&lt;timeExpression&gt;</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;10.4 <a href="#timing-time-intervals">Time Intervals</a><br>
+    11 <a href="#animation">Animation</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;11.1 <a href="#animation-element-vocabulary">Animation
+    Element Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;11.1.1 <a href=
+    "#animation-vocabulary-set">set</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;11.2 <a href="#animation-attribute-vocabulary">Animation
+    Attribute Vocabulary</a><br>
+    12 <a href="#metadata">Metadata</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;12.1 <a href="#metadata-element-vocabulary">Metadata Element
+    Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.1 <a href=
+    "#metadata-vocabulary-metadata">metadata</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.2 <a href=
+    "#metadata-vocabulary-title">ttm:title</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.3 <a href=
+    "#metadata-vocabulary-desc">ttm:desc</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.4 <a href=
+    "#metadata-vocabulary-copyright">ttm:copyright</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.5 <a href=
+    "#metadata-vocabulary-agent">ttm:agent</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.6 <a href=
+    "#metadata-vocabulary-name">ttm:name</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.7 <a href=
+    "#metadata-vocabulary-actor">ttm:actor</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;12.2 <a href="#metadata-attribute-vocabulary">Metadata
+    Attribute Vocabulary</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.2.1 <a href=
+    "#metadata-attribute-agent">ttm:agent</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.2.2 <a href=
+    "#metadata-attribute-role">ttm:role</a><br></p>
+
+    <h3><a id="appendices" name="appendices"></a>Appendices</h3>
+
+    <p class="toc">A <a href="#reduced-infoset">Reduced XML Infoset</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;A.1 <a href="#reduced-infoset-document">Document Information
+    Item</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;A.2 <a href="#reduced-infoset-element">Element Information
+    Item</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;A.3 <a href="#reduced-infoset-attribute">Attribute
+    Information Item</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;A.4 <a href="#reduced-infoset-character">Character
+    Information Item</a><br>
+    B <a href="#schemas">Schemas</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;B.1 <a href="#ttml-schema-rnc">Relax NG Compact (RNC)
+    Schema</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;B.2 <a href="#ttml-schema-xsd">XML Schema Definition (XSD)
+    Schema</a><br>
+    C <a href="#media-types-registration">Media Type Registration</a><br>
+    D <a href="#features">Features</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;D.1 <a href="#feature-designations">Feature
+    Designations</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.1 <a href=
+    "#feature-animation">#animation</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.2 <a href=
+    "#feature-backgroundColor">#backgroundColor</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.3 <a href=
+    "#feature-backgroundColor-block">#backgroundColor-block</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.4 <a href=
+    "#feature-backgroundColor-inline">#backgroundColor-inline</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.5 <a href=
+    "#feature-backgroundColor-region">#backgroundColor-region</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.6 <a href=
+    "#feature-bidi">#bidi</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.7 <a href=
+    "#feature-cellResolution">#cellResolution</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.8 <a href=
+    "#feature-clockMode">#clockMode</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.9 <a href=
+    "#feature-clockMode-gps">#clockMode-gps</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.10 <a href=
+    "#feature-clockMode-local">#clockMode-local</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.11 <a href=
+    "#feature-clockMode-utc">#clockMode-utc</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.12 <a href=
+    "#feature-color">#color</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.13 <a href=
+    "#feature-content">#content</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.14 <a href=
+    "#feature-core">#core</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.15 <a href=
+    "#feature-direction">#direction</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.16 <a href=
+    "#feature-display">#display</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.17 <a href=
+    "#feature-display-block">#display-block</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.18 <a href=
+    "#feature-display-inline">#display-inline</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.19 <a href=
+    "#feature-display-region">#display-region</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.20 <a href=
+    "#feature-displayAlign">#displayAlign</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.21 <a href=
+    "#feature-dropMode">#dropMode</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.22 <a href=
+    "#feature-dropMode-dropNTSC">#dropMode-dropNTSC</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.23 <a href=
+    "#feature-dropMode-dropPAL">#dropMode-dropPAL</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.24 <a href=
+    "#feature-dropMode-nonDrop">#dropMode-nonDrop</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.25 <a href=
+    "#feature-extent">#extent</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.26 <a href=
+    "#feature-extent-region">#extent-region</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.27 <a href=
+    "#feature-extent-root">#extent-root</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.28 <a href=
+    "#feature-fontFamily">#fontFamily</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.29 <a href=
+    "#feature-fontFamily-generic">#fontFamily-generic</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.30 <a href=
+    "#feature-fontFamily-non-generic">#fontFamily-non-generic</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.31 <a href=
+    "#feature-fontSize">#fontSize</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.32 <a href=
+    "#feature-fontSize-anamorphic">#fontSize-anamorphic</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.33 <a href=
+    "#feature-fontSize-isomorphic">#fontSize-isomorphic</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.34 <a href=
+    "#feature-fontStyle">#fontStyle</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.35 <a href=
+    "#feature-fontStyle-italic">#fontStyle-italic</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.36 <a href=
+    "#feature-fontStyle-oblique">#fontStyle-oblique</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.37 <a href=
+    "#feature-fontWeight">#fontWeight</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.38 <a href=
+    "#feature-fontWeight-bold">#fontWeight-bold</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.39 <a href=
+    "#feature-frameRate">#frameRate</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.40 <a href=
+    "#feature-frameRateMultiplier">#frameRateMultiplier</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.41 <a href=
+    "#feature-layout">#layout</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.42 <a href=
+    "#feature-length">#length</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.43 <a href=
+    "#feature-length-cell">#length-cell</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.44 <a href=
+    "#feature-length-em">#length-em</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.45 <a href=
+    "#feature-length-integer">#length-integer</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.46 <a href=
+    "#feature-length-negative">#length-negative</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.47 <a href=
+    "#feature-length-percentage">#length-percentage</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.48 <a href=
+    "#feature-length-pixel">#length-pixel</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.49 <a href=
+    "#feature-length-positive">#length-positive</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.50 <a href=
+    "#feature-length-real">#length-real</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.51 <a href=
+    "#feature-lineBreak-uax14">#lineBreak-uax14</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.52 <a href=
+    "#feature-lineHeight">#lineHeight</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.53 <a href=
+    "#feature-markerMode">#markerMode</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.54 <a href=
+    "#feature-markerMode-continuous">#markerMode-continuous</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.55 <a href=
+    "#feature-markerMode-discontinuous">#markerMode-discontinuous</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.56 <a href=
+    "#feature-metadata">#metadata</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.57 <a href=
+    "#feature-nested-div">#nested-div</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.58 <a href=
+    "#feature-nested-span">#nested-span</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.59 <a href=
+    "#feature-opacity">#opacity</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.60 <a href=
+    "#feature-origin">#origin</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.61 <a href=
+    "#feature-overflow">#overflow</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.62 <a href=
+    "#feature-overflow-visible">#overflow-visible</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.63 <a href=
+    "#feature-padding">#padding</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.64 <a href=
+    "#feature-padding-1">#padding-1</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.65 <a href=
+    "#feature-padding-2">#padding-2</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.66 <a href=
+    "#feature-padding-3">#padding-3</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.67 <a href=
+    "#feature-padding-4">#padding-4</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.68 <a href=
+    "#feature-pixelAspectRatio">#pixelAspectRatio</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.69 <a href=
+    "#feature-presentation">#presentation</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.70 <a href=
+    "#feature-profile">#profile</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.71 <a href=
+    "#feature-showBackground">#showBackground</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.72 <a href=
+    "#feature-structure">#structure</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.73 <a href=
+    "#feature-styling">#styling</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.74 <a href=
+    "#feature-styling-chained">#styling-chained</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.75 <a href=
+    "#feature-styling-inheritance-content">#styling-inheritance-content</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.76 <a href=
+    "#feature-styling-inheritance-region">#styling-inheritance-region</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.77 <a href=
+    "#feature-styling-inline">#styling-inline</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.78 <a href=
+    "#feature-styling-nested">#styling-nested</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.79 <a href=
+    "#feature-styling-referential">#styling-referential</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.80 <a href=
+    "#feature-subFrameRate">#subFrameRate</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.81 <a href=
+    "#feature-textAlign">#textAlign</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.82 <a href=
+    "#feature-textAlign-absolute">#textAlign-absolute</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.83 <a href=
+    "#feature-textAlign-relative">#textAlign-relative</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.84 <a href=
+    "#feature-textDecoration">#textDecoration</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.85 <a href=
+    "#feature-textDecoration-over">#textDecoration-over</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.86 <a href=
+    "#feature-textDecoration-through">#textDecoration-through</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.87 <a href=
+    "#feature-textDecoration-under">#textDecoration-under</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.88 <a href=
+    "#feature-textOutline">#textOutline</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.89 <a href=
+    "#feature-textOutline-blurred">#textOutline-blurred</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.90 <a href=
+    "#feature-textOutline-unblurred">#textOutline-unblurred</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.91 <a href=
+    "#feature-tickRate">#tickRate</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.92 <a href=
+    "#feature-timeBase-clock">#timeBase-clock</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.93 <a href=
+    "#feature-timeBase-media">#timeBase-media</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.94 <a href=
+    "#feature-timeBase-smpte">#timeBase-smpte</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.95 <a href=
+    "#feature-timeContainer">#timeContainer</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.96 <a href=
+    "#feature-time-clock">#time-clock</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.97 <a href=
+    "#feature-time-clock-with-frames">#time-clock-with-frames</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.98 <a href=
+    "#feature-time-offset">#time-offset</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.99 <a href=
+    "#feature-time-offset-with-frames">#time-offset-with-frames</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.100 <a href=
+    "#feature-time-offset-with-ticks">#time-offset-with-ticks</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.101 <a href=
+    "#feature-timing">#timing</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.102 <a href=
+    "#feature-transformation">#transformation</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.103 <a href=
+    "#feature-unicodeBidi">#unicodeBidi</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.104 <a href=
+    "#feature-visibility">#visibility</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.105 <a href=
+    "#feature-visibility-block">#visibility-block</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.106 <a href=
+    "#feature-visibility-inline">#visibility-inline</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.107 <a href=
+    "#feature-visibility-region">#visibility-region</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.108 <a href=
+    "#feature-wrapOption">#wrapOption</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.109 <a href=
+    "#feature-writingMode">#writingMode</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.110 <a href=
+    "#feature-writingMode-vertical">#writingMode-vertical</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.111 <a href=
+    "#feature-writingMode-horizontal">#writingMode-horizontal</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.112 <a href=
+    "#feature-writingMode-horizontal-lr">#writingMode-horizontal-lr</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.113 <a href=
+    "#feature-writingMode-horizontal-rl">#writingMode-horizontal-rl</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.114 <a href=
+    "#feature-zIndex">#zIndex</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;D.2 <a href="#feature-support">Feature Support</a><br>
+    E <a href="#extensions">Extensions</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;E.1 <a href="#extension-designations">Extension
+    Designations</a><br>
+    F <a href="#profiles">Profiles</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;F.1 <a href="#profile-dfxp-transformation">DFXP
+    Transformation Profile</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;F.2 <a href="#profile-dfxp-presentation">DFXP Presentation
+    Profile</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;F.3 <a href="#profile-dfxp-full">DFXP Full Profile</a><br>
+    G <a href="#references">References</a><br>
+    H <a href="#other-references">Other References</a> (Non-Normative)<br>
+    I <a href="#requirements">Requirements</a> (Non-Normative)<br>
+    J <a href="#derivation">Vocabulary Derivation</a> (Non-Normative)<br>
+    &nbsp;&nbsp;&nbsp;&nbsp;J.1 <a href="#d3e18678">Element Derivation</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;J.2 <a href="#d3e19157">Attribute Derivation</a><br>
+    K <a href="#qa">QA Framework Compliance</a> (Non-Normative)<br>
+    &nbsp;&nbsp;&nbsp;&nbsp;K.1 <a href="#d3e20043">Requirements</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;K.2 <a href="#d3e20207">Guidelines</a><br>
+    L <a href="#streaming">Streaming TTML Content</a> (Non-Normative)<br>
+    M <a href="#concrete-encoding">Concrete Encoding</a> (Non-Normative)<br>
+    N <a href="#time-expression-semantics">Time Expression Semantics</a>
+    (Non-Normative)<br>
+    &nbsp;&nbsp;&nbsp;&nbsp;N.1 <a href="#time-expression-semantics-clock">Clock Time
+    Base</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;N.2 <a href="#time-expression-semantics-media">Media Time
+    Base</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;N.3 <a href="#time-expression-semantics-smpte">SMPTE Time
+    Base</a><br>
+    O <a href="#common-styling">Common Caption Style Examples</a> (Non-Normative)<br>
+    &nbsp;&nbsp;&nbsp;&nbsp;O.1 <a href="#pop-on-example">Pop-On Caption Example</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;O.2 <a href="#roll-up-example">Roll-Up Caption
+    Example</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;O.3 <a href="#paint-on-example">Paint-On Caption
+    Example</a><br>
+    P <a href="#acknowledgments">Acknowledgments</a> (Non-Normative)<br></p>
+  </div>
+  <hr>
+
+  <div class="body">
+    <div class="div1">
+      <h2><a id="intro" name="intro"></a>1 Introduction</h2>
+
+      <p><em>Unless specified otherwise, this section and its sub-sections are
+      non-normative.</em></p>
+
+      <p>The Timed Text Markup Language (TTML) 1.0 provides a standardized representation
+      of a particular subset of textual information with which stylistic, layout, and
+      timing semantics are associated by an author or an authoring system for the purpose
+      of interchange and processing.</p>
+
+      <p>TTML is expressly designed to meet only a limited set of requirements
+      established by <a href="#ttaf1-req">[TTAF1-REQ]</a>, and summarized in <a href=
+      "#requirements"><b>I Requirements</b></a>. In particular, only those requirements
+      which service the need of performing interchange with existing, legacy distribution
+      systems are satisfied.</p>
+
+      <p>In addition to being used for interchange among legacy distribution content
+      formats, TTML Content may be used directly as a distribution format (as implied by
+      the acronym DFXP), providing, for example, a standard content format to reference
+      from a <code>&lt;track&gt;</code> element in an HTML5 document, or a
+      <code>&lt;text&gt;</code> or <code>&lt;textstream&gt;</code> media element in a
+      <a href="#smil21">[SMIL 2.1]</a> document. Certain properties of TTML support
+      streamability of content, as described in <a href="#streaming"><b>L Streaming TTML
+      Content</b></a>.</p>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>While TTML was not expressly designed for direct (embedded) integration into
+        an HTML or a SMIL document instance, such integration is not precluded.</p>
+      </div>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>In some contexts of use, it may be appropriate to employ animated content to
+        depict sign language representations of the same content as expressed by a Timed
+        Text <em>Document Instance</em>. This use case is not explicitly addressed by
+        TTML mechanisms, but may be addressed by some external multimedia integration
+        technology, such as SMIL.</p>
+      </div>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>In previous drafts of this specification, TTML was referred to as DFXP
+        (Distribution Format Exchange Profile). This latter term is retained for
+        historical reasons in certain contexts, such as profile names and designators,
+        and the short name <code>ttaf1-dfxp</code> used in URLs to refer to this
+        specification.</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="model" name="model"></a>1.1 System Model</h3>
+
+        <p>Use of TTML is intended to function in a wider context of Timed Text Authoring
+        and Distribution mechanisms that are based upon the system model depicted in
+        <a href="#model-graphic"><b>Figure 1 – System Model</b></a>, wherein the Timed
+        Text Markup Language serves as a bidirectional interchange format among a
+        heterogeneous collection of authoring systems, and as a unidirectional
+        interchange format to a heterogeneous collection of distribution formats after
+        undergoing transcoding or compilation to the target distribution formats as
+        required, and where one particular distribution format is TTML (labeled as "DFXP"
+        in the figure).</p><a id="model-graphic" name="model-graphic"></a>
+
+        <table class="example-images">
+          <caption>
+            Figure 1 – System Model
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/model.png" alt="System Model"></td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+
+      <div class="div2">
+        <h3><a id="example" name="example"></a>1.2 Document Example</h3>
+
+        <p>A TTML <em>Document Instance</em> consists of a <code>tt</code> document
+        element that contains a header and a body, where the header specifies document
+        level metadata, styling definitions and layout definitions, and the body
+        specifies text content intermixed with references to style and layout information
+        and inline styling and timing information.</p><a id=
+        "ttml-example-document-structure" name="ttml-example-document-structure"></a>
+
+        <table class="example">
+          <caption>
+            Example Fragment – TTML Document Structure
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
+  &lt;head&gt;
+    &lt;metadata/&gt;
+    &lt;styling/&gt;
+    &lt;layout/&gt;
+  &lt;/head&gt;
+  &lt;body/&gt;
+&lt;/tt&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>Document level metadata may specify a document title, description, and
+        copyright information. In addition, arbitrary metadata drawn from other
+        namespaces may be specified.</p><a id="ttml-example-metadata" name=
+        "ttml-example-metadata"></a>
+
+        <table class="example">
+          <caption>
+            Example Fragment – TTML Metadata
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
+  &lt;ttm:title&gt;Timed Text TTML Example&lt;/ttm:title&gt;
+  &lt;ttm:copyright&gt;The Authors (c) 2006&lt;/ttm:copyright&gt;
+&lt;/metadata&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>Styling information may be specified in the form of style specification
+        definitions that are referenced by layout and content information, specified
+        inline with content information, or both.</p>
+
+        <p>In <a href="#ttml-example-styling"><b>Example Fragment – TTML Styling</b></a>,
+        four style sets of specifications are defined, with one set serving as a
+        collection of default styles.</p><a id="ttml-example-styling" name=
+        "ttml-example-styling"></a>
+
+        <table class="example">
+          <caption>
+            Example Fragment – TTML Styling
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;styling xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;!-- s1 specifies default color, font, and text alignment --&gt;
+  &lt;style xml:id="s1"
+    tts:color="white"
+    tts:fontFamily="proportionalSansSerif"
+    tts:fontSize="22px"
+    tts:textAlign="center"
+  /&gt;
+  &lt;!-- alternative using yellow text but otherwise the same as style s1 --&gt;
+  &lt;style xml:id="s2" style="s1" tts:color="yellow"/&gt;
+  &lt;!-- a style based on s1 but justified to the right --&gt;
+  &lt;style xml:id="s1Right" style="s1" tts:textAlign="end" /&gt;     
+  &lt;!-- a style based on s2 but justified to the left --&gt;
+  &lt;style xml:id="s2Left" style="s2" tts:textAlign="start" /&gt;
+&lt;/styling&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>Layout information defines one or more regions into which content is intended
+        to be presented. A region definition may reference one or more sets of style
+        specifications in order to permit content flowed in the region to inherit from
+        these styles. In <a href="#ttml-example-layout"><b>Example Fragment – TTML
+        Layout</b></a>, the region definition makes reference to style specification
+        <code>s1</code> augmented by specific inline styles which, together, allow
+        content flowed into the region to inherit from the region's styles (in the case
+        that a style is not already explicitly specified on content or inherited via the
+        content hierarchy.)</p><a id="ttml-example-layout" name=
+        "ttml-example-layout"></a>
+
+        <table class="example">
+          <caption>
+            Example Fragment – TTML Layout
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;layout xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;region xml:id="subtitleArea"
+    style="s1"
+    tts:extent="560px 62px"
+    tts:padding="5px 3px"
+    tts:backgroundColor="black"
+    tts:displayAlign="after"
+  /&gt;
+&lt;/layout&gt;  
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The content of a <em>Document Instance</em> is expressed in its body, which is
+        organized in terms of block and inline text elements. The hierarchical
+        organization of content elements serves a primary role in determining both
+        spatial and temporal relationships. For example, in <a href=
+        "#ttml-example-body"><b>Example Fragment – TTML Body</b></a>, each paragraph
+        (<code>p</code> element) is flowed into its target region in the specified
+        lexical order; furthermore, the active time interval of each paragraph is timed
+        in accordance to its parent or sibling according to the applicable time
+        containment semantics — in this case, the division parent is interpreted (by
+        default) as a parallel time container.</p><a id="ttml-example-body" name=
+        "ttml-example-body"></a>
+
+        <table class="example">
+          <caption>
+            Example Fragment – TTML Body
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;body region="subtitleArea"&gt;
+  &lt;div&gt;
+    &lt;p xml:id="subtitle1" begin="0.76s" end="3.45s"&gt;
+      It seems a paradox, does it not,
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle2" begin="5.0s" end="10.0s"&gt;
+      that the image formed on&lt;br/&gt;
+      the Retina should be inverted?
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle3" begin="10.0s" end="16.0s" style="s2"&gt;
+      It is puzzling, why is it&lt;br/&gt;
+      we do not see things upside-down?
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle4" begin="17.2s" end="23.0s"&gt;
+      You have never heard the Theory,&lt;br/&gt;
+      then, that the Brain also is inverted?
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle5" begin="23.0s" end="27.0s" style="s2"&gt;
+      No indeed! What a beautiful fact!
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle6a" begin="28.0s" end="34.6s" style="s2Left"&gt;
+      But how is it proved?
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle6b" begin="28.0s" end="34.6s" style="s1Right"&gt;
+      Thus: what we call
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle7" begin="34.6s" end="45.0s" style="s1Right"&gt;
+      the vertex of the Brain&lt;br/&gt;
+      is really its base
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle8" begin="45.0s" end="52.0s" style="s1Right"&gt;
+      and what we call its base&lt;br/&gt;
+      is really its vertex,
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle9a" begin="53.5s" end="58.7s"&gt;
+      it is simply a question of nomenclature.
+    &lt;/p&gt;
+    &lt;p xml:id="subtitle9b" begin="53.5s" end="58.7s" style="s2"&gt;
+      How truly delightful!
+    &lt;/p&gt;
+  &lt;/div&gt;    
+&lt;/body&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The first subtitle <a href="#ttml-example-subtitle-1"><b>Subtitle 1 – Time
+        Interval [0.76, 3.45)</b></a> is presented during the time interval 0.76 to 3.45
+        seconds. This subtitle inherits its font family, font size, foreground color, and
+        text alignment from the region into which it is presented. Since no region is
+        explicitly specified on the paragraph, the nearest ancestor that specifies a
+        region determines the targeted region. Note also that content is presented at the
+        bottom (after edge) of the containing region due to the
+        <code>tts:displayAlign="after"</code> being specified on the region
+        definition.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>The notation "[<em>X</em>,<em>Y</em>]" denotes a closed interval from
+          <em>X</em> to <em>Y</em>, including <em>X</em> and <em>Y</em>;
+          "[<em>X</em>,<em>Y</em>)" denotes a right half-open interval from <em>X</em> to
+          <em>Y</em>, including <em>X</em> but not including <em>Y</em>;
+          "(<em>X</em>,<em>Y</em>]" denotes a left half-open interval from <em>X</em> to
+          <em>Y</em>, not including <em>X</em> but including <em>Y</em>;
+          "(<em>X</em>,<em>Y</em>)" denotes an open interval from <em>X</em> to
+          <em>Y</em>, not including <em>X</em> or <em>Y</em>.</p>
+        </div><a id="ttml-example-subtitle-1" name="ttml-example-subtitle-1"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitle 1 – Time Interval [0.76, 3.45)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle1.png" alt="Subtitle 1"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The second subtitle continues with the default style, except that it contains
+        two lines of text with an intervening author-specified line break. Note the
+        effects of the use of <code>tts:textAlign="center"</code> to specify the
+        paragraph's alignment in the inline progression direction.</p><a id=
+        "ttml-example-subtitle-2" name="ttml-example-subtitle-2"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitle 2 – Time Interval [5.0, 10.0)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle2.png" alt="Subtitle 2"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The third subtitle continues, using a variant style which overrides the
+        default style's foreground color with a different color.</p><a id=
+        "ttml-example-subtitle-3" name="ttml-example-subtitle-3"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitle 3 – Time Interval [10.0, 16.0)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle3.png" alt="Subtitle 3"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The fourth subtitle reverts to the default style.</p><a id=
+        "ttml-example-subtitle-4" name="ttml-example-subtitle-4"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitle 4 – Time Interval [17.2, 23.0)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle4.png" alt="Subtitle 4"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The fifth subtitle continues, again using a variant style which overrides the
+        default style's foreground color with a different color.</p><a id=
+        "ttml-example-subtitle-5" name="ttml-example-subtitle-5"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitle 5 – Time Interval [23.0, 27.0)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle5.png" alt="Subtitle 5"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>During the next active time interval, two distinct subtitles are
+        simultaneously active, with the paragraphs expressing each subtitle using
+        different styles that override color and paragraph text alignment of the default
+        style. Note that the flow order is determined by the lexical order of elements as
+        they appear in the content hierarchy.</p><a id="ttml-example-subtitle-6" name=
+        "ttml-example-subtitle-6"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitles 6a and 6b – Time Interval [28.0, 34.6)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle6.png" alt="Subtitles 6a and 6b"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The next subtitle is specified in a similar manner using a style override to
+        give the paragraph right (end) justification in the inline progression
+        direction.</p><a id="ttml-example-subtitle-7" name="ttml-example-subtitle-7"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitle 7 – Time Interval [34.6, 45.0)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle7.png" alt="Subtitles 7a and 7b"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The eighth subtitle uses the same style override as the previous subtitle in
+        order to maintain the right (end) justification of the paragraph.</p><a id=
+        "ttml-example-subtitle-8" name="ttml-example-subtitle-8"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitle 8 – Time Interval [47.3, 49.0)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle8.png" alt="Subtitle 8"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>During the final (ninth) active time interval, two distinct subtitles are
+        again simultaneously active, but with a different style applied to the second
+        paragraph to override the default color. Note that the flow order is determined
+        by the lexical order of elements as they appear in the content
+        hierarchy.</p><a id="ttml-example-subtitle-9" name="ttml-example-subtitle-9"></a>
+
+        <table class="example-images">
+          <caption>
+            Subtitles 9a and 9b – Time Interval [53.5, 58.7)
+          </caption>
+
+          <tbody>
+            <tr>
+              <td><img src="images/subtitle9.png" alt="Subtitles 9a and 9b"></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The examples shown above demonstrate the primary types of information that may
+        be authored using TTML: metadata, styling, layout, timing, and content. In
+        typical cases, styling and layout information are separately specified in a
+        <em>Document Instance</em>. Content information is expressed in a hierarchical
+        fashion that embodies the organization of both spatial (flow) and timing
+        information. Content makes direct or indirect references to styling and layout
+        information and may specify inline overrides to styling.</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="definitions" name="definitions"></a>2 Definitions</h2>
+
+      <div class="div2">
+        <h3><a id="acronyms" name="acronyms"></a>2.1 Acronyms</h3>
+
+        <table class="acronyms" summary="Glossary List">
+          <tr>
+            <td class="label"><b>DFXP</b></td>
+
+            <td class="def">
+              <p>Distribution Format Exchange Profile</p>
+            </td>
+          </tr>
+
+          <tr>
+            <td class="label"><b>TT</b></td>
+
+            <td class="def">
+              <p>Timed Text</p>
+            </td>
+          </tr>
+
+          <tr>
+            <td class="label"><b>TTML</b></td>
+
+            <td class="def">
+              <p>Timed Text Markup Language</p>
+            </td>
+          </tr>
+
+          <tr>
+            <td class="label"><b>TTAF</b></td>
+
+            <td class="def">
+              <p>Timed Text Authoring Format</p>
+            </td>
+          </tr>
+
+          <tr>
+            <td class="label"><b>TTWG</b></td>
+
+            <td class="def">
+              <p>Timed Text Working Group</p>
+            </td>
+          </tr>
+        </table>
+      </div>
+
+      <div class="div2">
+        <h3><a id="terms" name="terms"></a>2.2 Terminology</h3>
+
+        <dl>
+          <dt class="label">Abstract Document Instance</dt>
+
+          <dd>
+            <p>An instance of an abstract data set as represented by a <em>Reduced XML
+            Infoset</em>.</p>
+          </dd>
+
+          <dt class="label">Abstract Document Type</dt>
+
+          <dd>
+            <p>A set of constraints that defines a class of <em>XML Information Sets</em>
+            <a href="#infoset">[XML InfoSet]</a>.</p>
+          </dd>
+
+          <dt class="label">Attribute Information Item</dt>
+
+          <dd>
+            <p>Each specified or defaulted attribute of an XML document corresponds with
+            an attribute information item as defined by <a href="#infoset">[XML
+            InfoSet]</a>, §2.3.</p>
+          </dd>
+
+          <dt class="label">Character Information Item</dt>
+
+          <dd>
+            <p>Each data character appearing in an XML document corresponds with a
+            character information item as defined by <a href="#infoset">[XML
+            InfoSet]</a>, §2.6.</p>
+          </dd>
+
+          <dt class="label">Computed Cell Size</dt>
+
+          <dd>
+            <p>The size (extent) of a cell computed by dividing the width of the <em>Root
+            Container Region</em> by the column count, i.e., the number of cells in the
+            horizontal axis, and by dividing the height of the <em>Root Container
+            Region</em> by the row count, i.e., the number of cells in the vertical axis,
+            where the column and row counts are determined by the
+            <code>ttp:cellResolution</code> parameter attribute.</p>
+          </dd>
+
+          <dt class="label">Content Processor</dt>
+
+          <dd>
+            <p>A processing system capable of importing (receiving) Timed Text Markup
+            Language content for the purpose of transforming, presenting, or otherwise
+            processing the content.</p>
+          </dd>
+
+          <dt class="label">Content Profile</dt>
+
+          <dd>
+            <p>A collection of features and extensions that are (or may be) employed by
+            Timed Text Markup Language content.</p>
+          </dd>
+
+          <dt class="label">Content Region</dt>
+
+          <dd>
+            <p>A logical region into which rendered content is placed when modeling or
+            performing presentation processing.</p>
+          </dd>
+
+          <dt class="label">Document Instance</dt>
+
+          <dd>
+            <p>A concrete realization of a Timed Text Markup Language document, where the
+            concrete form is specific to the context of reference. For example, a
+            sequence of bytes that represents an XML serialization of a Timed Text
+            document, an internal, parsed representation of such a Timed Text document,
+            etc.</p>
+          </dd>
+
+          <dt class="label">Document Interchange Context</dt>
+
+          <dd>
+            <p>The implied context or environment external to a <em>Content
+            Processor</em> in which document interchange occurs, and in which out-of-band
+            protocols or specifications may define certain behavioral defaults, such as
+            an implied <em>Content Profile</em>.</p>
+          </dd>
+
+          <dt class="label">Document Processing Context</dt>
+
+          <dd>
+            <p>The implied context or environment internal to a <em>Content
+            Processor</em> in which document processing occurs, and in which out-of-band
+            protocols or specifications may define certain behavioral defaults, such as
+            the establishment or creation of a <em>Synthetic Document Syncbase</em>.</p>
+          </dd>
+
+          <dt class="label">Element Information Item</dt>
+
+          <dd>
+            <p>Each element appearing in an XML document corresponds with an element
+            information item as defined by <a href="#infoset">[XML InfoSet]</a>,
+            §2.2.</p>
+          </dd>
+
+          <dt class="label">Exchange Profile</dt>
+
+          <dd>
+            <p>A content profile that serves a set of needs for content interchange.</p>
+          </dd>
+
+          <dt class="label">Extension</dt>
+
+          <dd>
+            <p>A syntactic or semantic expression or capability that is defined and
+            labeled (using a extension designation) in another (public or private)
+            specification.</p>
+          </dd>
+
+          <dt class="label">Feature</dt>
+
+          <dd>
+            <p>A syntactic or semantic expression or capability that is defined and
+            labeled (using a feature designation) in this specification (or a future
+            revision of this specification).</p>
+          </dd>
+
+          <dt class="label">Presentation Processor</dt>
+
+          <dd>
+            <p>A <em>Content Processor</em> which purpose is to layout, format, and
+            render, i.e., to present, <em>Timed Text Markup Language</em> content by
+            applying the presentation semantics defined in this specification.</p>
+          </dd>
+
+          <dt class="label">Processor</dt>
+
+          <dd>
+            <p>See <em>Content Processor</em>.</p>
+          </dd>
+
+          <dt class="label">Processor Profile</dt>
+
+          <dd>
+            <p>A collection of features and extensions that must or may be implemented
+            (supported) by a content processor.</p>
+          </dd>
+
+          <dt class="label">Profile Definition Document</dt>
+
+          <dd>
+            <p>A document that defines a specific collection of features and extensions
+            for which support is required or optional in a recipient content
+            processor.</p>
+          </dd>
+
+          <dt class="label">Region</dt>
+
+          <dd>
+            <p>A logical construct that models authorial intention regarding desired or
+            potential presentation processing, and which is represented as a rectangular
+            area of a presentation surface into which content is composed and rendered
+            during presentation processing.</p>
+          </dd>
+
+          <dt class="label">Reduced XML Infoset</dt>
+
+          <dd>
+            <p>An XML Information Set <a href="#infoset">[XML InfoSet]</a> that satisfies
+            the constraints specify by <a href="#reduced-infoset"><b>A Reduced XML
+            Infoset</b></a>.</p>
+          </dd>
+
+          <dt class="label">Related Media Object</dt>
+
+          <dd>
+            <p>A (possibly null) media object associated with or otherwise related to a
+            <em>Document Instance</em>. For example, an aggregate audio/video media
+            object for which a <em>Document Instance</em> provides caption or subtitle
+            information, and with which that <em>Document Instance</em> is
+            associated.</p>
+          </dd>
+
+          <dt class="label">Related Media Object Region</dt>
+
+          <dd>
+            <p>When a non-null <em>Related Media Object</em> exists, the region in which
+            a presentation processor presents this media object.</p>
+          </dd>
+
+          <dt class="label">Root Container Region</dt>
+
+          <dd>
+            <p>A logical region that establishes a coordinate system into which
+            <em>Document Instance</em> content regions are placed and optionally
+            clipped.</p>
+          </dd>
+
+          <dt class="label">Root Temporal Extent</dt>
+
+          <dd>
+            <p>The temporal extent (interval) defined by the temporal beginning and
+            ending of a <em>Document Instance</em> in relationship with some external
+            application or presentation context.</p>
+          </dd>
+
+          <dt class="label">SMPTE Time Code</dt>
+
+          <dd>
+            <p>A time code whose format and semantics are established by <a href=
+            "#smpte12m">[SMPTE 12M]</a>, which may be embedded into or otherwise
+            associated with media content, such as a broadcast audio/video stream.</p>
+          </dd>
+
+          <dt class="label">Synthetic Document Syncbase</dt>
+
+          <dd>
+            <p>A document level <a href=
+            "http://www.w3.org/TR/2005/REC-SMIL2-20051213/smil-timing.html#Timing-Syncbases">
+            syncbase</a> <a href="#smil21">[SMIL 2.1]</a>, § 10.7.1, synthesized or
+            otherwise established by the <em>Document Processing Context</em> in
+            accordance with the <em>Related Media Object</em> or other processing
+            criteria.</p>
+          </dd>
+
+          <dt class="label">Synthetic SMPTE Document Syncbase</dt>
+
+          <dd>
+            <p>A <em>Synthetic Document Syncbase</em> constructed from <em>SMPTE Time
+            Code</em> values embedded in or associated with the <em>Related Media
+            Object</em> or otherwise determined by the <em>Document Processing
+            Context</em>.</p>
+          </dd>
+
+          <dt class="label">Timed Text</dt>
+
+          <dd>
+            <p>Textual information that is intrinsically or extrinsically associated with
+            timing information.</p>
+          </dd>
+
+          <dt class="label">Timed Text Markup Language</dt>
+
+          <dd>
+            <p>A content type that represents timed text media for the purpose of
+            interchange among authoring systems.</p>
+          </dd>
+
+          <dt class="label">Timed Text Authoring System</dt>
+
+          <dd>
+            <p>A content authoring system capable of importing and exporting Timed Text
+            Markup Language content.</p>
+          </dd>
+
+          <dt class="label">Transformation Processor</dt>
+
+          <dd>
+            <p>A <em>Content Processor</em> which purpose is to transform or otherwise
+            rewrite <em>Timed Text Markup Language</em> content to either <em>Timed Text
+            Markup Language</em> or to another (arbitrary) content format. An example of
+            the first is a processor that removes or rewrites TTML features so as to
+            conform to a profile of TTML. An example of the latter is a processor that
+            translates TTML into a completely different timed text format. Because this
+            specification does not otherwise define a target profile or format for
+            transformation processing, no further transformation semantics are defined by
+            this specification.</p>
+          </dd>
+
+          <dt class="label">Valid Abstract Document Instance</dt>
+
+          <dd>
+            <p>An <em>Abstract Document Instance</em> which has been assessed for
+            validity and found to be valid as defined by <a href="#doctypes"><b>4
+            Document Types</b></a>.</p>
+          </dd>
+        </dl>
+      </div>
+
+      <div class="div2">
+        <h3><a id="conventions" name="conventions"></a>2.3 Documentation Conventions</h3>
+
+        <p>Within normative prose in this specification, the words <em>may</em>,
+        <em>should</em>, and <em>must</em> are defined as follows:</p>
+
+        <dl class="conformance-keywords">
+          <dt class="label">may</dt>
+
+          <dd>
+            <p>Conforming documents and/or TTML processors are permitted to, but need not
+            behave as described.</p>
+          </dd>
+
+          <dt class="label">should</dt>
+
+          <dd>
+            <p>Conforming documents and/or TTML processors are strongly recommended to,
+            but need not behave as described.</p>
+          </dd>
+
+          <dt class="label">must</dt>
+
+          <dd>
+            <p>Conforming documents and/or TTML processors are required to behave as
+            described; otherwise, they are in error.</p>
+          </dd>
+        </dl>
+
+        <p>If normative specification language takes an imperative form, then it is to be
+        treated as if the term <span class="strong">must</span> applies. Furthermore, if
+        normative language takes a declarative form, and this language is governed by
+        <span class="strong">must</span>, then it is also to be treated as if the term
+        <span class="strong">must</span> applies.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>For example, the phrases "treat X as an error" and "consider X as an error"
+          are to be read as mandatory requirements in the context of use. Similarly, if
+          the specification prose is "X must apply", "X applies", or "X is mandatory",
+          and "X" is further defined as "X is Y and Z", then, by transitive closure, this
+          last declarative phrase is to be read as "Y is mandatory" and "Z is mandatory"
+          in the context of use.</p>
+        </div>
+
+        <p>All normative syntactic definitions of XML representations and other related
+        terms are depicted with a light yellow-orange background color and labeled as
+        "XML Representation" or "Syntax Representation", such as in the
+        following:</p><a id="elt-syntax-example" name="elt-syntax-example"></a>
+
+        <table class="syntax">
+          <caption>
+            XML Representation – Element Information Item: example
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;example
+  <span class="reqattr">count</span> = integer
+  size = (<em>large</em>|<em>medium</em>|<em>small</em>) : medium&gt;
+  <em>Content:</em> (all | any*)
+&lt;/example&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>In an XML representation, bold-face attribute names (e.g. <span class=
+        "strong">count</span> above) indicate a required attribute information item, and
+        the rest are optional. Where an attribute information item has an enumerated type
+        definition, the values are shown separated by vertical bars, as for
+        <code>size</code> above; if there is a default value, it is shown following a
+        colon. Where an attribute information item has a built-in simple type definition
+        defined in <a href="#xsd-2">[XML Schema Part 2]</a>, a hyperlink to its
+        definition therein is given.</p>
+
+        <p>The allowed content of the information item is shown as a grammar fragment,
+        using the Kleene operators <code>?</code>, <code>*</code> and <code>+</code>.
+        Each element name therein is a hyperlink to its own illustration.</p>
+
+        <p>The term linear white-space (LWSP) is to be interpreted as a non-empty
+        sequence of SPACE (U+0020), TAB (U+0009), CARRIAGE RETURN (U+000D), or LINE FEED
+        (U+000A), which corresponds to production [3] <code>S</code> as defined by
+        <a href="#xml10">[XML 1.0]</a>.</p>
+
+        <p>All content of this specification that is not explicitly marked as
+        non-normative is considered to be normative. If a section or appendix header
+        contains the expression "Non-Normative", then the entirety of the section or
+        appendix is considered non-normative.</p>
+
+        <p>All paragraphs marked as a <span class="strong">Note</span> are considered
+        non-normative.</p>
+
+        <p>Example code fragments are depicted with a light blue-green background color
+        and labeled as "Example Fragment", such as in the following:</p><a id=
+        "example-fragment-1" name="example-fragment-1"></a>
+
+        <table class="example">
+          <caption>
+            Example Fragment – Sample
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
+  &lt;head&gt;
+    &lt;metadata/&gt;
+    &lt;styling/&gt;
+    &lt;layout/&gt;
+  &lt;/head&gt;
+  &lt;body/&gt;
+&lt;/tt&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="conformance" name="conformance"></a>3 Conformance</h2>
+
+      <p>This section specifies the general conformance requirements for TTML Content and
+      processors.</p>
+
+      <div class="div2">
+        <h3><a id="conformance-content" name="conformance-content"></a>3.1 Content
+        Conformance</h3>
+
+        <p>A TTML <em>Document Instance</em> conforms to this specification if the
+        following criteria are satisfied:</p>
+
+        <ol class="enumar">
+          <li>
+            <p>When transporting a <em>Document Instance</em> in a <em>Document
+            Interchange Context</em> in which a Media Type <a href="#media-types">[Media
+            Types]</a> identifies the content type of the interchanged <em>Document
+            Instance</em>, then the specified media type is
+            <code>application/ttml+xml</code> in conformance with <a href=
+            "#xml-media">[XML Media Types]</a> § 7, with which an optional
+            <code>profile</code> parameter may appear, the value of which conforms to a
+            profile designator as defined by <a href="#vocabulary-profiles"><b>5.2
+            Profiles</b></a>.</p>
+          </li>
+
+          <li>
+            <p>The <em>Document Instance</em> is or can be represented as a Reduced XML
+            Infoset as defined by <a href="#reduced-infoset"><b>A Reduced XML
+            Infoset</b></a>.</p>
+          </li>
+
+          <li>
+            <p>The Reduced XML Infoset that corresponds to the <em>Document Instance</em>
+            is or can be associated with one of the <em>Abstract Document Types</em>
+            defined by <a href="#doctypes"><b>4 Document Types</b></a>.</p>
+          </li>
+
+          <li>
+            <p>The <em>Reduced XML Infoset</em> that corresponds to the <em>Document
+            Instance</em> is a <em>Valid Abstract Document Instance</em> of the
+            associated <em>Abstract Document Type</em>.</p>
+          </li>
+
+          <li>
+            <p>The <em>Reduced XML Infoset</em> satisfies all additional mandatory
+            syntactic and semantic constraints defined by this specification. In
+            addition, this Infoset should satisfy the web content accessibility
+            guidelines specified by <a href="#wcag">[WCAG]</a>.</p>
+          </li>
+        </ol>
+      </div>
+
+      <div class="div2">
+        <h3><a id="conformance-processor" name="conformance-processor"></a>3.2 Processor
+        Conformance</h3>
+
+        <div class="div3">
+          <h4><a id="conformance-generic-processor" name=
+          "conformance-generic-processor"></a>3.2.1 Generic Processor Conformance</h4>
+
+          <p>A TTML <em>Content Processor</em> conforms to this specification if the
+          following generic processor criteria are satisfied:</p>
+
+          <ol class="enumar">
+            <li>
+              <p>The processor provides at least one mechanism for notionally
+              instantiating a Reduced XML Infoset representation of a conformant
+              <em>Document Instance</em>.</p>
+            </li>
+
+            <li>
+              <p>If a process does or can perform validation of a candidate <em>Document
+              Instance</em>, then it provides at least one mechanism to implicitly or
+              explicitly associate the <em>Reduced XML Infoset</em> representation of a
+              conformant <em>Document Instance</em> with one of the <em>Abstract Document
+              Types</em> defined by <a href="#doctypes"><b>4 Document Types</b></a>.</p>
+            </li>
+
+            <li>
+              <p>The processor does not <em>a priori</em> reject or abort the processing
+              of a conformant <em>Document Instance</em> unless the processor does not
+              support some required (mandatory) feature specified or implied by a TTML
+              Content profile declared to apply to the <em>Document Instance</em>.</p>
+            </li>
+
+            <li>
+              <p>The processor supports all mandatory processing semantics defined by
+              this specification.</p>
+
+              <div class="note">
+                <p class="prefix"><b>Note:</b></p>
+
+                <p>The phrase <em>mandatory semantics</em> refers to all explicit use of
+                the conformance key phrases <span class="strong">must</span> and
+                <span class="strong">must not</span> as well as any declarative statement
+                that can be reasonably inferred from such key phrases. For example, these
+                mandatory semantics include support for all features marked as mandatory
+                in <a href="#feature-support"><b>D.2 Feature Support</b></a>.</p>
+              </div>
+            </li>
+
+            <li>
+              <p>If the processor supports some optional processing semantics defined by
+              this specification, then it does so in a manner consistent with the defined
+              semantics.</p>
+
+              <div class="note">
+                <p class="prefix"><b>Note:</b></p>
+
+                <p>The phrase <em>optional semantics</em> refers to all explicit use of
+                the conformance key phrases <span class="strong">should</span>,
+                <span class="strong">should not</span>, <span class="strong">may</span>,
+                and <span class="strong">may not</span>, as well as any declarative
+                statement that can be reasonably inferred from such key phrases. For
+                example, these optional semantics include support for all features marked
+                as optional in <a href="#feature-support"><b>D.2 Feature
+                Support</b></a>.</p>
+              </div>
+            </li>
+          </ol>
+        </div>
+
+        <div class="div3">
+          <h4><a id="conformance-transformation-processor" name=
+          "conformance-transformation-processor"></a>3.2.2 Transformation Processor
+          Conformance</h4>
+
+          <p>A TTML <em>Content Processor</em> is a conformant TTML <em>Transformation
+          Processor</em> if the following criteria are satisfied:</p>
+
+          <ol class="enumar">
+            <li>
+              <p>The processor satisfies all requirements specified by <a href=
+              "#conformance-generic-processor"><b>3.2.1 Generic Processor
+              Conformance</b></a>.</p>
+            </li>
+
+            <li>
+              <p>The processor supports the DFXP Transformation profile as specified by
+              <a href="#profile-dfxp-transformation"><b>F.1 DFXP Transformation
+              Profile</b></a>.</p>
+            </li>
+          </ol>
+        </div>
+
+        <div class="div3">
+          <h4><a id="conformance-presentation-processor" name=
+          "conformance-presentation-processor"></a>3.2.3 Presentation Processor
+          Conformance</h4>
+
+          <p>A TTML <em>Content Processor</em> is a conformant TTML <em>Presentation
+          Processor</em> if the following criteria are satisfied:</p>
+
+          <ol class="enumar">
+            <li>
+              <p>The processor satisfies all requirements specified by <a href=
+              "#conformance-generic-processor"><b>3.2.1 Generic Processor
+              Conformance</b></a>.</p>
+            </li>
+
+            <li>
+              <p>The processor supports the DFXP Presentation profile as specified by
+              <a href="#profile-dfxp-presentation"><b>F.2 DFXP Presentation
+              Profile</b></a>.</p>
+            </li>
+          </ol>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="claims" name="claims"></a>3.3 Claims</h3>
+
+        <p>Any claim of compliance with respect to the conformance of a TTML <em>Document
+        Instance</em> or <em>Content Processor</em> must make reference to an
+        implementation compliance statement (ICS).</p>
+
+        <p>An implementation compliance statement must identify all mandatory and
+        optional features of this specification that are satisfied by the document
+        instance or the content processor implementation. In particular, the statement
+        must identify the utilized or supported TTML vocabulary profile(s) as defined by
+        <a href="#vocabulary-profiles"><b>5.2 Profiles</b></a>, and, if a subset or
+        superset profile is used or supported, then what features are excluded or
+        included in the subset or superset profile.</p>
+
+        <p>A <em>Document Instance</em> for which a compliance claim is made must specify
+        either (1) a <code>ttp:profile</code> attribute on its root <code>tt</code>
+        element as defined by <a href="#parameter-attribute-profile"><b>6.2.8
+        ttp:profile</b></a> or (2) a <code>ttp:profile</code> element as a child of the
+        <code>head</code> element as defined by <a href=
+        "#parameter-vocabulary-profile"><b>6.1.1 ttp:profile</b></a>.</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="doctypes" name="doctypes"></a>4 Document Types</h2>
+
+      <p>This section defines the following TTML <em>Abstract Document Types</em>:</p>
+
+      <ul>
+        <li>
+          <p><a href="#ttml-content-doctype"><b>4.1 TTML Content</b></a></p>
+        </li>
+      </ul>
+
+      <p>Each <em>Abstract Document Type</em> consists of the following constraints:</p>
+
+      <ul>
+        <li>
+          <p>a non-empty collection of element types, where each element type consists of
+          a name, a (possibly empty) collection of attributes, and a content
+          specification</p>
+        </li>
+
+        <li>
+          <p>a non-empty collection of element types that may appear as the document
+          element</p>
+        </li>
+      </ul>
+
+      <p>An <em>Abstract Document Instance</em> may be assessed in terms of validity, and
+      is considered to be a <em>Valid Abstract Document Instance</em> if it satisfies the
+      following condition: if after</p>
+
+      <ol class="enumar">
+        <li>
+          <p>pruning all element information items whose names are not members of the
+          collection of element types defined by the associated <em>Abstract Document
+          Type</em>, then</p>
+        </li>
+
+        <li>
+          <p>pruning character information item children from any remaining element in
+          case that all character children of the element denote XML whitespace
+          characters and the element's type is defined as empty in the associated
+          <em>Abstract Document Type</em>, and then</p>
+        </li>
+
+        <li>
+          <p>pruning all attribute information items having expanded names such that the
+          namespace URI of the expanded names are not listed in <a href=
+          "#namespace-vocab-table"><b>Table 1 – Namespaces</b></a>,</p>
+        </li>
+      </ol>
+
+      <p>then the document element is one of the document element types permitted by the
+      associated <em>Abstract Document Type</em>, the descendants of the document element
+      satisfy their respective element type's content specifications, all required
+      attributes are present, and the declared value of each attribute satisfies the type
+      declared by the associated <em>Abstract Document Type</em>.</p>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>While a conformant processor may not <em>a priori</em> reject a conformant
+        <em>Document Instance</em> that adheres to a supported content profile, a given
+        <em>Document Instance</em> may be constrained by the author or authoring tool to
+        satisfy a more restrictive definition of validity.</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="ttml-content-doctype" name="ttml-content-doctype"></a>4.1 TTML
+        Content</h3>
+
+        <p>TTML Content is an <em>Abstract Document Type</em> of a profile of the Timed
+        Text Markup Language intended to be used for interchange among distribution
+        systems. This document type is defined in terms of the element and attribute
+        vocabulary specified in <a href="#vocabulary"><b>5 Vocabulary</b></a>.</p>
+
+        <p>This specification references two types of schemas that may be used to
+        validate a superset/subset of conformant TTML Content <em>Document
+        Instances</em>:</p>
+
+        <ul>
+          <li>
+            <p><a href="#ttml-schema-rnc"><b>B.1 Relax NG Compact (RNC)
+            Schema</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#ttml-schema-xsd"><b>B.2 XML Schema Definition (XSD)
+            Schema</b></a></p>
+          </li>
+        </ul>
+
+        <p>The (root) document element of a TTML Content <em>Document Instance</em> must
+        be a <code>tt</code> element, as defined by <a href=
+        "#document-structure-vocabulary-tt"><b>7.1.1 tt</b></a>.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>The schemas referenced by this specification do not validate all syntactic
+          constraints defined by this specification, and, as such, represent a superset
+          of conformant TTML Content. In particular, performing validation with one of
+          the above referenced schemas may result in a <em>false positive</em> indication
+          of validity. For example, both the RNC and XSD schemas specify that a
+          <code>tts:fontFamily</code> attribute must satisfy the <code>xs:string</code>
+          XSD data type; however, this data type is a superset of the values permitted to
+          be used with the <code>tts:fontFamily</code> attribute.</p>
+
+          <p>In addition, the RNC schema may produce a <em>false negative</em> indication
+          of validity when using the <code>xml:id</code> attribute with an element in a
+          foreign namespace, thus representing a subset of conformant TTML Content. This
+          is due to a specific limitation in expressing wildcard patterns involving
+          <code>xsd:ID</code> typed attributes in Relax NG schemas. Note that this
+          specification defines the formal validity of a <em>Document Instance</em> to be
+          based on an <em>Abstract Document Instance</em> from which all foreign
+          namespace elements and attributes have been removed. Therefore, the exceptional
+          reporting of this false negative does not impact the formal assessment of
+          <em>Document Instance</em> validity.</p>
+        </div>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="vocabulary" name="vocabulary"></a>5 Vocabulary</h2>
+
+      <p>This section defines the namespaces, profiles, and vocabulary (as an element and
+      attribute catalog) of the Timed Text Markup Language (TTML) as follows:</p>
+
+      <ul>
+        <li>
+          <p><a href="#vocabulary-namespaces"><b>5.1 Namespaces</b></a></p>
+        </li>
+
+        <li>
+          <p><a href="#vocabulary-profiles"><b>5.2 Profiles</b></a></p>
+        </li>
+
+        <li>
+          <p><a href="#vocabulary-overview"><b>5.3 Catalog</b></a></p>
+        </li>
+      </ul>
+
+      <div class="div2">
+        <h3><a id="vocabulary-namespaces" name="vocabulary-namespaces"></a>5.1
+        Namespaces</h3>
+
+        <p>The Timed Text Markup Language (TTML) employs a number of XML Namespaces
+        <a href="#xmlns10">[XML Namespaces 1.0]</a> for elements and certain global
+        attributes. The following table specifies this set of namespaces and indicates
+        the default prefix used within this specification and the normative URI that
+        denotes each namespace.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>In a specific <em>Document Instance</em>, it is not required that the
+          default prefixes shown below are used. Any prefix or namespace binding that
+          satisfies the constraints of XML Namespaces <a href="#xmlns10">[XML Namespaces
+          1.0]</a> may be used that is associated with the specified namespace URI.</p>
+        </div><a id="namespace-vocab-table" name="namespace-vocab-table"></a>
+
+        <table class="common">
+          <caption>
+            Table 1 – Namespaces
+          </caption>
+          <col width="30%" span="1">
+          <col span="1">
+          <col span="1">
+
+          <tbody>
+            <tr>
+              <th>Name</th>
+
+              <th>Prefix</th>
+
+              <th>Value</th>
+            </tr>
+
+            <tr>
+              <td>TT</td>
+
+              <td><code>tt:</code></td>
+
+              <td><code>http://www.w3.org/ns/ttml</code></td>
+            </tr>
+
+            <tr>
+              <td>TT Parameter</td>
+
+              <td><code>ttp:</code></td>
+
+              <td><code>http://www.w3.org/ns/ttml#parameter</code></td>
+            </tr>
+
+            <tr>
+              <td>TT Style</td>
+
+              <td><code>tts:</code></td>
+
+              <td><code>http://www.w3.org/ns/ttml#styling</code></td>
+            </tr>
+
+            <tr>
+              <td>TT Metadata</td>
+
+              <td><code>ttm:</code></td>
+
+              <td><code>http://www.w3.org/ns/ttml#metadata</code></td>
+            </tr>
+
+            <tr>
+              <td>TT Profile</td>
+
+              <td><em>none</em></td>
+
+              <td><code>http://www.w3.org/ns/ttml/profile/</code></td>
+            </tr>
+
+            <tr>
+              <td>TT Feature</td>
+
+              <td><em>none</em></td>
+
+              <td><code>http://www.w3.org/ns/ttml/feature/</code></td>
+            </tr>
+
+            <tr>
+              <td>TT Extension</td>
+
+              <td><em>none</em></td>
+
+              <td><code>http://www.w3.org/ns/ttml/extension/</code></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>If a reference to an element type is used in this specification and the name
+          of the element type is not namespace qualified, then the TT Namespace
+          applies.</p>
+
+          <p>For certain namespaces defined above, the default prefix is specified as
+          <em>none</em> if no XML vocabulary is defined in the namespace by this
+          specification (nor expected to be defined in a future version of this
+          specification). In such cases, the use of the namespace URI is for purposes
+          other than defining XML vocabulary, e.g., for designating profiles, features,
+          extensions and for dereferencing standard profile definitions.</p>
+        </div>
+
+        <p>All TTML Namespaces are <a href=
+        "http://www.w3.org/2001/tag/doc/namespaceState#namespacedef"><em>mutable</em></a>
+        <a href="#nsstate">[NSState]</a>; all undefined names in these namespaces are
+        reserved for future standardization by the W3C.</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="vocabulary-profiles" name="vocabulary-profiles"></a>5.2 Profiles</h3>
+
+        <p>The Timed Text Markup Language (TTML) employs a number of standard, predefined
+        profiles of its vocabulary and associated semantics. The following table
+        specifies this set of profiles, indicating a normative name and designator for
+        each predefined profile, and where each of these profiles is formally elaborated
+        in <a href="#profiles"><b>F Profiles</b></a> or in another TTWG
+        specification.</p><a id="profile-vocab-table" name="profile-vocab-table"></a>
+
+        <table class="common">
+          <caption>
+            Table 2 – Profiles
+          </caption>
+          <col width="25%" span="1">
+          <col span="1">
+
+          <tbody>
+            <tr>
+              <th>Name</th>
+
+              <th>Designator</th>
+            </tr>
+
+            <tr>
+              <td>DFXP Transformation</td>
+
+              <td><code>http://www.w3.org/ns/ttml/profile/dfxp-transformation</code></td>
+            </tr>
+
+            <tr>
+              <td>DFXP Presentation</td>
+
+              <td><code>http://www.w3.org/ns/ttml/profile/dfxp-presentation</code></td>
+            </tr>
+
+            <tr>
+              <td>DFXP Full</td>
+
+              <td><code>http://www.w3.org/ns/ttml/profile/dfxp-full</code></td>
+            </tr>
+
+            <tr>
+              <td>SDP US</td>
+
+              <td><code>http://www.w3.org/ns/ttml/profile/sdp-us</code></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p></p>
+
+        <p>A profile designator must adhere to the <code>xsd:anyURI</code> data type
+        defined by <a href="#xsd-2">[XML Schema Part 2]</a>, §3.2.17. If the profile
+        designator is expressed as a relative URI, then it must be absolutized by using
+        the TT Profile Namespace value as the base URI.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>For example, if a profile designator is expressed as
+          <code>dfxp-presentation</code>, then the absolutized profile designator would
+          be <code>http://www.w3.org/ns/ttml/profile/dfxp-presentation</code>.</p>
+        </div>
+
+        <p>All profile designators which have the TT Profile Namespace as a prefix but
+        are otherwise not listed in <a href="#profile-vocab-table"><b>Table 2 –
+        Profiles</b></a> are reserved for future standardization, and must not be appear
+        in a conformant <em>Document Instance</em>. Nothwithstanding this constraint, a
+        profile designator is not restricted to the set of designators enumerated in
+        <a href="#profile-vocab-table"><b>Table 2 – Profiles</b></a>, but may be any URI
+        that feasibly dereferences a TTML <em>Profile Definition Document</em> provided
+        it does not use the TT Profile Namespace as a prefix.</p>
+
+        <p>The profile of TTML that must be supported by a TTML <em>Content
+        Processor</em> in order to process a <em>Document Instance</em> is determined
+        either (1) by specifying a <code>ttp:profile</code> attribute on the root
+        <code>tt</code> element, as defined by <a href=
+        "#parameter-attribute-profile"><b>6.2.8 ttp:profile</b></a>, or (2) by including
+        one or more <code>ttp:profile</code> elements in the <code>head</code> element,
+        in accordance with <a href="#parameter-vocabulary-profile"><b>6.1.1
+        ttp:profile</b></a>.</p>
+
+        <p>If a <code>ttp:profile</code> element appears as a descendant of the
+        <code>tt</code> element, then the <a href=
+        "#parameter-attribute-profile"><code>ttp:profile</code></a> attribute should not
+        be specified on the <code>tt</code> element. If both a <code>ttp:profile</code>
+        element and a <code>ttp:profile</code> attribute are present (in a given
+        <em>Document Instance</em>), then the <code>ttp:profile</code> attribute must be
+        ignored for the purpose of determining the declared profile requirements.</p>
+
+        <p>If more than one <code>ttp:profile</code> element appears in a <em>Document
+        Instance</em>, then all specified profiles apply simultaneously. In such a case,
+        if some feature or some extension is specified by one profile to be used
+        (mandatory and enabled) and by another profile to be required (mandatory) or
+        optional (voluntary), then that feature or extension must be considered to be
+        used (mandatory and enabled); if some feature or some extension is specified by
+        one profile to be merely required (mandatory) and by another profile to be
+        optional (voluntary), then that feature or extension must be considered to be
+        required (mandatory).</p>
+
+        <p>If neither <a href="#parameter-attribute-profile"><code>ttp:profile</code></a>
+        attribute nor <a href=
+        "#parameter-vocabulary-profile"><code>ttp:profile</code></a> element is present
+        in a <em>Document Instance</em>, and if the <em>Document Interchange Context</em>
+        does not make an implicit or explicit reference to a pre-defined Content Profile
+        or does not specify a <em>Profile Definition Document</em> or another equivalent
+        set of feature designations, then the DFXP Transformation profile applies.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>It is not a requirement on a conformant <em>Document Instance</em> that a
+          <em>Content Profile</em> be internally defined by use of a
+          <code>ttp:profile</code> element or internally referenced by a
+          <code>ttp:profile</code> attribute. More specifically, it is permitted that the
+          <em>Document Interchange Context</em> determines the applicable <em>Content
+          Profile</em> through private agreement, out-of-band protocol, or common use
+          (between sender and receiver) of a profile defined by an external
+          specification.</p>
+        </div>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>It is intended that the <code>ttp:profile</code> attribute be used when the
+          author wishes to reference one of the standard, predefined profiles of TTML
+          Content, and does not wish to modify (by supersetting or subsetting) that
+          profile. This attribute may also be used by an author to indicate the use of a
+          non-standard profile, in which case the specified profile designator expresses
+          a URI that denotes an externally defined <em>Profile Definition Document</em>.
+          However, it is not required that a conformant TTML Content processor be able to
+          dereference such an externally specified profile definition.</p>
+
+          <p>In contrast, it is intended that the <code>ttp:profile</code> element be
+          used when the author wishes to make use of a modified predefined profile or
+          wishes to include in the <em>Document Instance</em> a non-standard profile
+          definition not based upon one of the predefined profiles.</p>
+
+          <p>A predefined profile is supersetted by specifying some feature or extension
+          to be required (mandatory) that was either not specified in the underlying,
+          baseline profile or was specified as optional (voluntary) in the baseline
+          profile. A predefined profile is subsetted by specifying some feature or
+          extension to be optional (voluntary) that was specified as required in the
+          underlying, baseline profile.</p>
+
+          <p>When a baseline profile is modified by subsetting, the resulting, derived
+          profile is referred to as a <em>subtractive</em> profile; when modified by
+          supersetting, the result is referred to as an <em>additive</em> profile. It is
+          also possible to define a derived profile that is simultaneously subtractive
+          and additive.</p>
+        </div>
+
+        <p>If a <em>Document Instance</em> makes use of a feature defined by <a href=
+        "#feature-designations"><b>D.1 Feature Designations</b></a> and if the intended
+        use of the document requires the recognition and processing of that feature, then
+        the document must include a <em>required feature</em> or a <em>used feature</em>
+        specification in one of its declared or referenced profiles. If a <em>Document
+        Instance</em> makes use of an extension designatable by <a href=
+        "#extension-designations"><b>E.1 Extension Designations</b></a> and if the
+        intended use of the document requires the recognition and processing of that
+        extension, then the document must include a <em>required extension</em> or a
+        <em>used extension</em> specification in one of its declared or referenced
+        profiles.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>A required or used feature specification is expressed directly (or
+          indirectly by referring to a profile) by means of a <a href=
+          "#parameter-vocabulary-feature"><code>ttp:feature</code></a> element where the
+          value of its <code>value</code> attribute is <code>required</code> or
+          <code>use</code>, respectively. A required or used extension specification is
+          expressed directly (or indirectly by referring to a profile) by means of a
+          <a href="#parameter-vocabulary-extension"><code>ttp:extension</code></a>
+          element where the value of its <code>value</code> attribute is
+          <code>required</code> or <code>use</code>, respectively.</p>
+        </div>
+
+        <p>An example of an author defined additive, derived profile of the DFXP
+        Presentation profile is shown below in <a href=
+        "#ttml-example-sub-profile"><b>Example Fragment – DFXP Additive
+        Profile</b></a>.</p><a id="ttml-example-sub-profile" name=
+        "ttml-example-sub-profile"></a>
+
+        <table class="example">
+          <caption>
+            Example Fragment – DFXP Additive Profile
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
+ &lt;head&gt;
+   &lt;profile use="dfxp-presentation" xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
+     &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
+       &lt;feature value="required"&gt;#fontStyle-italic&lt;/feature&gt;
+     &lt;/features&gt;
+   &lt;/profile&gt;
+ &lt;/head&gt;
+ &lt;body/&gt;
+&lt;/tt&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>In the above example, the baseline profile is declared to be the DFXP
+          Presentation profile, which is then additively modified by making the
+          <code>#fontStyle-italic</code> feature required (rather than optional as it is
+          defined in <a href="#profile-dfxp-presentation"><b>F.2 DFXP Presentation
+          Profile</b></a>). Note also the resetting of the default XMLNS binding on the
+          <code>profile</code> element to the TT Parameter Namespace.</p>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="vocabulary-overview" name="vocabulary-overview"></a>5.3 Catalog</h3>
+
+        <p>The vocabulary of the Timed Text Markup Language (TTML) is defined in the
+        following major catalogs (divisions of vocabulary):</p>
+
+        <ul>
+          <li>
+            <p><a href="#core-vocabulary-overview"><b>5.3.1 Core Catalog</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#extension-vocabulary-overview"><b>5.3.2 Extension
+            Catalog</b></a></p>
+          </li>
+        </ul>
+
+        <p>The core catalog defines the baseline, core vocabulary of TTML, and, in
+        particular, the vocabulary of TTML Content. The extension catalog serves as a
+        placeholder for extensions to the core vocabulary defined by TTML.</p>
+
+        <div class="div3">
+          <h4><a id="core-vocabulary-overview" name="core-vocabulary-overview"></a>5.3.1
+          Core Catalog</h4>
+
+          <p>The core vocabulary catalog is intended to satisfy the needs of TTML while
+          providing a baseline vocabulary for future profiles. This vocabulary is divided
+          into distinct categories, specified in detail in the following sections:</p>
+
+          <ul>
+            <li>
+              <p><a href="#parameters"><b>6 Parameters</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content"><b>7 Content</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#styling"><b>8 Styling</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#layout"><b>9 Layout</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#timing"><b>10 Timing</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#animation"><b>11 Animation</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata"><b>12 Metadata</b></a></p>
+            </li>
+          </ul>
+
+          <p>The core element vocabulary specified for use with a <em>Document
+          Instance</em> is enumerated in <a href="#element-vocab-table"><b>Table 3 –
+          Element Vocabulary</b></a>.</p><a id="element-vocab-table" name=
+          "element-vocab-table"></a>
+
+          <table class="common">
+            <caption>
+              Table 3 – Element Vocabulary
+            </caption>
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <th>Module</th>
+
+                <th>Elements</th>
+              </tr>
+
+              <tr>
+                <td>Animation</td>
+
+                <td><a href="#animation-vocabulary-set">set</a></td>
+              </tr>
+
+              <tr>
+                <td>Content</td>
+
+                <td><a href="#document-structure-vocabulary-body">body</a>, <a href=
+                "#content-vocabulary-div">div</a>, <a href="#content-vocabulary-p">p</a>,
+                <a href="#content-vocabulary-span">span</a>, <a href=
+                "#content-vocabulary-br">br</a></td>
+              </tr>
+
+              <tr>
+                <td>Document</td>
+
+                <td><a href="#document-structure-vocabulary-tt">tt</a></td>
+              </tr>
+
+              <tr>
+                <td>Head</td>
+
+                <td><a href="#document-structure-vocabulary-head">head</a></td>
+              </tr>
+
+              <tr>
+                <td>Layout</td>
+
+                <td><a href="#layout-vocabulary-layout">layout</a>, <a href=
+                "#layout-vocabulary-region">region</a></td>
+              </tr>
+
+              <tr>
+                <td>Metadata</td>
+
+                <td><a href="#metadata-vocabulary-metadata">metadata</a></td>
+              </tr>
+
+              <tr>
+                <td>Metadata Items</td>
+
+                <td><a href="#metadata-vocabulary-actor">ttm:actor</a>, <a href=
+                "#metadata-vocabulary-agent">ttm:agent</a>, <a href=
+                "#metadata-vocabulary-copyright">ttm:copyright</a>, <a href=
+                "#metadata-vocabulary-desc">ttm:desc</a>, <a href=
+                "#metadata-vocabulary-name">ttm:name</a>, <a href=
+                "#metadata-vocabulary-title">ttm:title</a></td>
+              </tr>
+
+              <tr>
+                <td>Parameter Items</td>
+
+                <td><a href="#parameter-vocabulary-profile">ttp:profile</a>, <a href=
+                "#parameter-vocabulary-features">ttp:features</a>, <a href=
+                "#parameter-vocabulary-feature">ttp:feature</a>, <a href=
+                "#parameter-vocabulary-extensions">ttp:extensions</a>, <a href=
+                "#parameter-vocabulary-extension">ttp:extension</a></td>
+              </tr>
+
+              <tr>
+                <td>Styling</td>
+
+                <td><a href="#styling-vocabulary-styling">styling</a>, <a href=
+                "#styling-vocabulary-style">style</a></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p>
+
+          <p>Element vocabulary groups that are used in defining content models for TTML
+          element types are enumerated in <a href="#element-vocab-group-table"><b>Table 4
+          – Element Vocabulary Groups</b></a>.</p><a id="element-vocab-group-table" name=
+          "element-vocab-group-table"></a>
+
+          <table class="common">
+            <caption>
+              Table 4 – Element Vocabulary Groups
+            </caption>
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <th>Group</th>
+
+                <th>Elements</th>
+              </tr>
+
+              <tr>
+                <td>Animation.class</td>
+
+                <td><a href="#animation-vocabulary-set">set</a></td>
+              </tr>
+
+              <tr>
+                <td>Block.class</td>
+
+                <td><a href="#content-vocabulary-div">div</a> | <a href=
+                "#content-vocabulary-p">p</a></td>
+              </tr>
+
+              <tr>
+                <td>Inline.class</td>
+
+                <td><a href="#content-vocabulary-span">span</a> | <a href=
+                "#content-vocabulary-span">br</a> | <code>#PCDATA</code></td>
+              </tr>
+
+              <tr>
+                <td>Metadata.class</td>
+
+                <td><a href="#metadata-vocabulary-metadata">metadata</a> | <a href=
+                "#metadata-vocabulary-copyright">ttm:agent</a> | <a href=
+                "#metadata-vocabulary-copyright">ttm:copyright</a> | <a href=
+                "#metadata-vocabulary-desc">ttm:desc</a> | <a href=
+                "#metadata-vocabulary-title">ttm:title</a></td>
+              </tr>
+
+              <tr>
+                <td>Parameters.class</td>
+
+                <td><a href="#parameter-vocabulary-profile">ttp:profile</a></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p>
+
+          <p>The attribute vocabulary specified for use with the core vocabulary catalog
+          is enumerated in <a href="#attribute-vocab-table"><b>Table 5 – Attribute
+          Vocabulary</b></a>.</p><a id="attribute-vocab-table" name=
+          "attribute-vocab-table"></a>
+
+          <table class="common">
+            <caption>
+              Table 5 – Attribute Vocabulary
+            </caption>
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <th>Module</th>
+
+                <th>Attributes</th>
+              </tr>
+
+              <tr>
+                <td>Core Attributes</td>
+
+                <td><a href="#content-attribute-id">xml:id</a>, <a href=
+                "#content-attribute-lang">xml:lang</a>, <a href=
+                "#content-attribute-space">xml:space</a></td>
+              </tr>
+
+              <tr>
+                <td>Layout</td>
+
+                <td><a href="#layout-attribute-region">region</a></td>
+              </tr>
+
+              <tr>
+                <td>Metadata Attributes</td>
+
+                <td><a href="#metadata-attribute-agent">ttm:agent</a>, <a href=
+                "#metadata-attribute-role">ttm:role</a></td>
+              </tr>
+
+              <tr>
+                <td>Parameter Attributes</td>
+
+                <td><a href="#parameter-attribute-cellResolution">ttp:cellResolution</a>,
+                <a href="#parameter-attribute-clockMode">ttp:clockMode</a>, <a href=
+                "#parameter-attribute-dropMode">ttp:dropMode</a>, <a href=
+                "#parameter-attribute-frameRate">ttp:frameRate</a>, <a href=
+                "#parameter-attribute-frameRateMultiplier">ttp:frameRateMultipler</a>,
+                <a href="#parameter-attribute-markerMode">ttp:markerMode</a>, <a href=
+                "#parameter-attribute-pixelAspectRatio">ttp:pixelAspectRatio</a>,
+                <a href="#parameter-attribute-profile">ttp:profile</a>, <a href=
+                "#parameter-attribute-subFrameRate">ttp:subFrameRate</a>, <a href=
+                "#parameter-attribute-tickRate">ttp:tickRate</a>, <a href=
+                "#parameter-attribute-timeBase">ttp:timeBase</a></td>
+              </tr>
+
+              <tr>
+                <td>Styling</td>
+
+                <td><a href="#style-attribute-style">style</a></td>
+              </tr>
+
+              <tr>
+                <td>Styling Attributes</td>
+
+                <td><a href="#style-attribute-backgroundColor">tts:backgroundColor</a>,
+                <a href="#style-attribute-color">tts:color</a>, <a href=
+                "#style-attribute-direction">tts:direction</a>, <a href=
+                "#style-attribute-display">tts:display</a>, <a href=
+                "#style-attribute-displayAlign">tts:displayAlign</a>, <a href=
+                "#style-attribute-extent">tts:extent</a>, <a href=
+                "#style-attribute-fontFamily">tts:fontFamily</a>, <a href=
+                "#style-attribute-fontSize">tts:fontSize</a>, <a href=
+                "#style-attribute-fontStyle">tts:fontStyle</a>, <a href=
+                "#style-attribute-fontWeight">tts:fontWeight</a>, <a href=
+                "#style-attribute-lineHeight">tts:lineHeight</a>, <a href=
+                "#style-attribute-opacity">tts:opacity</a>, <a href=
+                "#style-attribute-origin">tts:origin</a>, <a href=
+                "#style-attribute-overflow">tts:overflow</a>, <a href=
+                "#style-attribute-padding">tts:padding</a>, <a href=
+                "#style-attribute-showBackground">tts:showBackground</a>, <a href=
+                "#style-attribute-textAlign">tts:textAlign</a>, <a href=
+                "#style-attribute-textDecoration">tts:textDecoration</a>, <a href=
+                "#style-attribute-textOutline">tts:textOutline</a>, <a href=
+                "#style-attribute-unicodeBidi">tts:unicodeBidi</a>, <a href=
+                "#style-attribute-visibility">tts:visibility</a>, <a href=
+                "#style-attribute-wrapOption">tts:wrapOption</a>, <a href=
+                "#style-attribute-writingMode">tts:writingMode</a>, <a href=
+                "#style-attribute-zIndex">tts:zIndex</a></td>
+              </tr>
+
+              <tr>
+                <td>Timing Attributes</td>
+
+                <td><a href="#timing-attribute-begin">begin</a>, <a href=
+                "#timing-attribute-dur">dur</a>, <a href="#timing-attribute-end">end</a>,
+                <a href="#timing-attribute-timeContainer">timeContainer</a></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Only those attributes defined as either (1) global, i.e., namespace
+            qualified, or (2) shared element-specific, i.e., not namespace qualified but
+            shared across multiple element types, are listed in <a href=
+            "#attribute-vocab-table"><b>Table 5 – Attribute Vocabulary</b></a> above.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>All vocabulary defined by TTML consistently makes use of the so-called
+            <em>lowerCamelCase</em> naming convention. In some cases, this results in the
+            change of a name when the name was based upon another specification that used
+            a different naming convention.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="extension-vocabulary-overview" name=
+          "extension-vocabulary-overview"></a>5.3.2 Extension Catalog</h4>
+
+          <p>The extension vocabulary catalog is intended for use by future profiles of
+          TTML, and is not further defined by this version of this specification.</p>
+
+          <p>In addition to standardized extension vocabulary, a conforming <em>Document
+          Instance</em> may contain arbitrary namespace qualified elements that reside in
+          any namespace other than those namespaces defined for use with this
+          specification. Furthermore, a conforming <em>Document Instance</em> may contain
+          arbitrary namespace qualified attributes on TTML defined vocabulary where such
+          attributes reside in any namespace other than those defined for use with this
+          specification.</p>
+        </div>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="parameters" name="parameters"></a>6 Parameters</h2>
+
+      <p>This section specifies the <em>parameters</em> matter of the core vocabulary
+      catalog, where parameters are to be understood as information that is either (1)
+      essential or (2) of significant importance for the purpose of interpreting the
+      semantics of other types of information expressed by core vocabulary items or for
+      establishing a <em>Document Processing Context</em> by means of which TTML Content
+      can be related to an external environment.</p>
+
+      <div class="div2">
+        <h3><a id="parameter-element-vocabulary" name=
+        "parameter-element-vocabulary"></a>6.1 Parameter Element Vocabulary</h3>
+
+        <p>The following elements, all defined in the TT Parameter Namespace, specify
+        parametric information that applies to a <em>Document Instance</em> or
+        <em>Content Processor</em>:</p>
+
+        <ul>
+          <li>
+            <p><a href="#parameter-vocabulary-profile"><b>6.1.1 ttp:profile</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-vocabulary-features"><b>6.1.2 ttp:features</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-vocabulary-feature"><b>6.1.3 ttp:feature</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-vocabulary-extensions"><b>6.1.4
+            ttp:extensions</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-vocabulary-extension"><b>6.1.5
+            ttp:extension</b></a></p>
+          </li>
+        </ul>
+
+        <div class="div3">
+          <h4><a id="parameter-vocabulary-profile" name=
+          "parameter-vocabulary-profile"></a>6.1.1 ttp:profile</h4>
+
+          <p>The <code>ttp:profile</code> element is used to specify a collection of used
+          (mandatory and enabled), required (mandatory), and optional (voluntary)
+          features and extensions that must or may be supported by a <em>Content
+          Processor</em> in order to process a <em>Document Instance</em> that makes (or
+          may make) use of such features and extensions.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The difference between a <em>feature</em> and an <em>extension</em> is
+            where it is defined and how it is labeled: if defined in this specification
+            (or a future revision thereof) and labeled with a feature designation in
+            <a href="#features"><b>D Features</b></a>, then it is considered to be a
+            feature; if defined in another specification and labeled there with an
+            extension designation, then it is considered to be an extension. In general,
+            features are expected to be defined by the W3C standards process, while
+            extensions are expected to be defined by third parties.</p>
+          </div>
+
+          <p>This specification defines two distinct uses of the <code>ttp:profile</code>
+          element:</p>
+
+          <ul>
+            <li>
+              <p>as a child of the <code>head</code> element within a TTML <em>Document
+              Instance</em>;</p>
+            </li>
+
+            <li>
+              <p>as the root element of a TTML <em>Profile Definition Document</em>
+              instance;</p>
+            </li>
+          </ul>
+
+          <p>When a <code>tt:profile</code> element appears within a TTML <em>Document
+          Instance</em>, its purpose is to express authorial intentions about which
+          features and extensions must or may be supported by a recipient content
+          processor. In addition, the element indirectly expresses information about the
+          set of features or extensions that are (or may expected to be) used by the
+          <em>Document Instance</em>.</p>
+
+          <p>When a <code>tt:profile</code> element is used by a TTML <em>Profile
+          Definition Document</em> instance, it serves to publish a machine readable
+          specification of a specific TTML Content profile, of which this specification
+          defines three such <em>Profile Definition Documents</em> in <a href=
+          "#profiles"><b>F Profiles</b></a>.</p>
+
+          <p>The <code>ttp:profile</code> element accepts as its children zero or more
+          elements in the <code>Metadata.class</code> element group, followed by zero or
+          more <code>ttp:features</code> elements, followed by zero or more
+          <code>ttp:extensions</code> elements.</p><a id="elt-syntax-parameter-profile"
+          name="elt-syntax-parameter-profile"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttp:profile
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttp:profile
+  use = string
+  <a href="#content-attribute-id">xml:id</a> = ID
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#parameter-vocabulary-features">ttp:features</a>*, <a href=
+"#parameter-vocabulary-extensions">ttp:extensions</a>*
+&lt;/ttp:profile&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If specified, the <code>use</code> attribute must adhere to the
+          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
+          2]</a>, §3.2.17, and, furthermore, must denote a profile designator in
+          accordance with <a href="#vocabulary-profiles"><b>5.2 Profiles</b></a>. In this
+          case, the profile designator must refer to (1) a standard, predefined
+          <em>Profile Definition Document</em> as defined by <a href="#profiles"><b>F
+          Profiles</b></a>, or (2) a feasibly dereferenceable resource representing a
+          valid <em>Profile Definition Document</em> instance. In either case, the
+          referenced profile serves as the baseline profile of the specifying
+          <code>ttp:profile</code> element.</p>
+
+          <p>If the <code>use</code> attribute is not specified, then the baseline
+          profile of the <code>ttp:profile</code> element must be considered to be the
+          empty (null) profile, i.e., a profile definition containing no feature or
+          extension specifications.</p>
+
+          <p>The collection of features and extensions of a profile are determined
+          according to the following ordered rules:</p>
+
+          <ol class="enumar">
+            <li>
+              <p>initialize the features and extensions of the profile to the empty
+              set;</p>
+            </li>
+
+            <li>
+              <p>if a <code>use</code> attribute is present, then augment the profile
+              with the set of features and extensions specified by the referenced
+              baseline profile;</p>
+            </li>
+
+            <li>
+              <p>for each <code>ttp:feature</code> and <code>ttp:extension</code> element
+              descendant of the <code>ttp:profile</code> element, using a post-order
+              traversal, merge the specified feature or extension with the features and
+              extensions of the profile, where merging a feature or extension entails
+              replacing an existing feature or extension specification, if it already
+              exists, or adding a new feature or extension specification, if it does not
+              yet exist in the profile;</p>
+            </li>
+          </ol>
+
+          <p>A conformant TTML processor is not required to be able to dereference a
+          <em>Profile Definition Document</em> that is not one of the standard,
+          predefined profiles defined by <a href="#profiles"><b>F Profiles</b></a>.
+          Furthermore, a conformant TTML processor may make use of a built-in, static
+          form of each standard, predefined profile so as not to require dereferencing a
+          network resource.</p>
+
+          <p>If a TTML processor is unable to dereference a non-standard <em>Profile
+          Definition Document</em>, then it must not further process the document without
+          the presence of an explicit override from an end-user or some implementation
+          specific parameter traceable to an end-user or to a user or system
+          configuration setting. If a TTML processor aborts processing of a <em>Document
+          Instance</em> due to the inability to reference a non-standard <em>Profile
+          Definition Document</em>, then some end-user notification should be given
+          unless the end-user or system has disabled such a notification, or if the
+          processor does not permit or entail the intervention of an end-user.</p>
+
+          <p>The <code>ttp:profile</code> element is illustrated by the following
+          example.</p><a id="parameter-vocabulary-profile-example-1" name=
+          "parameter-vocabulary-profile-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – ttp:profile
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttp:profile use="dfxp-presentation"&gt;
+  &lt;ttp:features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
+    &lt;ttp:feature&gt;#text-outline&lt;/ttp:feature&gt;
+  &lt;/ttp:features&gt;
+&lt;/ttp:profile&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, the DFXP presentation profile is used as the
+            baseline profile. This baseline profile is then supersetted (thus creating an
+            additive derived profile) by requiring support for <code>#text-outline</code>
+            feature.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-vocabulary-features" name=
+          "parameter-vocabulary-features"></a>6.1.2 ttp:features</h4>
+
+          <p>The <code>ttp:features</code> element is a container element used to group
+          infomation about feature support requirements.</p>
+
+          <p>The <code>ttp:features</code> element accepts as its children zero or more
+          elements in the <code>Metadata.class</code> element group, followed by zero or
+          more <code>ttp:feature</code> elements.</p><a id=
+          "elt-syntax-parameter-features" name="elt-syntax-parameter-features"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttp:features
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttp:features
+  xml:base = string : <em>TT Feature Namespace</em>
+  <a href="#content-attribute-id">xml:id</a> = ID
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#parameter-vocabulary-feature">ttp:feature</a>*
+&lt;/ttp:features&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If specified, the <code>xml:base</code> attribute must (1) adhere to the
+          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
+          2]</a>, §3.2.17, (2) express an absolute URI that adheres to <a href=
+          "#xmlbase">[XML Base]</a> and, (3) express a feature namespace as defined by
+          <a href="#feature-designations"><b>D.1 Feature Designations</b></a>. If not
+          specified, the <code>xml:base</code> attribute's default value applies, which
+          is the TT Feature Namespace.</p>
+
+          <p>The <code>xml:base</code> attribute is used to permit the abbreviation of
+          feature designation URIs expressed by child <code>ttp:feature</code>
+          elements.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-vocabulary-feature" name=
+          "parameter-vocabulary-feature"></a>6.1.3 ttp:feature</h4>
+
+          <p>The <code>ttp:feature</code> element is used to specify infomation about
+          support requirements for a particular feature.</p>
+
+          <p>The children of the <code>ttp:feature</code> element must express a
+          non-empty sequence of character information items that adheres to the
+          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
+          2]</a>, §3.2.17.</p><a id="elt-syntax-parameter-feature" name=
+          "elt-syntax-parameter-feature"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttp:feature
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttp:feature
+  value = (optional|required|use) : required
+  <a href="#content-attribute-id">xml:id</a> = ID
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> #PCDATA
+&lt;/ttp:feature&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the URI expressed by the content of the <code>ttp:feature</code> element
+          is a relative URI, then, when combined with the feature namespace value
+          expressed by the <code>xml:base</code> attribute of the nearest ancestor
+          <code>ttp:features</code> element, it must express an absolute URI. In either
+          case (original absolute URI or resulting absolutized URI), the URI expressed by
+          the <code>ttp:feature</code> element must further adhere to the syntax of a
+          feature designation as defined by <a href="#feature-designations"><b>D.1
+          Feature Designations</b></a>, and, furthermore, the specific designation that
+          appears in this URI, i.e., the portion of the feature designation that starts
+          with the fragment identifier separator '#', must be defined by this
+          specification or some published version thereof (that has achieved REC
+          status).</p>
+
+          <p>If the URI expressed by the content of the <code>ttp:feature</code> element
+          is a relative URI, then an <code>xml:base</code> attribute should be specified
+          on the nearest ancestor <code>ttp:features</code> element.</p>
+
+          <p>The <code>value</code> attribute specifies whether a conforming TTML
+          processor must or may implement the designated feature in order to process the
+          document. If the value of the <code>value</code> attribute is
+          <code>optional</code>, then the processor need not implement or otherwise
+          support the feature in order to process the document; if the value is
+          <code>required</code>, then the processor must implement or otherwise support
+          the feature, irrespective of whether the feature is enabled or disabled, in
+          order to process the document; if the value is <code>use</code>, then the
+          processor must both (1) implement or otherwise support the feature and (2) have
+          enabled (activated) use of the feature.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The default value of the <code>value</code> attribute is
+            <code>required</code>, as indicated in the above element information item
+            definition. Therefore, if a <code>value</code> attribute is not specified on
+            a <code>ttp:feature</code> element, it is equivalent to specifying that
+            support for the feature is required.</p>
+          </div>
+
+          <p>If the value of the <code>value</code> attribute is <code>required</code> or
+          <code>use</code> and the TTML processor implementation does not support the
+          feature, or if the <code>value</code> attribute is <code>use</code> and the
+          TTML processor implementation supports but has disabled that feature, then it
+          must not further process the document without the presence of an explicit
+          override from an end-user or some implementation specific parameter traceable
+          to an end-user or to a user or system configuration setting. If a TTML
+          processor aborts processing of a <em>Document Instance</em> due to the
+          specification of a required, but unsupported feature by this element, then some
+          end-user notification should be given unless the end-user or system has
+          disabled such a notification, or if the processor does not permit or entail the
+          intervention of an end-user.</p>
+
+          <p>If the value of the <code>value</code> attribute is <code>optional</code>,
+          and if the TTML processor implementation does not support the feature, then it
+          may further process the document even in the case that some use of the feature
+          is present in the document. In the case of actual use of a feature designated
+          as optional, the default semantics associated with that feature apply; that is,
+          the processor may behave as if the feature were not actually used or referenced
+          by the document. Notwithstanding the above, the syntactic presence or reference
+          to an optional feature by a document must not be considered to be a violation
+          of document validity or a barrier to further processing if the syntactic
+          expression is well-formed and valid.</p>
+
+          <p>If some defined (i.e., standardized) or otherwise well known feature is not
+          specified by a <code>ttp:feature</code> element in a given profile, then it
+          must be interpreted as if the feature were specified with the
+          <code>value</code> attribute equal to <code>optional</code>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In particular, if some feature is not present in a profile definition,
+            then it is not to be interpreted as meaning the use of that feature (in a
+            <em>Document Instance</em>) is disallowed or otherwise prohibited.</p>
+          </div>
+
+          <p>The <code>ttp:feature</code> element is illustrated by the following
+          example.</p><a id="parameter-vocabulary-feature-example-1" name=
+          "parameter-vocabulary-feature-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – ttp:feature
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-presentation"&gt;
+  &lt;ttp:features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
+    <span class=
+"strong">&lt;ttp:feature value="required"&gt;#fontStyle-italic&lt;/ttp:feature&gt;</span>
+    <span class=
+"strong">&lt;ttp:feature value="required"&gt;#textDecoration-under&lt;/ttp:feature&gt;</span>
+  &lt;/ttp:features&gt;
+&lt;/ttp:profile&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, the DFXP presentation profile is used as the
+            baseline profile. This baseline profile is then modified by two
+            <code>ttp:feature</code> elements in order to superset the baseline profile
+            (since neither <code>#fontStyle-italic</code> nor
+            <code>#textDecoration-under</code> are required by the DFXP presentation
+            profile).</p>
+
+            <p>The effect of this example is to express authorial intentions that italic
+            font style and text underlining must be supported.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-vocabulary-extensions" name=
+          "parameter-vocabulary-extensions"></a>6.1.4 ttp:extensions</h4>
+
+          <p>The <code>ttp:extensions</code> element is a container element used to group
+          infomation about extension support requirements.</p>
+
+          <p>The <code>ttp:extensions</code> element accepts as its children zero or more
+          elements in the <code>Metadata.class</code> element group, followed by zero or
+          more <code>ttp:extension</code> elements.</p><a id=
+          "elt-syntax-parameter-extensions" name="elt-syntax-parameter-extensions"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttp:extensions
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttp:extensions
+  xml:base = string : <em>TT Extension Namespace</em>
+  <a href="#content-attribute-id">xml:id</a> = ID
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#parameter-vocabulary-extension">ttp:extension</a>*
+&lt;/ttp:extensions&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If specified, the <code>xml:base</code> attribute must (1) adhere to the
+          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
+          2]</a>, §3.2.17, (2) express an absolute URI that adheres to <a href=
+          "#xmlbase">[XML Base]</a> and, (3) express an extension namespace as defined by
+          <a href="#extension-designations"><b>E.1 Extension Designations</b></a>. If not
+          specified, the <code>xml:base</code> attribute's default value applies, which
+          is the TT Extension Namespace.</p>
+
+          <p>The <code>xml:base</code> attribute is used to permit the abbreviation of
+          feature designation URIs expressed by child <code>ttp:extension</code>
+          elements.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-vocabulary-extension" name=
+          "parameter-vocabulary-extension"></a>6.1.5 ttp:extension</h4>
+
+          <p>The <code>ttp:extension</code> element is used to specify infomation about
+          support requirements for a particular extension.</p>
+
+          <p>The children of the <code>ttp:extension</code> element must express a
+          non-empty sequence of character information items that adheres to the
+          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
+          2]</a>, §3.2.17.</p><a id="elt-syntax-parameter-extension" name=
+          "elt-syntax-parameter-extension"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttp:extension
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttp:extension
+  value = (optional|required|use) : required
+  <a href="#content-attribute-id">xml:id</a> = ID
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> #PCDATA
+&lt;/ttp:extension&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the URI expressed by the content of the <code>ttp:extension</code>
+          element is a relative URI, then, when combined with the extension namespace
+          value expressed by the <code>xml:base</code> attribute of the nearest ancestor
+          <code>ttp:extensions</code> element, it must express an absolute URI. In either
+          case (original absolute URI or resulting absolutized URI), the URI expressed by
+          the <code>ttp:extension</code> element must further adhere to the syntax of an
+          extension designation as defined by <a href="#extension-designations"><b>E.1
+          Extension Designations</b></a>.</p>
+
+          <p>If the URI expressed by the content of the <code>ttp:feature</code> element
+          is a relative URI, then an <code>xml:base</code> attribute should be specified
+          on the nearest ancestor <code>ttp:extensions</code> element.</p>
+
+          <p>The <code>value</code> attribute specifies whether a conforming TTML
+          processor must or may implement the designated extension in order to process
+          the document. If the value of the <code>value</code> attribute is
+          <code>optional</code>, then the processor need not implement or otherwise
+          support the extension in order to process the document; if the value is
+          <code>required</code>, then the processor must implement or otherwise support
+          the extension in order to process the document; if the value is
+          <code>use</code>, then the processor must both (1) implement or otherwise
+          support the extension and (2) enable (activate) use of the extension.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The default value of the <code>value</code> attribute is
+            <code>required</code>, as indicated in the above element information item
+            definition. Therefore, if a <code>value</code> attribute is not specified on
+            a <code>ttp:extension</code> element, it is equivalent to specifying that
+            support for the extension is required.</p>
+          </div>
+
+          <p>If the value of the <code>value</code> attribute is <code>required</code> or
+          <code>use</code> and the TTML processor implementation does not support the
+          extension, or if the <code>value</code> attribute is <code>use</code> and the
+          TTML processor implementation supports but has disabled that extension, then it
+          must not further process the document without the presence of an explicit
+          override from an end-user or some implementation specific parameter traceable
+          to an end-user or to a user or system configuration setting. If a TTML
+          processor aborts processing of a <em>Document Instance</em> due to the
+          specification of a required, but unsupported extension by this element, then
+          some end-user notification should be given unless the end-user or system has
+          disabled such a notification, or if the processor does not permit or entail the
+          intervention of an end-user.</p>
+
+          <p>If the value of the <code>value</code> attribute is <code>optional</code>,
+          and if the TTML processor implementation does not support the extension, then
+          it may further process the document even in the case that some use of the
+          extension is present in the document. In the case of actual use of an extension
+          designated as optional, the default semantics associated with that extension
+          apply; that is, the processor may behave as if the extension were not actually
+          used or referenced by the document. Notwithstanding the above, the syntactic
+          presence or reference to an optional extension by a document must not be
+          considered to be a violation of document validity or a barrier to further
+          processing if the syntactic expression is well-formed and valid.</p>
+
+          <p>If some well known extension is not specified by a
+          <code>ttp:extension</code> element in a given profile, then it must be
+          interpreted as if the extension were specified with the <code>value</code>
+          attribute equal to <code>optional</code>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In particular, if some extension is not present in a profile definition,
+            then it is not to be interpreted as meaning the use of that extension (in a
+            <em>Document Instance</em>) is disallowed or otherwise prohibited.</p>
+          </div>
+
+          <p>The <code>ttp:extension</code> element is illustrated by the following
+          example.</p><a id="parameter-vocabulary-extension-example-1" name=
+          "parameter-vocabulary-extension-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – ttp:extension
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-transformation"&gt;
+  &lt;ttp:extensions xml:base="http://example.org/ttml/extension/"&gt;
+    <span class=
+"strong">&lt;ttp:extension value="use"&gt;#prefilter-by-language&lt;/ttp:extension&gt;</span>
+  &lt;/ttp:extensions&gt;
+&lt;/ttp:profile&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, the DFXP transformation profile is used as the
+            baseline profile. This baseline profile is then supersetted by specifying
+            that support and use is required for a private extension defined in a third
+            party namespace.</p>
+
+            <p>The effect of this example is to express authorial intentions that a
+            recipient processor must support the DFXP transformation profile and must
+            also support and enable an extension defined by a third party.</p>
+          </div>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="parameter-attribute-vocabulary" name=
+        "parameter-attribute-vocabulary"></a>6.2 Parameter Attribute Vocabulary</h3>
+
+        <p>The following attributes are defined in the TT Parameter Namespace.</p>
+
+        <ul>
+          <li>
+            <p><a href="#parameter-attribute-cellResolution"><b>6.2.1
+            ttp:cellResolution</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-clockMode"><b>6.2.2
+            ttp:clockMode</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-dropMode"><b>6.2.3 ttp:dropMode</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-frameRate"><b>6.2.4
+            ttp:frameRate</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-frameRateMultiplier"><b>6.2.5
+            ttp:frameRateMultiplier</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-markerMode"><b>6.2.6
+            ttp:markerMode</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-pixelAspectRatio"><b>6.2.7
+            ttp:pixelAspectRatio</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-profile"><b>6.2.8 ttp:profile</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-subFrameRate"><b>6.2.9
+            ttp:subFrameRate</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-tickRate"><b>6.2.10 ttp:tickRate</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a></p>
+          </li>
+        </ul>
+
+        <p>Unless explicitly stated otherwise, linear white-space (LWSP) must appear
+        between adjacent non-terminal components of a TT Parameter value unless some
+        other delimiter is permitted and used.</p>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-cellResolution" name=
+          "parameter-attribute-cellResolution"></a>6.2.1 ttp:cellResolution</h4>
+
+          <p>The <code>ttp:cellResolution</code> attribute may be used by an author to
+          express the number of horizontal and vertical cells into which the <em>Root
+          Container Region</em> area is divided for the purpose of expressing
+          presentation semantics in terms of a uniform grid.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-cellResolution-syntax" name=
+          "parameter-attribute-cellResolution-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:cellResolution
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:cellResolution
+  : columns rows                            // <em>columns</em> != 0; <em>rows</em> != 0
+
+columns | rows
+  : <a href="#style-value-digit">&lt;digit&gt;</a>+
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If not specified, the number of columns and rows must be considered to be 32
+          and 15, respectively. If specified, then columns or rows must not be zero
+          (0).</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The choice of values 32 and 15 are based on this being the maximum number
+            of columns and rows defined by <a href="#cea608c">[CEA-608-C]</a>.</p>
+          </div>
+
+          <p>A <code>ttp:cellResolution</code> attribute is considered to be significant
+          only when specified on the <code>tt</code> element.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The use of a uniform grid is employed only for the purpose of measuring
+            lengths and expressing coordinates. In particular, it is not assumed that the
+            presentation of text or the alignment of individual glyph areas is
+            coordinated with this grid. Such alignment is possible, but requires the use
+            of a monospaced font and a font size whose EM square exactly matches the cell
+            size.</p>
+          </div>
+
+          <p>Except where indicated otherwise, when a <a href=
+          "#style-value-length">&lt;length&gt;</a> expressed in cells denotes a dimension
+          parallel to the inline or block progression dimension, the cell's dimension in
+          the inline or block progression dimension applies, respectively.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>For example, if padding (on all four edges) is specified as 0.1c, the cell
+            resolution is 20 by 10, and the extent of the <em>Root Container Region</em>
+            is 640 by 480, then, assuming top to bottom, left to right writing mode, the
+            start and end padding will be (640 / 20) * 0.1 pixels and the before and
+            after padding will be (480 / 10) * 0.1 pixels.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-clockMode" name=
+          "parameter-attribute-clockMode"></a>6.2.2 ttp:clockMode</h4>
+
+          <p>The <code>ttp:clockMode</code> attribute is used to specify the
+          interpretation of time expressions as real-time time coordinates when operating
+          with time base of <code>clock</code> as defined by <a href=
+          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>See <a href="#timing-time-value-expressions"><b>10.3 Time Value
+            Expressions</b></a> for the specification of time expression syntax and
+            semantics.</p>
+          </div>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-clockMode-syntax" name=
+          "parameter-attribute-clockMode-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:clockMode
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:clockMode
+  : "local"
+  | "gps"
+  | "utc"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the time base, defined by <a href=
+          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is designated
+          as <code>clock</code>, then this parameter applies as follows: if the
+          parameter's value is <code>local</code>, then time expressions are interpreted
+          as local wall-clock time coordinates; if <code>utc</code>, then time
+          expressions are interpreted as UTC time coordinates <a href="#utc">[UTC]</a>;
+          if <code>gps</code>, then time expressions are interpreted as GPS time
+          coordinates <a href="#gps">[GPS]</a>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The primary difference between GPS time and UTC time is that GPS time is
+            not adjusted for leap seconds, while UTC time is adjusted as follows: UTC =
+            TAI (<em>Temp Atomique International</em>) + <em>leap seconds accumulated
+            since 1972</em>. TAI is maintained by the <em>Bureau International des Poids
+            et Mesures</em> (BIPM) in Sevres, France. The GPS system time is steered to a
+            Master Clock (MC) at the US Naval Observatory which is kept within a close
+            but unspecified tolerance of TAI.</p>
+          </div>
+
+          <p>If not specified, the value of this parameter must be considered to be
+          <code>utc</code>.</p>
+
+          <p>A <code>ttp:clockMode</code> attribute is considered to be significant only
+          when specified on the <code>tt</code> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-dropMode" name=
+          "parameter-attribute-dropMode"></a>6.2.3 ttp:dropMode</h4>
+
+          <p>The <code>ttp:dropMode</code> attribute is used to specify constraints on
+          the interpretation and use of frame counts that correspond with <a href=
+          "#smpte12m">[SMPTE 12M]</a> time coordinates when operating with time base of
+          <code>smpte</code> as defined by <a href=
+          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-dropMode-syntax" name=
+          "parameter-attribute-dropMode-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:dropMode
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:dropMode
+  : "dropNTSC"
+  | "dropPAL"
+  | "nonDrop"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the time base, defined by <a href=
+          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is designated
+          as <code>smpte</code>, then this parameter applies as follows: if the
+          parameter's value is <code>nonDrop</code>, then, within any given second of a
+          time expression, frames count from 0 to <em>N−1</em>, where <em>N</em> is the
+          value specified by the <code>ttp:frameRate</code> parameter, but while ignoring
+          any value specified by the <code>ttp:frameRateMultiplier</code> parameter.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>When operating in <code>nonDrop</code> mode, a second of a time expression
+            may or may not be equal to a second of real time during normal (1x speed)
+            forward playback. If the <code>ttp:frameRateMultiplier</code> parameter is
+            specified and is not equal to 1:1, then a second of a time expression will
+            either be shorter or longer than a second of elapsed play in real time.</p>
+          </div>
+
+          <p>If this parameter's value is <code>dropNTSC</code>, then, within any given
+          second of a time expression except the second <code>00</code>, frames count
+          from 0 to <em>N−1</em>, where <em>N</em> is the value specified by the
+          <code>ttp:frameRate</code> parameter, but while ignoring any value specified by
+          the <code>ttp:frameRateMultiplier</code> parameter. If the second of a time
+          expression is <code>00</code> and the minute of the time expression is not
+          <code>00</code>, <code>10</code>, <code>20</code>, <code>30</code>,
+          <code>40</code>, or <code>50</code>, then frame codes <code>00</code> and
+          <code>01</code> are dropped during that second; otherwise, these frame codes
+          are not dropped.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>For example, when operating in <code>dropNTSC</code> mode with
+            <code>ttp:frameRate</code> of <code>30</code>, a discontinuity in frame count
+            occurs between consecutive frames as shown in the following sequence of time
+            expressions: <code>01:08:59:28</code>, <code>01:08:59:29</code>,
+            <code>01:09:00:02</code>, <code>01:09:00:03</code>.</p>
+          </div>
+
+          <p>If this parameter's value is <code>dropPAL</code>, then, within any given
+          second of a time expression except the second <code>00</code>, frames count
+          from 0 to <em>N−1</em>, where <em>N</em> is the value specified by the
+          <code>ttp:frameRate</code> parameter, but while ignoring any value specified by
+          the <code>ttp:frameRateMultiplier</code> parameter. If the second of a time
+          expression is <code>00</code> and the minute of the time expression is even but
+          not <code>00</code>, <code>20</code>, or <code>40</code>, then frame codes
+          <code>00</code> through <code>03</code> are dropped during that second;
+          otherwise, these frame codes are not dropped.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>For example, when operating in <code>dropPAL</code> mode with
+            <code>ttp:frameRate</code> of <code>30</code>, a discontinuity in frame count
+            occurs between consecutive frames as shown in the following sequence of time
+            expressions: <code>01:09:59:28</code>, <code>01:09:59:29</code>,
+            <code>01:10:00:04</code>, <code>01:10:00:05</code>.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The <code>dropPAL</code> mode is also known as the <em>M/PAL</em> or
+            <em>PAL (M)</em> drop-frame code, which uses PAL modulation with the NTSC
+            frame rate of ~29.97 frames/second. The M/PAL system is used primarily in
+            Brazil.</p>
+          </div>
+
+          <p>If not specified, then <code>nonDrop</code> must be assumed to apply.</p>
+
+          <p>A <code>ttp:dropMode</code> attribute is considered to be significant only
+          when specified on the <code>tt</code> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-frameRate" name=
+          "parameter-attribute-frameRate"></a>6.2.4 ttp:frameRate</h4>
+
+          <p>The <code>ttp:frameRate</code> attribute is used to specify the frame rate
+          of a related media object or the intrinsic frame rate of a <em>Document
+          Instance</em> in case it is intended to function as an independent media
+          object.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-frameRate-syntax" name=
+          "parameter-attribute-frameRate-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:frameRate
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:frameRate
+  : <a href=
+"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The frame rate that applies to a <em>Document Instance</em> is used to
+          interpret time expressions that are expressed in <em>frames</em> as defined by
+          <a href="#timing-value-timeExpression"><b>10.3.1
+          &lt;timeExpression&gt;</b></a>.</p>
+
+          <p>If the <code>media</code> time base applies and the effective frame rate is
+          integral, then a frame is interpreted as a division of a second of media time,
+          such that if the frame rate is specified as <em>F</em>, then a second of media
+          time is divided into <em>F</em> intervals of equal duration, where each
+          interval is labeled as frame <em>f</em>, with <em>f</em> ∈
+          [0…<em>F−1</em>].</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
+            Base</b></a> for further details on the interpretation of time expressions
+            for the <code>media</code> time base.</p>
+          </div>
+
+          <p>If not specified, the frame rate must be considered to be equal to some
+          application defined frame rate, or if no application defined frame rate
+          applies, then thirty (30) frames per second. If specified, then the frame rate
+          must be greater than zero (0).</p>
+
+          <p>A <code>ttp:frameRate</code> attribute is considered to be significant only
+          when specified on the <code>tt</code> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-frameRateMultiplier" name=
+          "parameter-attribute-frameRateMultiplier"></a>6.2.5
+          ttp:frameRateMultiplier</h4>
+
+          <p>The <code>ttp:frameRateMultiplier</code> attribute is used to specify a
+          multiplier to be applied to the frame rate specified by a
+          <code>ttp:frameRate</code> attribute in order to compute the effective frame
+          rate.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-frameRateMultiplier-syntax" name=
+          "parameter-attribute-frameRateMultiplier-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:frameRateMultiplier
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:frameRateMultiplier
+  : numerator denominator                   // <em>numerator</em> != 0; <em>denominator</em> != 0
+
+numerator | denominator
+  : <a href="#style-value-digit">&lt;digit&gt;</a>+
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>A frame rate multiplier is used when the desired frame rate cannot be
+          expressed as an integral number of frames per second.</p>
+
+          <p>If not specified, the frame rate multiplier must be considered to be equal
+          to one (1:1). Both numerator and denominator must be non-zero.</p>
+
+          <p>A <code>ttp:frameRateMultiplier</code> attribute is considered to be
+          significant only when specified on the <code>tt</code> element.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The frame rate multiplier used for synchronizing with NTSC <a href=
+            "#smpte170m">[SMPTE 170M]</a> formatted video objects at 30 frames per second
+            is nominally 1000:1001. The nominal frame rate of NTSC video is defined as
+            the chrominance sub-carrier frequency of 3,579,545.45…Hz (= 5.0MHz × 63/88)
+            times the ratio 2/455 divided by the number of horizontal lines per frame of
+            525, which yields a frame rate of 29.970029970029… (= 30 × 1000/1001) frames
+            per second. Other frame rate multipliers apply to different regions of usage
+            and video format standards.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Except in the case of PAL/M, the frame rate multiplier used for
+            synchronizing with PAL formatted video objects at 25 frames per second is
+            nominally 1:1.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-markerMode" name=
+          "parameter-attribute-markerMode"></a>6.2.6 ttp:markerMode</h4>
+
+          <p>The <code>ttp:markerMode</code> attribute is used to specify constraints on
+          the interpretation and use of time expressions that correspond with <a href=
+          "#smpte12m">[SMPTE 12M]</a> time coordinates when operating with time base of
+          <code>smpte</code> as defined by <a href=
+          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-markerMode-syntax" name=
+          "parameter-attribute-markerMode-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:markerMode
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:markerMode
+  : "continuous"
+  | "discontinuous"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the time base, defined by <a href=
+          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is designated
+          as <code>smpte</code>, then this parameter applies as follows: if the
+          parameter's value is <code>continuous</code>, then <a href="#smpte12m">[SMPTE
+          12M]</a> time coordinates may be assumed to be linear and either monotonically
+          increasing or decreasing; however, if <code>discontinuous</code>, then any
+          assumption must not be made regarding linearity or monotonicity of time
+          coordinates.</p>
+
+          <p>If not specified, the value of this parameter must be considered to be
+          <code>discontinuous</code>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The default value for this parameter was originally specified (in <a href=
+            "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">TTML 1.0 First
+            Edition</a>) as <code>continuous</code>; however, further evaluation of the
+            state of the industry indicates this choice was incorrect, and that the most
+            common default is <code>discontinuous</code>.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Due to lack of industry consensus on the utility and interpretation of the
+            <code>continuous</code> marker mode, authors are advised to avoid its use.
+            Furthermore, the <code>ttp:markerMode</code> is being considered for
+            deprecation in the next revision of this specification.</p>
+          </div>
+
+          <p>A <code>ttp:markerMode</code> attribute is considered to be significant only
+          when specified on the <code>tt</code> element.</p>
+
+          <p>If a value of <code>continuous</code> applies, then time expressions may be
+          converted to real time coordinates by taking into account the computed frame
+          rate and drop mode as expressed by the <code>ttp:dropMode</code> parameter. In
+          this case, the <em>Content Processor</em> must create and maintain a
+          <em>Synthetic SMPTE Document Syncbase</em> within which these time expressions
+          are interpreted as further described in <a href=
+          "#timing-time-intervals"><b>10.4 Time Intervals</b></a>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>When operating with <code>smpte</code> time base and
+            <code>continuous</code> marker mode, there is an implied time coordinate
+            space, the <em>Synthetic SMPTE Document Syncbase</em>, defined by the
+            monotonically increasing (or decreasing) <a href="#smpte12m">[SMPTE 12M]</a>
+            time coordinates, while taking into account the computed frame rate and drop
+            mode. All time expressions are interpreted in relationship to this time
+            coordinate space based upon <em>SMPTE Time Code</em> synchronization events
+            (markers), where the <em>Document Processing Context</em> emits these events
+            with implied constraints regarding time coordinate monoticity and
+            resynchronization in the presence of dropped frames.</p>
+
+            <p>Use of <code>continuous</code> marker mode with the <code>smpte</code>
+            time base is different from using the <code>media</code> time base because
+            (1) the semantics of the <code>ttp:dropMode</code> parameter apply to the
+            former, but not the latter, and (2) <a href="#smpte12m">[SMPTE 12M]</a> time
+            coordinates may be applied monotonically to media which has been subjected to
+            dilation in time, constriction in time, or reversal in time.</p>
+          </div>
+
+          <p>If a value of <code>discontinuous</code> applies, then time expressions must
+          not be converted to real time coordinates, arithmetical operators (addition,
+          multiplication) are not defined on time expressions, and, consequently, any
+          (well-formed) expression of a duration must be considered to be invalid.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>When operating with <code>smpte</code> time base and
+            <code>discontinuous</code> marker mode, there is no effective time coordinate
+            space; rather, all time expressions are interpreted as labeled
+            synchronization events (markers), where the <em>Document Processing
+            Context</em> emits these events, which, when they correspond with time
+            expressions that denote the same label, cause a temporal interval to begin or
+            end accordingly.</p>
+
+            <p>An additional side-effect of operating in <code>discontinuous</code> mode
+            is that time expressions of children have no necessary relationship with time
+            expressions of their temporal container; that is, temporal containers and
+            children of these containers are temporally activated and inactivated
+            independently based on the occurrence of a labeled synchronization (marker)
+            event.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The notion of marker discontinuity as captured by this parameter is
+            logically independent from the method used to count frames as expressed by
+            the <code>ttp:dropMode</code> parameter. In particular, even if the
+            <code>ttp:dropMode</code> parameter is specified as <code>dropNTSC</code> or
+            <code>dropPAL</code>, the marker mode may be specified as
+            <code>continuous</code>, even in the presence of frame count discontinuities
+            induced by the frame counting method, unless there were some other
+            non-linearity or discontinuity in marker labeling, for example, two
+            consecutive frames labeled as <code>10:00:00:00</code> and
+            <code>10:00:01:00</code>.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-pixelAspectRatio" name=
+          "parameter-attribute-pixelAspectRatio"></a>6.2.7 ttp:pixelAspectRatio</h4>
+
+          <p>The <code>ttp:pixelAspectRatio</code> attribute may be used by a content
+          author to express the aspect ratio of non-square pixels in the production of
+          content that makes use of pixel coordinates.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-pixelAspectRatio-syntax" name=
+          "parameter-attribute-pixelAspectRatio-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:pixelAspectRatio
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:pixelAspectRatio
+  : width height                            // <em>width</em> != 0; <em>height</em> != 0
+
+width | height
+  : <a href="#style-value-digit">&lt;digit&gt;</a>+
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If not specified, then square pixels (i.e., aspect ratio 1:1) must be
+          assumed to apply. If specified, then both width and height must be
+          non-zero.</p>
+
+          <p>A <code>ttp:pixelAspectRatio</code> attribute is considered to be
+          significant only when specified on the <code>tt</code> element.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>This parameter may be used by a content transcoder or translator in order
+            to convert pixel measurements between different pixel aspect ratios while
+            still maintaining authorial layout intentions.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-profile" name=
+          "parameter-attribute-profile"></a>6.2.8 ttp:profile</h4>
+
+          <p>The <code>ttp:profile</code> attribute may be used by a content author to
+          express the profile of the Timed Text Markup Language (TTML) used in a
+          <em>Document Instance</em>.</p>
+
+          <p>If specified, the value of this attribute must adhere to the
+          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML Schema Part
+          2]</a>, §3.2.17, and, further, must specify a profile designator in accordance
+          with <a href="#vocabulary-profiles"><b>5.2 Profiles</b></a>.</p>
+
+          <p>A <code>ttp:profile</code> attribute is considered to be significant only
+          when specified on the <code>tt</code> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-subFrameRate" name=
+          "parameter-attribute-subFrameRate"></a>6.2.9 ttp:subFrameRate</h4>
+
+          <p>The <code>ttp:subFrameRate</code> attribute is used to specify the sub-frame
+          rate of a related media object or the intrinsic sub-frame rate of a
+          <em>Document Instance</em> in case it is intended to function as an independent
+          media object.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-subFrameRate-syntax" name=
+          "parameter-attribute-subFrameRate-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:subFrameRate
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:subFrameRate
+  : <a href=
+"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The sub-frame rate that applies to a <em>Document Instance</em> is used to
+          interpret time expressions that are expressed in <em>sub-frames</em> as defined
+          by <a href="#timing-value-timeExpression"><b>10.3.1
+          &lt;timeExpression&gt;</b></a>.</p>
+
+          <p>If the <code>media</code> time base applies and the effective frame rate is
+          integral, a sub-frame is interpreted as a division of a frame of media time,
+          such that if the sub-frame rate is specified as <em>S</em>, then a frame of
+          media time is divided into <em>S</em> intervals of equal duration, where each
+          interval is labeled as sub-frame <em>s</em>, with <em>s</em> ∈
+          [0…<em>S−1</em>].</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
+            Base</b></a> for further details on the interpretation of time expressions
+            for the <code>media</code> time base.</p>
+          </div>
+
+          <p>If not specified, the sub-frame rate must be considered to be equal to one
+          (1). If specified, then the sub-frame rate must be greater than zero (0).</p>
+
+          <p>A <code>ttp:subFrameRate</code> attribute is considered to be significant
+          only when specified on the <code>tt</code> element.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The sub-frame is sometimes referred to as a <em>field</em> in the context
+            of synchronization with an interlaced video media object.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-tickRate" name=
+          "parameter-attribute-tickRate"></a>6.2.10 ttp:tickRate</h4>
+
+          <p>The <code>ttp:tickRate</code> attribute is used to specify the tick rate of
+          a related media object or the intrinsic tick rate of content of a <em>Document
+          Instance</em> in case it is intended to function as an independent media
+          object.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-tickRate-syntax" name=
+          "parameter-attribute-tickRate-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:tickRate
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:tickRate
+  : <a href=
+"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The tick rate that applies to a <em>Document Instance</em> is used to
+          interpret time expressions that are expressed in <em>ticks</em> by using the
+          <code>t</code> metric as defined by <a href=
+          "#timing-value-timeExpression"><b>10.3.1 &lt;timeExpression&gt;</b></a>.</p>
+
+          <p>If the <code>media</code> time base applies, a tick is interpreted as an
+          integral division of a second of media time, such that if the tick rate is
+          specified as <em>T</em>, then a second of media time is divided into <em>T</em>
+          intervals of equal duration, where each interval is labeled as tick <em>t</em>,
+          with <em>t</em> ∈ [0…<em>T−1</em>].</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
+            Base</b></a> for further details on the interpretation of time expressions
+            for the <code>media</code> time base.</p>
+          </div>
+
+          <p>If not specified, then if a frame rate is specified, the tick rate must be
+          considered to be the effective frame rate multiplied by the sub-frame rate
+          (i.e., ticks are interpreted as sub-frames); or, if no frame rate is specified,
+          the tick rate must be considered to be one (1) tick per second of media time.
+          If specified, then the tick rate must not be zero (0).</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>There is no predefined relationship between ticks and frames or
+            sub-frames. Ticks are an arbitrary division of seconds that permit use of
+            fixed point arithmetic rather than fractional (and potentially inexact)
+            expressions of seconds.</p>
+          </div>
+
+          <p>A <code>ttp:tickRate</code> attribute is considered to be significant only
+          when specified on the <code>tt</code> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="parameter-attribute-timeBase" name=
+          "parameter-attribute-timeBase"></a>6.2.11 ttp:timeBase</h4>
+
+          <p>The <code>ttp:timeBase</code> attribute is used to specify the temporal
+          coordinate system by means of which time expressions are interpreted in a
+          <em>Document Instance</em>.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax:</p><a id="parameter-attribute-timeBase-syntax" name=
+          "parameter-attribute-timeBase-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttp:timeBase
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttp:timeBase
+  : "media"
+  | "smpte"
+  | "clock"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the time base is designated as <code>media</code>, then a time expression
+          denotes a coordinate in some media object's time line, where the media object
+          may be an external media object with which the content of a <em>Document
+          Instance</em> is to be synchronized, or it may be the content of a <em>Document
+          Instance</em> itself in a case where the timed text content is intended to
+          establish an independent time line.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>When using a media time base, if that time base is paused or scaled
+            positively or negatively, i.e., the media play rate is not unity, then it is
+            expected that the presentation of associated Timed Text content will be
+            similarly paused, accelerated, or decelerated, respectively. The means for
+            controlling an external media time base is outside the scope of this
+            specification.</p>
+          </div>
+
+          <p>If the time base is designated as <code>smpte</code>, then a time expression
+          denotes a <a href="#smpte12m">[SMPTE 12M]</a> time coordinate with which the
+          content of a <em>Document Instance</em> is to be synchronized. In this case,
+          the value of the <code>ttp:markerMode</code> and <code>ttp:dropMode</code>
+          parameters apply, as defined by <a href=
+          "#parameter-attribute-markerMode"><b>6.2.6 ttp:markerMode</b></a> and <a href=
+          "#parameter-attribute-dropMode"><b>6.2.3 ttp:dropMode</b></a>,
+          respectively.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>When the time base is designated as <code>smpte</code>, every time
+            expression denotes a media marker value akin to that defined by <a href=
+            "#smil21">[SMIL 2.1]</a>, § 10.4.1, except instead of using an opaque marker
+            name, a structured <a href="#smpte12m">[SMPTE 12M]</a> time coordinate serves
+            as the marker name.</p>
+          </div>
+
+          <p>If the time base is designated as <code>clock</code>, then the time
+          expression denotes a coordinate in some real-world time line as established by
+          some real-time clock, such as the local wall-clock time or UTC (Coordinated
+          Universal Time) or GPS (Global Positioning System) time lines.</p>
+
+          <p>If not specified, the default time base must be considered to be
+          <code>media</code>.</p>
+
+          <p>A <code>ttp:timeBase</code> attribute is considered to be significant only
+          when specified on the <code>tt</code> element.</p>
+
+          <p>When operating with either <code>media</code> or <code>smpte</code> time
+          bases, a diachronic presentation of a <em>Document Instance</em> may be subject
+          to transformations of the controlling time line, such as temporal reversal,
+          dilation (expansion), or constriction (compression); however, when operating
+          with the <code>clock</code> time base, no transformations are permitted, and
+          diachronic presentation proceeds on a linear, monotonically increasing time
+          line based on the passage of real time.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Due to there being only one time base parameter that applies to a given
+            <em>Document Instance</em>, the interpretation of time expressions is uniform
+            throughout the <em>Document Instance</em>.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>See <a href="#time-expression-semantics"><b>N Time Expression
+            Semantics</b></a> for further details on the interpretation of time
+            expressions according to the designated time base.</p>
+          </div>
+        </div>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="content" name="content"></a>7 Content</h2>
+
+      <p>This section specifies the <em>content</em> matter of the core vocabulary
+      catalog.</p>
+
+      <div class="div2">
+        <h3><a id="content-element-vocabulary" name="content-element-vocabulary"></a>7.1
+        Content Element Vocabulary</h3>
+
+        <p>The following elements specify the structure and principal content aspects of
+        a <em>Document Instance</em>:</p>
+
+        <ul>
+          <li>
+            <p><a href="#document-structure-vocabulary-tt"><b>7.1.1 tt</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#document-structure-vocabulary-head"><b>7.1.2 head</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#document-structure-vocabulary-body"><b>7.1.3 body</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#content-vocabulary-div"><b>7.1.4 div</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#content-vocabulary-p"><b>7.1.5 p</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#content-vocabulary-span"><b>7.1.6 span</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#content-vocabulary-br"><b>7.1.7 br</b></a></p>
+          </li>
+        </ul>
+
+        <div class="div3">
+          <h4><a id="document-structure-vocabulary-tt" name=
+          "document-structure-vocabulary-tt"></a>7.1.1 tt</h4>
+
+          <p>The <code>tt</code> element serves as the root document element of a
+          <em>Document Instance</em>.</p>
+
+          <p>The <code>tt</code> element accepts as its children zero or one
+          <code>head</code> element followed by zero or one <code>body</code>
+          element.</p><a id="elt-syntax-tt" name="elt-syntax-tt"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: tt
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;tt
+  <a href="#style-attribute-extent">tts:extent</a> = string
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang"><span class="reqattr">xml:lang</span></a> = string
+  <a href=
+"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>) : default
+  {<em>any attribute in TT Parameter namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#document-structure-vocabulary-head">head</a>?, <a href=
+"#document-structure-vocabulary-body">body</a>?
+&lt;/tt&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The <em>Root Temporal Extent</em>, i.e., the time interval over which a
+          <em>Document Instance</em> is active, has an implicit duration that is equal to
+          the implicit duration of the <code>body</code> element of the document, if the
+          <code>body</code> element is present, or zero, if the <code>body</code> element
+          is absent.</p>
+
+          <p>If the <code>tts:extent</code> attribute is specified on the <code>tt</code>
+          element, then it must adhere to <a href="#style-attribute-extent"><b>8.2.7
+          tts:extent</b></a>, in which case it specifies the spatial extent of the
+          <em>Root Container Region</em> in which content regions are located and
+          presented. If no <code>tts:extent</code> attribute is specified, then the
+          spatial extent of the <em>Root Container Region</em> is considered to be
+          determined by the <em>Document Processing Context</em>. The origin of the
+          <em>Root Container Region</em> is determined by the <em>Document Processing
+          Context</em>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the absence of other requirements, and if a <em>Related Media
+            Object</em> exists, then it is recommended that the <em>Document Processing
+            Context</em> determine that:</p>
+
+            <ul>
+              <li>
+                <p>if no <code>tts:extent</code> is specified on the root <code>tt</code>
+                element, the extent of the <em>Root Container Region</em> be established
+                as equal to the extent of the <em>Related Media Object Region</em>;
+                and</p>
+              </li>
+
+              <li>
+                <p>the origin of the <em>Root Container Region</em> be established so
+                that this region is centered in the <em>Related Media Object
+                Region</em>.</p>
+              </li>
+            </ul>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>If an author desires to signal the (storage or image) aspect ratio of the
+            <em>Root Container Region</em> without specifying its resolution, then this
+            may be accomplished by using metadata specified in an external namespace,
+            such as <code>m708:aspectRatio</code> as defined in <a href=
+            "#smpte2052">[SMPTE 2052-11]</a>, §5.4.4. This would permit, for example, the
+            interchange of information that reflects the the semantics of <a href=
+            "#cea708d">[CEA-708-D]</a> , §4.5 “Caption Service Metadata”, “ASPECT
+            RATIO”.</p>
+          </div>
+
+          <p>An <code>xml:lang</code> attribute must be specified on the <code>tt</code>
+          element. If the attribute value is empty, it signifies that there is no default
+          language that applies to the text contained within the <em>Document
+          Instance</em>.</p>
+
+          <p>If no <code>xml:space</code> attribute is specified upon the <code>tt</code>
+          element, then it must be considered as if the attribute had been specified with
+          a value of <code>default</code>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="document-structure-vocabulary-head" name=
+          "document-structure-vocabulary-head"></a>7.1.2 head</h4>
+
+          <p>The <code>head</code> element is a container element used to group header
+          matter, including metadata, profile, styling, and layout information.</p>
+
+          <p>The <code>head</code> element accepts as its children zero or more elements
+          in the <code>Metadata.class</code> element group, followed by zero or more
+          elements in the <code>Parameters.class</code> element group, followed by zero
+          or one <code>styling</code> element, followed by zero or one
+          <code>layout</code> element.</p>
+
+          <p>Any metadata specified by children in the <code>Metadata.class</code>
+          element group applies semantically to the <em>Document Instance</em> as a
+          whole, and not just the <code>head</code> element.</p>
+
+          <p>Any parameters specified by children in the <code>Parameters.class</code>
+          element group applies semantically to the <em>Document Instance</em> as a
+          whole, and not just the <code>head</code> element.</p>
+
+          <p>A <code>styling</code> child element is used to specify style constructs
+          that are referenced from other style constructs, by layout constructs, and by
+          content elements.</p>
+
+          <p>A <code>layout</code> child element is used to specify layout constructs
+          that are referenced by content elements.</p><a id="elt-syntax-head" name=
+          "elt-syntax-head"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: head
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;head
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#element-vocab-group-table">Parameters.class</a>*, <a href=
+"#styling-vocabulary-styling">styling</a>?, <a href=
+"#layout-vocabulary-layout">layout</a>?
+&lt;/head&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>To the extent that time semantics apply to the content of the
+          <code>head</code> element, the implied time interval of this element is defined
+          to be coterminous with the <em>Root Temporal Extent</em>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="document-structure-vocabulary-body" name=
+          "document-structure-vocabulary-body"></a>7.1.3 body</h4>
+
+          <p>The <code>body</code> element functions as a logical container and a
+          temporal structuring element for a sequence of textual content units
+          represented as logical divisions.</p>
+
+          <p>The <code>body</code> element accepts as its children zero or more elements
+          in the <code>Metadata.class</code> element group, followed by zero or more
+          elements in the <code>Animation.class</code> element group, followed by zero or
+          more <code>div</code> elements.</p>
+
+          <p>Any metadata specified by children in the <code>Metadata.class</code>
+          element group applies semantically to the <code>body</code> element and its
+          descendants as a whole.</p>
+
+          <p>Any animation elements specified by children in the
+          <code>Animation.class</code> element group apply semantically to the
+          <code>body</code> element.</p><a id="elt-syntax-body" name=
+          "elt-syntax-body"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: body
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;body
+  <a href="#timing-attribute-begin">begin</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-dur">dur</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-end">end</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#layout-attribute-region">region</a> = IDREF
+  <a href="#style-attribute-style">style</a> = IDREFS
+  <a href=
+"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute in TT Metadata namespace</em>}
+  {<em>any attribute in TT Style namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#element-vocab-group-table">Animation.class</a>*, <a href=
+"#content-vocabulary-div">div</a>*
+&lt;/body&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>An author may specify a temporal interval for a <code>body</code> element
+          using the <code>begin</code>, <code>dur</code>, and <code>end</code>
+          attributes. If the begin point of this interval remains unspecified, then the
+          begin point is interpreted as the beginning point of the <em>Root Temporal
+          Extent</em>. Similarly, if the end point of this interval remains unspecified,
+          then the end point is interpreted as the ending point of the <em>Root Temporal
+          Extent</em>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>A <em>Document Instance</em> referenced from a SMIL presentation is
+            expected to follow the same timing rules as apply to other SMIL media
+            objects.</p>
+          </div>
+
+          <p>If relative begin or end times are specified on the <code>body</code>
+          element, then these times are resolved by reference to the beginning and ending
+          time of the <em>Root Temporal Extent</em>.</p>
+
+          <p>If the <em>Root Temporal Extent</em> is shorter than the computed duration
+          of the <code>body</code> element, then the active time interval of a
+          <code>body</code> element is truncated to the active end point of the <em>Root
+          Temporal Extent</em>.</p>
+
+          <p>An author may associate a set of style properties with a <code>body</code>
+          element by means of either the <code>style</code> attribute or inline style
+          attributes or a combination thereof.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Style properties that are associated with a <code>body</code> element in a
+            <em>Document Instance</em> are available for style inheritance by descendant
+            content elements such as <code>div</code>, <code>p</code>, <code>span</code>
+            and <code>br</code>.</p>
+          </div>
+
+          <p>If no <code>timeContainer</code> attribute is specified on a
+          <code>body</code> element, then it must be interpreted as having
+          <em>parallel</em> time containment semantics.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="content-vocabulary-div" name="content-vocabulary-div"></a>7.1.4
+          div</h4>
+
+          <p>The <code>div</code> element functions as a logical container and a temporal
+          structuring element for a sequence of textual content units represented as
+          logical sub-divisions or paragraphs.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>When rendered on a continuous (non-paged) visual presentation medium, a
+            <code>div</code> element is expected to generate one or more block areas that
+            contain zero or more child block areas generated by the <code>div</code>
+            element's descendant <code>p</code> elements.</p>
+
+            <p>If some block area generated by a <code>div</code> element does not
+            contain any child areas, then it is not expected to be presented.</p>
+          </div>
+
+          <p>The <code>div</code> element accepts as its children zero or more elements
+          in the <code>Metadata.class</code> element group, followed by zero or more
+          elements in the <code>Animation.class</code> element group, followed by zero or
+          more <code>div</code> or <code>p</code> elements.</p>
+
+          <p>Any metadata specified by children in the <code>Metadata.class</code>
+          element group applies semantically to the <code>div</code> element and its
+          descendants as a whole.</p>
+
+          <p>Any animation elements specified by children in the
+          <code>Animation.class</code> element group apply semantically to the
+          <code>div</code> element.</p><a id="elt-syntax-div" name="elt-syntax-div"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: div
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;div
+  <a href="#timing-attribute-begin">begin</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-dur">dur</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-end">end</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#layout-attribute-region">region</a> = IDREF
+  <a href="#style-attribute-style">style</a> = IDREFS
+  <a href=
+"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute in TT Metadata namespace</em>}
+  {<em>any attribute in TT Style namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#element-vocab-group-table">Animation.class</a>*, <a href=
+"#element-vocab-group-table">Block.class</a>*
+&lt;/div&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>An author may associate a set of style properties with a <code>div</code>
+          element by means of either the <code>style</code> attribute or inline style
+          attributes or a combination thereof.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Style properties that are associated with a <code>div</code> element in a
+            <em>Document Instance</em> are available for style inheritance by descendant
+            content elements such as <code>div</code>, <code>p</code>, <code>span</code>,
+            and <code>br</code>.</p>
+          </div>
+
+          <p>If no <code>timeContainer</code> attribute is specified on a
+          <code>div</code> element, then it must be interpreted as having
+          <em>parallel</em> time containment semantics.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="content-vocabulary-p" name="content-vocabulary-p"></a>7.1.5 p</h4>
+
+          <p>A <code>p</code> element represents a logical paragraph, serving as a
+          transition between block level and inline level formatting semantics.</p>
+
+          <p>The <code>p</code> element accepts as its children zero or more elements in
+          the <code>Metadata.class</code> element group, followed by zero or more
+          elements in the <code>Animation.class</code> element group, followed by zero or
+          more intermixed <code>span</code> elements, <code>br</code> elements, or text
+          nodes interpreted as an anonymous spans.</p>
+
+          <p>Any metadata specified by children in the <code>Metadata.class</code>
+          element group applies semantically to the <code>p</code> element and its
+          descendants as a whole.</p>
+
+          <p>Any animation elements specified by children in the
+          <code>Animation.class</code> element group apply semantically to the
+          <code>p</code> element.</p><a id="elt-syntax-p" name="elt-syntax-p"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: p
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;p
+  <a href="#timing-attribute-begin">begin</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-dur">dur</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-end">end</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#layout-attribute-region">region</a> = IDREF
+  <a href="#style-attribute-style">style</a> = IDREFS
+  <a href=
+"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute in TT Metadata namespace</em>}
+  {<em>any attribute in TT Style namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#element-vocab-group-table">Animation.class</a>*, <a href=
+"#element-vocab-group-table">Inline.class</a>*
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>An author may associate a set of style properties with a <code>p</code>
+          element by means of either the <code>style</code> attribute or inline style
+          attributes or a combination thereof.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Style properties that are associated with a <code>p</code> element in a
+            <em>Document Instance</em> are available for style inheritance by descendant
+            content elements such as <code>span</code> and <code>br</code>.</p>
+          </div>
+
+          <p>If no <code>timeContainer</code> attribute is specified on a <code>p</code>
+          element, then it must be interpreted as having <em>parallel</em> time
+          containment semantics.</p>
+
+          <p>If a sequence of children of a <code>p</code> element consists solely of
+          character information items, then that sequence must be considered to be an
+          <em>anonymous span</em> for the purpose of applying style properties that apply
+          to <code>span</code> elements.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The presentation semantics of TTML effectively implies that a
+            <code>p</code> element constitutes a line break. In particular, it is
+            associated with a block-stacking constraint both before the first generated
+            line area and after the last generated line area. See <a href=
+            "#semantics-region-layout-step-2"><b>9.3.3 Synchronic Flow Processing</b></a>
+            for further details.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="content-vocabulary-span" name="content-vocabulary-span"></a>7.1.6
+          span</h4>
+
+          <p>The <code>span</code> element functions as a logical container and a
+          temporal structuring element for a sequence of textual content units having
+          inline level formatting semantics.</p>
+
+          <p>When presented on a visual medium, a <code>span</code> element is intended
+          to generate a sequence of inline areas, each containing one or more glyph
+          areas.</p>
+
+          <p>The <code>span</code> element accepts as its children zero or more elements
+          in the <code>Metadata.class</code> element group, followed by zero or more
+          elements in the <code>Animation.class</code> element group, followed by zero or
+          more intermixed <code>span</code> elements, <code>br</code> elements, or text
+          nodes interpreted as anonymous spans.</p>
+
+          <p>Any metadata specified by children in the <code>Metadata.class</code>
+          element group applies semantically to the <code>span</code> element and its
+          descendants as a whole.</p>
+
+          <p>Any animation elements specified by children in the
+          <code>Animation.class</code> element group apply semantically to the
+          <code>span</code> element.</p><a id="elt-syntax-span" name=
+          "elt-syntax-span"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: span
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;span
+  <a href="#timing-attribute-begin">begin</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-dur">dur</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-end">end</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#layout-attribute-region">region</a> = IDREF
+  <a href="#style-attribute-style">style</a> = IDREFS
+  <a href=
+"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute in TT Metadata namespace</em>}
+  {<em>any attribute in TT Style namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#element-vocab-group-table">Animation.class</a>*, <a href=
+"#element-vocab-group-table">Inline.class</a>*
+&lt;/span&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>An author may associate a set of style properties with a <code>span</code>
+          element by means of either the <code>style</code> attribute or inline style
+          attributes or a combination thereof.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Style properties that are associated with a <code>span</code> element in a
+            <em>Document Instance</em> are available for style inheritance by descendant
+            content elements such as <code>span</code> and <code>br</code>.</p>
+          </div>
+
+          <p>If no <code>timeContainer</code> attribute is specified on a
+          <code>span</code> element, then it must be interpreted as having
+          <em>parallel</em> time containment semantics.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="content-vocabulary-br" name="content-vocabulary-br"></a>7.1.7
+          br</h4>
+
+          <p>The <code>br</code> element denotes an explicit line break.</p><a id=
+          "elt-syntax-br" name="elt-syntax-br"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: br
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;br
+  <a href="#style-attribute-style">style</a> = IDREFS
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute in TT Metadata namespace</em>}
+  {<em>any attribute in TT Style namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#element-vocab-group-table">Animation.class</a>*
+&lt;/br&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>When presented on a visual medium, the presence of a <code>br</code> element
+          must be interpreted as a forced line break.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The visual presentation of a <code>br</code> element is intended to
+            produce the same effect as the control character <code>CR</code> (U+000D)
+            followed by the control code <code>LF</code> (U+000A) when presented on a
+            teletype device. Therefore, two <code>br</code> elements in sequence will
+            produce a different effect than a single <code>br</code> element.</p>
+          </div>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="content-attribute-vocabulary" name=
+        "content-attribute-vocabulary"></a>7.2 Content Attribute Vocabulary</h3>
+
+        <p>This section defines the following common attributes used with many or all
+        element types in the core vocabulary catalog:</p>
+
+        <ul>
+          <li>
+            <p><a href="#content-attribute-id"><b>7.2.1 xml:id</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#content-attribute-lang"><b>7.2.2 xml:lang</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#content-attribute-space"><b>7.2.3 xml:space</b></a></p>
+          </li>
+        </ul>
+
+        <div class="div3">
+          <h4><a id="content-attribute-id" name="content-attribute-id"></a>7.2.1
+          xml:id</h4>
+
+          <p>The <code>xml:id</code> attribute is used as defined by <a href=
+          "#xmlid">[XML ID]</a>.</p>
+
+          <p>The <code>xml:id</code> attribute may be used with any element in the core
+          vocabulary catalog.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="content-attribute-lang" name="content-attribute-lang"></a>7.2.2
+          xml:lang</h4>
+
+          <p>The <code>xml:lang</code> attribute is used as defined by <a href=
+          "#xml10">[XML 1.0]</a>, §2.12, <em>Language Identification</em>.</p>
+
+          <p>The <code>xml:lang</code> attribute must be specified on the <code>tt</code>
+          element and may be specified by an instance of any other element type in the
+          core vocabulary catalog except parameter vocabulary.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="content-attribute-space" name="content-attribute-space"></a>7.2.3
+          xml:space</h4>
+
+          <p>The <code>xml:space</code> attribute is used as defined by <a href=
+          "#xml10">[XML 1.0]</a>, §2.10, <em>White Space Handling</em>.</p>
+
+          <p>The <code>xml:space</code> attribute may be used with any element in the
+          core vocabulary catalog except parameter vocabulary.</p>
+
+          <p>The semantics of the value <code>default</code> are fixed to mean that when
+          performing presentation processing of a <em>Document Instance</em> as described
+          by <a href="#semantics-region-layout-step-2"><b>9.3.3 Synchronic Flow
+          Processing</b></a>, processing must occur as if the following properties were
+          specified on the affected elements of an equivalent intermediate XSL-FO
+          document:</p>
+
+          <ul>
+            <li>
+              <p><code>suppress-at-line-break="auto"</code></p>
+            </li>
+
+            <li>
+              <p><code>linefeed-treatment="treat-as-space"</code></p>
+            </li>
+
+            <li>
+              <p><code>white-space-collapse="true"</code></p>
+            </li>
+
+            <li>
+              <p><code>white-space-treatment="ignore-if-surrounding-linefeed"</code></p>
+            </li>
+          </ul>
+
+          <p>Similarly, the semantics of the value <code>preserve</code> are fixed to
+          mean that when performing presentation processing, processing must occur as if
+          the following properties were specified on the affected elements of an
+          equivalent intermediate XSL-FO document:</p>
+
+          <ul>
+            <li>
+              <p><code>suppress-at-line-break="retain"</code></p>
+            </li>
+
+            <li>
+              <p><code>linefeed-treatment="preserve"</code></p>
+            </li>
+
+            <li>
+              <p><code>white-space-collapse="false"</code></p>
+            </li>
+
+            <li>
+              <p><code>white-space-treatment="preserve"</code></p>
+            </li>
+          </ul>
+
+          <p>When performing other types of processing intended to eventually result in a
+          visual presentation by means other than those described in this specification,
+          the semantics of space collapsing and preservation as described above should be
+          respected. For other types of processing, the treatment of the
+          <code>xml:space</code> attribute is processor dependent, but should respect the
+          semantics described above if possible.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the above four cited XSL-FO properties are defined by by
+            <a href="#xsl11">[XSL 1.1]</a>, § 7.17.3, 7.16.7, 7.16.12, and 7.16.8,
+            respectively.</p>
+          </div>
+        </div>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="styling" name="styling"></a>8 Styling</h2>
+
+      <p>This section specifies the <em>styling</em> matter of the core vocabulary
+      catalog, where styling is to be understood as a separable layer of information that
+      applies to content and that denotes authorial intentions about the presentation of
+      that content.</p>
+
+      <p>Styling attributes are included in TTML to enable authorial intent of
+      presentation to be included within a self-contained document. This section
+      describes the semantics of style presentation in terms of a standard processing
+      model. TTML Processors are not required to present <em>Document Instances</em> in
+      any particular way; but an implementation of this model by a TTML Presentation
+      Processor that provides externally observable results that are consistent with this
+      model is likely to lead to a user experience that closely resembles the experience
+      intended by the documents' authors.</p>
+
+      <p>The semantics of TTML style presentation are described in terms of the model in
+      <a href="#xsl11">[XSL 1.1]</a>. The effects of the attributes in this section are
+      intended to be compatible with the layout and formatting model of XSL; however,
+      Presentation agents may use any technology to satisfy the authorial intent of the
+      document. In particular since <a href="#css2">[CSS2]</a> is a subset of this model,
+      a CSS processor may be used for the features that the models have in common.</p>
+
+      <p>No normative use of an <code>&lt;?xml-stylesheet ... ?&gt;</code> processing
+      instruction is defined by this specification.</p>
+
+      <div class="div2">
+        <h3><a id="styling-element-vocabulary" name="styling-element-vocabulary"></a>8.1
+        Styling Element Vocabulary</h3>
+
+        <p>The following elements specify the structure and principal styling aspects of
+        a <em>Document Instance</em>:</p>
+
+        <ul>
+          <li>
+            <p><a href="#styling-vocabulary-styling"><b>8.1.1 styling</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#styling-vocabulary-style"><b>8.1.2 style</b></a></p>
+          </li>
+        </ul>
+
+        <div class="div3">
+          <h4><a id="styling-vocabulary-styling" name=
+          "styling-vocabulary-styling"></a>8.1.1 styling</h4>
+
+          <p>The <code>styling</code> element is a container element used to group
+          styling matter, including metadata that applies to styling matter.</p>
+
+          <p>The <code>styling</code> element accepts as its children zero or more
+          elements in the <code>Metadata.class</code> element group, followed by zero or
+          more <code>style</code> elements.</p><a id="elt-syntax-styling" name=
+          "elt-syntax-styling"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: styling
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;styling
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#styling-vocabulary-style">style</a>*
+&lt;/styling&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>To the extent that time semantics apply to the content of the
+          <code>styling</code> element, the implied time interval of this element is
+          defined to be coterminous with the <em>Root Temporal Extent</em>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="styling-vocabulary-style" name="styling-vocabulary-style"></a>8.1.2
+          style</h4>
+
+          <p>The <code>style</code> element is used to define a set of style
+          specifications expressed as a specified style set in accordance with <a href=
+          "#semantics-style-resolution-processing-sss"><b>8.4.4.2 Specified Style Set
+          Processing</b></a>.</p>
+
+          <p>The <code>style</code> element accepts as its children zero or more
+          <code>metadata</code> elements.</p><a id="elt-syntax-style" name=
+          "elt-syntax-style"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: style
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;style
+  <a href="#style-attribute-style">style</a> = IDREFS
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute in TT Style namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+ <em>Content:</em> EMPTY
+&lt;/style&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If a <code>style</code> element appears as a descendant of a
+          <code>region</code> element, then the <code>style</code> element must be
+          ignored for the purpose of computing referential styles as defined by <a href=
+          "#semantics-style-association-referential"><b>8.4.1.2 Referential
+          Styling</b></a> and <a href=
+          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
+          Referential Styling</b></a>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>That is to say, when referential styling is used by an element to refer to
+            a <code>style</code> element, then the referenced <code>style</code> element
+            must appear as a descendant of the <code>styling</code> element, and not in
+            any other context.</p>
+          </div>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="styling-attribute-vocabulary" name=
+        "styling-attribute-vocabulary"></a>8.2 Styling Attribute Vocabulary</h3>
+
+        <p>This section defines the <a href="#style-attribute-style"><b>8.2.1
+        style</b></a> attribute used with both style definition elements as well as
+        content elements.</p>
+
+        <p>In addition, this section specifies the following attributes in the TT Style
+        Namespace for use with style definition elements, certain layout elements, and
+        content elements that support inline style specifications:</p>
+
+        <ul>
+          <li>
+            <p><a href="#style-attribute-backgroundColor"><b>8.2.2
+            tts:backgroundColor</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-color"><b>8.2.3 tts:color</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-direction"><b>8.2.4 tts:direction</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-display"><b>8.2.5 tts:display</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-displayAlign"><b>8.2.6
+            tts:displayAlign</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-extent"><b>8.2.7 tts:extent</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-fontFamily"><b>8.2.8 tts:fontFamily</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-fontSize"><b>8.2.9 tts:fontSize</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-fontStyle"><b>8.2.10 tts:fontStyle</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-fontWeight"><b>8.2.11 tts:fontWeight</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-lineHeight"><b>8.2.12 tts:lineHeight</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-opacity"><b>8.2.13 tts:opacity</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-origin"><b>8.2.14 tts:origin</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-overflow"><b>8.2.15 tts:overflow</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-padding"><b>8.2.16 tts:padding</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-showBackground"><b>8.2.17
+            tts:showBackground</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-textAlign"><b>8.2.18 tts:textAlign</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-textDecoration"><b>8.2.19
+            tts:textDecoration</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-textOutline"><b>8.2.20
+            tts:textOutline</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-unicodeBidi"><b>8.2.21
+            tts:unicodeBidi</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-visibility"><b>8.2.22 tts:visibility</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-wrapOption"><b>8.2.23 tts:wrapOption</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-writingMode"><b>8.2.24
+            tts:writingMode</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-attribute-zIndex"><b>8.2.25 tts:zIndex</b></a></p>
+          </li>
+        </ul>
+
+        <p>Unless explicitly stated otherwise, linear white-space (LWSP) must appear
+        between adjacent non-terminal components of a value of a TT Style or TT Style
+        Extension Property value unless some other delimiter is permitted and used.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>This specification makes use of <em>lowerCamelCased</em> local names for
+          style attributes that are based upon like-named properties defined by <a href=
+          "#xsl11">[XSL 1.1]</a>. This convention is likewise extended to token values of
+          such properties.</p>
+        </div>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>A style property may be expressed as a specified attribute on any content
+          element type independently of whether the property applies to that element
+          type. This capability permits the expression of an inheritable style property
+          on ancestor elements to which the property does not apply.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-style" name="style-attribute-style"></a>8.2.1
+          style</h4>
+
+          <p>The <code>style</code> attribute is used by referential style association to
+          reference one or more <code>style</code> elements each of which define a style
+          (property) set.</p>
+
+          <p>The <code>style</code> attribute may be specified by an instance of the
+          following element types:</p>
+
+          <ul>
+            <li>
+              <p><a href="#document-structure-vocabulary-body"><code>body</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#layout-vocabulary-region"><code>region</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#styling-vocabulary-style"><code>style</code></a></p>
+            </li>
+          </ul>
+
+          <p>If specified, the value of a <code>style</code> attribute must adhere to the
+          <code>IDREFS</code> data type defined by <a href="#xsd-2">[XML Schema Part
+          2]</a>, § 3.3.10, and, furthermore, each IDREF must reference a
+          <code>style</code> element which has a <code>styling</code> element as an
+          ancestor.</p>
+
+          <p>If the same IDREF, <em>ID<sub>1</sub></em>, appears more than one time in
+          the value of a <code>style</code> attribute, then there should be an
+          intervening IDREF, <em>ID<sub>2</sub></em>, where <em>ID<sub>2</sub></em> is
+          not equal to <em>ID<sub>1</sub></em>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>This constraint is intended to discourage the use of redundant referential
+            styling while still allowing the same style to be referenced multiple times
+            in order to potentially override prior referenced styles, e.g., when an
+            intervening, distinct style is referenced in the IDREFS list.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>See the specific element type definitions that permit use of the
+            <code>style</code> attribute, as well as <a href=
+            "#semantics-style-association-referential"><b>8.4.1.2 Referential
+            Styling</b></a> and <a href=
+            "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
+            Referential Styling</b></a>, for further information on its semantics.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-backgroundColor" name=
+          "style-attribute-backgroundColor"></a>8.2.2 tts:backgroundColor</h4>
+
+          <p>The <code>tts:backgroundColor</code> attribute is used to specify a style
+          property that defines the background color of a region or an area generated by
+          content flowed into a region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-backgroundColor" name=
+          "style-property-details-backgroundColor"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><a href="#style-value-color">&lt;color&gt;</a></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>transparent</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
+                <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
+                "#content-vocabulary-p"><code>p</code></a>, <a href=
+                "#layout-vocabulary-region"><code>region</code></a>, <a href=
+                "#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>The <code>tts:backgroundColor</code> style is illustrated by the following
+          example.</p><a id="style-attribute-backgroundColor-example-1" name=
+          "style-attribute-backgroundColor-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Background Color
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="306px 114px"/&gt;
+  &lt;style <span class="strong">tts:backgroundColor="red"</span>/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:padding="3px 40px"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1" <span class=
+"strong">tts:backgroundColor="purple"</span> tts:textAlign="center"&gt;
+  Twinkle, twinkle, little bat!&lt;br/&gt;
+  How &lt;span <span class=
+"strong">tts:backgroundColor="green"</span>&gt;I wonder&lt;/span&gt; where you're at!
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-backgroundColor-example-1-images" name=
+          "style-attribute-backgroundColor-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Background Color
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/backgroundColor.png" alt=
+                "TTML backgroundColor style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.8.2.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-color" name="style-attribute-color"></a>8.2.3
+          tts:color</h4>
+
+          <p>The <code>tts:color</code> attribute is used to specify a style property
+          that defines the foreground color of marks associated with an area generated by
+          content flowed into a region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-color" name=
+          "style-property-details-color"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><a href="#style-value-color">&lt;color&gt;</a></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td>see prose</td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>The initial value of the <code>tts:color</code> property is considered to be
+          implementation dependent. In the absence of end-user preference information, a
+          conformant presentation processor should use an initial value that is highly
+          contrastive to the background color of the <em>Root Container Region</em>.</p>
+
+          <p>The <code>tts:color</code> style is illustrated by the following
+          example.</p><a id="style-attribute-color-example-1" name=
+          "style-attribute-color-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Color
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style <span class="strong">tts:color="white"</span>/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  In spring, when woods are &lt;span <span class=
+"strong">tts:color="green"</span>&gt;getting green&lt;/span&gt;,&lt;br/&gt;
+  I'll try and tell you what I mean.
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-color-example-1-images" name=
+          "style-attribute-color-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Color
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/color.png" alt="TTML color style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.18.1.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-direction" name=
+          "style-attribute-direction"></a>8.2.4 tts:direction</h4>
+
+          <p>The <code>tts:direction</code> attribute is used to specify a style property
+          that defines the directionality of an embedding or override according to the
+          Unicode bidirectional algorithm.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-direction" name=
+          "style-property-details-direction"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>ltr</code> | <code>rtl</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>ltr</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-p"><code>p</code></a>, <a href=
+                "#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must ignore the attribute.</p>
+
+          <p>The <code>tts:direction</code> style is illustrated by the following
+          example.</p><a id="style-attribute-direction-example-1" name=
+          "style-attribute-direction-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Direction
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="265px 84px"/&gt;
+  &lt;style tts:padding="5px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  Little birds are playing&lt;br/&gt;
+  Bagpipes on the shore,&lt;br/&gt;
+  &lt;span tts:unicodeBidi="bidiOverride" <span class=
+"strong">tts:direction="rtl"</span>&gt;where the tourists snore.&lt;/span&gt;
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-direction-example-1-images" name=
+          "style-attribute-direction-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Direction
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/direction.png" alt=
+                "TTML direction style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.29.1.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-display" name="style-attribute-display"></a>8.2.5
+          tts:display</h4>
+
+          <p>The <code>tts:display</code> attribute is used to specify a style property
+          that defines whether an element is a candidate for layout and composition in a
+          region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-display" name=
+          "style-property-details-display"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>auto</code> | <code>none</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>auto</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
+                <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
+                "#content-vocabulary-p"><code>p</code></a>, <a href=
+                "#layout-vocabulary-region"><code>region</code></a>, <a href=
+                "#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>If the value of this attribute is <code>auto</code>, then the affected
+          element is a candidate for region layout and presentation; however, if the
+          value is <code>none</code>, then the affected element and its descendants must
+          be considered ineligible for region layout and presentation.</p>
+
+          <p>The <code>tts:display</code> style is illustrated by the following
+          example.</p><a id="style-attribute-display-example-1" name=
+          "style-attribute-display-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Display
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="369px 119px"
+            tts:backgroundColor="black"
+            tts:color="white"
+            tts:displayAlign="before"
+            tts:textAlign="start"/&gt;
+&lt;/region&gt;
+...
+&lt;div region="r1"&gt;
+  &lt;p dur="5s"&gt;
+    [[[
+    &lt;span <span class="strong">tts:display="none"</span>&gt;
+      &lt;set begin="1s" dur="1s" <span class="strong">tts:display="auto"</span>/&gt;
+      Beautiful soup,
+    &lt;/span&gt;
+    &lt;span <span class="strong">tts:display="none"</span>&gt;
+      &lt;set begin="2s" dur="1s" <span class="strong">tts:display="auto"</span>/&gt;
+      so rich and green,
+    &lt;/span&gt;
+    &lt;span <span class="strong">tts:display="none"</span>&gt;
+      &lt;set begin="3s" dur="1s" <span class="strong">tts:display="auto"</span>/&gt;
+      waiting in a hot tureen!
+    &lt;/span&gt;
+    ]]]
+  &lt;/p&gt;
+&lt;/div&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-display-example-1-images" name=
+          "style-attribute-display-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Display
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/display_0.png" alt=
+                "TTML display style property - [0,1)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/display_1.png" alt=
+                "TTML display style property - [1,2)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/display_2.png" alt=
+                "TTML display style property - [2,3)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/display_3.png" alt=
+                "TTML display style property - [3,4)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/display_4.png" alt=
+                "TTML display style property - [4,5)"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#css2">[CSS2]</a>, § 9.2.4.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-displayAlign" name=
+          "style-attribute-displayAlign"></a>8.2.6 tts:displayAlign</h4>
+
+          <p>The <code>tts:displayAlign</code> attribute is used to specify a style
+          property that defines the alignment of block areas in the block progression
+          direction.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-displayAlign" name=
+          "style-property-details-displayAlign"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>before</code> | <code>center</code> | <code>after</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>before</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>before</code> were
+          specified.</p>
+
+          <p>The <code>tts:displayAlign</code> style is illustrated by the following
+          example.</p><a id="style-attribute-displayAlign-example-1" name=
+          "style-attribute-displayAlign-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Display Align
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="128px 66px" tts:origin="0px 0px"
+       tts:backgroundColor="black" tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:displayAlign="before"</span>/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r2"&gt;
+  &lt;style tts:extent="192px 66px" tts:origin="128px 66px"/&gt;
+       tts:backgroundColor="green" tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:displayAlign="after"</span>/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r3"&gt;
+  &lt;style tts:extent="128px 66px"/&gt; style tts:origin="0px 132px"
+       tts:backgroundColor="black" tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:displayAlign="before"</span>/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r4"&gt;
+  &lt;style tts:extent="192px 66px" tts:origin="128px 198px"/&gt;
+       tts:backgroundColor="green" tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:displayAlign="after"</span>/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+&lt;/region&gt;
+...
+&lt;div&gt;
+  &lt;p region="r1"&gt;I sent a message to the fish:&lt;/p&gt;
+  &lt;p region="r2"&gt;I told them&lt;br/&gt; "This is what I wish."&lt;/p&gt;
+  &lt;p region="r3"&gt;The little fishes of the sea,&lt;/p&gt;
+  &lt;p region="r4"&gt;They sent an&lt;br/&gt; answer back to me.&lt;/p&gt;
+&lt;/div&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-displayAlign-example-1-images" name=
+          "style-attribute-displayAlign-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Display Align
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/displayAlign.png" alt=
+                "TTML displayAlign style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.14.4.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-extent" name="style-attribute-extent"></a>8.2.7
+          tts:extent</h4>
+
+          <p>The <code>tts:extent</code> attribute is used to specify the <em>width</em>
+          and <em>height</em> of a region area (which may be the <em>Root Container
+          Region</em>).</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-extent" name=
+          "style-property-details-extent"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>auto</code> | <a href="#style-value-length">&lt;length&gt;</a>
+                <a href="#style-value-length">&lt;length&gt;</a></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>auto</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#document-structure-vocabulary-tt"><code>tt</code></a>,
+                <a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>relative to width and height of <em>Root Container Region</em></td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the value of this attribute consists of two <a href=
+          "#style-value-length">&lt;length&gt;</a> specifications, then they must be
+          interpreted as <em>width</em> and <em>height</em>, where the first
+          specification is the <em>width</em>, and the second specification is the
+          <em>height</em>.</p>
+
+          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used to
+          express extent must be non-negative.</p>
+
+          <p>If the value of this attribute is <code>auto</code>, then the initial value
+          of the style property must be considered to be the same as the extent of the
+          <em>Root Container Region</em>.</p>
+
+          <p>The extent of the <em>Root Container Region</em> is determined either by a
+          <code>tts:extent</code> specified on the <code>tt</code> element, if present,
+          or as described by <a href="#document-structure-vocabulary-tt"><b>7.1.1
+          tt</b></a> if not present. If <code>tts:extent</code> is specified on the
+          <code>tt</code> element, then the width and height must be expressed in terms
+          of two <a href="#style-value-length">&lt;length&gt;</a> specifications, and
+          these specifications must be expressed as non-percentage, definite lengths
+          using pixel units.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>auto</code> were
+          specified.</p>
+
+          <p>The <code>tts:extent</code> style is illustrated by the following
+          example.</p><a id="style-attribute-extent-example-1" name=
+          "style-attribute-extent-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Extent
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style <span class="strong">tts:extent="330px 122px"</span>/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  'Tis the voice of the Lobster:&lt;br/&gt;
+  I heard him declare,&lt;br/&gt;
+  "You have baked me too brown,&lt;br/&gt;
+  I must sugar my hair."
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-extent-example-1-images" name=
+          "style-attribute-extent-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Extent
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/extent.png" alt="TTML extent style property"></td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-fontFamily" name=
+          "style-attribute-fontFamily"></a>8.2.8 tts:fontFamily</h4>
+
+          <p>The <code>tts:fontFamily</code> attribute is used to specify a style
+          property that defines the font family from which glyphs are selected for glyph
+          areas generated by content flowed into a region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-fontFamily" name=
+          "style-property-details-fontFamily"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td>(<a href="#style-value-familyName">&lt;familyName&gt;</a> | <a href=
+                "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a>)
+                (<code>","</code> &nbsp;(<a href=
+                "#style-value-familyName">&lt;familyName&gt;</a> | <a href=
+                "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a>))*</td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>default</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The initial value, <code>default</code>, is a generic font family name,
+            and is further described in <a href="#style-value-genericFamilyName"><b>8.3.6
+            &lt;genericFamilyName&gt;</b></a> below.</p>
+          </div>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>If a specified font family is not available, then a presentation processor
+          must attempt to map the specified font family to an available font family that
+          has similar typographic characteristics, or, in the absence of such a mapping,
+          it must interpret the font family as if the value <code>default</code> were
+          specified.</p>
+
+          <p>The <code>tts:fontFamily</code> style is illustrated by the following
+          example.</p><a id="style-attribute-fontFamily-example-1" name=
+          "style-attribute-fontFamily-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Font Family
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="474px 146px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="center"/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+  &lt;style <span class="strong">tts:fontFamily="proportionalSansSerif"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;div region="r1"&gt;
+  &lt;p&gt;
+    "The time has come," the Walrus said,&lt;br/&gt;
+    "to talk of many things:
+  &lt;/p&gt;
+  &lt;p tts:textAlign="end" <span class=
+"strong">tts:fontFamily="monospaceSerif"</span>&gt;
+    Of shoes, and ships, and sealing wax,&lt;br/&gt;
+    Of cabbages and kings,
+  &lt;/p&gt;
+  &lt;p&gt;
+    And why the sea is boiling hot,&lt;br/&gt;
+    and whether pigs have wings."
+  &lt;/p&gt;
+&lt;/div&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-fontFamily-example-1-images" name=
+          "style-attribute-fontFamily-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Font Family
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/fontFamily.png" alt=
+                "TTML fontFamily style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.9.2.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-fontSize" name="style-attribute-fontSize"></a>8.2.9
+          tts:fontSize</h4>
+
+          <p>The <code>tts:fontSize</code> attribute is used to specify a style property
+          that defines the font size for glyphs that are selected for glyph areas
+          generated by content flowed into a region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-fontSize" name=
+          "style-property-details-fontSize"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><a href="#style-value-length">&lt;length&gt;</a> <a href=
+                "#style-value-length">&lt;length&gt;</a>?</td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>1c</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>relative to parent element's font size, or if no parent element, then
+                relative to the <em>Computed Cell Size</em></td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If a single <a href="#style-value-length">&lt;length&gt;</a> value is
+          specified, then this length applies equally to horizontal and vertical scaling
+          of a glyph's EM square; if two <a href="#style-value-length">&lt;length&gt;</a>
+          values are specified, then the first expresses the horizontal scaling and the
+          second expresses vertical scaling.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Use of independent horizontal and vertical font sizes is expected to be
+            used with cell based units in order to denote fonts that are two rows in
+            height and one column in width.</p>
+          </div>
+
+          <p>If horizontal and vertical sizes are expressed independently, then the units
+          of the <a href="#style-value-length">&lt;length&gt;</a> values must be the
+          same.</p>
+
+          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used to
+          express font size must be non-negative.</p>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the closest supported value were
+          specified.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The expression <code>1c</code> means one cell, where <code>'c'</code>
+            expresses the <em>cell</em> length unit as defined by <a href=
+            "#style-value-length"><b>8.3.9 &lt;length&gt;</b></a>. When a single
+            &lt;length&gt; is expressed using cell units, then it refers to the height of
+            the <em>Computed Cell Size</em>.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>As specified above, the use of percentage units to express font size are
+            interpreted as relative to <em>Computed Cell Size</em> when there is no
+            parent element. For example, if cell resolution is 32 by 15, and the extent
+            of the <em>Root Container Region</em> is 640 by 480, then the <em>Computed
+            Cell Size</em> is [20px, 32px], i.e., 640px/32 (width) and 480px/15 (height).
+            Consequently, if <code>tts:fontSize</code> were specified as 75% on the root
+            <code>tt</code> element, then this would be equivalent to specifying 24px,
+            i.e., 32px cell height * 75%. If two length expressions (independent
+            horizontal and vertical font scaling) were specified, e.g., "80% 75%", then
+            this would be equivalent to specifying "16px 24px", i.e., 80% of 20px cell
+            width is 16px, and 75% of 32px cell height is 24px.</p>
+          </div>
+
+          <p>The <code>tts:fontSize</code> style is illustrated by the following
+          example.</p><a id="style-attribute-fontSize-example-1" name=
+          "style-attribute-fontSize-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Font Size
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="299px 97px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="center"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
+  &lt;style <span class="strong">tts:fontSize="18px"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  Then fill up the glasses&lt;br/&gt;
+  with treacle and ink,&lt;br/&gt;
+  Or anything else&lt;br/&gt;
+  that is &lt;span <span class=
+"strong">tts:fontSize="24px"</span>&gt;pleasant&lt;/span&gt; to drink.
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-fontSize-example-1-images" name=
+          "style-attribute-fontSize-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Font Size
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/fontSize.png" alt=
+                "TTML fontSize style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.9.4. The
+            addition of a second length component to permit specifying font width and
+            height independently is an extension introduced by TTML.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-fontStyle" name=
+          "style-attribute-fontStyle"></a>8.2.10 tts:fontStyle</h4>
+
+          <p>The <code>tts:fontStyle</code> attribute is used to specify a style property
+          that defines the font style to apply to glyphs that are selected for glyph
+          areas generated by content flowed into a region, where the mapping from font
+          style value to specific font face or style parameterization is not determined
+          by this specification.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-fontStyle" name=
+          "style-property-details-fontStyle"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>normal</code> | <code>italic</code> | <code>oblique</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>normal</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>Use of the value <code>oblique</code> denotes a shear transformation (at an
+          unspecified angle) in the inline progression dimension.</p>
+
+          <p>If a specified font style is not available, then a presentation processor
+          must attempt to map the specified font style to an available font style that
+          has similar typographic characteristics, or, in the absence of such a mapping,
+          it must interpret the font style as if the value <code>normal</code> were
+          specified.</p>
+
+          <p>The <code>tts:fontStyle</code> style is illustrated by the following
+          example.</p><a id="style-attribute-fontStyle-example-1" name=
+          "style-attribute-fontStyle-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Font Style
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="331px 84px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  In autumn, when the leaves are brown,&lt;br/&gt;
+  Take pen and ink, and &lt;span <span class=
+"strong">tts:fontStyle="italic"</span>&gt;write it down.&lt;/span&gt;
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-fontStyle-example-1-images" name=
+          "style-attribute-fontStyle-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Font Style
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/fontStyle.png" alt=
+                "TTML fontStyle style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.9.7.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-fontWeight" name=
+          "style-attribute-fontWeight"></a>8.2.11 tts:fontWeight</h4>
+
+          <p>The <code>tts:fontWeight</code> attribute is used to specify a style
+          property that defines the font weight to apply to glyphs that are selected for
+          glyph areas generated by content flowed into a region, where the mapping from
+          font weight value to specific font face or weight parameterization is not
+          determined by this specification.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-fontWeight" name=
+          "style-property-details-fontWeight"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>normal</code> | <code>bold</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>normal</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>If a specified font weight is not available, then a presentation processor
+          must attempt to map the specified font weight to an available font weight that
+          has similar typographic characteristics, or, in the absence of such a mapping,
+          it must interpret the font weight as if the value <code>normal</code> were
+          specified.</p>
+
+          <p>The <code>tts:fontWeight</code> style is illustrated by the following
+          example.</p><a id="style-attribute-fontWeight-example-1" name=
+          "style-attribute-fontWeight-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Font Weight
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="376px 95px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="center"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  They told me you had been to her,&lt;br/&gt;
+  &lt;span <span class=
+"strong">tts:fontWeight="bold"</span>&gt;and mentioned me to him:&lt;/span&gt;&lt;br/&gt;
+  She gave me a good character&lt;br/&gt;
+  &lt;span <span class=
+"strong">tts:fontWeight="bold"</span>&gt;but said I could not swim.&lt;/span&gt;
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-fontWeight-example-1-images" name=
+          "style-attribute-fontWeight-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Font Weight
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/fontWeight.png" alt=
+                "TTML fontWeight style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.9.9.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-lineHeight" name=
+          "style-attribute-lineHeight"></a>8.2.12 tts:lineHeight</h4>
+
+          <p>The <code>tts:lineHeight</code> attribute is used to specify a style
+          property that defines the inter-baseline separation between line areas
+          generated by content flowed into a region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-lineHeight" name=
+          "style-property-details-lineHeight"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>normal</code> | <a href=
+                "#style-value-length">&lt;length&gt;</a></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>normal</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-p"><code>p</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>relative to this element's font size</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the value of this attribute is <code>normal</code>, then the initial
+          value of the style property must be considered to be the same as the largest
+          font size that applies to any descendant element.</p>
+
+          <p>If specified as a <a href="#style-value-length">&lt;length&gt;</a>, then the
+          length must be non-negative.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>normal</code> were
+          specified.</p>
+
+          <p>The <code>tts:lineHeight</code> style is illustrated by the following
+          example.</p><a id="style-attribute-lineHeight-example-1" name=
+          "style-attribute-lineHeight-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Line Height
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="255px 190px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="center"/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
+  &lt;style tts:fontSize="16px"/&gt;
+  &lt;style <span class="strong">tts:lineHeight="32px"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  He thought he saw an elephant,&lt;br/&gt;
+  That practised on a fife:&lt;br/&gt;
+  He looked again, and found it was&lt;br/&gt;
+  A letter from his wife.&lt;br/&gt;
+  "At length I realise," he said,&lt;br/&gt;
+  "The bitterness of Life.
+"&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-lineHeight-example-1-images" name=
+          "style-attribute-lineHeight-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Line Height
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/lineHeight.png" alt=
+                "TTML lineHeight style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.16.4.
+            Furthermore, it is the intention of this specification that the allocation
+            rectangle of a line be consistent with the <span class=
+            "strong">per-inline-height-rectangle</span> as defined by <a href=
+            "#xsl11">[XSL 1.1]</a>, § 4.5, i.e., that a CSS-style line box stacking
+            strategy be used.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-opacity" name="style-attribute-opacity"></a>8.2.13
+          tts:opacity</h4>
+
+          <p>The <code>tts:opacity</code> attribute is used to specify a style property
+          that defines the opacity (or conversely, the transparency) of marks associated
+          with a region.</p>
+
+          <p>When presented onto a visual medium, the opacity of the region is applied
+          uniformly and on a linear scale to all marks produced by content targeted to
+          the region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-opacity" name=
+          "style-property-details-opacity"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><a href="#style-value-alpha">&lt;alpha&gt;</a></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>1.0</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The <code>tts:opacity</code> style is illustrated by the following
+          example.</p><a id="style-attribute-opacity-example-1" name=
+          "style-attribute-opacity-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Opacity
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1" dur="5s"&gt;
+  &lt;set begin="0s" dur="1s" <span class="strong">tts:opacity="1.00"</span>/&gt;
+  &lt;set begin="1s" dur="1s" <span class="strong">tts:opacity="0.75"</span>/&gt;
+  &lt;set begin="2s" dur="1s" <span class="strong">tts:opacity="0.50"</span>/&gt;
+  &lt;set begin="3s" dur="1s" <span class="strong">tts:opacity="0.25"</span>/&gt;
+  &lt;set begin="4s" dur="1s" <span class="strong">tts:opacity="0.00"</span>/&gt;
+  &lt;style tts:extent="304px 77px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  The sun was shining on the sea
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-opacity-example-1-images" name=
+          "style-attribute-opacity-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Opacity
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/opacity_0.png" alt=
+                "TTML opacity style property - [0,1)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/opacity_1.png" alt=
+                "TTML opacity style property - [1,2)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/opacity_2.png" alt=
+                "TTML opacity style property - [2,3)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/opacity_3.png" alt=
+                "TTML opacity style property - [3,4)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/opacity_4.png" alt=
+                "TTML opacity style property - [4,5)"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#css3-color">[CSS3 Color]</a>, § 3.2.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-origin" name="style-attribute-origin"></a>8.2.14
+          tts:origin</h4>
+
+          <p>The <code>tts:origin</code> attribute is used to specify the <em>x</em> and
+          <em>y</em> coordinates of the origin of a region area with respect to the
+          origin of the <em>Root Container Region</em>.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-origin" name=
+          "style-property-details-origin"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>auto</code> | <a href="#style-value-length">&lt;length&gt;</a>
+                <a href="#style-value-length">&lt;length&gt;</a></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>auto</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>relative to width and height of <em>Root Container Region</em></td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the value of this attribute consists of two <a href=
+          "#style-value-length">&lt;length&gt;</a> specifications, then they must be
+          interpreted as <em>x</em> and <em>y</em> coordinates, where the first
+          specification is the <em>x</em> coordinate, and the second specification is the
+          <em>y</em> coordinate.</p>
+
+          <p>If the value of this attribute is <code>auto</code>, then the initial value
+          of the style property must be considered to be the same as the origin of the
+          <em>Root Container Region</em>.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>auto</code> were
+          specified.</p>
+
+          <p>The <code>tts:origin</code> style is illustrated by the following
+          example.</p><a id="style-attribute-origin-example-1" name=
+          "style-attribute-origin-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Origin
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style <span class="strong">tts:origin="40px 40px"</span>/&gt;
+  &lt;style tts:extent="308px 92px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="center"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  "To dine!" she shrieked in dragon-wrath.&lt;br/&gt;
+  "To swallow wines all foam and froth!&lt;br/&gt;
+   To simper at a table-cloth!"
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-origin-example-1-images" name=
+          "style-attribute-origin-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Origin
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/origin.png" alt="TTML origin style property"></td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-overflow" name="style-attribute-overflow"></a>8.2.15
+          tts:overflow</h4>
+
+          <p>The <code>tts:overflow</code> attribute is used to specify a style property
+          that defines whether a region area is clipped or not if the descendant areas of
+          the region overflow its extent.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-overflow" name=
+          "style-property-details-overflow"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>visible</code> | <code>hidden</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>hidden</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the value of this attribute is <code>visible</code>, then content should
+          not be clipped outside of the affected region, and region composition and
+          layout must be performed as if the region's width and height were
+          unconstrained, but with a well-defined origin. If the value is
+          <code>hidden</code>, then content should be clipped outside of the affected
+          region.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Unless a manual line break element <code>br</code> is used by the content
+            author, a paragraph of a given region will generate no more than one line
+            area in that region if the value of the <code>tts:overflow</code> style that
+            applies to the region is <code>visible</code> and if the applicable
+            <code>tts:wrapOption</code> style is <code>noWrap</code>.</p>
+          </div>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>hidden</code> were
+          specified.</p>
+
+          <p>The <code>tts:overflow</code> style is illustrated by the following
+          example.</p><a id="style-attribute-overflow-example-1" name=
+          "style-attribute-overflow-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Overflow
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="232px 40px"/&gt;
+  &lt;style tts:origin="0px 0px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="red"/&gt;
+  &lt;style tts:displayAlign="before"/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
+  &lt;style tts:fontSize="18px"/&gt;
+  &lt;style tts:wrapOption="noWrap"/&gt;
+  &lt;style <span class="strong">tts:overflow="visible"</span>/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r2"&gt;
+  &lt;style tts:extent="232px 40px"/&gt;
+  &lt;style tts:origin="0px 43px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="red"/&gt;
+  &lt;style tts:displayAlign="before"/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
+  &lt;style tts:fontSize="18px"/&gt;
+  &lt;style tts:wrapOption="noWrap"/&gt;
+  &lt;style <span class="strong">tts:overflow="hidden"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  "But wait a bit," the Oysters cried,&lt;br/&gt;
+  "Before we have our chat;
+&lt;/p&gt;
+&lt;p region="r2"&gt;
+  For some of us are out of breath,&lt;br/&gt;
+  And all of us are fat!"
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-overflow-example-1-images" name=
+          "style-attribute-overflow-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Overflow
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/overflow.png" alt=
+                "TTML overflow style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, the <code>tts:noWrap</code> is set to
+            <code>noWrap</code> to prevent automatic line wrapping (breaking); if this
+            were not specified, then overflow would occur in the block progression
+            direction as opposed to the inline progression direction.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.21.2.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-padding" name="style-attribute-padding"></a>8.2.16
+          tts:padding</h4>
+
+          <p>The <code>tts:padding</code> attribute is used to specify padding (or inset)
+          space on all sides of a region area.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-padding" name=
+          "style-property-details-padding"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><a href="#style-value-length">&lt;length&gt;</a> | <a href=
+                "#style-value-length">&lt;length&gt;</a> <a href=
+                "#style-value-length">&lt;length&gt;</a> | <a href=
+                "#style-value-length">&lt;length&gt;</a> <a href=
+                "#style-value-length">&lt;length&gt;</a> <a href=
+                "#style-value-length">&lt;length&gt;</a> | <a href=
+                "#style-value-length">&lt;length&gt;</a> <a href=
+                "#style-value-length">&lt;length&gt;</a> <a href=
+                "#style-value-length">&lt;length&gt;</a> <a href=
+                "#style-value-length">&lt;length&gt;</a></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>0px</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>relative to width and height of region</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the value of this attribute consists of one <a href=
+          "#style-value-length">&lt;length&gt;</a> specification, then that length
+          applies to all edges of the affected areas. If the value consists of two
+          <a href="#style-value-length">&lt;length&gt;</a> specifications, then the first
+          applies to the before and after edges, and the second applies to the start and
+          end edges. If three <a href="#style-value-length">&lt;length&gt;</a>
+          specifications are provided, then the first applies to the before edge, the
+          second applies to the start and end edges, and the third applies to the after
+          edge. If four <a href="#style-value-length">&lt;length&gt;</a> specifications
+          are provided, then they apply to before, end, after, and start edges,
+          respectively.</p>
+
+          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used to
+          express padding must be non-negative.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>0px</code> were
+          specified.</p>
+
+          <p>The <code>tts:padding</code> style is illustrated by the following
+          example.</p><a id="style-attribute-padding-example-1" name=
+          "style-attribute-padding-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Padding
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="446px 104px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+  &lt;style <span class="strong">tts:padding="10px 40px"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1" tts:backgroundColor="red"&gt;
+  Just the place for a Snark! I have said it twice:&lt;br/&gt;
+  That alone should encourage the crew.&lt;br/&gt;
+  Just the place for a Snark! I have said it thrice:&lt;br/&gt;
+  What I tell you three times is true.
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>When rendering an area to which padding applies, the background color that
+          applies to the area is rendered into the padded portion of the area.</p><a id=
+          "style-attribute-padding-example-1-images" name=
+          "style-attribute-padding-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Padding
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/padding.png" alt="TTML padding style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.31.15, except
+            that individual shorthand values map to writing mode relative padding values
+            as defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.8.31, 7.8.32, 7.8.33, and
+            7.8.34.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-showBackground" name=
+          "style-attribute-showBackground"></a>8.2.17 tts:showBackground</h4>
+
+          <p>The <code>tts:showBackground</code> attribute is used to specify constraints
+          on when the background color of a region is intended to be presented.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-showBackground" name=
+          "style-property-details-showBackground"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>always</code> | <code>whenActive</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>always</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If the value of this attribute is <code>always</code>, then the background
+          color of a region is always rendered when performing presentation processing on
+          a visual medium; if the value is <code>whenActive</code>, then the background
+          color of a region is rendered only when some content is flowed into the
+          region.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>always</code> were
+          specified.</p>
+
+          <p>The <code>tts:showBackground</code> style is illustrated by the following
+          example.</p><a id="style-attribute-showBackground-example-1" name=
+          "style-attribute-showBackground-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Show Background
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:origin="0px 0px"/&gt;
+  &lt;style tts:extent="265px 100px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style <span class="strong">tts:showBackground="always"</span>/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="before"/&gt;
+  &lt;style tts:textAlign="start"/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r2"&gt;
+  &lt;style tts:origin="205px 60px"/&gt;
+  &lt;style tts:extent="290px 100px"/&gt;
+  &lt;style tts:backgroundColor="red"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="before"/&gt;
+  &lt;style tts:textAlign="end"/&gt;
+  &lt;style <span class="strong">tts:showBackground="whenActive"</span>/&gt;
+&lt;/region&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#smil21">[SMIL 2.1]</a>, § 5.3.3.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-textAlign" name=
+          "style-attribute-textAlign"></a>8.2.18 tts:textAlign</h4>
+
+          <p>The <code>tts:textAlign</code> attribute is used to specify a style property
+          that defines how inline areas are aligned within a containing block area in the
+          inline progression direction.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-textAlign" name=
+          "style-property-details-textAlign"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>left</code> | <code>center</code> | <code>right</code> |
+                <code>start</code> | <code>end</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>start</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-p"><code>p</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>start</code> were
+          specified.</p>
+
+          <p>The <code>tts:textAlign</code> style is illustrated by the following
+          example.</p><a id="style-attribute-textAlign-example-1" name=
+          "style-attribute-textAlign-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Text Align
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="355px 43px"/&gt;
+  &lt;style tts:origin="0px 0px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:textAlign="start"</span>/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r2"&gt;
+  &lt;style tts:extent="355px 43px"/&gt;
+  &lt;style tts:origin="0px 47px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:textAlign="end"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  Beware the Jabberwock, my son!&lt;br/&gt;
+  The jaws that bite, the claws that catch!
+&lt;/p&gt;
+&lt;p region="r2"&gt;
+  Beware the Jubjub bird, and shun&lt;br/&gt;
+  The frumious Bandersnatch!
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-textAlign-example-1-images" name=
+          "style-attribute-textAlign-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Text Align
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/textAlign.png" alt=
+                "TTML textAlign style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.16.9.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-textDecoration" name=
+          "style-attribute-textDecoration"></a>8.2.19 tts:textDecoration</h4>
+
+          <p>The <code>tts:textDecoration</code> attribute is used to specify a style
+          property that defines a text decoration effect to apply to glyph areas or other
+          inline areas that are generated by content flowed into a region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-textDecoration" name=
+          "style-property-details-textDecoration"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>none</code> | [ [ <code>underline</code> |
+                <code>noUnderline</code> ] || [ <code>lineThrough</code> |
+                <code>noLineThrough</code> ] || [ <code>overline</code> |
+                <code>noOverline</code> ] ]</td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>none</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>none</code> were
+          specified.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The syntax used above in defining the value of this property is based on
+            the value component syntax defined in <a href="#css2">[CSS2]</a>, § 1.4.2.1.
+            In essence, one or more of the values separated by <code>||</code> may appear
+            in the property value in any order, such as <code>"noUnderline overline
+            lineThrough"</code>.</p>
+          </div>
+
+          <p>The <code>tts:textDecoration</code> style is illustrated by the following
+          example.</p><a id="style-attribute-textDecoration-example-1" name=
+          "style-attribute-textDecoration-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Text Decoration
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="385px 82px"/&gt;
+  &lt;style tts:origin="0px 0px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:padding="5px 2px"/&gt;
+  &lt;style <span class="strong">tts:textDecoration="underline"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  The sea was wet&lt;span <span class=
+"strong">tts:textDecoration="noUnderline"</span>&gt; as &lt;/span&gt;wet
+  &lt;span <span class="strong">tts:textDecoration="noUnderline"</span>&gt;
+    could be,&lt;br/&gt;
+    The sand was dry as dry.&lt;br/&gt;
+    &lt;span <span class=
+"strong">tts:textDecoration="lineThrough"</span>&gt;There weren't any&lt;/span&gt;
+    You &lt;span <span class=
+"strong">tts:textDecoration="lineThrough"</span>&gt;couldn't&lt;/span&gt;
+    could not see a cloud&lt;br/&gt;
+    Because no cloud was in the sky.
+  &lt;/span&gt;
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-textDecoration-example-1-images" name=
+          "style-attribute-textDecoration-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Text Decoration
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/textDecoration.png" alt=
+                "TTML textDecoration style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.17.4.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-textOutline" name=
+          "style-attribute-textOutline"></a>8.2.20 tts:textOutline</h4>
+
+          <p>The <code>tts:textOutline</code> attribute is used to specify a style
+          property that defines a text outline effect to apply to glyphs that are
+          selected for glyph areas generated by content flowed into a region.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-textOutline" name=
+          "style-property-details-textOutline"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>none</code> | <a href="#style-value-color">&lt;color&gt;</a>?
+                <a href="#style-value-length">&lt;length&gt;</a> <a href=
+                "#style-value-length">&lt;length&gt;</a>?</td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>none</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>relative to this element's font size</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>The value of this attribute consists of an optional <a href=
+          "#style-value-color">&lt;color&gt;</a> term followed by one or two <a href=
+          "#style-value-length">&lt;length&gt;</a> terms. If a <em>color</em> term is
+          present, then it denotes the outline color; if no <em>color</em> term is
+          present, the computed value of the <code>tts:color</code> applies. The first
+          <em>length</em> term denotes the outline thickness and the second length term,
+          if present, indicates the blur radius.</p>
+
+          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used to
+          express thickness and blur radius must be non-negative.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>When a <a href="#style-value-length">&lt;length&gt;</a> expressed in cells
+            is used in a <code>tts:textOutline</code> value, the cell's dimension in the
+            block progression dimension applies. For example, if text outline thickness
+            is specified as 0.1c, the cell resolution is 20 by 10, and the extent of the
+            <em>Root Container Region</em> is 640 by 480, then the outline thickness will
+            be a nominal 480 / 10 * 0.1 pixels, i.e., 4.8px, without taking into account
+            rasterization effects.</p>
+          </div>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>none</code> were
+          specified.</p>
+
+          <p>The <code>tts:textOutline</code> style is illustrated by the following
+          example.</p><a id="style-attribute-textOutline-example-1" name=
+          "style-attribute-textOutline-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Text Outline
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:backgroundColor="transparent"/&gt;
+  &lt;style tts:color="yellow"/&gt;
+  &lt;style <span class="strong">tts:textOutline="black 2px 0px"</span>/&gt;
+  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
+  &lt;style tts:fontSize="24px"/&gt;
+&lt;/region&gt;
+...
+&lt;p&gt;
+  How doth the little crocodile&lt;br/&gt;
+  Improve its shining tail,&lt;br/&gt;
+  And pour the waters of the Nile&lt;br/&gt;
+  On every golden scale!&lt;br/&gt;
+  How cheerfully he seems to grin,&lt;br/&gt;
+  How neatly spreads his claws,&lt;br/&gt;
+  And welcomes little fishes in,&lt;br/&gt;
+  With gently smiling jaws!
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-textOutline-example-1-images" name=
+          "style-attribute-textOutline-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Text Outline
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/textOutline.png" alt=
+                "backgroundColor style property"></td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-unicodeBidi" name=
+          "style-attribute-unicodeBidi"></a>8.2.21 tts:unicodeBidi</h4>
+
+          <p>The <code>tts:unicodeBidi</code> attribute is used to specify a style
+          property that defines a directional embedding or override according to the
+          Unicode bidirectional algorithm.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-unicodeBidi" name=
+          "style-property-details-unicodeBidi"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>normal</code> | <code>embed</code> |
+                <code>bidiOverride</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>normal</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-p"><code>p</code></a>, <a href=
+                "#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>normal</code> were
+          specified.</p>
+
+          <p>The <code>tts:unicodeBidi</code> style is illustrated by the following
+          example.</p><a id="style-attribute-unicodeBidi-example-1" name=
+          "style-attribute-unicodeBidi-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Unicode Bidirectionality
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="265px 84px"/&gt;
+  &lt;style tts:padding="5px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:textAlign="center"/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  Little birds are playing&lt;br/&gt;
+  Bagpipes on the shore,&lt;br/&gt;
+  &lt;span <span class=
+"strong">tts:unicodeBidi="bidiOverride"</span> tts:direction="rtl"&gt;where the tourists snore.&lt;/span&gt;
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-unicodeBidi-example-1-images" name=
+          "style-attribute-unicodeBidi-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Unicode Bidirectionality
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/unicodeBidi.png" alt=
+                "TTML unicodeBidi style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.29.6.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-visibility" name=
+          "style-attribute-visibility"></a>8.2.22 tts:visibility</h4>
+
+          <p>The <code>tts:visibility</code> attribute is used to specify a style
+          property that defines whether generated areas are visible or not when rendered
+          on a visual presentation medium.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-visibility" name=
+          "style-property-details-visibility"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>visible</code> | <code>hidden</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>visible</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
+                <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
+                "#content-vocabulary-p"><code>p</code></a>, <a href=
+                "#layout-vocabulary-region"><code>region</code></a>, <a href=
+                "#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>The <code>tts:visibility</code> style has no affect on content layout or
+          composition, but merely determines whether composed content is visible or
+          not.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>visible</code>
+          were specified.</p>
+
+          <p>The <code>tts:visibility</code> style is illustrated by the following
+          example.</p><a id="style-attribute-visibility-example-1" name=
+          "style-attribute-visibility-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Visibility
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="398px 121px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1" dur="4s"&gt;
+  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
+    &lt;set begin="1s" <span class="strong">tts:visibility="visible"</span>/&gt;
+    Curiouser
+  &lt;/span&gt;
+  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
+    &lt;set begin="2s" <span class="strong">tts:visibility="visible"</span>/&gt;
+    and
+  &lt;/span&gt;
+  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
+    &lt;set begin="3s" <span class="strong">tts:visibility="visible"</span>/&gt;
+    curiouser!
+  &lt;/span&gt;
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-visibility-example-1-images" name=
+          "style-attribute-visibility-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Visibility
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/visibility_0.png" alt=
+                "TTML visibility style property - [0,1)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/visibility_1.png" alt=
+                "TTML visibility style property - [1,2)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/visibility_2.png" alt=
+                "TTML visibility style property - [2,3)"></td>
+              </tr>
+
+              <tr>
+                <td><img src="images/visibility_3.png" alt=
+                "TTML visibility style property - [3,4)"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.30.17.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-wrapOption" name=
+          "style-attribute-wrapOption"></a>8.2.23 tts:wrapOption</h4>
+
+          <p>The <code>tts:wrapOption</code> attribute is used to specify a style
+          property that defines whether or not automatic line wrapping (breaking) applies
+          within the context of the affected element.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-wrapOption" name=
+          "style-property-details-wrapOption"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>wrap</code> | <code>noWrap</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>wrap</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#content-vocabulary-span"><code>span</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>yes</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>For the purpose of determining applicability of this style property, each
+          character child of a <code>p</code> element is considered to be enclosed in an
+          anonymous span.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>wrap</code> were
+          specified.</p>
+
+          <p>The <code>tts:wrapOption</code> style is illustrated by the following
+          example.</p><a id="style-attribute-wrapOption-example-1" name=
+          "style-attribute-wrapOption-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Wrap Option
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="192px 117px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:displayAlign="after"/&gt;
+  &lt;style tts:overflow="hidden"/&gt;
+  &lt;style <span class="strong">tts:wrapOption="noWrap"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p&gt;
+  I'll tell thee everything I can:&lt;br/&gt;
+  There's little to relate.&lt;br/&gt;
+  I saw an aged aged man,&lt;br/&gt;
+  A-sitting on a gate.
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-wrapOption-example-1-images" name=
+          "style-attribute-wrapOption-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Wrap Option
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/wrapOption.png" alt=
+                "TTML wrapOption style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.16.13.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-writingMode" name=
+          "style-attribute-writingMode"></a>8.2.24 tts:writingMode</h4>
+
+          <p>The <code>tts:writingMode</code> attribute is used to specify a style
+          property that defines the block and inline progression directions to be used
+          for the purpose of stacking block and inline areas within a region area.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-writingMode" name=
+          "style-property-details-writingMode"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>lrtb</code> | <code>rltb</code> | <code>tbrl</code> |
+                <code>tblr</code> | <code>lr</code> | <code>rl</code> |
+                <code>tb</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>lrtb</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>lrtb</code> were
+          specified.</p>
+
+          <p>The <code>tts:writingMode</code> style is illustrated by the following
+          example.</p><a id="style-attribute-writingMode-example-1" name=
+          "style-attribute-writingMode-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Writing Mode
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:extent="50px 570px"/&gt;
+  &lt;style tts:origin="0px 0px"/&gt;
+  &lt;style tts:padding="10px 3px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:writingMode="tbrl"</span>/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r2"&gt;
+  &lt;style tts:extent="310px 50px"/&gt;
+  &lt;style tts:origin="70px 120px"/&gt;
+  &lt;style tts:padding="10px 3px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:writingMode="rltb"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  I sometimes dig for buttered rolls,&lt;br/&gt;
+  Or set limed twigs for crabs:
+&lt;/p&gt;
+&lt;p region="r2" tts:direction="rtl" tts:unicodeBidi="bidiOverride"&gt;
+  I sometimes search the grassy knolls for the wheels of Hansom-cabs.
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p><a id="style-attribute-writingMode-example-1-images" name=
+          "style-attribute-writingMode-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Writing Mode
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/writingMode.png" alt=
+                "TTML writingMode style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the second paragraph in the above example that targets region
+            <code>r2</code>, the <code>tts:unicodeBidi</code> and
+            <code>tts:direction</code> properties are set to <code>bidiOverride</code>
+            and <code>rtl</code>, respectively, in order to override the normally
+            left-to-right directionality of characters in the Latin script.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.29.7.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-attribute-zIndex" name="style-attribute-zIndex"></a>8.2.25
+          tts:zIndex</h4>
+
+          <p>The <code>tts:zIndex</code> attribute is used to specify a style property
+          that defines the front-to-back ordering of region areas in the case that they
+          overlap.</p>
+
+          <p>This attribute may be specified by any element type that permits use of
+          attributes in the TT Style Namespace; however, this attribute applies as a
+          style property only to those element types indicated in the following
+          table.</p><a id="style-property-details-zIndex" name=
+          "style-property-details-zIndex"></a>
+
+          <table class="common">
+            <col width="25%" span="1">
+            <col span="1">
+
+            <tbody>
+              <tr>
+                <td><em>Values:</em></td>
+
+                <td><code>auto</code> | <a href=
+                "#style-value-integer">&lt;integer&gt;</a></td>
+              </tr>
+
+              <tr>
+                <td><em>Initial:</em></td>
+
+                <td><code>auto</code></td>
+              </tr>
+
+              <tr>
+                <td><em>Applies to:</em></td>
+
+                <td><a href="#layout-vocabulary-region"><code>region</code></a></td>
+              </tr>
+
+              <tr>
+                <td><em>Inherited:</em></td>
+
+                <td>no</td>
+              </tr>
+
+              <tr>
+                <td><em>Percentages:</em></td>
+
+                <td>N/A</td>
+              </tr>
+
+              <tr>
+                <td><em>Animatable:</em></td>
+
+                <td>discrete</td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If two areas are associated with the same Z-index value, then, if those
+          areas overlap in space, the area(s) generated by lexically subsequent elements
+          must be rendered over area(s) generated by lexically prior elements, where
+          lexical order is defined as the postorder traversal of a <em>Document
+          Instance</em>.</p>
+
+          <p>The semantics of the value <code>auto</code> are those defined by <a href=
+          "#xsl11">[XSL 1.1]</a>, § 7.30.18, where the <code>tt</code> element is
+          considered to establish the root stacking context.</p>
+
+          <p>If a specified value of this attribute is not supported, then a presentation
+          processor must interpret the attribute as if the value <code>auto</code> were
+          specified.</p>
+
+          <p>The <code>tts:zIndex</code> style is illustrated by the following
+          example.</p><a id="style-attribute-zIndex-example-1" name=
+          "style-attribute-zIndex-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Z Index
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region xml:id="r1"&gt;
+  &lt;style tts:origin="0px 0px"/&gt;
+  &lt;style tts:extent="400px 100px"/&gt;
+  &lt;style tts:padding="5px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:zIndex="0"</span>/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r2"&gt;
+  &lt;style tts:origin="100px 60px"/&gt;
+  &lt;style tts:extent="400px 100px"/&gt;
+  &lt;style tts:padding="5px"/&gt;
+  &lt;style tts:backgroundColor="red"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:textAlign="end"/&gt;
+  &lt;style <span class="strong">tts:zIndex="1"</span>/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r3"&gt;
+  &lt;style tts:origin="0px 120px"/&gt;
+  &lt;style tts:extent="400px 100px"/&gt;
+  &lt;style tts:padding="5px"/&gt;
+  &lt;style tts:backgroundColor="black"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style <span class="strong">tts:zIndex="2"</span>/&gt;
+&lt;/region&gt;
+&lt;region xml:id="r4"&gt;
+  &lt;style tts:origin="100px 180px"/&gt;
+  &lt;style tts:extent="400px 100px"/&gt;
+  &lt;style tts:padding="5px"/&gt;
+  &lt;style tts:backgroundColor="red"/&gt;
+  &lt;style tts:color="white"/&gt;
+  &lt;style tts:textAlign="end"/&gt;
+  &lt;style <span class="strong">tts:zIndex="3"</span>/&gt;
+&lt;/region&gt;
+...
+&lt;p region="r1"&gt;
+  I passed by his garden, and marked, with one eye,&lt;br/&gt;
+  How the Owl and the Panther were sharing a pie.
+&lt;/p&gt;
+&lt;p region="r2"&gt;
+  The Panther took pie-crust, and gravy, and meat,&lt;br/&gt;
+  While the Owl had the dish as its share of the treat.
+&lt;/p&gt;
+&lt;p region="r3"&gt;
+  When the pie was all finished, the Owl, as a boon,&lt;br/&gt;
+  Was kindly permitted to pocket the spoon:
+&lt;/p&gt;
+&lt;p region="r4"&gt;
+  While the Panther received knife and fork&lt;br/&gt;
+  with a growl,&lt;br/&gt;
+  And concluded the banquet by...
+&lt;/p&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p>
+
+          <p></p><a id="style-attribute-zIndex-example-1-images" name=
+          "style-attribute-zIndex-example-1-images"></a>
+
+          <table class="example-images">
+            <caption>
+              Example Rendition – Z Index
+            </caption>
+
+            <tbody>
+              <tr>
+                <td><img src="images/zIndex.png" alt="TTML zIndex style property"></td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the style property represented by this attribute are
+            based upon that defined by <a href="#xsl11">[XSL 1.1]</a>, § 7.30.18.</p>
+          </div>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="styling-style-value-expressions" name=
+        "styling-style-value-expressions"></a>8.3 Style Value Expressions</h3>
+
+        <p>Style property values include the use of the following expressions:</p>
+
+        <ul>
+          <li>
+            <p><a href="#style-value-alpha"><b>8.3.1 &lt;alpha&gt;</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-value-color"><b>8.3.2 &lt;color&gt;</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-value-digit"><b>8.3.3 &lt;digit&gt;</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-value-familyName"><b>8.3.5 &lt;familyName&gt;</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-value-genericFamilyName"><b>8.3.6
+            &lt;genericFamilyName&gt;</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-value-hexDigit"><b>8.3.7 &lt;hexDigit&gt;</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-value-integer"><b>8.3.8 &lt;integer&gt;</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-value-length"><b>8.3.9 &lt;length&gt;</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#style-value-namedColor"><b>8.3.10 &lt;namedColor&gt;</b></a></p>
+          </li>
+        </ul>
+
+        <p>In the syntax representations defined in this section, no linear whitespace
+        (LWSP) is implied or permitted between tokens unless explicitly specified.</p>
+
+        <div class="div3">
+          <h4><a id="style-value-alpha" name="style-value-alpha"></a>8.3.1
+          &lt;alpha&gt;</h4>
+
+          <p>An &lt;alpha&gt; expression is used to express an opacity value, where 0
+          means fully transparent and 1 means fully opaque.</p><a id=
+          "alpha-style-expression-syntax" name="alpha-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;alpha&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;alpha&gt;
+  : <em>float</em>
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>In the above syntax representation, the syntactic element
+          <em><code>float</code></em> must adhere to the lexical representation defined
+          by <a href="#xsd-2">[XML Schema Part 2]</a>&nbsp;§ 3.2.4.1. If the value
+          represented is less than 0.0, then it must be interpreted as equal to 0.0;
+          similarly, if the value represented is greater than 1.0, then it must be
+          interpreted as 1.0. The value NaN must be interpreted as 0.0.</p>
+
+          <p>A specified value for &lt;alpha&gt; should not be <code>NaN</code>, less
+          than 0, or greater than 1.</p>
+
+          <p>If a presentation processor does not support a specific, valid opacity
+          value, then it must interpret it as being equal to the closest supported
+          value.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-color" name="style-value-color"></a>8.3.2
+          &lt;color&gt;</h4>
+
+          <p>A &lt;color&gt; expression is used to specify a named color, exact RGB color
+          triple, or exact RGBA color tuple, where the alpha component, if expressed, is
+          maximum (255) at 100% opacity and minimum (0) at 0% opacity, and where the
+          applicable color space is defined by <a href="#srgb">[SRGB]</a>.</p><a id=
+          "color-style-expression-syntax" name="color-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;color&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;color&gt;
+  : "#" rrggbb
+  | "#" rrggbbaa
+  | "rgb" "(" r-value "," g-value "," b-value ")"
+  | "rgba" "(" r-value "," g-value "," b-value "," a-value ")"
+  | <a href="#style-value-namedColor">&lt;namedColor&gt;</a>
+
+rrggbb
+  :  <a href="#style-value-hexDigit">&lt;hexDigit&gt;</a>{6}
+
+rrggbbaa
+  :  <a href="#style-value-hexDigit">&lt;hexDigit&gt;</a>{8}
+
+r-value | g-value | b-value | a-value
+  : component-value
+
+component-value
+  : non-negative-integer                    // valid range: [0,255]
+
+non-negative-integer
+  : <a href="#style-value-digit">&lt;digit&gt;</a>+
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>When expressing RGB component values, these values are considered to
+          <span class="strong">not</span> be premultiplied by alpha.</p>
+
+          <p>For the purpose of performing presentation processing such that non-opaque
+          or non-transparent alpha or opacity values apply, then the semantics of
+          compositing functions are defined with respect to the use of the <a href=
+          "#srgb">[SRGB]</a> color space for both inputs and outputs of the composition
+          function.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The use of <a href="#srgb">[SRGB]</a> for the stated semantics of
+            composition is not meant to prevent an actual processor from using some other
+            color space either for internal or external purposes. For example, a
+            presentation processor may ultimately convert the SRGB values used here to
+            the YUV color space for rendition on a television device.</p>
+          </div>
+
+          <p>If a presentation processor does not support a specific, valid color or
+          alpha value, then it must interpret it as being equal to the closest supported
+          value.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-digit" name="style-value-digit"></a>8.3.3
+          &lt;digit&gt;</h4>
+
+          <p>A &lt;digit&gt; is used to express integers and other types of numbers or
+          tokens.</p><a id="digit-style-expression-syntax" name=
+          "digit-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;digit&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;digit&gt;
+  : "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-duration" name="style-value-duration"></a>8.3.4
+          Deleted</h4>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The information from this section has been removed due to lack of any
+            normative use within this specification. This section is retained in its
+            empty form in order to prevent section renumbering.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-familyName" name="style-value-familyName"></a>8.3.5
+          &lt;familyName&gt;</h4>
+
+          <p>A &lt;familyName&gt; expression specifies a font family name.</p><a id=
+          "familyName-style-expression-syntax" name=
+          "familyName-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;familyName&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;familyName&gt;
+  : unquoted-string
+  | quoted-string
+
+unquoted-string
+  : identifier ( lwsp identifier )*
+
+lwsp
+  : ( ' ' | '\t' | '\n' | '\r' )+
+
+identifier
+  : [-]? identifier-start identifier-following*
+
+identifier-start
+  : [_a-zA-Z]
+  | non-ascii-or-c1
+  | escape
+
+identifier-following
+  : [_a-zA-Z0-9-]
+  | non-ascii-or-c1
+  | escape
+
+non-ascii-or-c1
+  : [^\0-\237]
+
+escape
+  : '\\' <em>char</em>
+
+quoted-string
+  : double-quoted-string
+  | single-quoted-string
+
+double-quoted-string
+  : '"' ( [^"\\] | escape )+ '"'
+
+single-quoted-string
+  : "'" ( [^'\\] | escape )+ "'"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>In addition to adhering to the syntax rules specified above, the following
+          semantic rules apply:</p>
+
+          <ul>
+            <li>
+              <p>the semantic value of a &lt;familyName&gt; expression is the semantic
+              value of its <code>unquoted-string</code> or <code>quoted-string</code>
+              non-terminal, according to whichever applies;</p>
+            </li>
+
+            <li>
+              <p>the semantic value of an <code>unquoted-string</code> non-terminal is a
+              pair <code>&lt;</code><em>quoted</em>, <em>content</em><code>&gt;</code>,
+              where <em>quoted</em> is a boolean <code>false</code>, and where
+              <em>content</em> is the result of appending the value of each
+              <code>identifier</code> non-terminal, in lexical order, where the value of
+              each identifier is preceded by a single SPACE (U+0020) character if it is
+              not the first identifier;</p>
+            </li>
+
+            <li>
+              <p>the semantic value of a <code>quoted-string</code> non-terminal is a
+              pair <code>&lt;</code><em>quoted</em>, <em>content</em><code>&gt;</code>,
+              where <em>quoted</em> is a boolean <code>true</code>, and where
+              <em>content</em> is the unquoted content of the quoted string, i.e., the
+              sequence of characters between the delimiting quotes.</p>
+            </li>
+
+            <li>
+              <p>the semantic value of an <code>escape</code> non-terminal is the value
+              of the escaped <code>char</code>;</p>
+            </li>
+
+            <li>
+              <p>a &lt;familyName&gt; that takes the form of an
+              <code>unquoted-string</code> that contains an <code>identifier</code> that
+              starts with two <code>-</code> HYPHEN-MINUS (U+002D) characters must be
+              considered to be invalid;</p>
+            </li>
+
+            <li>
+              <p>a &lt;familyName&gt; that takes the form of an
+              <code>unquoted-string</code> that contains a single <code>identifier</code>
+              that matches (by case sensitive comparison) a &lt;genericFamilyName&gt;
+              must be interpreted as that &lt;genericFamilyName&gt;;</p>
+            </li>
+
+            <li>
+              <p>a &lt;familyName&gt; that takes the form of a <code>quoted-string</code>
+              whose content (unquoted value) matches (by case sensitive comparison) a
+              &lt;genericFamilyName&gt; must not be interpreted as that
+              &lt;genericFamilyName&gt;, but as the actual name of a non-generic font
+              family.</p>
+            </li>
+          </ul>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The syntactic element <em><code>char</code></em> is to be interpreted
+            according to the <code>Char</code> production defined by <a href=
+            "#xml10">[XML 1.0]</a>&nbsp;§2.2.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The <code>{unicode}</code> escape mechanism defined by <a href=
+            "#css2">[CSS2]</a>&nbsp;§4.1.1 is not supported by this syntax; rather,
+            authors are expected to either (1) directly encode the character using the
+            document encoding or (2) use an XML character reference according to <a href=
+            "#xml10">[XML 1.0]</a>&nbsp;§4.1. When a syntactically significant character
+            needs to be used without its normal syntactic interpretation, it may be be
+            escaped using the backslash (reverse solidus) <code>escape</code>
+            non-terminal specified above.</p>
+
+            <p>When using the backslash (reverse solidus) <code>escape</code>
+            non-terminal, the above syntax does not place any restriction on what
+            character may be escaped, e.g., <code>\\[\n\r\f0-9a-f]</code> are permitted.
+            If one of these latter escapes appears in a &lt;familyName&gt; expression,
+            then it will need to be converted to a <code>{unicode}</code> escape if it is
+            to be used with a standard XSL-FO or CSS parser. In particular, a backslash
+            followed by a newline is ignored by CSS, while it is not ignored by the above
+            syntax. Such an unignored escaped newline would need to be represented using
+            an equivalent <code>{unicode}</code> escape, such as <code>\a</code>, to
+            order to express in CSS.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-genericFamilyName" name=
+          "style-value-genericFamilyName"></a>8.3.6 &lt;genericFamilyName&gt;</h4>
+
+          <p>A &lt;genericFamilyName&gt; expression specifies a font family using a
+          general token that indicates a class of font families.</p>
+
+          <p>The resolution of a generic family name to a concrete font instance is
+          considered to be implementation dependent, both in the case of content
+          authoring and content interpretation.</p><a id=
+          "genericFamilyName-style-expression-syntax" name=
+          "genericFamilyName-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;genericFamilyName&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;genericFamilyName&gt;
+  : "default"
+  | "monospace"
+  | "sansSerif"
+  | "serif"
+  | "monospaceSansSerif"
+  | "monospaceSerif"
+  | "proportionalSansSerif"
+  | "proportionalSerif"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The mapping between a generic (font) family name and an actual font is not
+          determined by this specification; however, the distinction of monospace versus
+          proportional and serif versus sans-serif should be maintained if possible when
+          performing presentation.</p>
+
+          <p>If a generic (font) family name of <code>monospace</code> is specified, then
+          it may be interpreted as equivalent to either <code>monospaceSansSerif</code>
+          or <code>monospaceSerif</code>. The generic family names <code>sansSerif</code>
+          and <code>serif</code> are to be interpreted as equivalent to
+          <code>proportionalSansSerif</code> and <code>proportionalSerif</code>,
+          respectively.</p>
+
+          <p>If the generic family name <code>default</code> is specified (or implied by
+          an initial value), then its typographic characteristics are considered to be
+          implementation dependent; however, it is recommended that this default font
+          family be mapped to an monospaced, sans-serif font.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-hexDigit" name="style-value-hexDigit"></a>8.3.7
+          &lt;hexDigit&gt;</h4>
+
+          <p>A &lt;hexDigit&gt; is used to express integers and other types of numbers or
+          tokens that employ base 16 arithmetic.</p>
+
+          <p>For the purpose of parsing, a distinction must not be made between lower and
+          upper case.</p><a id="hexDigit-style-expression-syntax" name=
+          "hexDigit-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;hexDigit&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;hexDigit&gt;
+  : <a href="#style-value-digit">&lt;digit&gt;</a>
+  | "a" | "b" | "c" | "d" | "e" | "f"
+  | "A" | "B" | "C" | "D" | "E" | "F"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-integer" name="style-value-integer"></a>8.3.8
+          &lt;integer&gt;</h4>
+
+          <p>An &lt;integer&gt; expression is used to express an arbitrary, signed
+          integral value.</p><a id="integer-style-expression-syntax" name=
+          "integer-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;integer&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;integer&gt;
+  : ( "+" | "-" )? <a href="#style-value-digit">&lt;digit&gt;</a>+
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-length" name="style-value-length"></a>8.3.9
+          &lt;length&gt;</h4>
+
+          <p>A &lt;length&gt; expression is used to express either a coordinate component
+          of point in a cartesian space or a distance between two points in a cartesian
+          space.</p><a id="length-style-expression-syntax" name=
+          "length-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;length&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;length&gt;
+  : scalar
+  | percentage
+
+scalar
+  : number units
+
+percentage
+  : number "%"
+
+sign
+  : "+" | "-"
+
+number
+  : sign? non-negative-number
+
+non-negative-number
+  : non-negative-integer
+  | non-negative-real
+
+non-negative-integer
+  : <a href="#style-value-digit">&lt;digit&gt;</a>+
+
+non-negative-real
+  : <a href="#style-value-digit">&lt;digit&gt;</a>* "." <a href=
+"#style-value-digit">&lt;digit&gt;</a>+
+
+units
+  : "px"
+  | "em"
+  | "c"                                     // abbreviation of "cell"
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>It is an error to omit the units component of a scalar length value.</p>
+
+          <p>The semantics of the unit of measure <code>px</code> (pixel) are as defined
+          by <a href="#xsl11">[XSL 1.1]</a>, § 5.9.13.</p>
+
+          <p>When specified relative to a font whose size is expressed as a single length
+          measure or as two length measures of equal length, the unit of measure
+          <code>em</code> is considered to be identical to that defined by <a href=
+          "#xsl11">[XSL 1.1]</a>, § 5.9.13; however, when specified relative to a font
+          whose size is expressed as two length measures of non-equal lengths, then one
+          <code>em</code> is equal to the inline progression dimension of the
+          anamorphically scaled font when used to specify lengths in the inline
+          progression direction and equal to the block progression dimension of the
+          scaled font when used to specify lengths in the block progression
+          direction.</p>
+
+          <p>The semantics of the unit of measure <code>c</code> (cell) are defined by
+          the parameter <a href="#parameter-attribute-cellResolution"><b>6.2.1
+          ttp:cellResolution</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-namedColor" name="style-value-namedColor"></a>8.3.10
+          &lt;namedColor&gt;</h4>
+
+          <p>A &lt;namedColor&gt; is used to express an RGBA color with a convenient
+          name, and where the applicable color space is defined by <a href=
+          "#srgb">[SRGB]</a>.</p>
+
+          <p>For the purpose of parsing, a distinction must not be made between lower and
+          upper case.</p><a id="namedColor-style-expression-syntax" name=
+          "namedColor-style-expression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;namedColor&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;namedColor&gt;
+  : "transparent"                           // #00000000
+  | "black"                                 // #000000ff
+  | "silver"                                // #c0c0c0ff
+  | "gray"                                  // #808080ff
+  | "white"                                 // #ffffffff
+  | "maroon"                                // #800000ff
+  | "red"                                   // #ff0000ff
+  | "purple"                                // #800080ff
+  | "fuchsia"                               // #ff00ffff
+  | "magenta"                               // #ff00ffff (= fuchsia)
+  | "green"                                 // #008000ff
+  | "lime"                                  // #00ff00ff
+  | "olive"                                 // #808000ff
+  | "yellow"                                // #ffff00ff
+  | "navy"                                  // #000080ff
+  | "blue"                                  // #0000ffff
+  | "teal"                                  // #008080ff
+  | "aqua"                                  // #00ffffff
+  | "cyan"                                  // #00ffffff (= aqua)
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Except for <code>transparent</code>, the set of named colors specified
+            above constitutes a proper subset of the set of named colors specified by
+            <a href="#svg11">[SVG 1.1]</a>, § 4.2.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-quotedString" name="style-value-quotedString"></a>8.3.11
+          Deleted</h4>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The information from this section has been incorporated into <a href=
+            "#style-value-familyName"><b>8.3.5 &lt;familyName&gt;</b></a>. This section
+            is retained in its empty form in order to prevent section renumbering.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="style-value-string" name="style-value-string"></a>8.3.12
+          Deleted</h4>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The information from this section has been incorporated into <a href=
+            "#style-value-familyName"><b>8.3.5 &lt;familyName&gt;</b></a>. This section
+            is retained in its empty form in order to prevent section renumbering.</p>
+          </div>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="semantics-style-resolution" name="semantics-style-resolution"></a>8.4
+        Style Resolution</h3>
+
+        <p>This section defines the semantics of style resolution in terms of a standard
+        processing model as follows:</p>
+
+        <ul>
+          <li>
+            <p><a href="#semantics-style-association"><b>8.4.1 Style
+            Association</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#semantics-style-inheritance"><b>8.4.2 Style
+            Inheritance</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#semantics-style-resolution-value-categories"><b>8.4.3 Style
+            Resolution Value Categories</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#semantics-style-resolution-processing"><b>8.4.4 Style Resolution
+            Processing</b></a></p>
+          </li>
+        </ul>
+
+        <p>Any implementation of this model is permitted provided that the externally
+        observable results are consistent with the results produced by this model.</p>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>The semantics of style resolution employed here are based upon <a href=
+          "#xsl11">[XSL 1.1]</a>, § 5.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="semantics-style-association" name=
+          "semantics-style-association"></a>8.4.1 Style Association</h4>
+
+          <p>Style association is a sub-process of <a href=
+          "#semantics-style-resolution-processing"><b>8.4.4 Style Resolution
+          Processing</b></a> used to determine the specified style set of each content
+          and layout element.</p>
+
+          <p>Style matter may be associated with content and layout matter in a number of
+          ways:</p>
+
+          <ul>
+            <li>
+              <p><a href="#semantics-style-association-inline">inline styling</a></p>
+            </li>
+
+            <li>
+              <p><a href="#semantics-style-association-referential">referential
+              styling</a></p>
+            </li>
+
+            <li>
+              <p><a href="#semantics-style-association-chained-referential">chained
+              referential styling</a></p>
+            </li>
+          </ul>
+
+          <p>In addition to the above, style matter may be associated with layout matter
+          using:</p>
+
+          <ul>
+            <li>
+              <p><a href="#semantics-style-association-nested">nested styling</a></p>
+            </li>
+          </ul>
+
+          <div class="div4">
+            <h5><a id="semantics-style-association-inline" name=
+            "semantics-style-association-inline"></a>8.4.1.1 Inline Styling</h5>
+
+            <p>Style properties may be expressed in an inline manner by direct
+            specification of an attribute from the TT Style Namespace on the affected
+            element. When expressed in this manner, the association of style information
+            is referred to as <em>inline styling</em>.</p>
+
+            <p>Style properties associated by inline styling are afforded a higher
+            priority than all other forms of style association.</p><a id=
+            "style-association-example-1" name="style-association-example-1"></a>
+
+            <table class="example">
+              <caption>
+                Example – Inline Styling
+              </caption>
+
+              <tbody>
+                <tr>
+                  <td>
+                    <div class="exampleInner">
+                      <pre>
+&lt;p <span class="strong">tts:color="white"</span>&gt;White 1 &lt;span <span class=
+"strong">tts:color="yellow"</span>&gt;Yellow&lt;/span&gt; White 2&lt;/p&gt;
+</pre>
+                    </div>
+                  </td>
+                </tr>
+              </tbody>
+            </table>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>In the above example, the two text fragments <code>"White 1 "</code> and
+              <code>" White 2"</code>, which are interpreted as anonymous spans, are not
+              associated with a color style property; rather, they inherit their color
+              style from their parent <code>p</code> element as described in <a href=
+              "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
+              Inheritance</b></a> below.</p>
+            </div>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-association-referential" name=
+            "semantics-style-association-referential"></a>8.4.1.2 Referential
+            Styling</h5>
+
+            <p>Style properties may be expressed in an out-of-line manner and referenced
+            by the affected element using the <code>style</code> attribute. When
+            expressed in this manner, the association of style information is referred to
+            as <em>referential styling</em>.</p>
+
+            <p>If a <code>style</code> attribute specifies multiple references, then
+            those references are evaluated in the specified order, and that order applies
+            to resolution of the value of a style property in the case that it is
+            specified along multiple reference paths.</p>
+
+            <p>The use of referential styling is restricted to making reference to
+            <code>style</code> element descendants of a <code>styling</code> element. It
+            is considered an error to reference a <code>style</code> element that is a
+            descendant of a <code>layout</code> element.</p>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>The use of referential styling encourages the reuse of style
+              specifications while sacrificing locality of reference.</p>
+            </div>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>A single content element may be associated with style properties by a
+              hybrid mixture of inline and referential styling, in which case inline
+              styling is given priority as described above by <a href=
+              "#semantics-style-association-inline"><b>8.4.1.1 Inline
+              Styling</b></a>.</p>
+            </div><a id="style-association-example-2" name=
+            "style-association-example-2"></a>
+
+            <table class="example">
+              <caption>
+                Example – Referential Styling
+              </caption>
+
+              <tbody>
+                <tr>
+                  <td>
+                    <div class="exampleInner">
+                      <pre>
+&lt;style <span class="strong">xml:id="s1"</span> tts:color="white"/&gt;
+&lt;style <span class="strong">xml:id="s2"</span> tts:color="yellow"/&gt;
+...
+&lt;p <span class="strong">style="s1"</span>&gt;White 1 &lt;span <span class=
+"strong">style="s2"</span>&gt;Yellow&lt;/span&gt; White 2&lt;/p&gt;
+</pre>
+                    </div>
+                  </td>
+                </tr>
+              </tbody>
+            </table>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>In the above example, the two text fragments <code>"White 1 "</code> and
+              <code>" White 2"</code>, which are interpreted as anonymous spans, are not
+              associated with a color style property; rather, they inherit their color
+              style from their parent <code>p</code> element as described in <a href=
+              "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
+              Inheritance</b></a> below.</p>
+            </div>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-association-chained-referential" name=
+            "semantics-style-association-chained-referential"></a>8.4.1.3 Chained
+            Referential Styling</h5>
+
+            <p>Style properties may be expressed in an out-of-line manner and may
+            themselves reference other out-of-line style properties, thus creating a
+            chain of references starting at the affected element. When expressed in this
+            manner, the association of style information is referred to as <em>chained
+            referential styling</em>.</p>
+
+            <p>If the same style property is specified in more than one referenced style
+            set, then the last referenced style set applies, where the order of
+            application starts from the affected element and proceeds to referenced style
+            sets, and, in turn, to subsequent referenced style sets.</p>
+
+            <p>A loop in a sequence of chained style references must be considered an
+            error.</p>
+
+            <p>The use of referential styling is restricted to making reference to
+            <code>style</code> element descendants of a <code>styling</code> element. It
+            is considered an error to reference a <code>style</code> element that is a
+            descendant of a <code>layout</code> element.</p>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>The use of chained referential styling encourages the grouping of style
+              specifications into general and specific sets, which further aids in style
+              specification reuse.</p>
+            </div>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>A single content element may be associated with style properties by a
+              hybrid mixture of inline, referential styling, and chained referential
+              styling, in which case inline styling is given priority as described above
+              by <a href="#semantics-style-association-inline"><b>8.4.1.1 Inline
+              Styling</b></a>.</p>
+            </div><a id="style-association-example-3" name=
+            "style-association-example-3"></a>
+
+            <table class="example">
+              <caption>
+                Example – Chained Referential Styling
+              </caption>
+
+              <tbody>
+                <tr>
+                  <td>
+                    <div class="exampleInner">
+                      <pre>
+&lt;style <span class=
+"strong">xml:id="s1"</span> tts:color="white" tts:fontFamily="monospaceSerif"/&gt;
+&lt;style <span class="strong">xml:id="s2"</span> <span class=
+"strong">style="s1"</span> tts:color="yellow"/&gt;
+...
+&lt;p <span class="strong">style="s1"</span>&gt;White Monospace&lt;/p&gt;
+&lt;p <span class="strong">style="s2"</span>&gt;Yellow Monospace&lt;/p&gt;
+</pre>
+                    </div>
+                  </td>
+                </tr>
+              </tbody>
+            </table>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-association-nested" name=
+            "semantics-style-association-nested"></a>8.4.1.4 Nested Styling</h5>
+
+            <p>Style properties may be expressed in a nested manner by direct
+            specification of one or more <code>style</code> element children of the
+            affected element. When expressed in this manner, the association of style
+            information is referred to as <em>nested styling</em>.</p>
+
+            <p>Style properties associated by nested styling are afforded a lower
+            priority than inline styling but with higher priority than referential
+            styling.</p><a id="style-association-example-4" name=
+            "style-association-example-4"></a>
+
+            <table class="example">
+              <caption>
+                Example – Nested Styling
+              </caption>
+
+              <tbody>
+                <tr>
+                  <td>
+                    <div class="exampleInner">
+                      <pre>
+&lt;region xml:id="r1"&gt;
+  <span class="strong">&lt;style tts:extent="128px 66px"/&gt;</span>
+  <span class="strong">&lt;style tts:origin="0px 0px"/&gt;</span>
+  <span class="strong">&lt;style tts:displayAlign="center"/&gt;</span>
+&lt;/region&gt;
+</pre>
+                    </div>
+                  </td>
+                </tr>
+              </tbody>
+            </table>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>In this version of this specification, nested styling applies only to
+              the <code>region</code> element.</p>
+            </div>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="semantics-style-inheritance" name=
+          "semantics-style-inheritance"></a>8.4.2 Style Inheritance</h4>
+
+          <p>Style inheritance is a sub-process of <a href=
+          "#semantics-style-resolution-processing"><b>8.4.4 Style Resolution
+          Processing</b></a> used to determine the specified style set of each content
+          and layout element.</p>
+
+          <p>Styles are further propagated to content matter using:</p>
+
+          <ul>
+            <li>
+              <p><a href="#semantics-style-inheritance-content">content style
+              inheritance</a></p>
+            </li>
+
+            <li>
+              <p><a href="#semantics-style-inheritance-content">region style
+              inheritance</a></p>
+            </li>
+          </ul>
+
+          <p>For the purpose of determining inherited styles, the element hierarchy of an
+          intermediate synchronic document form of a <em>Document Instance</em> must be
+          used, where such intermediate forms are defined by <a href=
+          "#semantics-region-layout-step-1"><b>9.3.2 Intermediate Synchronic Document
+          Construction</b></a>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The intermediate synchronic document form is utilized rather than the
+            original form in order to facilitate region inheritance processing.</p>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-inheritance-content" name=
+            "semantics-style-inheritance-content"></a>8.4.2.1 Content Style
+            Inheritance</h5>
+
+            <p>Style properties are inherited from ancestor content elements within an
+            intermediate synchronic document if a style property is not associated with a
+            content element (or an anonymous span) and the style property is designated
+            as inheritable.</p>
+
+            <p>If a style property is determined to require inheritance, then the
+            inherited value must be the value of the same named style property in the
+            computed style set of the element's immediate ancestor element within the
+            applicable intermediate synchronic document.</p><a id=
+            "style-inheritance-example-2" name="style-inheritance-example-2"></a>
+
+            <table class="example">
+              <caption>
+                Example – Content Style Inheritance
+              </caption>
+
+              <tbody>
+                <tr>
+                  <td>
+                    <div class="exampleInner">
+                      <pre>
+&lt;p <span class="strong">tts:fontFamily="monospaceSansSerif"</span>&gt;
+  &lt;span tts:color="yellow"&gt;Yellow Monospace&lt;/span&gt;
+&lt;/p&gt;
+</pre>
+                    </div>
+                  </td>
+                </tr>
+              </tbody>
+            </table>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>In the above example, the <code>span</code> element that encloses the
+              character items <code>Yellow Monospace</code> is not associated with a
+              <code>tts:fontFamily</code> style property and this property is
+              inheritable; therefore, the value of the <code>tts:fontFamily</code> style
+              is inherited from the computed style set of the ancestor <code>p</code>
+              element, and is added to the specified style set of the <code>span</code>
+              element.</p>
+            </div>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-inheritance-region" name=
+            "semantics-style-inheritance-region"></a>8.4.2.2 Region Style
+            Inheritance</h5>
+
+            <p>Style properties are inherited from a region element in the following
+            case:</p>
+
+            <ol class="enumar">
+              <li>
+                <p>if a style property <em>P</em> is not associated with a content
+                element or an anonymous span <em>E</em> and the style property is
+                designated as inheritable, and</p>
+              </li>
+
+              <li>
+                <p>if that style property <em>P</em> is in the computed style set of
+                region <em>R</em>, and</p>
+              </li>
+
+              <li>
+                <p>if that element <em>E</em> is flowed into (presented within) region
+                <em>R</em>.</p>
+              </li>
+            </ol><a id="style-inheritance-example-3" name=
+            "style-inheritance-example-3"></a>
+
+            <table class="example">
+              <caption>
+                Example – Region Style Inheritance
+              </caption>
+
+              <tbody>
+                <tr>
+                  <td>
+                    <div class="exampleInner">
+                      <pre>
+&lt;region <span class="strong">xml:id="r1"</span>&gt;
+  &lt;style tts:color="yellow"/&gt;
+  &lt;style tts:fontFamily="monospaceSerif"/&gt;
+&lt;/region&gt;
+...
+&lt;p <span class="strong">region="r1"</span>&gt;Yellow Monospace&lt;/p&gt;
+</pre>
+                    </div>
+                  </td>
+                </tr>
+              </tbody>
+            </table>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>In the above example, the anonymous span that encloses the character
+              items <code>Yellow Monospace</code> effectively inherits the
+              <code>tts:color</code> and <code>tts:fontFamily</code> styles specified on
+              the <code>region</code> element into which the <code>p</code> element is
+              flowed (presented).</p>
+            </div>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="semantics-style-resolution-value-categories" name=
+          "semantics-style-resolution-value-categories"></a>8.4.3 Style Resolution Value
+          Categories</h4>
+
+          <p>During style resolution, layout, and presentation processing, three
+          categories of style property values are distinguished as follows:</p>
+
+          <ul>
+            <li>
+              <p><a href="#semantics-style-resolved-value-category-specified">specified
+              values</a></p>
+            </li>
+
+            <li>
+              <p><a href="#semantics-style-resolved-value-category-computed">computed
+              values</a></p>
+            </li>
+
+            <li>
+              <p><a href="#semantics-style-resolved-value-category-actual">actual
+              values</a></p>
+            </li>
+          </ul>
+
+          <div class="div4">
+            <h5><a id="semantics-style-resolved-value-category-specified" name=
+            "semantics-style-resolved-value-category-specified"></a>8.4.3.1 Specified
+            Values</h5>
+
+            <p>Values of style properties that are associated with or inherited by an
+            element or anonymous span are referred to as <em>specified values</em>. The
+            set of all specified style properties of a given element is referred to as
+            the <em>specified style set</em> of that element.</p>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-resolved-value-category-computed" name=
+            "semantics-style-resolved-value-category-computed"></a>8.4.3.2 Computed
+            Values</h5>
+
+            <p>When style properties are specified using relative value expressions, such
+            as a named color, a relative unit (e.g., cell), or a percentage, then they
+            need to be further resolved into absolute units, such as an RGB triple,
+            pixels, etc.</p>
+
+            <p>During the style resolution process, all specified style values are
+            reinterpreted (or recalculated) in absolute terms, and then recorded as
+            <em>computed values</em>. The set of all computed style properties of a given
+            element is referred to as the <em>computed style set</em> of that
+            element.</p>
+
+            <p>When a style value is inherited, either explicitly or implicitly, it is
+            the computed value of the style that is inherited from an ancestor element.
+            This is required since the resolution of certain relative units, such as
+            percentage, require evaluating the expression in the immediate (local)
+            context of reference, and not in a distant (remote) context of reference
+            where the related (resolving) expression is not available.</p>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-resolved-value-category-actual" name=
+            "semantics-style-resolved-value-category-actual"></a>8.4.3.3 Actual
+            Values</h5>
+
+            <p>During the actual presentation process, other transformations occur that
+            map some value expressions to concrete, physical values. For example, the
+            colors of computed style values are further subjected to closest color
+            approximation and gamma correction during the display process. In addition,
+            length value expressions that use pixels in computed style values are
+            considered to express logical rather than physical (device) pixels.
+            Consequently, these logical pixels are subject to being further transformed
+            or mapped to physical (device) pixels during presentation.</p>
+
+            <p>The final values that result from the logical to device mapping process
+            are referred to as <em>actual values</em>. The set of all actual style
+            properties of a given element is referred to as the <em>actual style set</em>
+            of that element.</p>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>More than one set of actual values may be produced during the process of
+              presentation. For example, a TTML presentation processor device may output
+              an RGBA component video signal which is then further transformed by an NTSC
+              or PAL television to produce a final image. In this case, both color and
+              dimensions may further be modified prior to presentation.</p>
+            </div>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>In general, a TTML presentation processor will not have access to actual
+              style set values; as a consequence, no further use or reference to actual
+              values is made below when formally describing the style resolution
+              process.</p>
+            </div>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="semantics-style-resolution-processing" name=
+          "semantics-style-resolution-processing"></a>8.4.4 Style Resolution
+          Processing</h4>
+
+          <p>The process of style resolution is defined herein as the procedure (and
+          results thereof) for resolving (determining) the computed values of all style
+          properties that apply to content and layout elements:</p>
+
+          <ul>
+            <li>
+              <p><a href="#semantics-style-resolution-processing-definitions"><b>8.4.4.1
+              Conceptual Definitions</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#semantics-style-resolution-processing-sss"><b>8.4.4.2
+              Specified Style Set Processing</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#semantics-style-resolution-processing-css"><b>8.4.4.3 Computed
+              Style Set Processing</b></a></p>
+            </li>
+
+            <li>
+              <p><a href="#semantics-style-resolution-process-overall"><b>8.4.4.4 Style
+              Resolution Process</b></a></p>
+            </li>
+          </ul>
+
+          <p>The process described here forms an integral sub-process of <a href=
+          "#semantics-region-layout"><b>9.3 Region Layout and Presentation</b></a>.</p>
+
+          <div class="div4">
+            <h5><a id="semantics-style-resolution-processing-definitions" name=
+            "semantics-style-resolution-processing-definitions"></a>8.4.4.1 Conceptual
+            Definitions</h5>
+
+            <p>For the purpose of interpreting the style resolution processing model
+            specified below, the following conceptual definitions apply:</p>
+
+            <dl>
+              <dt class="label">[style property]</dt>
+
+              <dd>
+                <p>a style property, <em>P</em>, is considered to consist of a tuple
+                <code>[name, value]</code>, where the name of the property is a tuple
+                <code>[namespace value, unqualified name]</code> and the value of the
+                property is a tuple <code>[category, type, value
+                expression]</code></p><a id=
+                "conceptual-definition-example-style-property" name=
+                "conceptual-definition-example-style-property"></a>
+
+                <table class="example">
+                  <caption>
+                    Example – conceptual style property
+                  </caption>
+
+                  <tbody>
+                    <tr>
+                      <td>
+                        <div class="exampleInner">
+                          <pre>
+[
+  ["http://www.w3.org/ns/ttml#styling", "color"],
+  ["specified", <em>color</em>, "red"]
+]
+</pre>
+                        </div>
+                      </td>
+                    </tr>
+                  </tbody>
+                </table>
+
+                <p></p>
+              </dd>
+
+              <dt class="label">[style (property) set]</dt>
+
+              <dd>
+                <p>a style (property) set consists of an unordered collection of style
+                properties, where no two style properties within the set have an
+                identical name, where by "identical name" is meant equality of namespace
+                value of name tuple and unqualified name of name tuple;</p>
+
+                <p>in a specified style (property) set, the category of each style
+                property is "specified"; a specified style (property) set of an element
+                <em>E</em> is referred to as <em>SSS(E)</em>;</p><a id=
+                "conceptual-definition-example-specified-style-set" name=
+                "conceptual-definition-example-specified-style-set"></a>
+
+                <table class="example">
+                  <caption>
+                    Example – conceptual (specified) style (property) set
+                  </caption>
+
+                  <tbody>
+                    <tr>
+                      <td>
+                        <div class="exampleInner">
+                          <pre>
+{
+  [
+    ["http://www.w3.org/ns/ttml#styling", "backgroundColor"],
+    ["specified", <em>color</em>, 0x00FF00 ]
+  ],
+  [
+    ["http://www.w3.org/ns/ttml#styling", "color"],
+    ["specified", <em>color</em>, "red" ]
+  ],
+  [
+    ["http://www.w3.org/ns/ttml#styling", "fontSize"],
+    ["specified", <em>length</em>, "1c" ]
+  ],
+  [
+    ["http://www.w3.org/ns/ttml#styling", "lineHeight"],
+    ["specified", <em>length</em>, "117%" ]
+  ]
+}
+</pre>
+                        </div>
+                      </td>
+                    </tr>
+                  </tbody>
+                </table>
+
+                <p>in a computed style (property) set, the category of each style
+                property is either "specified" or "computed"; a computed style (property)
+                set of an element <em>E</em> is referred to as <em>CSS(E)</em>;</p><a id=
+                "conceptual-definition-example-computed-style-set" name=
+                "conceptual-definition-example-computed-style-set"></a>
+
+                <table class="example">
+                  <caption>
+                    Example – conceptual (computed) style (property) set
+                  </caption>
+
+                  <tbody>
+                    <tr>
+                      <td>
+                        <div class="exampleInner">
+                          <pre>
+{
+  [
+    ["http://www.w3.org/ns/ttml#styling", "backgroundColor"],
+    ["specified", <em>color</em>, 0x00FF00 ]
+  ],
+  [
+    ["http://www.w3.org/ns/ttml#styling", "color"],
+    ["computed", <em>color</em>, 0xFF0000 ]
+  ],
+  [
+    ["http://www.w3.org/ns/ttml#styling", "fontSize"],
+    ["computed", <em>length</em>, "24px" ]
+  ],
+  [
+    ["http://www.w3.org/ns/ttml#styling", "lineHeight"],
+    ["computed", <em>length</em>, "28px" ]
+  ]
+}
+</pre>
+                        </div>
+                      </td>
+                    </tr>
+                  </tbody>
+                </table>
+
+                <p></p>
+              </dd>
+
+              <dt class="label">[style (property) merging]</dt>
+
+              <dd>
+                <p>a style property <em>P<sub>new</sub></em> is merged into a style
+                (property) set, <em>SS</em>, as follows: if a style property
+                <em>P<sub>old</sub></em> is already present in <em>SS</em> where the name
+                of <em>P<sub>new</sub></em> is identical to the name of
+                <em>P<sub>old</sub></em>, then replace <em>P<sub>old</sub></em> in
+                <em>SS</em> with <em>P<sub>new</sub></em>; otherwise, add
+                <em>P<sub>new</sub></em> to <em>SS</em>;</p>
+              </dd>
+
+              <dt class="label">[style (property) set merging]</dt>
+
+              <dd>
+                <p>a style (property) set <em>SS<sub>new</sub></em> is merged into an
+                existing style (property) set <em>SS<sub>old</sub></em> as follows: for
+                each style property <em>P<sub>new</sub></em> in
+                <em>SS<sub>new</sub></em>, merge <em>P<sub>new</sub></em> into
+                <em>SS<sub>old</sub></em>;</p>
+              </dd>
+            </dl>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-resolution-processing-sss" name=
+            "semantics-style-resolution-processing-sss"></a>8.4.4.2 Specified Style Set
+            Processing</h5>
+
+            <p>The specified style set <em>SSS</em> of an element or anonymous span
+            <em>E</em>, <em>SSS(E)</em>, is determined according to the following ordered
+            rules:</p>
+
+            <ol class="enumar">
+              <li>
+                <p><span class="strong">[initialization]</span> initialize the specified
+                style set <em>SSS</em> of <em>E</em> to the empty set;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[referential and chained referential
+                styling]</span> for each <code>style</code> element
+                <em>S<sub>REF</sub></em> referenced by a <code>style</code> attribute
+                specified on <em>E</em>, and in the order specified in the
+                <code>style</code> attribute, then, if <em>S<sub>REF</sub></em> is a
+                descendant of a <code>styling</code> element, merge the specified style
+                set of <em>S<sub>REF</sub></em>, <em>SSS(S<sub>REF</sub>)</em>, into the
+                specified style set of <em>E</em>, <em>SSS(E)</em>;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[nested styling]</span> for each nested
+                <code>style</code> element child <em>S<sub>NEST</sub></em> of <em>E</em>,
+                and in the specified order of child elements, merge the specified style
+                set of <em>S<sub>NEST</sub></em>, <em>SSS(S<sub>NEST</sub>)</em>, into
+                the specified style set of <em>E</em>, <em>SSS(E)</em>;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[inline styling]</span> for each style property
+                <em>P</em> expressed as a specified styling attribute of <em>E</em>,
+                merge <em>P</em> into the specified style set of <em>E</em>,
+                <em>SSS(E)</em>;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[animation styling]</span> for each style
+                property <em>P</em> expressed as a specified styling attribute of an
+                immediate animation (<code>set</code>) element child of element
+                <em>E</em>, merge <em>P</em> into the specified style set of <em>E</em>,
+                <em>SSS(E)</em>;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[implicit inheritance]</span> if the element type
+                of <em>E</em> is not the styling element type <code>style</code>, then
+                for each inheritable style property <em>P<sub>INH</sub></em> in the set
+                of style properties defined above in <a href=
+                "#styling-attribute-vocabulary"><b>8.2 Styling Attribute
+                Vocabulary</b></a>, perform the following ordered sub-steps:</p>
+
+                <ol class="enumla">
+                  <li>
+                    <p>if <em>P<sub>INH</sub></em> is present in the specified style set
+                    of <em>E</em>, <em>SSS(E)</em>, then continue to the next inheritable
+                    style property;</p>
+                  </li>
+
+                  <li>
+                    <p>if the element type of <em>E</em> is the layout element type
+                    <code>region</code>, then set <em>P′</em> to the initial value of
+                    property <em>P</em>, where the initial value of a property is
+                    determined according to the specific property definition found above
+                    in <a href="#styling-attribute-vocabulary"><b>8.2 Styling Attribute
+                    Vocabulary</b></a>;</p>
+                  </li>
+
+                  <li>
+                    <p>if the element type of <em>E</em> is a content element type or
+                    anonymous span, then set <em>P′</em> to the result of looking up the
+                    value of <em>P</em> in the computed style set of the immediate
+                    ancestor element of <em>E</em>, i.e., <em>CSS(PARENT(E))</em>;</p>
+                  </li>
+
+                  <li>
+                    <p>if the value of <em>P′</em> is not undefined, then merge
+                    <em>P′</em> into the specified style set of <em>E</em>,
+                    <em>SSS(E)</em>.</p>
+                  </li>
+                </ol>
+              </li>
+            </ol>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-resolution-processing-css" name=
+            "semantics-style-resolution-processing-css"></a>8.4.4.3 Computed Style Set
+            Processing</h5>
+
+            <p>The computed style set <em>CSS</em> of an element or anonymous span
+            <em>E</em>, <em>CSS(E)</em>, is determined according to the following ordered
+            rules:</p>
+
+            <ol class="enumar">
+              <li>
+                <p><span class="strong">[resolve specified styles]</span> determine
+                (obtain) the specified style set <em>SSS</em> of <em>E</em>, namely,
+                <em>SSS(E)</em>, in accordance with <a href=
+                "#semantics-style-resolution-processing-sss"><b>8.4.4.2 Specified Style
+                Set Processing</b></a>;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[initialization]</span> initialize
+                <em>CSS(E)</em> to a (deep) copy of <em>SSS(E)</em>;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[filter]</span> if <em>E</em> is a
+                <code>style</code> element, then return <em>CSS(E)</em> as the resulting
+                computed style set without further resolution; otherwise, continue with
+                the next rule;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[relative value resolution]</span> for each style
+                property <em>P</em> in <em>CSS(E)</em>, where the value type of
+                <em>P</em> is relative, perform the following ordered sub-steps:</p>
+
+                <ol class="enumla">
+                  <li>
+                    <p>replace the relative value of <em>P</em> with an equivalent,
+                    non-relative (computed) value;</p>
+                  </li>
+
+                  <li>
+                    <p>set the category of <em>P</em> to "computed";</p>
+                  </li>
+                </ol>
+              </li>
+            </ol>
+
+            <div class="note">
+              <p class="prefix"><b>Note:</b></p>
+
+              <p>As a result of the filtering rule above, the computed style set of a
+              <code>style</code> element includes only specified values, in which case
+              relative value expressions remain relative; consequently, the resolution of
+              relative value expressions (that may be assigned by means of referential
+              style association) always takes place in the context of a layout or content
+              element which has a presentation context, and not in the non-presentation,
+              declaration context of a referentiable <code>style</code> element.</p>
+            </div>
+          </div>
+
+          <div class="div4">
+            <h5><a id="semantics-style-resolution-process-overall" name=
+            "semantics-style-resolution-process-overall"></a>8.4.4.4 Style Resolution
+            Process</h5>
+
+            <p>The top-level style resolution process is defined as follows: using a
+            preorder traversal of each element and anonymous span, <em>E</em>, of an
+            intermediate synchronic document, <em>DOC<sub>inter</sub></em>, perform the
+            following ordered sub-steps:</p>
+
+            <ol class="enumar">
+              <li>
+                <p><span class="strong">[filter]</span> if the element type of <em>E</em>
+                is not the styling element type <code>style</code>, is not the layout
+                element type <code>region</code>, and is not one of the content element
+                types <code>body</code>, <code>div</code>, <code>p</code>,
+                <code>span</code>, <code>br</code>, or anonymous span, then continue to
+                the next element in the preorder traversal;</p>
+              </li>
+
+              <li>
+                <p><span class="strong">[resolve computed styles]</span> determine
+                (obtain) the computed style set <em>CSS</em> of <em>E</em>, namely,
+                <em>CSS(E)</em>, in accordance with <a href=
+                "#semantics-style-resolution-processing-css"><b>8.4.4.3 Computed Style
+                Set Processing</b></a>.</p>
+              </li>
+            </ol>
+          </div>
+        </div>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="layout" name="layout"></a>9 Layout</h2>
+
+      <p>This section specifies the <em>layout</em> matter of the core vocabulary
+      catalog, where layout is to be understood as a separable layer of information that
+      applies to content and that denotes authorial intentions about the presentation of
+      that content.</p>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>The two layers of layout and style matter are considered to be independently
+        separable. Layout matter specifies one or more spaces or areas into which content
+        is intended to be presented, while style matter specifies the manner in which
+        presentation occurs within the layout.</p>
+
+        <p>In certain cases, a content author may choose to embed (inline) style matter
+        directly into layout or content matter. In such cases, an alternative exists –
+        use of referential styling – in which the style matter is not embedded
+        (inlined).</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="layout-element-vocabulary" name="layout-element-vocabulary"></a>9.1
+        Layout Element Vocabulary</h3>
+
+        <p>The following elements specify the structure and principal layout aspects of a
+        <em>Document Instance</em>:</p>
+
+        <ul>
+          <li>
+            <p><a href="#layout-vocabulary-layout"><b>9.1.1 layout</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#layout-vocabulary-region"><b>9.1.2 region</b></a></p>
+          </li>
+        </ul>
+
+        <div class="div3">
+          <h4><a id="layout-vocabulary-layout" name="layout-vocabulary-layout"></a>9.1.1
+          layout</h4>
+
+          <p>The <code>layout</code> element is a container element used to group layout
+          matter, including metadata that applies to layout matter.</p>
+
+          <p>The <code>layout</code> element accepts as its children zero or more
+          elements in the <code>Metadata.class</code> element group, followed by zero or
+          more <code>region</code> elements.</p><a id="elt-syntax-layout" name=
+          "elt-syntax-layout"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: layout
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;layout
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#layout-vocabulary-region">region</a>*
+&lt;/layout&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>To the extent that time semantics apply to the content of the
+          <code>layout</code> element, the implied time interval of this element is
+          defined to be coterminous with the <em>Root Temporal Extent</em>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="layout-vocabulary-region" name="layout-vocabulary-region"></a>9.1.2
+          region</h4>
+
+          <p>The <code>region</code> element is used to define a rectangular space or
+          area into which content is to be flowed for the purpose of presentation.</p>
+
+          <p>In addition, and in accordance with <a href=
+          "#semantics-style-inheritance-region"><b>8.4.2.2 Region Style
+          Inheritance</b></a>, the <code>region</code> element may be used to specify
+          inheritable style properties to be inherited by content that is flowed into
+          it.</p>
+
+          <p>The <code>region</code> element accepts as its children zero or more
+          elements in the <code>Metadata.class</code> element group, followed by zero or
+          more elements in the <code>Animation.class</code> element group, followed by
+          zero or more <code>style</code> elements.</p>
+
+          <p>Any metadata specified by children in the <code>Metadata.class</code>
+          element group applies semantically to the <code>region</code> element and its
+          descendants as a whole. Any animation elements specified by children in the
+          <code>Animation.class</code> element group apply semantically to the
+          <code>region</code> element. Any <code>style</code> child element must be
+          considered a local style definition that applies only to the containing
+          <code>region</code> element, i.e., does not apply for resolving referential
+          styling (but does apply for region style inheritance).</p><a id=
+          "elt-syntax-region" name="elt-syntax-region"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: region
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;region
+  <a href="#timing-attribute-begin">begin</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-dur">dur</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-end">end</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#style-attribute-style">style</a> = IDREFS
+  <a href=
+"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
+  <a href="#metadata-attribute-role">ttm:role</a> = string
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute in TT Style namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*, <a href=
+"#element-vocab-group-table">Animation.class</a>*, <a href=
+"#styling-vocabulary-style">style</a>*
+&lt;/region&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If <code>begin</code> and (or) <code>end</code> attributes are specified on
+          a <code>region</code> element, then they specify the beginning and (or) ending
+          points of a time interval during which the region is eligible for activation
+          and with respect to which animation child elements of the region are timed. If
+          specified, these begin and end points are relative to the time interval of the
+          nearest ancestor element associated with a time interval, irregardless of
+          whether that interval is explicit or implied.</p>
+
+          <p>The nearest ancestor element of a <code>region</code> element that is
+          associated with a time interval is the <code>layout</code> element.</p>
+
+          <p>If a <code>dur</code> attribute is specified on the <code>region</code>
+          element, then it specifies the simple duration of the region.</p>
+
+          <p>For the purpose of determining the semantics of presentation processing, a
+          region that is temporally inactive must not produce any visible marks when
+          presented on a visual medium.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>A <code>region</code> element may be associated with a time interval for
+            two purposes: (1) in order to temporally bound the presentation of the region
+            and its content, and (2) to provide a temporal context in which animations of
+            region styles may be effected.</p>
+
+            <p>For example, an author may wish to specify a region that is otherwise
+            empty, but may have a visible background color to be presented starting at
+            some time and continuing over the region's duration. The simple duration of
+            the region serves additionally to scope the presentation effects of content
+            that is targeted to the region. An author may also wish to move a region
+            within the <em>Root Container Region</em> or change a region's background
+            color by means of animation effects. In both of these cases, it is necessary
+            to posit an active time interval for a region.</p>
+          </div>
+
+          <p>If no <code>timeContainer</code> attribute is specified on a
+          <code>region</code> element, then it must be interpreted as having
+          <em>parallel</em> time containment semantics.</p>
+
+          <p>If a <a href="#metadata-attribute-role"><code>ttm:role</code></a> attribute
+          is specified on a <code>region</code> element, then it must adhere to the value
+          syntax defined by <a href="#metadata-attribute-role-syntax"><b>Syntax
+          Representation – ttm:role</b></a>, and where the roles identified by this
+          attribute express the semantic roles of the region independently from the
+          semantic roles of any content targeted to (associated with) the region.</p>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="layout-attribute-vocabulary" name=
+        "layout-attribute-vocabulary"></a>9.2 Layout Attribute Vocabulary</h3>
+
+        <p>This section defines the <a href="#layout-attribute-region"><b>9.2.1
+        region</b></a> attribute used with content elements.</p>
+
+        <div class="div3">
+          <h4><a id="layout-attribute-region" name="layout-attribute-region"></a>9.2.1
+          region</h4>
+
+          <p>The <code>region</code> attribute is used to reference a <code>region</code>
+          element which defines a space or area into which a content element is intended
+          to be flowed.</p>
+
+          <p>If specified, the value of a <code>region</code> attribute must adhere to
+          the <code>IDREF</code> data type defined by <a href="#xsd-2">[XML Schema Part
+          2]</a>, § 3.3.9, and, furthermore, this IDREF must reference a
+          <code>region</code> element which has a <code>layout</code> element as an
+          ancestor.</p>
+
+          <p>The <code>region</code> attribute may be specified by an instance of the
+          following element types:</p>
+
+          <ul>
+            <li>
+              <p><a href="#document-structure-vocabulary-body"><code>body</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
+            </li>
+          </ul>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>See <a href="#semantics-region-layout"><b>9.3 Region Layout and
+            Presentation</b></a> below for further information on content flow in a
+            region.</p>
+          </div>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="semantics-region-layout" name="semantics-region-layout"></a>9.3 Region
+        Layout and Presentation</h3>
+
+        <p>This section defines the semantics of region layout and presentation in terms
+        of a standard processing model as follows:</p>
+
+        <ul>
+          <li>
+            <p><a href="#semantics-default-region"><b>9.3.1 Default Region</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#semantics-region-layout-step-1"><b>9.3.2 Intermediate Synchronic
+            Document Construction</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#semantics-region-layout-step-2"><b>9.3.3 Synchronic Flow
+            Processing</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#semantics-region-layout-example"><b>9.3.4 Elaborated Example
+            (Informative)</b></a></p>
+          </li>
+        </ul>
+
+        <p>Any implementation is permitted provided that the externally observable
+        results are consistent with the results produced by this model.</p>
+
+        <div class="div3">
+          <h4><a id="semantics-default-region" name="semantics-default-region"></a>9.3.1
+          Default Region</h4>
+
+          <p>If a <em>Document Instance</em> does not specify a <a href=
+          "#layout-vocabulary-region"><code>region</code></a> element, then a <em>default
+          region</em> is implied with the following characteristics:</p>
+
+          <ul>
+            <li>
+              <p>the identity of the default region is considered to be anonymous;</p>
+            </li>
+
+            <li>
+              <p>the extent of the default region is the same as the extent of the
+              <em>Root Container Region</em>;</p>
+            </li>
+
+            <li>
+              <p>the temporal interval of the default region is the same as the interval
+              defined by the <em>Root Temporal Extent</em>;</p>
+            </li>
+          </ul>
+
+          <p>Furthermore, if no <a href=
+          "#layout-vocabulary-region"><code>region</code></a> element is specified, then
+          the <a href="#layout-attribute-region"><code>region</code></a> attribute must
+          not be specified on any content element in the <em>Document Instance</em>.</p>
+
+          <p>If a default region is implied for a given <em>Document Instance</em>, then
+          the <a href="#document-structure-vocabulary-body"><code>body</code></a> element
+          is implicitly targeted to (associated with) the default region.</p>
+
+          <p>When implying a default region, the <em>Document Instance</em> is to be
+          treated as if a <a href="#layout-vocabulary-region"><code>region</code></a>
+          element and its parent <a href=
+          "#layout-vocabulary-layout"><code>layout</code></a> element were specified in a
+          <a href="#document-structure-vocabulary-head"><code>head</code></a> element,
+          and a matching <a href="#layout-attribute-region"><code>region</code></a>
+          attribute were specified on the <a href=
+          "#document-structure-vocabulary-body"><code>body</code></a> element as shown in
+          the following example:</p><a id="semantics-default-region-example" name=
+          "semantics-default-region-example"></a>
+
+          <table class="example">
+            <caption>
+              Example – Implied Default Region
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
+  &lt;head&gt;
+    <span class="strong">&lt;layout&gt;
+      &lt;region xml:id="anonymous"/&gt;
+    &lt;/layout&gt;</span>
+  &lt;/head&gt;
+  &lt;body <span class="strong">region="anonymous"</span>/&gt;
+&lt;/tt&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, a default <code>region</code> element and
+            <code>region</code> attribute are implied. In addition, a <code>layout</code>
+            container element is implied for the implied <code>region</code> element.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="semantics-region-layout-step-1" name=
+          "semantics-region-layout-step-1"></a>9.3.2 Intermediate Synchronic Document
+          Construction</h4>
+
+          <p>For the purposes of performing presentation processing, the active time
+          duration of a <em>Document Instance</em> is divided into a sequence of time
+          coordinates where at each time coordinate, some element becomes temporally
+          active or inactive, then, at each such time coordinate, a <em>Document
+          Instance</em> is mapped from its original, source form,
+          <em>DOC<sub>source</sub></em> , to an intermediate synchronic document form,
+          <em>DOC<sub>inter</sub></em> , according to the <span class="strong">[construct
+          intermediate document]</span> procedure:</p>
+
+          <dl>
+            <dt class="label">[construct intermediate document]</dt>
+
+            <dd>
+              <ol class="enumar">
+                <li>
+                  <p>for each temporally active region <em>R</em>, replicate the sub-tree
+                  of <em>DOC<sub>source</sub></em> headed by the <code>body</code>
+                  element;</p>
+                </li>
+
+                <li>
+                  <p>evaluating this sub-tree in a postorder traversal, prune elements if
+                  they are not a content element, if they are temporally inactive, if
+                  they are empty, or if they aren't associated with region <em>R</em>
+                  according to the <span class="strong">[associate region]</span>
+                  procedure;</p>
+                </li>
+
+                <li>
+                  <p>if the pruned sub-tree is non-empty, then reparent it to the
+                  <em>R</em> element;</p>
+                </li>
+
+                <li>
+                  <p>finally, after completing the above steps, prune the original
+                  <code>body</code> element from the intermediate document, then prune
+                  all <code>region</code>, <code>begin</code>, <code>end</code>, and
+                  <code>dur</code> attributes, which are no longer semantically
+                  relevant;</p>
+                </li>
+              </ol>
+
+              <div class="note">
+                <p class="prefix"><b>Note:</b></p>
+
+                <p>In this section, the term <em>prune</em>, when used in reference to an
+                element, means that the element is to be removed from its parent's
+                children, which, in turn, implies that the descendants of the pruned
+                element will no longer be descendants of the element's parent. When
+                <em>prune</em> is used in reference to an attribute, it means that
+                attribute is to be removed from its associated (owning) element node.</p>
+              </div>
+            </dd>
+
+            <dt class="label">[associate region]</dt>
+
+            <dd>
+              <p>A content element is associated with a region according to the following
+              ordered rules, where the first rule satisfied is used and remaining rules
+              are skipped:</p>
+
+              <ol class="enumar">
+                <li>
+                  <p>if the element specifies a <a href=
+                  "#layout-attribute-region"><code>region</code></a> attribute, then the
+                  element is associated with the region referenced by that attribute;</p>
+                </li>
+
+                <li>
+                  <p>if some ancestor of that element specifies a <a href=
+                  "#layout-attribute-region"><code>region</code></a> attribute, then the
+                  element is associated with the region referenced by the most immediate
+                  ancestor that specifies this attribute;</p>
+                </li>
+
+                <li>
+                  <p>if the element contains a descendant element that specifies a
+                  <a href="#layout-attribute-region"><code>region</code></a> attribute,
+                  then the element is associated with the region referenced by that
+                  attribute;</p>
+                </li>
+
+                <li>
+                  <p>if a default region was implied (due to the absence of any <a href=
+                  "#layout-vocabulary-region"><code>region</code></a> element), then the
+                  element is associated with the default region;</p>
+                </li>
+
+                <li>
+                  <p>the element is not associated with any region.</p>
+                </li>
+              </ol>
+            </dd>
+          </dl>
+
+          <p>The result of performing the processing described above will be a sequence
+          of <em>N</em> intermediate synchronic <em>Document Instances</em>,
+          <em>DOC<sub><span>inter<sub>0</sub></span></sub></em> …
+          <em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>.</p>
+
+          <div class="note" id="semantics-smooth-scrolling-recommendation">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Where an implementation is able to detect significant similarity between
+            two adjacent synchronic <em>Document Instances</em>,
+            <em>DOC<sub><span>inter<sub>N</sub></span></sub></em>
+            <em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>, then it is preferred
+            that the implementation make the transition between presenting the two
+            instances as smooth as possible, e.g., as described by <a href=
+            "#cea608c">[CEA-608-C]</a>, § C.3.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="semantics-region-layout-step-2" name=
+          "semantics-region-layout-step-2"></a>9.3.3 Synchronic Flow Processing</h4>
+
+          <p>Subsequent to performing a temporal (synchronic) slice and subsequent
+          remapping of regionally selected content hierarchy, the resulting intermediate
+          synchronic document is subjected to a flow transformation step that produces a
+          rooted flow object tree represented as an XSL FO document instance as defined
+          by <a href="#xsl11">[XSL 1.1]</a>, and semantically extended by TTML specific
+          style properties that have no XSL FO counterpart.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In this section, the use of XSL FO is intended to be conceptual only,
+            employed solely for the purpose of defining the normative presentation
+            semantics of TTML. An actual implementation of this algorithm is not required
+            to create or process XSL-FO representations. In particular, it is possible to
+            implement these semantics using alternative presentation models, such as
+            Cascading Style Sheets (CSS).</p>
+          </div>
+
+          <p>Each intermediate synchronic document produced by <a href=
+          "#semantics-region-layout-step-1"><b>9.3.2 Intermediate Synchronic Document
+          Construction</b></a> is mapped to an XSL FO document instance, <em>F</em>, as
+          follows:</p>
+
+          <ol class="enumar">
+            <li>
+              <p>perform the following ordered sub-steps to create anonymous spans:</p>
+
+              <ol class="enumla">
+                <li>
+                  <p>for each significant text node in a content element, synthesize an
+                  anonymous span to enclose the text node, substituting the new anonymous
+                  span for the original text node child in its sibling and parent
+                  hierarchy;</p>
+                </li>
+
+                <li>
+                  <p>for each contiguous sequence of anonymous spans, replace the
+                  sequence with a single anonymous span which contains a sequence of text
+                  nodes representing the individual text node children of the original
+                  sequence of anonymous spans;</p>
+                </li>
+
+                <li>
+                  <p>for each span element whose child is a single anonymous span,
+                  replace the anonymous span with its sequence of child text nodes;</p>
+                </li>
+              </ol>
+            </li>
+
+            <li>
+              <p>resolve styles according to <a href=
+              "#semantics-style-resolution-process-overall"><b>8.4.4.4 Style Resolution
+              Process</b></a>;</p>
+            </li>
+
+            <li>
+              <p>map the <code>tt</code> element to an <code>fo:root</code> element,
+              populated initially with an <code>fo:layout-master-set</code> element that
+              contains a valid <code>fo:simple-page-master</code> that, in turn, contains
+              an <code>fo:region-body</code> child, where the extent of the <em>Root
+              Container Region</em> expressed on the <code>tt</code> element is mapped to
+              <code>page-width</code> and <code>page-height</code> attributes on the
+              <code>fo:simple-page-master</code> element;</p>
+            </li>
+
+            <li>
+              <p>map the <code>layout</code> element to an <code>fo:page-sequence</code>
+              element and a child <code>fo:flow</code> element that reference the page
+              master and page region defined by the simple page master produced
+              above;</p>
+            </li>
+
+            <li>
+              <p>map each non-empty <code>region</code> element to an
+              <code>fo:block-container</code> element with an
+              <code>absolute-position</code> attribute with value <code>absolute</code>,
+              with <code>top</code>, <code>left</code>, <code>bottom</code>, and
+              <code>right</code> attributes that express a rectangle equivalent to the
+              region's origin and extent, and with a <code>line-stacking-strategy</code>
+              attribute with value <code>line-height</code>;</p>
+            </li>
+
+            <li>
+              <p>for each <code>body</code>, <code>div</code>, and <code>p</code> element
+              that is not associated with a <code>tts:display</code> style property with
+              the value <code>none</code>, map the element to a distinct
+              <code>fo:block</code> element, populating the style properties of
+              <code>fo:block</code> by using the computed style set associated with each
+              original TTML Content element;</p>
+            </li>
+
+            <li>
+              <p>for the resulting <code>fo:block</code> formatting object produced in
+              the previous step that corresponds to the <code>body</code> element,
+              perform the following ordered sub-steps:</p>
+
+              <ol class="enumla">
+                <li>
+                  <p>if the <code>display-align</code> style property of this
+                  <code>fo:block</code> has the value <code>center</code> or
+                  <code>after</code>, then synthesize and insert as the first child of
+                  this <code>fo:block</code> an empty <code>fo:block</code> with the
+                  following attributes: <code>space-after.optimum</code>,
+                  <code>space-after.maximum</code>, and
+                  <code>space-after.conditionality</code>, where the value of the former
+                  two attributes is the height or width of the containing
+                  <code>fo:block-container</code> element, whichever of these is
+                  designated as the block progression dimension, and where the value of
+                  the last is <code>retain</code>;</p>
+                </li>
+
+                <li>
+                  <p>if the <code>display-align</code> style property of this
+                  <code>fo:block</code> has the value <code>center</code> or
+                  <code>before</code>, then synthesize and insert as the last child of
+                  this <code>fo:block</code> an empty <code>fo:block</code> with the
+                  following attributes: <code>space-after.optimum</code>,
+                  <code>space-after.maximum</code>, and
+                  <code>space-after.conditionality</code>, where the value of the former
+                  two attributes is the height or width of the containing
+                  <code>fo:block-container</code> element, whichever of these is
+                  designated as the block progression dimension, and where the value of
+                  the last is <code>retain</code>;</p>
+                </li>
+              </ol>
+            </li>
+
+            <li>
+              <p>for each <code>span</code> element that is not associated with a
+              <code>tts:display</code> style property with the value <code>none</code>
+              and for each anonymous span that is a child of a <code>p</code> or
+              <code>span</code> element, map the element or sequence of character items
+              to a distinct <code>fo:inline</code> element, populating the style
+              properties of <code>fo:inline</code> by using the computed style set
+              associated with each original TTML Content element or anonymous span;</p>
+            </li>
+
+            <li>
+              <p>for each <code>br</code> element that is not associated with a
+              <code>tts:display</code> style property with the value <code>none</code>,
+              map the element to a distinct <code>fo:character</code> element having the
+              following properties:</p>
+
+              <ul>
+                <li>
+                  <p><code>character="&amp;#x000A;"</code></p>
+                </li>
+
+                <li>
+                  <p><code>suppress-at-line-break="retain"</code></p>
+                </li>
+              </ul>
+            </li>
+
+            <li>
+              <p>for each TTML style property attribute in some computed style set that
+              has no counterpart in <a href="#xsl11">[XSL 1.1]</a>, map that attribute
+              directly through to the relevant formatting object produced by the input
+              TTML Content element to which the style property applies;</p>
+            </li>
+
+            <li>
+              <p>optionally, synthesize a unique <code>id</code> attribute on each
+              resulting formatting object element that relates that element to the input
+              element that resulted in that formatting object element;</p>
+            </li>
+          </ol>
+
+          <p>For each resulting document instance F, if processing requires presentation
+          on a visual medium, then apply formatting and rendering semantics consistent
+          with that prescribed by <a href="#xsl11">[XSL 1.1]</a>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In an XSL FO area tree produced by formatting <em>F</em> using an <a href=
+            "#xsl11">[XSL 1.1]</a> formatting processor, the
+            <code>page-viewport-area</code>, which is generated by
+            <code>fo:page-sequence</code> element by reference to the sole generated
+            <code>fo:simple-page-master</code> element, would correspond to the <em>Root
+            Container Region</em> defined above in <a href="#definitions"><b>2
+            Definitions</b></a>.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Due to the possible presence of TTML style properties or style property
+            values in a given <em>Document Instance</em> for which there is no <a href=
+            "#xsl11">[XSL 1.1]</a> counterpart, Implementors should recognize that it is
+            the layout model of <a href="#xsl11">[XSL 1.1]</a> that is being referenced
+            by this specification, not the requirement to use a compliant <a href=
+            "#xsl11">[XSL 1.1]</a> formatting processor, since such would not necessarily
+            be sufficient to satisfy the full presentation semantics defined by this
+            specification, and would contain a large number of features not needed to
+            implement the presentation semantics of TTML.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The purpose of inserting additional, collapsible space in the block
+            progression dimension of the <code>fo:block</code> that corresponds with the
+            <code>body</code> element is to ensure that the before and after edges of
+            this <code>fo:block</code> are coincident with the before and after edges of
+            the <code>fo:block-container</code> that corresponds to the containing
+            <code>region</code>, while simultaneously taking into account the needs to
+            satisfy alignment in the block progression dimension. For example, this
+            assures that the background color associated with the <code>body</code>
+            element, if not <code>transparent</code>, will fill the containing region
+            wholly.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="semantics-region-layout-example" name=
+          "semantics-region-layout-example"></a>9.3.4 Elaborated Example
+          (Informative)</h4>
+
+          <p>An example of the processing steps described above is elaborated below,
+          starting with <a href="#region-mapping-example-1-s"><b>Example – Sample Source
+          Document</b></a>.</p><a id="region-mapping-example-1-s" name=
+          "region-mapping-example-1-s"></a>
+
+          <table class="example">
+            <caption>
+              Example – Sample Source Document
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;tt tts:extent="640px 480px" xml:lang="en"
+  xmlns="http://www.w3.org/ns/ttml"
+  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;head&gt;
+    &lt;layout&gt;
+      &lt;region xml:id="r1"&gt;
+        &lt;style tts:origin="10px 100px"/&gt;
+        &lt;style tts:extent="620px 96px"/&gt;
+        &lt;style tts:fontSize="40px"/&gt;
+        &lt;style tts:fontWeight="bold"/&gt;
+        &lt;style tts:backgroundColor="black"/&gt;
+        &lt;style tts:color="red"/&gt;
+        &lt;style tts:textAlign="center"/&gt;
+        &lt;style tts:displayAlign="center"/&gt;
+      &lt;/region&gt;
+      &lt;region xml:id="r2"&gt;
+        &lt;style tts:origin="10px 300px"/&gt;
+        &lt;style tts:extent="620px 96px"/&gt;
+        &lt;style tts:fontSize="40px"/&gt;
+        &lt;style tts:fontWeight="bold"/&gt;
+        &lt;style tts:backgroundColor="black"/&gt;
+        &lt;style tts:color="yellow"/&gt;
+        &lt;style tts:textAlign="center"/&gt;
+        &lt;style tts:displayAlign="center"/&gt;
+      &lt;/region&gt;
+    &lt;/layout&gt;
+  &lt;/head&gt;
+  &lt;body xml:id="b1"&gt;
+    &lt;div xml:id="d1" begin="0s" dur="2s"&gt;
+      &lt;p xml:id="p1" region="r1"&gt;Text 1&lt;/p&gt;
+      &lt;p xml:id="p2" region="r2"&gt;Text 2&lt;/p&gt;
+    &lt;/div&gt;
+    &lt;div xml:id="d2" begin="1s" dur="2s"&gt;
+      &lt;p xml:id="p3" region="r2"&gt;Text 3&lt;/p&gt;
+      &lt;p xml:id="p4" region="r1"&gt;Text 4&lt;/p&gt;
+    &lt;/div&gt;
+  &lt;/body&gt;
+&lt;/tt&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>In the above document, the content hierarchy consists of two divisions, each
+          containing two paragraphs. This content is targeted (associated with) one of
+          two non-overlapping regions that are styled identically except for their
+          position and their foreground colors, the latter of which is inherited by and
+          applies to the (and, in this case, anonymous) spans reparented into the
+          regions.</p>
+
+          <p>The following, first intermediate document shows the synchronic state for
+          time interval [0,1), during which time only division <code>d1</code> is
+          temporally active, and where paragraphs <code>p1</code> and <code>p2</code>
+          (and their ancestors) are associated with regions <code>r1</code> and
+          <code>r2</code>, respectively.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The intermediate documents shown below are not valid <em>Document
+            Instances</em>, but rather, are representations of possible internal
+            processing states used for didactic purposes.</p>
+          </div><a id="region-mapping-example-1-i0" name=
+          "region-mapping-example-1-i0"></a>
+
+          <table class="example">
+            <caption>
+              Example – Intermediate Document – [0s,1s)
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;tt tts:extent="640px 480px" xml:lang="en"
+  xmlns="http://www.w3.org/ns/ttml"
+  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;head&gt;
+    &lt;layout&gt;
+      &lt;region xml:id="r1"&gt;
+        &lt;style tts:origin="10px 100px"/&gt;
+        &lt;style tts:extent="620px 96px"/&gt;
+        &lt;style tts:fontSize="40px"/&gt;
+        &lt;style tts:fontWeight="bold"/&gt;
+        &lt;style tts:backgroundColor="black"/&gt;
+        &lt;style tts:color="red"/&gt;
+        &lt;style tts:textAlign="center"/&gt;
+        &lt;style tts:displayAlign="center"/&gt;
+        &lt;body xml:id="b1-1"&gt;
+          &lt;div xml:id="d1-1"&gt;
+            &lt;p xml:id="p1"&gt;Text 1&lt;/p&gt;
+          &lt;/div&gt;
+        &lt;/body&gt;
+      &lt;/region&gt;
+      &lt;region xml:id="r2"&gt;
+        &lt;style tts:origin="10px 300px"/&gt;
+        &lt;style tts:extent="620px 96px"/&gt;
+        &lt;style tts:fontSize="40px"/&gt;
+        &lt;style tts:fontWeight="bold"/&gt;
+        &lt;style tts:backgroundColor="black"/&gt;
+        &lt;style tts:color="yellow"/&gt;
+        &lt;style tts:textAlign="center"/&gt;
+        &lt;style tts:displayAlign="center"/&gt;
+        &lt;body xml:id="b1-2"&gt;
+          &lt;div xml:id="d1-2"&gt;
+            &lt;p xml:id="p2"&gt;Text 2&lt;/p&gt;
+          &lt;/div&gt;
+        &lt;/body&gt;
+      &lt;/region&gt;
+    &lt;/layout&gt;
+  &lt;/head&gt;
+&lt;/tt&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>An XSL FO document instance that would yield rendering consistent with TTML,
+          and which may be produced by performing flow processing upon the first
+          intermediate document is illustrated below.</p><a id=
+          "region-mapping-example-1-f0" name="region-mapping-example-1-f0"></a>
+
+          <table class="example">
+            <caption>
+              Example – XSL FO Document – [0s,1s)
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format"&gt;
+  &lt;fo:layout-master-set&gt;
+    &lt;fo:simple-page-master master-name="m1"
+      page-width="640px" page-height="480px"&gt;
+      &lt;fo:region-body/&gt;
+    &lt;/fo:simple-page-master&gt;
+  &lt;/fo:layout-master-set&gt;
+  &lt;fo:page-sequence master-reference="m1"&gt;
+    &lt;fo:flow flow-name="xsl-region-body"&gt;
+      &lt;!-- region (r1) --&gt;
+      &lt;fo:block-container id="r1" absolute-position="absolute"
+        left="10px" top="100px" width="620px" height="96px"
+        background-color="black" display-align="center"&gt;
+        &lt;!-- body (b1) --&gt;
+        &lt;fo:block id="b1-1"&gt;
+          &lt;!-- body's space (before) filler --&gt;
+          &lt;fo:block
+            space-after.optimum="96px"
+            space-after.maximum="96px"
+            space-after.conditionality="retain"/&gt;
+          &lt;!-- div (d1) --&gt;
+          &lt;fo:block id="d1-1"&gt;
+            &lt;!-- p (p1) --&gt;
+            &lt;fo:block id="p1" text-align="center"&gt;
+              &lt;fo:inline font-size="40px" font-weight="bold"
+              color="red"&gt;Text 1&lt;/fo:inline&gt;
+            &lt;/fo:block&gt;
+          &lt;/fo:block&gt;
+          &lt;!-- body's space (after) filler --&gt;
+          &lt;fo:block
+            space-after.optimum="96px"
+            space-after.maximum="96px"
+            space-after.conditionality="retain"/&gt;
+        &lt;/fo:block&gt;
+      &lt;/fo:block-container&gt;
+      &lt;!-- region (r2) --&gt;
+      &lt;fo:block-container id="r2" absolute-position="absolute"
+        left="10px" top="300px" width="620px" height="96px"
+        background-color="black" display-align="center"&gt;
+        &lt;!-- body (b1) --&gt;
+        &lt;fo:block id="b1-2"&gt;
+          &lt;!-- body's space (before) filler --&gt;
+          &lt;fo:block
+            space-after.optimum="96px"
+            space-after.maximum="96px"
+            space-after.conditionality="retain"/&gt;
+          &lt;!-- div (d1) --&gt;
+          &lt;fo:block id="d1-2"&gt;
+            &lt;!-- p (p2) --&gt;
+            &lt;fo:block id="p2" text-align="center"&gt;
+              &lt;fo:inline font-size="40px" font-weight="bold"
+              color="yellow"&gt;Text 2&lt;/fo:inline&gt;
+            &lt;/fo:block&gt;
+          &lt;/fo:block&gt;
+          &lt;!-- body's space (after) filler --&gt;
+          &lt;fo:block
+            space-after.optimum="96px"
+            space-after.maximum="96px"
+            space-after.conditionality="retain"/&gt;
+        &lt;/fo:block&gt;
+      &lt;/fo:block-container&gt;
+    &lt;/fo:flow&gt;
+  &lt;/fo:page-sequence&gt;
+&lt;/fo:root&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The following, second intermediate document shows the synchronic state for
+          time interval [1,2), during which time both divisions <code>d1</code> and
+          <code>d2</code> are temporally active, and where paragraphs <code>p1</code> and
+          <code>p4</code> (and their ancestors) are associated with region
+          <code>r1</code> and paragraphs <code>p2</code> and <code>p3</code> (and their
+          ancestors) are associated with region <code>r2</code>.</p><a id=
+          "region-mapping-example-1-i1" name="region-mapping-example-1-i1"></a>
+
+          <table class="example">
+            <caption>
+              Example – Intermediate Document – [1s,2s)
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;tt tts:extent="640px 480px" xml:lang="en"
+  xmlns="http://www.w3.org/ns/ttml"
+  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;head&gt;
+    &lt;layout&gt;
+      &lt;region xml:id="r1"&gt;
+        &lt;style tts:origin="10px 100px"/&gt;
+        &lt;style tts:extent="620px 96px"/&gt;
+        &lt;style tts:fontSize="40px"/&gt;
+        &lt;style tts:fontWeight="bold"/&gt;
+        &lt;style tts:backgroundColor="black"/&gt;
+        &lt;style tts:color="red"/&gt;
+        &lt;style tts:textAlign="center"/&gt;
+        &lt;style tts:displayAlign="center"/&gt;
+        &lt;body xml:id="b1-1"&gt;
+          &lt;div xml:id="d1-1"&gt;
+            &lt;p xml:id="p1"&gt;Text 1&lt;/p&gt;
+          &lt;/div&gt;
+          &lt;div xml:id="d2-1"&gt;
+            &lt;p xml:id="p4"&gt;Text 4&lt;/p&gt;
+          &lt;/div&gt;
+        &lt;/body&gt;
+      &lt;/region&gt;
+      &lt;region xml:id="r2"&gt;
+        &lt;style tts:origin="10px 300px"/&gt;
+        &lt;style tts:extent="620px 96px"/&gt;
+        &lt;style tts:fontSize="40px"/&gt;
+        &lt;style tts:fontWeight="bold"/&gt;
+        &lt;style tts:backgroundColor="black"/&gt;
+        &lt;style tts:color="yellow"/&gt;
+        &lt;style tts:textAlign="center"/&gt;
+        &lt;style tts:displayAlign="center"/&gt;
+        &lt;body xml:id="b1-2"&gt;
+          &lt;div xml:id="d1-2"&gt;
+            &lt;p xml:id="p2"&gt;Text 2&lt;/p&gt;
+          &lt;/div&gt;
+          &lt;div xml:id="d2-2"&gt;
+            &lt;p xml:id="p3"&gt;Text 3&lt;/p&gt;
+          &lt;/div&gt;
+        &lt;/body&gt;
+      &lt;/region&gt;
+    &lt;/layout&gt;
+  &lt;/head&gt;
+&lt;/tt&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The following, third intermediate document shows the synchronic state for
+          time interval [2,3), during which time only division <code>d2</code> is
+          temporally active, and where paragraphs <code>p4</code> and <code>p3</code>
+          (and their ancestors) are associated with regions <code>r1</code> and
+          <code>r2</code>, respectively.</p><a id="region-mapping-example-1-i2" name=
+          "region-mapping-example-1-i2"></a>
+
+          <table class="example">
+            <caption>
+              Example – Intermediate Document – [2s,3s)
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;tt tts:extent="640px 480px" xml:lang="en"
+  xmlns="http://www.w3.org/ns/ttml"
+  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;head&gt;
+    &lt;layout&gt;
+      &lt;region xml:id="r1"&gt;
+        &lt;style tts:origin="10px 100px"/&gt;
+        &lt;style tts:extent="620px 96px"/&gt;
+        &lt;style tts:fontSize="40px"/&gt;
+        &lt;style tts:fontWeight="bold"/&gt;
+        &lt;style tts:backgroundColor="black"/&gt;
+        &lt;style tts:color="red"/&gt;
+        &lt;style tts:textAlign="center"/&gt;
+        &lt;style tts:displayAlign="center"/&gt;
+        &lt;body xml:id="b1-1"&gt;
+          &lt;div xml:id="d2-1"&gt;
+            &lt;p xml:id="p4"&gt;Text 4&lt;/p&gt;
+          &lt;/div&gt;
+        &lt;/body&gt;
+      &lt;/region&gt;
+      &lt;region xml:id="r2"&gt;
+        &lt;style tts:origin="10px 300px"/&gt;
+        &lt;style tts:extent="620px 96px"/&gt;
+        &lt;style tts:fontSize="40px"/&gt;
+        &lt;style tts:fontWeight="bold"/&gt;
+        &lt;style tts:backgroundColor="black"/&gt;
+        &lt;style tts:color="yellow"/&gt;
+        &lt;style tts:textAlign="center"/&gt;
+        &lt;style tts:displayAlign="center"/&gt;
+        &lt;body xml:id="b1-2"&gt;
+          &lt;div xml:id="d2-2"&gt;
+            &lt;p xml:id="p3"&gt;Text 3&lt;/p&gt;
+          &lt;/div&gt;
+        &lt;/body&gt;
+      &lt;/region&gt;
+    &lt;/layout&gt;
+  &lt;/head&gt;
+&lt;/tt&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="semantics-line-layout" name="semantics-line-layout"></a>9.4 Line
+        Layout</h3>
+
+        <p>If a profile that applies to a <em>Document Instance</em> requires use of the
+        <a href="#feature-lineBreak-uax14">#lineBreak-uax14</a> feature (i.e., the value
+        attribute for the feature is specified as <code>use</code>), then the
+        recommendations defined by <a href=
+        "http://www.unicode.org/reports/tr14/#Algorithm">Line Breaking Algorithm</a>
+        <a href="#uax14">[UAX14]</a> apply when performing line layout on the content of
+        the <em>Document Instance</em>.</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="timing" name="timing"></a>10 Timing</h2>
+
+      <p>This section specifies the <em>timing</em> matter of the core vocabulary
+      catalog, where timing is to be understood as a separable layer of information that
+      applies to content and that denotes authorial intentions about the temporal
+      presentation of that content.</p>
+
+      <div class="div2">
+        <h3><a id="timing-element-vocabulary" name="timing-element-vocabulary"></a>10.1
+        Timing Element Vocabulary</h3>
+
+        <p>No timing related element vocabulary is defined for use in the core vocabulary
+        catalog.</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="timing-attribute-vocabulary" name=
+        "timing-attribute-vocabulary"></a>10.2 Timing Attribute Vocabulary</h3>
+
+        <p>This section defines the following basic timing attributes for use with timed
+        elements:</p>
+
+        <ul>
+          <li>
+            <p><a href="#timing-attribute-begin"><b>10.2.1 begin</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#timing-attribute-end"><b>10.2.2 end</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#timing-attribute-dur"><b>10.2.3 dur</b></a></p>
+          </li>
+        </ul>
+
+        <p>In addition, this section defines the <a href=
+        "#timing-attribute-timeContainer"><b>10.2.4 timeContainer</b></a> attribute for
+        use with timed elements that serve simultaneously as timing containers.</p>
+
+        <div class="div3">
+          <h4><a id="timing-attribute-begin" name="timing-attribute-begin"></a>10.2.1
+          begin</h4>
+
+          <p>The <code>begin</code> attribute is used to specify the begin point of a
+          temporal interval associated with a timed element. If specified, the value of a
+          <code>begin</code> attribute must adhere to a &lt;timeExpression&gt;
+          specification as defined by <a href="#timing-value-timeExpression"><b>10.3.1
+          &lt;timeExpression&gt;</b></a>.</p>
+
+          <p>The begin point of a temporal interval is included in the interval; i.e.,
+          the interval is left-wise closed.</p>
+
+          <p>The semantics of the <code>begin</code> attribute are those defined by
+          <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking into account any
+          overriding semantics defined by this specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="timing-attribute-end" name="timing-attribute-end"></a>10.2.2
+          end</h4>
+
+          <p>The <code>end</code> attribute is used to specify the ending point of a
+          temporal interval associated with a timed element. If specified, the value of
+          an <code>end</code> attribute must adhere to a &lt;timeExpression&gt;
+          specification as defined by <a href="#timing-value-timeExpression"><b>10.3.1
+          &lt;timeExpression&gt;</b></a>.</p>
+
+          <p>The ending point of a temporal interval is not included in the interval;
+          i.e., the interval is right-wise open.</p>
+
+          <p>The presentation effects of a non-empty active temporal interval include the
+          frame immediately prior to the frame (or tick) equal to or immediately
+          following the time specified by the ending point, but do not extend into this
+          latter frame (or tick).</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>For example, if an active interval is [10s,10.33333s), and the frame rate
+            is 30 frames per second, then the presentation effects of the interval are
+            limited to frames 300 through 309 only (assuming that 0s corresponds with
+            frame 0). The same holds if the active interval is specified as
+            [300f,310f).</p>
+          </div>
+
+          <p>The semantics of the <code>end</code> attribute are those defined by
+          <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking into account any
+          overriding semantics defined by this specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="timing-attribute-dur" name="timing-attribute-dur"></a>10.2.3
+          dur</h4>
+
+          <p>The <code>dur</code> attribute is used to specify the duration of a temporal
+          interval associated with a timed element. If specified, the value of a
+          <code>dur</code> attribute must adhere to a &lt;timeExpression&gt;
+          specification as defined by <a href="#timing-value-timeExpression"><b>10.3.1
+          &lt;timeExpression&gt;</b></a>.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>When the <code>clock-time</code> form of a &lt;timeExpression&gt;
+            specification is used with a <code>dur</code> attribute, it is intended to be
+            interpreted as a difference between two implied clock time expressions.</p>
+          </div>
+
+          <p>When a <em>Document Instance</em> specifies the use of the
+          <code>smpte</code> time base and <code>discontinuous</code> marker mode, a
+          (well-formed) <code>dur</code> attribute must not be specified on any
+          element.</p>
+
+          <p>The semantics of the <code>dur</code> attribute are those defined by
+          <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking into account any
+          overriding semantics defined by this specification.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the context of the subset of <a href="#smil21">[SMIL 2.1]</a> semantics
+            supported by this specification, the active duration of an element that
+            specifies both <code>end</code> and <code>dur</code> attributes is equal to
+            the lesser of the value of the <code>dur</code> attribute and the difference
+            between the value of the <code>end</code> attribute and the element's begin
+            time.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="timing-attribute-timeContainer" name=
+          "timing-attribute-timeContainer"></a>10.2.4 timeContainer</h4>
+
+          <p>The <code>timeContainer</code> attribute is used to specify a local temporal
+          context by means of which timed child elements are temporally situated.</p>
+
+          <p>If specified, the value of a <code>timeContainer</code> attribute must be
+          one of the following:</p>
+
+          <ul>
+            <li>
+              <p><code>par</code></p>
+            </li>
+
+            <li>
+              <p><code>seq</code></p>
+            </li>
+          </ul>
+
+          <p>If the time container semantics of an element instance is <code>par</code>,
+          then the temporal intervals of child elements are considered to apply in
+          parallel, i.e., simultaneously in time. Furthermore, the specification of the
+          time interval of each child element is considered to be relative to the
+          temporal interval of the container element instance. For the purpose of
+          determining the <a href="#smil21">[SMIL 2.1]</a> <code>endsync</code> semantics
+          of a <code>par</code> time container, a default value of <code>all</code>
+          applies.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The use of a default value of <code>all</code> for the
+            <code>endsync</code> behavior is distinct from <a href="#smil21">[SMIL
+            2.1]</a> which uses a default value of <code>last</code>.</p>
+          </div>
+
+          <p>If the time container semantics of an element instance is <code>seq</code>,
+          then the temporal intervals of child elements are considered to apply in
+          sequence, i.e., sequentially in time. Furthermore, the specification of the
+          time interval of each child element is considered to be relative to the
+          temporal interval of its sibling elements, unless it is the first child
+          element, in which case it is considered to be relative to the temporal interval
+          of the container element instance.</p>
+
+          <p>Each time container is considered to constitute an independent time base,
+          i.e., time coordinate system.</p>
+
+          <p>If a <code>timeContainer</code> attribute is not specified on an element
+          that has time container semantics, then <code>par</code> time container
+          semantics must apply.</p>
+
+          <p>Time container semantics applies only to the following element types:</p>
+
+          <ul>
+            <li>
+              <p><a href="#document-structure-vocabulary-body"><code>body</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#layout-vocabulary-region"><code>region</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
+            </li>
+          </ul>
+
+          <p>The semantics of parallel and sequential time containment are those defined
+          by <a href="#smil21">[SMIL 2.1]</a>, § 10.4.2, while taking into account any
+          overriding semantics defined by this specification.</p>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="timing-time-value-expressions" name=
+        "timing-time-value-expressions"></a>10.3 Time Value Expressions</h3>
+
+        <p>Timing attribute values include the use of the following expressions:</p>
+
+        <ul>
+          <li>
+            <p><a href="#timing-value-timeExpression"><b>10.3.1
+            &lt;timeExpression&gt;</b></a></p>
+          </li>
+        </ul>
+
+        <div class="div3">
+          <h4><a id="timing-value-timeExpression" name=
+          "timing-value-timeExpression"></a>10.3.1 &lt;timeExpression&gt;</h4>
+
+          <p>A &lt;timeExpression&gt; is used to specify a coordinate within some time
+          base, where the applicable time base is determined by the
+          <code>ttp:timeBase</code> parameter, and where the semantics defined by
+          <a href="#time-expression-semantics"><b>N Time Expression Semantics</b></a>
+          apply.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>See <a href="#parameter-attribute-frameRate"><b>6.2.4
+            ttp:frameRate</b></a>, <a href="#parameter-attribute-subFrameRate"><b>6.2.9
+            ttp:subFrameRate</b></a>, <a href="#parameter-attribute-tickRate"><b>6.2.10
+            ttp:tickRate</b></a>, and <a href="#parameter-attribute-timeBase"><b>6.2.11
+            ttp:timeBase</b></a> for further information on explicit specification of
+            frame rate, sub-frame rate, tick rate, and time base.</p>
+          </div><a id="timeExpression-syntax" name="timeExpression-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – &lt;timeExpression&gt;
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;timeExpression&gt;
+  : clock-time
+  | offset-time
+
+clock-time
+  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?
+
+offset-time
+  : time-count fraction? metric
+
+hours
+  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
+"#style-value-digit">&lt;digit&gt;</a>
+  | <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
+"#style-value-digit">&lt;digit&gt;</a> <a href="#style-value-digit">&lt;digit&gt;</a>+
+
+minutes | seconds
+  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
+"#style-value-digit">&lt;digit&gt;</a>
+
+frames
+  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
+"#style-value-digit">&lt;digit&gt;</a>
+  | <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
+"#style-value-digit">&lt;digit&gt;</a> <a href="#style-value-digit">&lt;digit&gt;</a>+
+
+sub-frames
+  : <a href="#style-value-digit">&lt;digit&gt;</a>+
+
+fraction
+  : "." <a href="#style-value-digit">&lt;digit&gt;</a>+
+
+time-count
+  : <a href="#style-value-digit">&lt;digit&gt;</a>+
+
+metric
+  : "h"                 // hours
+  | "m"                 // minutes
+  | "s"                 // seconds
+  | "ms"                // milliseconds
+  | "f"                 // frames
+  | "t"                 // ticks
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>If a &lt;timeExpression&gt; is expressed in terms of a <em>clock-time</em>,
+          then leading zeroes are used when expressing hours, minutes, seconds, and
+          frames less than 10. Minutes are constrained to [0…59], while seconds
+          (including any fractional part) are constrained to the closed interval [0,60],
+          where the value 60 applies only to leap seconds.</p>
+
+          <p>If a &lt;timeExpression&gt; is expressed in terms of a <em>clock-time</em>
+          and a <em>frames</em> term is specified, then the value of this term must be
+          constrained to the interval [0…<em>F-1</em>], where <em>F</em> is the frame
+          rate determined by the <code>ttp:frameRate</code> parameter as defined by
+          <a href="#parameter-attribute-frameRate"><b>6.2.4 ttp:frameRate</b></a>. It is
+          considered an error if a <em>frames</em> term or <code>f</code> (frames) metric
+          is specified when the <code>clock</code> time base applies.</p>
+
+          <p>If a &lt;timeExpression&gt; is expressed in terms of a <em>clock-time</em>
+          and a <em>sub-frames</em> term is specified, then the value of this term must
+          be constrained to the interval [0…<em>S-1</em>], where <em>S</em> is the
+          sub-frame rate determined by the <code>ttp:subFrameRate</code> parameter as
+          defined by <a href="#parameter-attribute-subFrameRate"><b>6.2.9
+          ttp:subFrameRate</b></a>. It is considered an error if a <em>sub-frames</em>
+          term is specified when the <code>clock</code> time base applies.</p>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="timing-time-intervals" name="timing-time-intervals"></a>10.4 Time
+        Intervals</h3>
+
+        <p>The semantics of time containment, durations, and intervals defined by
+        <a href="#smil21">[SMIL 2.1]</a> apply to the interpretation of like-named timed
+        elements and timing vocabulary defined by this specification, given the following
+        constraints:</p>
+
+        <ul>
+          <li>
+            <p>The implicit duration of an anonymous span is defined as follows: if the
+            anonymous span's parent time container is a parallel time container, then the
+            implicit duration is equivalent to the <code>indefinite</code> duration value
+            as defined by <a href="#smil21">[SMIL 2.1]</a>; if the anonymous span's
+            parent time container is a sequential time container, then the implicit
+            duration is equivalent to zero.</p>
+          </li>
+
+          <li>
+            <p>The implicit duration of a <code>body</code>, <code>div</code>,
+            <code>p</code>, or <code>span</code> element is determined in accordance to
+            (1) whether the element is a parallel or sequential time container, (2) the
+            default <code>endsync</code> semantics defined above by <a href=
+            "#timing-attribute-timeContainer"><b>10.2.4 timeContainer</b></a>, and (3)
+            the semantics of <a href="#smil21">[SMIL 2.1]</a> as applied to these time
+            containers.</p>
+          </li>
+
+          <li>
+            <p>The implicit duration of the <code>region</code> element is defined to be
+            equivalent to the <code>indefinite</code> duration value as defined by
+            <a href="#smil21">[SMIL 2.1]</a>.</p>
+          </li>
+
+          <li>
+            <p>If the governing time base is <code>clock</code>, then time expressions
+            are considered to be equivalent to wall-clock based timing in <a href=
+            "#smil21">[SMIL 2.1]</a>, where the specific semantics of <a href=
+            "#time-expression-semantics-clock"><b>N.1 Clock Time Base</b></a> apply.</p>
+          </li>
+
+          <li>
+            <p>If the governing time base is <code>media</code>, then time expressions
+            are considered to be equivalent to offset based timing in <a href=
+            "#smil21">[SMIL 2.1]</a>, where the specific semantics of <a href=
+            "#time-expression-semantics-media"><b>N.2 Media Time Base</b></a> apply.</p>
+          </li>
+
+          <li>
+            <p>If the governing time base is <code>smpte</code>, then time expressions
+            are considered to be equivalent to either offset based timing or event based
+            timing in <a href="#smil21">[SMIL 2.1]</a>, where the specific semantics of
+            <a href="#time-expression-semantics-smpte"><b>N.3 SMPTE Time Base</b></a>
+            apply.</p>
+          </li>
+        </ul>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="animation" name="animation"></a>11 Animation</h2>
+
+      <p>This section specifies the <em>animation</em> matter of the core vocabulary
+      catalog, where animation is to be understood as a separable layer of information
+      that combines timing and styling in order to denote authorial intention about
+      (temporally) dynamic styling of content.</p>
+
+      <div class="div2">
+        <h3><a id="animation-element-vocabulary" name=
+        "animation-element-vocabulary"></a>11.1 Animation Element Vocabulary</h3>
+
+        <p>The following elements specify the structure and principal animation aspects
+        of a <em>Document Instance</em>:</p>
+
+        <ul>
+          <li>
+            <p><a href="#animation-vocabulary-set"><b>11.1.1 set</b></a></p>
+          </li>
+        </ul>
+
+        <div class="div3">
+          <h4><a id="animation-vocabulary-set" name="animation-vocabulary-set"></a>11.1.1
+          set</h4>
+
+          <p>The <code>set</code> element is used as a child element of a content element
+          or a <code>region</code> element in order to express a discrete change of some
+          style parameter value that applies over some time interval.</p>
+
+          <p>The <code>set</code> element accepts as its children zero or more elements
+          in the <code>Metadata.class</code> element group.</p><a id="elt-syntax-set"
+          name="elt-syntax-set"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: set
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;set
+  <a href="#timing-attribute-begin">begin</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-dur">dur</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#timing-attribute-end">end</a> = <a href=
+"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>a single attribute in TT Style namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*
+&lt;/set&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The use of multiple <code>set</code> element children may be used to
+            effect fade and position transitions.</p>
+          </div>
+
+          <p>An example of using the <code>set</code> element to animate content styling
+          is illustrated below:</p><a id="animation-vocabulary-set-example-1" name=
+          "animation-vocabulary-set-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Content Style Animation
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+...
+&lt;p dur="5s" tts:color="yellow"&gt;
+<span class="strong">&lt;set begin="1s" dur="1s" tts:color="red"/&gt;</span>
+<span class="strong">&lt;set begin="2s" dur="1s" tts:color="green"/&gt;</span>
+<span class="strong">&lt;set begin="3s" dur="1s" tts:color="red"/&gt;</span>
+Text with Flashing Colors!
+&lt;/p&gt;
+...
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, the foreground color of the content "Text with
+            Flashing Colors" is animated from yellow, to red, to green, to red, then back
+            to yellow over a 5 second period.</p>
+          </div>
+
+          <p>An example of using the <code>set</code> element to animate region styling
+          is illustrated below:</p><a id="animation-vocabulary-set-example-2" name=
+          "animation-vocabulary-set-example-2"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Region Style Animation
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"
+    xmlns:ttp="http://www.w3.org/ns/ttml#parameter"
+    xmlns:tts="http://www.w3.org/ns/ttml#styling"
+    ttp:cellResolution="40 16"&gt;
+    &lt;head&gt;
+      &lt;layout&gt;
+        &lt;region xml:id="r1" timeContainer="seq"&gt;
+          <span class="strong">&lt;set dur="10s" tts:origin=" 8c 14c"/&gt;</span>
+          <span class="strong">&lt;set dur="2s"  tts:origin=" 2c  2c"/&gt;</span>
+          <span class="strong">&lt;set dur="3s"  tts:origin=" 8c 14c"/&gt;</span>
+          <span class="strong">&lt;set dur="2s"  tts:origin="14c  4c"/&gt;</span>
+          <span class="strong">&lt;set dur="10s" tts:origin=" 8c 14c"/&gt;</span>
+          &lt;style tts:extent="24c 2c"/&gt;
+        &lt;/region&gt;
+      &lt;/layout&gt;
+    &lt;/head&gt;
+    &lt;body region="r1"&gt;...&lt;/body&gt;
+&lt;/tt&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, the <em>Root Container Region</em> is divided into a
+            cell grid of 40 columns and 16 rows. A region, <code>r1</code>, with
+            dimensions of 24 columns and 2 rows is then positioned within the <em>Root
+            Container Region</em>, with its position varying over time in order to create
+            an effect of moving the region, which may be desirable so as to avoid
+            obscuring characters in an underlying video with captions.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The semantics of the <code>set</code> element are based upon that defined
+            by <a href="#smil21">[SMIL 2.1]</a>, § 3.6.2.</p>
+          </div>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="animation-attribute-vocabulary" name=
+        "animation-attribute-vocabulary"></a>11.2 Animation Attribute Vocabulary</h3>
+
+        <p>No animation related attribute vocabulary is defined for use in the core
+        vocabulary catalog.</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="metadata" name="metadata"></a>12 Metadata</h2>
+
+      <p>This section specifies the <em>metadata</em> matter of the core vocabulary
+      catalog, where metadata is to be understood as a separable layer of information
+      that applies to parameters, content, style, layout, timing, and even metadata
+      itself, where the information represented by metadata takes one of two forms: (1)
+      metadata defined by this specification for standardized use in a <em>Document
+      Instance</em>, and (2) arbitrary metadata defined outside of the scope of this
+      specification, whose use and semantics depend entirely upon an application's use of
+      TTML Content.</p>
+
+      <div class="div2">
+        <h3><a id="metadata-element-vocabulary" name=
+        "metadata-element-vocabulary"></a>12.1 Metadata Element Vocabulary</h3>
+
+        <p>The <a href="#metadata-vocabulary-metadata"><b>12.1.1 metadata</b></a> element
+        serves as a generic container element for grouping metadata information.</p>
+
+        <p>In addition, the following elements, all defined in the TT Metadata Namespace,
+        provide standard representations for metadata that is expected to be commonly
+        used in a <em>Document Instances</em>:</p>
+
+        <ul>
+          <li>
+            <p><a href="#metadata-vocabulary-title"><b>12.1.2 ttm:title</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#metadata-vocabulary-desc"><b>12.1.3 ttm:desc</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#metadata-vocabulary-copyright"><b>12.1.4
+            ttm:copyright</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#metadata-vocabulary-agent"><b>12.1.5 ttm:agent</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#metadata-vocabulary-name"><b>12.1.6 ttm:name</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#metadata-vocabulary-actor"><b>12.1.7 ttm:actor</b></a></p>
+          </li>
+        </ul>
+
+        <div class="div3">
+          <h4><a id="metadata-vocabulary-metadata" name=
+          "metadata-vocabulary-metadata"></a>12.1.1 metadata</h4>
+
+          <p>The <code>metadata</code> element functions as a generic container for
+          metadata information.</p>
+
+          <p>Metadata information may be expressed with a <code>metadata</code> element
+          by specifying (1) one or more metadata attributes on the <code>metadata</code>
+          element, (2) one or more metadata child elements in the <code>metadata</code>
+          element, or (3) a combination of metadata attributes and metadata child
+          elements. Both types of metadata information are referred to in this document
+          as <em>metadata items</em>.</p><a id="elt-syntax-metadata" name=
+          "elt-syntax-metadata"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: metadata
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;metadata
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute in TT Metadata namespace</em>}
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> ({<em>any element in TT Metadata namespace</em>}|{<em>any element not in any TT namespace</em>})*
+&lt;/metadata&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>The meaning of a specific metadata item must be evaluated in the context
+            where it appears. The core vocabulary catalog permits an arbitrary number of
+            <code>metadata</code> element children on any content element type except for
+            the <code>tt</code> element. See specific element vocabulary definitions for
+            any constraints that apply to such usage.</p>
+          </div>
+
+          <p>The use of document metadata is illustrated by the following
+          example.</p><a id="metadata-vocabulary-metadata-example-1" name=
+          "metadata-vocabulary-metadata-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Document Metadata
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+...
+&lt;head&gt;
+  &lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
+    &lt;ttm:title&gt;Document Metadata Example&lt;/ttm:title&gt;
+    &lt;ttm:desc&gt;This document employs document metadata.&lt;/ttm:desc&gt;
+  &lt;/metadata&gt;
+&lt;/head&gt;
+...
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p>
+
+          <p>The use of element metadata is illustrated by the following
+          example.</p><a id="metadata-vocabulary-metadata-example-2" name=
+          "metadata-vocabulary-metadata-example-2"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Element Metadata
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+...
+&lt;div&gt;
+  &lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
+    &lt;ttm:title&gt;Chapter 6 – Sherlock Holmes Gives a Demonstration&lt;/ttm:title&gt;
+    &lt;ttm:desc&gt;Holmes shows Watson how the murderer entered the window.&lt;/ttm:desc&gt;
+  &lt;/metadata&gt;
+&lt;/div&gt;
+...
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p></p>
+
+          <p>The use of metadata attribute items is illustrated by the following
+          example.</p><a id="metadata-vocabulary-metadata-example-3" name=
+          "metadata-vocabulary-metadata-example-3"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Foreign Metadata Attribute Items
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+...
+&lt;div xmlns:ext="http://example.org/ttml#metadata"&gt;
+  &lt;metadata ext:ednote="remove this division prior to publishing"/&gt;
+&lt;/div&gt;
+...
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, a global attribute from a foreign (external)
+            namespace is used to express a metadata attribute that applies semantically
+            to the containing <code>div</code> element. Note that the attribute may also
+            be expressed directly on the <code>div</code> element; however, in this case
+            the author wishes to segregate certain metadata attributes by expressing them
+            indirectly on <code>metadata</code> elements.</p>
+          </div>
+
+          <p></p>
+
+          <p>The use of foreign element metadata is illustrated by the following
+          example.</p><a id="metadata-vocabulary-metadata-example-4" name=
+          "metadata-vocabulary-metadata-example-4"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Foreign Element Metadata
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+...
+&lt;metadata
+  xmlns:dc="http://purl.org/dc/elements/1.1/"
+  xmlns:dcterms="http://purl.org/dc/terms/"
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"&gt;
+  &lt;dc:title&gt;Foreign Element Metadata Example&lt;/dc:title&gt;
+  &lt;dc:description&gt;Express metadata using elements in foreign namespace.&lt;/dc:description&gt;
+  &lt;dc:format xsi:type="dcterms:IMT"&gt;application/ttml+xml&lt;/dc:format&gt;
+&lt;/metadata&gt;
+...
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, a number of elements defined by the Dublin Core
+            metadata vocabulary are used to express document level metadata.</p>
+          </div>
+
+          <p></p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="metadata-vocabulary-title" name=
+          "metadata-vocabulary-title"></a>12.1.2 ttm:title</h4>
+
+          <p>The <code>ttm:title</code> element is used to express a human-readable title
+          of a specific element instance.</p><a id="elt-syntax-metadata-title" name=
+          "elt-syntax-metadata-title"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttm:title
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttm:title
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> #PCDATA
+&lt;/ttm:title&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>No specific use of the <code>ttm:title</code> element is defined by this
+            specification.</p>
+          </div>
+
+          <p>Examples of the <code>ttm:title</code> element are shown above in <a href=
+          "#metadata-vocabulary-metadata-example-1"><b>Example Fragment – Document
+          Metadata</b></a> and <a href=
+          "#metadata-vocabulary-metadata-example-2"><b>Example Fragment – Element
+          Metadata</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="metadata-vocabulary-desc" name="metadata-vocabulary-desc"></a>12.1.3
+          ttm:desc</h4>
+
+          <p>The <code>ttm:desc</code> element is used to express a human-readable
+          description of a specific element instance.</p><a id="elt-syntax-metadata-desc"
+          name="elt-syntax-metadata-desc"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttm:desc
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttm:desc
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> #PCDATA
+&lt;/ttm:desc&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>No specific use of the <code>ttm:desc</code> element is defined by this
+            specification.</p>
+          </div>
+
+          <p>Examples of the <code>ttm:desc</code> element are shown above in <a href=
+          "#metadata-vocabulary-metadata-example-1"><b>Example Fragment – Document
+          Metadata</b></a> and <a href=
+          "#metadata-vocabulary-metadata-example-2"><b>Example Fragment – Element
+          Metadata</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="metadata-vocabulary-copyright" name=
+          "metadata-vocabulary-copyright"></a>12.1.4 ttm:copyright</h4>
+
+          <p>The <code>ttm:copyright</code> element is used to express a human-readable
+          copyright that applies to some scoping level.</p>
+
+          <p>A copyright statement that applies to a document as a whole should appear as
+          a child of the <code>head</code> element.</p><a id=
+          "elt-syntax-metadata-copyright" name="elt-syntax-metadata-copyright"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttm:copyright
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttm:copyright
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> #PCDATA
+&lt;/ttm:copyright&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>No specific use of the <code>ttm:copyright</code> element is defined by
+            this specification.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="metadata-vocabulary-agent" name=
+          "metadata-vocabulary-agent"></a>12.1.5 ttm:agent</h4>
+
+          <p>The <code>ttm:agent</code> element is used to define an agent for the
+          purpose of associating content information with an agent who is involved in the
+          production or expression of that content.</p>
+
+          <p>The <code>ttm:agent</code> element accepts as its children zero or more
+          <code>ttm:name</code> elements followed by zero or one <code>ttm:actor</code>
+          element.</p>
+
+          <p>At least one <code>ttm:name</code> element child should be specified that
+          expresses a name for the agent, whether it be the name of a person, character,
+          group, or organization.</p><a id="elt-syntax-metadata-agent" name=
+          "elt-syntax-metadata-agent"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttm:agent
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttm:agent
+  <span class=
+"reqattr">type</span> = (<em>person</em>|<em>character</em>|<em>group</em>|<em>organization</em>|<em>other</em>)
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> <a href="#metadata-vocabulary-name">ttm:name</a>*, <a href=
+"#metadata-vocabulary-actor">ttm:actor</a>?
+&lt;/ttm:agent&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>A <code>type</code> attribute must be specified on each
+          <code>ttm:agent</code> element, and, if specified, must have one of the
+          following values:</p>
+
+          <ul>
+            <li>
+              <p><code>person</code></p>
+            </li>
+
+            <li>
+              <p><code>character</code></p>
+            </li>
+
+            <li>
+              <p><code>group</code></p>
+            </li>
+
+            <li>
+              <p><code>organization</code></p>
+            </li>
+
+            <li>
+              <p><code>other</code></p>
+            </li>
+          </ul>
+
+          <p>If the value of the <code>type</code> attribute is <code>character</code>,
+          then the <code>ttm:agent</code> element instance should specify a
+          <code>ttm:actor</code> child that specifies the agent that plays the role of
+          the actor.</p>
+
+          <p>A <code>ttm:agent</code> metadata item is considered to be significant only
+          when specified as a child of the <code>head</code> element or as a child of a
+          <code>metadata</code> element child of the <code>head</code> element.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>A <code>ttm:agent</code> element instance is typically referenced using a
+            <code>ttm:agent</code> attribute on a content element.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>If a character agent is played by multiple actors, then multiple character
+            agents may be specified (and referenced) wherein different definitions of the
+            character specify different actors.</p>
+          </div>
+
+          <p>The use of agent metadata is illustrated by the following example.</p><a id=
+          "metadata-vocabulary-agent-example-1" name=
+          "metadata-vocabulary-agent-example-1"></a>
+
+          <table class="example">
+            <caption>
+              Example Fragment – Agent Metadata
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+
+&lt;tt xml:lang="en" xmlns="http://www.w3.org/ns/ttml" xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
+  &lt;head&gt;
+    <span class="strong">&lt;ttm:agent xml:id="connery" type="person"&gt;</span>
+      &lt;ttm:name type="family"&gt;Connery&lt;/ttm:name&gt;
+      &lt;ttm:name type="given"&gt;Thomas Sean&lt;/ttm:name&gt;
+      &lt;ttm:name type="alias"&gt;Sean&lt;/ttm:name&gt;
+      &lt;ttm:name type="full"&gt;Sir Thomas Sean Connery&lt;/ttm:name&gt;
+    <span class="strong">&lt;/ttm:agent&gt;</span>
+    <span class="strong">&lt;ttm:agent xml:id="bond" type="character"&gt;</span>
+      &lt;ttm:name type="family"&gt;Bond&lt;/ttm:name&gt;
+      &lt;ttm:name type="given"&gt;James&lt;/ttm:name&gt;
+      &lt;ttm:name type="alias"&gt;007&lt;/ttm:name&gt;
+      &lt;ttm:actor agent="connery"/&gt;
+    <span class="strong">&lt;/ttm:agent&gt;</span>
+  &lt;/head&gt;
+  &lt;body&gt;
+    &lt;div&gt;
+      ...  
+      &lt;p <span class=
+"strong">ttm:agent="bond"</span>&gt;I travel, a sort of licensed troubleshooter.&lt;/p&gt;
+      ...  
+    &lt;/div&gt;
+  &lt;/body&gt;
+&lt;/tt&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>In the above example, two agents, a real (person) agent, Sean Connery, and
+            a fictitious (character) agent, James Bond, are defined, where the latter is
+            linked to the former by means of the a <code>ttm:actor</code> element. A
+            reference is then made from content (the <code>p</code> element) to the
+            character agent associated with (responsible for producing) that content.
+            Note that in this example the <code>ttm:agent</code> metadata items are
+            specified as immediate children of the document's <code>head</code> element
+            rather than being placed in a container <code>metadata</code> element.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="metadata-vocabulary-name" name="metadata-vocabulary-name"></a>12.1.6
+          ttm:name</h4>
+
+          <p>The <code>ttm:name</code> element is used to specify a name of a person,
+          character, group, or organization.</p><a id="elt-syntax-metadata-name" name=
+          "elt-syntax-metadata-name"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttm:name
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttm:name
+  <span class=
+"reqattr">type</span> = (<em>full</em>|<em>family</em>|<em>given</em>|<em>alias</em>|<em>other</em>)
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> #PCDATA
+&lt;/ttm:name&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>A <code>type</code> attribute must be specified on each
+          <code>ttm:name</code> element, and, if specified, must have one of the
+          following values:</p>
+
+          <ul>
+            <li>
+              <p><code>full</code></p>
+            </li>
+
+            <li>
+              <p><code>family</code></p>
+            </li>
+
+            <li>
+              <p><code>given</code></p>
+            </li>
+
+            <li>
+              <p><code>alias</code></p>
+            </li>
+
+            <li>
+              <p><code>other</code></p>
+            </li>
+          </ul>
+
+          <p>The relationship between the type of a name and the syntactic expression of
+          the name is not defined by this specification.</p>
+
+          <p>Two examples of the <code>ttm:name</code> element are shown above in
+          <a href="#metadata-vocabulary-agent-example-1"><b>Example Fragment – Agent
+          Metadata</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="metadata-vocabulary-actor" name=
+          "metadata-vocabulary-actor"></a>12.1.7 ttm:actor</h4>
+
+          <p>The <code>ttm:actor</code> element is used to link the definition of a
+          (role-based) character agent with another agent that portrays the
+          character.</p><a id="elt-syntax-metadata-actor" name=
+          "elt-syntax-metadata-actor"></a>
+
+          <table class="syntax">
+            <caption>
+              XML Representation – Element Information Item: ttm:actor
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+&lt;ttm:actor
+  <span class="reqattr">agent</span> = IDREF
+  <a href="#content-attribute-id">xml:id</a> = ID
+  <a href="#content-attribute-lang">xml:lang</a> = string
+  <a href="#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
+  {<em>any attribute not in default or any TT namespace</em>}&gt;
+  <em>Content:</em> EMPTY
+&lt;/ttm:actor&gt;
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The <code>agent</code> attribute of a <code>ttm:actor</code> element must
+          reference a <code>ttm:agent</code> element that denotes the person, group, or
+          organization acting the part of a character.</p>
+
+          <p>An example of the <code>ttm:actor</code> element is shown above in <a href=
+          "#metadata-vocabulary-agent-example-1"><b>Example Fragment – Agent
+          Metadata</b></a>.</p>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="metadata-attribute-vocabulary" name=
+        "metadata-attribute-vocabulary"></a>12.2 Metadata Attribute Vocabulary</h3>
+
+        <p>This section specifies the following attributes in the TT Metadata Namespace
+        for use with the <code>metadata</code> element and with certain content
+        elements:</p>
+
+        <ul>
+          <li>
+            <p><a href="#metadata-attribute-agent"><b>12.2.1 ttm:agent</b></a></p>
+          </li>
+
+          <li>
+            <p><a href="#metadata-attribute-role"><b>12.2.2 ttm:role</b></a></p>
+          </li>
+        </ul>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>Only certain metadata item attributes may be used with content elements. See
+          the definitions of content elements to determine permissible usage.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="metadata-attribute-agent" name="metadata-attribute-agent"></a>12.2.1
+          ttm:agent</h4>
+
+          <p>The <code>ttm:agent</code> attribute takes an <code>IDREFS</code> value, and
+          is used with certain content elements to designate the agents that perform or
+          are involved in the performance of the content.</p>
+
+          <p>If specified, a <code>ttm:agent</code> attribute must reference
+          <code>ttm:agent</code> element instances that appear as a descendent of the
+          same <em>Document Instance</em> as that of the referring element.</p>
+
+          <p>The same IDREF, <em>ID</em>, should not appear more than once in the value
+          of a <code>ttm:agent</code> attribute.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>This constraint is intended to discourage the use of redundant agent
+            references.</p>
+          </div>
+
+          <p>An example of the <code>ttm:agent</code> attribute is shown above in
+          <a href="#metadata-vocabulary-agent-example-1"><b>Example Fragment – Agent
+          Metadata</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="metadata-attribute-role" name="metadata-attribute-role"></a>12.2.2
+          ttm:role</h4>
+
+          <p>The <code>ttm:role</code> attribute may be used by a content author to
+          express the roles, functions, or characteristics of some content element that
+          is so labeled.</p>
+
+          <p>If specified, the value of this attribute must adhere to the following
+          syntax, where the syntactic element <em>S</em> must adhere to production [3]
+          <code>S</code> as defined by <a href="#xml10">[XML 1.0]</a>&nbsp;§
+          2.3:</p><a id="metadata-attribute-role-syntax" name=
+          "metadata-attribute-role-syntax"></a>
+
+          <table class="syntax">
+            <caption>
+              Syntax Representation – ttm:role
+            </caption>
+
+            <tbody>
+              <tr>
+                <td>
+                  <div class="exampleInner">
+                    <pre>
+ttm:role
+  role ( <em>S</em> role )*
+
+role
+  : "action"
+  | "caption"
+  | "description"
+  | "dialog"
+  | "expletive"
+  | "kinesic"
+  | "lyrics"
+  | "music"
+  | "narration"
+  | "quality"
+  | "sound"
+  | "source"
+  | "suppressed"
+  | "reproduction"
+  | "thought"
+  | "title"
+  | "transcription"
+  | extension-role
+
+extension-role
+  : "x-" token-char+
+
+token-char
+  : { XML NameChar }    // XML 1.1 Production [4a]
+</pre>
+                  </div>
+                </td>
+              </tr>
+            </tbody>
+          </table>
+
+          <p>The same <code>role</code> token, <em>R</em>, should not appear more than
+          once in the value of a <code>ttm:role</code> attribute.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>This constraint is intended to discourage the use of redundant role
+            tokens.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>All values of <code>ttm:role</code> that do not start with the prefix
+            <code>x-</code> are reserved for future standardization.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>If using a custom <code>x-</code> prefixed form of <code>ttm:role</code>,
+            it is recommended that an organization unique infix be used as well in order
+            to prevent collisions. For example, <code>x-example-org-custom-role</code>.
+            Furthermore, a registry for role values is available at <a href=
+            "http://www.w3.org/wiki/TTML/RoleRegistry">http://www.w3.org/wiki/TTML/RoleRegistry</a>
+            in order to promote interoperability and collision avoidance.</p>
+          </div>
+        </div>
+      </div>
+    </div>
+  </div>
+
+  <div class="back">
+    <div class="div1">
+      <h2><a id="reduced-infoset" name="reduced-infoset"></a>A Reduced XML Infoset</h2>
+
+      <p><em>This appendix is normative.</em></p>
+
+      <p>For the purposes of this specification, a <em>Reduced XML Infoset</em> is an XML
+      Information Set <a href="#infoset">[XML InfoSet]</a> that consists of only the
+      following information items and information item properties:</p>
+
+      <div class="div2">
+        <h3><a id="reduced-infoset-document" name="reduced-infoset-document"></a>A.1
+        Document Information Item</h3>
+
+        <ul>
+          <li>
+            <p><code>[document element]</code></p>
+          </li>
+        </ul>
+      </div>
+
+      <div class="div2">
+        <h3><a id="reduced-infoset-element" name="reduced-infoset-element"></a>A.2
+        Element Information Item</h3>
+
+        <ul>
+          <li>
+            <p><code>[namespace URI]</code></p>
+          </li>
+
+          <li>
+            <p><code>[local name]</code></p>
+          </li>
+
+          <li>
+            <p><code>[children]</code></p>
+          </li>
+
+          <li>
+            <p><code>[attributes]</code></p>
+          </li>
+        </ul>
+
+        <p>Child information items <code>[children]</code> are reduced to only element
+        and character information items.</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="reduced-infoset-attribute" name="reduced-infoset-attribute"></a>A.3
+        Attribute Information Item</h3>
+
+        <ul>
+          <li>
+            <p><code>[namespace URI]</code></p>
+          </li>
+
+          <li>
+            <p><code>[local name]</code></p>
+          </li>
+
+          <li>
+            <p><code>[normalized value]</code></p>
+          </li>
+        </ul>
+      </div>
+
+      <div class="div2">
+        <h3><a id="reduced-infoset-character" name="reduced-infoset-character"></a>A.4
+        Character Information Item</h3>
+
+        <ul>
+          <li>
+            <p><code>[character code]</code></p>
+          </li>
+        </ul>
+
+        <p>Contiguous character information items are not required to be represented
+        distinctly, but may be aggregated (chunked) into a sequence of character codes
+        (i.e., a character string).</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="schemas" name="schemas"></a>B Schemas</h2>
+
+      <p><em>This appendix is normative.</em></p>
+
+      <p>This appendix specifies the following schemas for use with <em>Document
+      Instances</em>:</p>
+
+      <ul>
+        <li>
+          <p>Relax NG, Compact Syntax (RNC) Schema</p>
+        </li>
+
+        <li>
+          <p>XML Schema Definition (XSD) Schema</p>
+        </li>
+      </ul>
+
+      <p>In any case where a schema specified by this appendix differs from the normative
+      definitions of document type, element type, or attribute type as defined by the
+      body of this specification, then the body of this specification takes
+      precedence.</p>
+
+      <div class="div2">
+        <h3><a id="ttml-schema-rnc" name="ttml-schema-rnc"></a>B.1 Relax NG Compact (RNC)
+        Schema</h3>
+
+        <p>A Relax NG Compact Syntax (RNC) <a href="#rng">[RELAX NG]</a> based schema for
+        TTML Content is available at <a href="rnc/schema.zip">ZIP Archive</a>. This
+        schema does not normatively define the validity of Timed Text Markup Language
+        content as defined by this specification. In particular, the formal validity of
+        TTML Content is defined by <a href="#conformance-content"><b>3.1 Content
+        Conformance</b></a>.</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="ttml-schema-xsd" name="ttml-schema-xsd"></a>B.2 XML Schema Definition
+        (XSD) Schema</h3>
+
+        <p>A W3C XML Schema Definition (XSD) <a href="#xsd-1">[XML Schema Part 1]</a>
+        based schema for TTML Content is available at <a href="xsd/schema.zip">ZIP
+        Archive</a>. This schema does not normatively define the validity of Timed Text
+        Markup Language content as defined by this specification. In particular, the
+        formal validity of TTML Content is defined by <a href=
+        "#conformance-content"><b>3.1 Content Conformance</b></a>.</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="media-types-registration" name="media-types-registration"></a>C Media
+      Type Registration</h2>
+
+      <p><em>This appendix is normative.</em></p>
+
+      <p>This appendix registers a new media type, "application/ttml+xml" in conformance
+      with <a href="http://www.ietf.org/rfc/rfc4288.txt">BCP 13</a> and <a href=
+      "http://www.w3.org/2002/06/registering-mediatype.html">W3CRegMedia</a>. The
+      information in this appendix is being submitted to the Internet Engineering
+      Steering Group (IESG) for review, approval, and registration with the Internet
+      Assigned Numbers Authority (IANA).</p>
+
+      <dl>
+        <dt class="label">Type name:</dt>
+
+        <dd>
+          <p>application</p>
+        </dd>
+
+        <dt class="label">Subtype name:</dt>
+
+        <dd>
+          <p>ttml+xml</p>
+        </dd>
+
+        <dt class="label">Required parameters:</dt>
+
+        <dd>
+          <p>None.</p>
+        </dd>
+
+        <dt class="label">Optional parameters:</dt>
+
+        <dd>
+          <dl>
+            <dt class="label">charset</dt>
+
+            <dd>
+              <p>If specified, the <code>charset</code> parameter must match the XML
+              encoding declaration, or if absent, the actual encoding.</p>
+            </dd>
+
+            <dt class="label">profile</dt>
+
+            <dd>
+              <p>The document profile of a TTMLDocument Instance may be specified using
+              an optional <code>profile</code> parameter, which, if specified, the value
+              of which must adhere to the syntax and semantics of
+              <code>ttp:profile</code> parameter defined by Section <a href=
+              "#parameter-attribute-profile"><b>6.2.8 ttp:profile</b></a> of the
+              published specification.</p>
+            </dd>
+          </dl>
+        </dd>
+
+        <dt class="label">Encoding considerations:</dt>
+
+        <dd>
+          <p>Same for application/xml, except constrained to either UTF-8 or UTF-16. See
+          <a href="#xml-media">[XML Media Types]</a>, Section 3.2.</p>
+        </dd>
+
+        <dt class="label">Security considerations:</dt>
+
+        <dd>
+          <p>As with other XML types and as noted in <a href="#xml-media">[XML Media
+          Types]</a> Section 10, repeated expansion of maliciously constructed XML
+          entities can be used to consume large amounts of memory, which may cause XML
+          processors in constrained environments to fail.</p>
+
+          <p>In addition, because of the extensibility features for TTML and of XML in
+          general, it is possible that "application/ttml+xml" may describe content that
+          has security implications beyond those described here. However, TTML does not
+          provide for any sort of active or executable content, and if the processor
+          follows only the normative semantics of the published specification, this
+          content will be outside TTML namespaces and may be ignored. Only in the case
+          where the processor recognizes and processes the additional content, or where
+          further processing of that content is dispatched to other processors, would
+          security issues potentially arise. And in that case, they would fall outside
+          the domain of this registration document.</p>
+
+          <p>Although not prohibited, there are no expectations that XML signatures or
+          encryption would normally be employed.</p>
+        </dd>
+
+        <dt class="label">Interoperability considerations:</dt>
+
+        <dd>
+          <p>The published specification describes processing semantics that dictate
+          behavior that must be followed when dealing with, among other things,
+          unrecognized elements and attributes, both in TTML namespaces and in other
+          namespaces.</p>
+
+          <p>Because TTML is extensible, conformant "application/ttml+xml" processors may
+          expect (and enforce) that content received is well-formed XML, but it cannot be
+          guaranteed that the content is valid to a particular DTD or Schema or that the
+          processor will recognize all of the elements and attributes in the
+          document.</p>
+        </dd>
+
+        <dt class="label">Published specification:</dt>
+
+        <dd>
+          <p>This media type registration is extracted from Appendix C Media Type
+          Registration of the Timed Text Markup Language (TTML) 1.0 specification:
+          <a href="http://www.w3.org/TR/ttaf1-dfxp/">Timed Text Markup Language (TTML)
+          1.0</a>.</p>
+        </dd>
+
+        <dt class="label">Applications that use this media type:</dt>
+
+        <dd>
+          <p>TTML is used in the television industry for the purpose of authoring,
+          transcoding and exchanging timed text information and for delivering captions,
+          subtitles, and other metadata for television material repurposed for the Web
+          or, more generally, the Internet.</p>
+
+          <p>There is partial and full support of TTML in components used by several Web
+          browsers plugins, and in a number of caption authoring tools. A TTML
+          verification (including validation) utility is available in open source form at
+          <a href="http://github.com/skynav/ttv">http://github.com/skynav/ttv</a>.</p>
+        </dd>
+
+        <dt class="label">Additional information:</dt>
+
+        <dd>
+          <dl>
+            <dt class="label">Magic number(s):</dt>
+
+            <dt class="label">File extension(s):</dt>
+
+            <dd>
+              <p>.ttml</p>
+            </dd>
+
+            <dt class="label">Macintosh file type code(s):</dt>
+
+            <dd>
+              <p>"TTML"</p>
+            </dd>
+
+            <dt class="label">Fragment identifiers:</dt>
+
+            <dd>
+              <p>For documents labeled as application/ttml+xml, the fragment identifier
+              notation is intended to be used with xml:id attributes, as described in
+              section 7.2.1 of the <a href="http://www.w3.org/TR/ttaf1-dfxp/">Timed Text
+              Markup Language (TTML) 1.0</a> specification.</p>
+            </dd>
+          </dl>
+        </dd>
+
+        <dt class="label">Person &amp; email address to contact for further
+        information:</dt>
+
+        <dd>
+          <p>Timed Text Working Group (public-tt@w3.org)</p>
+        </dd>
+
+        <dt class="label">Intended usage:</dt>
+
+        <dd>
+          <p>COMMON</p>
+        </dd>
+
+        <dt class="label">Restrictions on usage:</dt>
+
+        <dd>
+          <p>None</p>
+        </dd>
+
+        <dt class="label">Author:</dt>
+
+        <dd>
+          <p>The published specification is a work product of the World Wide Web
+          Consortium's Timed Text (TT) Working Group.</p>
+        </dd>
+
+        <dt class="label">Change controller:</dt>
+
+        <dd>
+          <p>The W3C has change control over this specification.</p>
+        </dd>
+      </dl>
+    </div>
+
+    <div class="div1">
+      <h2><a id="features" name="features"></a>D Features</h2>
+
+      <p><em>This appendix is normative.</em></p>
+
+      <p>This appendix specifies (1) a set of feature designations, each of which labels
+      one or more syntactic and/or semantic features defined by this specification, and
+      (2) for each designated feature, whether the feature is mandatory or optional for a
+      transformation or presentation processor.</p>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>A TTML processor is said to <em>implement the transformation semantics</em> or
+        <em>implement the presentation semantics</em> of feature designation <em>F</em>
+        if it satisfies the requirements of this appendix with respect to the definition
+        of feature designation <em>F</em> as pertains to transformation or presentation
+        processing, respectively.</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="feature-designations" name="feature-designations"></a>D.1 Feature
+        Designations</h3>
+
+        <p>A feature designation is expressed as a string that adheres to the following
+        form:</p>
+
+        <div class="exampleInner">
+          <pre>
+feature-designation
+  : feature-namespace designation
+
+feature-namespace
+  : <em>TT Feature Namespace</em>                    // http://www.w3.org/ns/ttml/feature/
+
+designation
+  : "#" token-char+
+
+token-char
+  : { XML NameChar }                        // XML 1.1 Production [4a]
+</pre>
+        </div>
+
+        <p>All values of <code>feature-designation</code> not defined by this
+        specification are reserved for future standardization.</p>
+
+        <p>The following sub-sections define all feature designations, expressed as
+        relative URIs (fragment identifiers) with respect to the TT Feature Namespace
+        base URI.</p>
+
+        <div class="div3">
+          <h4><a id="feature-animation" name="feature-animation"></a>D.1.1
+          #animation</h4>
+
+          <p>A TTML transformation processor supports the <code>#animation</code> feature
+          if it recognizes and is capable of transforming the following vocabulary
+          defined by <a href="#animation"><b>11 Animation</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#animation-vocabulary-set"><code>set</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#animation</code> feature
+          if it implements presentation semantic support for the same vocabulary
+          enumerated above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-backgroundColor" name="feature-backgroundColor"></a>D.1.2
+          #backgroundColor</h4>
+
+          <p>A TTML transformation processor supports the <code>#backgroundColor</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#backgroundColor</code>
+          feature if it (1) implements presentation semantic support for the <a href=
+          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
+          attribute and (2) is capable of displaying or generating an output display
+          signal that distinguishes between at least sixteen (16) values of color,
+          including all primary and secondary colors of the SRGB color space.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-backgroundColor-block" name=
+          "feature-backgroundColor-block"></a>D.1.3 #backgroundColor-block</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#backgroundColor-block</code> feature if it recognizes and is capable of
+          transforming all defined values of the <a href=
+          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
+          attribute when applied to a content element that would generate a block area
+          during presentation processing.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#backgroundColor-block</code> feature if it (1) implements presentation
+          semantic support for the <a href=
+          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
+          attribute when applied to a content element that generates a block area and (2)
+          is capable of displaying or generating an output display signal that
+          distinguishes between at least sixteen (16) values of color, including all
+          primary and secondary colors of the SRGB color space.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-backgroundColor-inline" name=
+          "feature-backgroundColor-inline"></a>D.1.4 #backgroundColor-inline</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#backgroundColor-inline</code> feature if it recognizes and is capable of
+          transforming all defined values of the <a href=
+          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
+          attribute when applied to a content element that would generate an inline area
+          during presentation processing.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#backgroundColor-inline</code> feature if it (1) implements presentation
+          semantic support for the <a href=
+          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
+          attribute when applied to a content element that generates an inline area and
+          (2) is capable of displaying or generating an output display signal that
+          distinguishes between at least sixteen (16) values of color, including all
+          primary and secondary colors of the SRGB color space.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-backgroundColor-region" name=
+          "feature-backgroundColor-region"></a>D.1.5 #backgroundColor-region</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#backgroundColor-region</code> feature if it recognizes and is capable of
+          transforming all defined values of the <a href=
+          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
+          attribute when applied to a <a href=
+          "#layout-vocabulary-region"><code>region</code></a> element.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#backgroundColor-region</code> feature if it (1) implements presentation
+          semantic support for the <a href=
+          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
+          attribute when applied to a <a href=
+          "#layout-vocabulary-region"><code>region</code></a> element and (2) is capable
+          of displaying or generating an output display signal that distinguishes between
+          at least sixteen (16) values of color, including all primary and secondary
+          colors of the SRGB color space .</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-bidi" name="feature-bidi"></a>D.1.6 #bidi</h4>
+
+          <p>A TTML processor supports the <code>#bidi</code> feature if it supports the
+          following features:</p>
+
+          <ul>
+            <li>
+              <p><a href="#feature-direction"><code>#direction</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-unicodeBidi"><code>#unicodeBidi</code></a></p>
+            </li>
+
+            <li>
+              <p><a href=
+              "#feature-writingMode-horizontal"><code>#writingMode-horizontal</code></a></p>
+            </li>
+          </ul>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-cellResolution" name="feature-cellResolution"></a>D.1.7
+          #cellResolution</h4>
+
+          <p>A TTML transformation processor supports the <code>#cellResolution</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#cellResolution</code>
+          feature if it implements presentation semantic support for the <a href=
+          "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-clockMode" name="feature-clockMode"></a>D.1.8
+          #clockMode</h4>
+
+          <p>A TTML transformation processor supports the <code>#clockMode</code> feature
+          if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#clockMode</code> feature
+          if it implements presentation semantic support for the <a href=
+          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-clockMode-gps" name="feature-clockMode-gps"></a>D.1.9
+          #clockMode-gps</h4>
+
+          <p>A TTML transformation processor supports the <code>#clockMode-gps</code>
+          feature if it recognizes and is capable of transforming the <code>gps</code>
+          value of the <a href=
+          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#clockMode-gps</code>
+          feature if it implements presentation semantic support for the <code>gps</code>
+          value of the <a href=
+          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-clockMode-local" name="feature-clockMode-local"></a>D.1.10
+          #clockMode-local</h4>
+
+          <p>A TTML transformation processor supports the <code>#clockMode-local</code>
+          feature if it recognizes and is capable of transforming the <code>local</code>
+          value of the <a href=
+          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#clockMode-local</code>
+          feature if it implements presentation semantic support for the
+          <code>local</code> value of the <a href=
+          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-clockMode-utc" name="feature-clockMode-utc"></a>D.1.11
+          #clockMode-utc</h4>
+
+          <p>A TTML transformation processor supports the <code>#clockMode-utc</code>
+          feature if it recognizes and is capable of transforming the <code>utc</code>
+          value of the <a href=
+          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#clockMode-utc</code>
+          feature if it implements presentation semantic support for the <code>utc</code>
+          value of the <a href=
+          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-color" name="feature-color"></a>D.1.12 #color</h4>
+
+          <p>A TTML transformation processor supports the <code>#color</code> feature if
+          it recognizes and is capable of transforming the <a href=
+          "#style-attribute-color"><code>tts:color</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#color</code> feature if it
+          (1) implements presentation semantic support for the <a href=
+          "#style-attribute-color"><code>tts:color</code></a> attribute and (2) is
+          capable of displaying or generating an output display signal that distinguishes
+          between at least sixteen (16) values of color, including all primary and
+          secondary colors of the SRGB color space.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-content" name="feature-content"></a>D.1.13 #content</h4>
+
+          <p>A TTML transformation processor supports the <code>#content</code> feature
+          if it recognizes and is capable of transforming the following vocabulary
+          defined by <a href="#content"><b>7 Content</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#document-structure-vocabulary-body"><code>body</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-vocabulary-br"><code>br</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#content</code> feature if
+          it implements presentation semantic support for the same vocabulary enumerated
+          above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-core" name="feature-core"></a>D.1.14 #core</h4>
+
+          <p>A TTML transformation processor supports the <code>#core</code> feature if
+          it recognizes and is capable of transforming the following core attributes
+          vocabulary defined by <a href="#content"><b>7 Content</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#content-attribute-id">@<code>xml:id</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-attribute-id">@<code>xml:lang</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#content-attribute-id">@<code>xml:space</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#core</code> feature if it
+          implements presentation semantic support for the same vocabulary enumerated
+          above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-direction" name="feature-direction"></a>D.1.15
+          #direction</h4>
+
+          <p>A TTML transformation processor supports the <code>#direction</code> feature
+          if it recognizes and is capable of transforming all defined values of the
+          <a href="#style-attribute-direction"><code>tts:direction</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#direction</code> feature
+          if it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-direction"><code>tts:direction</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-display" name="feature-display"></a>D.1.16 #display</h4>
+
+          <p>A TTML transformation processor supports the <code>#display</code> feature
+          if it recognizes and is capable of transforming all defined values of the
+          <a href="#style-attribute-display"><code>tts:display</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#display</code> feature if
+          it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-display"><code>tts:display</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-display-block" name="feature-display-block"></a>D.1.17
+          #display-block</h4>
+
+          <p>A TTML transformation processor supports the <code>#display-block</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-display"><code>tts:display</code></a> attribute
+          when applied to a content element that would generate a block area during
+          presentation processing.</p>
+
+          <p>A TTML presentation processor supports the <code>#display-block</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href="#style-attribute-display"><code>tts:display</code></a>
+          attribute when applied to a content element that generates a block area.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-display-inline" name="feature-display-inline"></a>D.1.18
+          #display-inline</h4>
+
+          <p>A TTML transformation processor supports the <code>#display-inline</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-display"><code>tts:display</code></a> attribute
+          when applied to a content element that would generate an inline area during
+          presentation processing.</p>
+
+          <p>A TTML presentation processor supports the <code>#display-inline</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href="#style-attribute-display"><code>tts:display</code></a>
+          attribute when applied to a content element that generates an inline area.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-display-region" name="feature-display-region"></a>D.1.19
+          #display-region</h4>
+
+          <p>A TTML transformation processor supports the <code>#display-region</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-display"><code>tts:display</code></a> attribute
+          when applied to a <a href="#layout-vocabulary-region"><code>region</code></a>
+          element.</p>
+
+          <p>A TTML presentation processor supports the <code>#display-region</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href="#style-attribute-display"><code>tts:display</code></a>
+          attribute when applied to a <a href=
+          "#layout-vocabulary-region"><code>region</code></a> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-displayAlign" name="feature-displayAlign"></a>D.1.20
+          #displayAlign</h4>
+
+          <p>A TTML transformation processor supports the <code>#displayAlign</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-displayAlign"><code>tts:displayAlign</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#displayAlign</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href=
+          "#style-attribute-displayAlign"><code>tts:displayAlign</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-dropMode" name="feature-dropMode"></a>D.1.21 #dropMode</h4>
+
+          <p>A TTML transformation processor supports the <code>#dropMode</code> feature
+          if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#dropMode</code> feature if
+          it implements presentation semantic support for the <a href=
+          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-dropMode-dropNTSC" name=
+          "feature-dropMode-dropNTSC"></a>D.1.22 #dropMode-dropNTSC</h4>
+
+          <p>A TTML transformation processor supports the <code>#dropMode-dropNTSC</code>
+          feature if it recognizes and is capable of transforming the
+          <code>dropNTSC</code> value of the <a href=
+          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#dropMode-dropNTSC</code>
+          feature if it implements presentation semantic support for the
+          <code>dropNTSC</code> value of the <a href=
+          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-dropMode-dropPAL" name="feature-dropMode-dropPAL"></a>D.1.23
+          #dropMode-dropPAL</h4>
+
+          <p>A TTML transformation processor supports the <code>#dropMode-dropPAL</code>
+          feature if it recognizes and is capable of transforming the
+          <code>dropPAL</code> value of the <a href=
+          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#dropMode-dropPAL</code>
+          feature if it implements presentation semantic support for the
+          <code>dropPAL</code> value of the <a href=
+          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-dropMode-nonDrop" name="feature-dropMode-nonDrop"></a>D.1.24
+          #dropMode-nonDrop</h4>
+
+          <p>A TTML transformation processor supports the <code>#dropMode-nonDrop</code>
+          feature if it recognizes and is capable of transforming the
+          <code>nonDrop</code> value of the <a href=
+          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#dropMode-nonDrop</code>
+          feature if it implements presentation semantic support for the
+          <code>nonDrop</code> value of the <a href=
+          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-extent" name="feature-extent"></a>D.1.25 #extent</h4>
+
+          <p>A TTML transformation processor supports the <code>#extent</code> feature if
+          it recognizes and is capable of transforming the <a href=
+          "#style-attribute-extent"><code>tts:extent</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#extent</code> feature if
+          it implements presentation semantic support for the <a href=
+          "#style-attribute-extent"><code>tts:extent</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-extent-region" name="feature-extent-region"></a>D.1.26
+          #extent-region</h4>
+
+          <p>A TTML transformation processor supports the <code>#extent-region</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-extent"><code>tts:extent</code></a> attribute when applied to
+          a <a href="#layout-vocabulary-region"><code>region</code></a> element.</p>
+
+          <p>A TTML presentation processor supports the <code>#extent-region</code>
+          feature if it implements presentation semantic support for the <a href=
+          "#style-attribute-extent"><code>tts:extent</code></a> attribute when applied to
+          a <a href="#layout-vocabulary-region"><code>region</code></a> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-extent-root" name="feature-extent-root"></a>D.1.27
+          #extent-root</h4>
+
+          <p>A TTML transformation processor supports the <code>#extent-root</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-extent"><code>tts:extent</code></a> attribute when applied to
+          the <a href="#document-structure-vocabulary-tt"><code>tt</code></a>
+          element.</p>
+
+          <p>A TTML presentation processor supports the <code>#extent-root</code> feature
+          if it implements presentation semantic support for the <a href=
+          "#style-attribute-extent"><code>tts:extent</code></a> attribute when applied to
+          a <a href="#document-structure-vocabulary-tt"><code>tt</code></a> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontFamily" name="feature-fontFamily"></a>D.1.28
+          #fontFamily</h4>
+
+          <p>A TTML transformation processor supports the <code>#fontFamily</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontFamily</code> feature
+          if it implements presentation semantic support for the <a href=
+          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontFamily-generic" name=
+          "feature-fontFamily-generic"></a>D.1.29 #fontFamily-generic</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#fontFamily-generic</code> feature if it recognizes and is capable of
+          transforming <a href=
+          "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a> values when used
+          with the <a href="#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontFamily-generic</code>
+          feature if it implements presentation semantic support for <a href=
+          "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a> values when used
+          with the <a href="#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontFamily-non-generic" name=
+          "feature-fontFamily-non-generic"></a>D.1.30 #fontFamily-non-generic</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#fontFamily-non-generic</code> feature if it recognizes and is capable of
+          transforming <a href="#style-value-familyName">&lt;familyName&gt;</a> values
+          when used with the <a href=
+          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#fontFamily-non-generic</code> feature if it implements presentation
+          semantic support for <a href="#style-value-familyName">&lt;familyName&gt;</a>
+          values when used with the <a href=
+          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontSize" name="feature-fontSize"></a>D.1.31 #fontSize</h4>
+
+          <p>A TTML transformation processor supports the <code>#fontSize</code> feature
+          if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontSize</code> feature if
+          it implements presentation semantic support for the <a href=
+          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontSize-anamorphic" name=
+          "feature-fontSize-anamorphic"></a>D.1.32 #fontSize-anamorphic</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#fontSize-anamorphic</code> feature if it recognizes and is capable of
+          transforming values of the <a href=
+          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute that
+          consist of two <a href="#style-value-length">&lt;length&gt;</a>
+          specifications.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontSize-anamorphic</code>
+          feature if it implements presentation semantic support for defined values of
+          the <a href="#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute
+          that consist of two <a href="#style-value-length">&lt;length&gt;</a>
+          specifications.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontSize-isomorphic" name=
+          "feature-fontSize-isomorphic"></a>D.1.33 #fontSize-isomorphic</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#fontSize-isomorphic</code> feature if it recognizes and is capable of
+          transforming values of the <a href=
+          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute that
+          consist of a single <a href="#style-value-length">&lt;length&gt;</a>
+          specification.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontSize-isomorphic</code>
+          feature if it implements presentation semantic support for defined values of
+          the <a href="#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute
+          that consist of a single <a href="#style-value-length">&lt;length&gt;</a>
+          specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontStyle" name="feature-fontStyle"></a>D.1.34
+          #fontStyle</h4>
+
+          <p>A TTML transformation processor supports the <code>#fontStyle</code> feature
+          if it recognizes and is capable of transforming all defined values of the
+          <a href="#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontStyle</code> feature
+          if it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontStyle-italic" name="feature-fontStyle-italic"></a>D.1.35
+          #fontStyle-italic</h4>
+
+          <p>A TTML transformation processor supports the <code>#fontStyle-italic</code>
+          feature if it recognizes and is capable of transforming the <code>italic</code>
+          value of the <a href=
+          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontStyle-italic</code>
+          feature if it implements presentation semantic support for the
+          <code>italic</code> of the <a href=
+          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontStyle-oblique" name=
+          "feature-fontStyle-oblique"></a>D.1.36 #fontStyle-oblique</h4>
+
+          <p>A TTML transformation processor supports the <code>#fontStyle-oblique</code>
+          feature if it recognizes and is capable of transforming the
+          <code>oblique</code> value of the <a href=
+          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontStyle-oblique</code>
+          feature if it implements presentation semantic support for the
+          <code>oblique</code> of the <a href=
+          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontWeight" name="feature-fontWeight"></a>D.1.37
+          #fontWeight</h4>
+
+          <p>A TTML transformation processor supports the <code>#fontWeight</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontWeight</code> feature
+          if it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-fontWeight-bold" name="feature-fontWeight-bold"></a>D.1.38
+          #fontWeight-bold</h4>
+
+          <p>A TTML transformation processor supports the <code>#fontWeight-bold</code>
+          feature if it recognizes and is capable of transforming <code>bold</code> value
+          of the <a href="#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#fontWeight-bold</code>
+          feature if it implements presentation semantic support for the
+          <code>bold</code> of the <a href=
+          "#style-attribute-fontWeight"><code>tts:fontWeight</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-frameRate" name="feature-frameRate"></a>D.1.39
+          #frameRate</h4>
+
+          <p>A TTML transformation processor supports the <code>#frameRate</code> feature
+          if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#frameRate</code> feature
+          if it implements presentation semantic support for the <a href=
+          "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-frameRateMultiplier" name=
+          "feature-frameRateMultiplier"></a>D.1.40 #frameRateMultiplier</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#frameRateMultiplier</code> feature if it recognizes and is capable of
+          transforming the <a href=
+          "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#frameRateMultiplier</code>
+          feature if it implements presentation semantic support for the <a href=
+          "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-layout" name="feature-layout"></a>D.1.41 #layout</h4>
+
+          <p>A TTML transformation processor supports the <code>#layout</code> feature if
+          it (1) recognizes and is capable of transforming the following vocabulary
+          defined by <a href="#layout"><b>9 Layout</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#layout-vocabulary-layout"><code>layout</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#layout-vocabulary-region"><code>region</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#layout-attribute-region">@<code>region</code></a></p>
+            </li>
+          </ul>
+
+          <p>and (2) supports the following attributes when applied to the <a href=
+          "#layout-vocabulary-region"><code>region</code></a> element:</p>
+
+          <ul>
+            <li>
+              <p><a href="#style-attribute-extent"><code>tts:extent</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#style-attribute-origin"><code>tts:origin</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#layout</code> feature if
+          it implements presentation semantic support for the same vocabulary and
+          features enumerated above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length" name="feature-length"></a>D.1.42 #length</h4>
+
+          <p>A TTML transformation processor supports the <code>#length</code> feature if
+          it recognizes and is capable of transforming all defined values of the <a href=
+          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
+
+          <p>A TTML presentation processor supports the <code>#length</code> feature if
+          it implements presentation semantic support for all defined values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length</code> is intended to imply support for the
+            following features: <code>#length-integer</code>, <code>#length-real</code>,
+            <code>#length-positive</code>, <code>#length-negative</code>,
+            <code>#length-cell</code>, <code>#length-em</code>,
+            <code>#length-percentage</code>, and <code>#length-pixel</code>.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length-cell" name="feature-length-cell"></a>D.1.43
+          #length-cell</h4>
+
+          <p>A TTML transformation processor supports the <code>#length-cell</code>
+          feature if it recognizes and is capable of transforming scalar values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
+          use <code>c</code> (cell) units.</p>
+
+          <p>A TTML presentation processor supports the <code>#length-cell</code> feature
+          if it implements presentation semantic support for scalar values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
+          use <code>c</code> (cell) units.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-cell</code> does not, by itself, imply support
+            for <code>#length-integer</code>, <code>#length-real</code>,
+            <code>#length-positive</code>, or <code>#length-negative</code> features.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length-em" name="feature-length-em"></a>D.1.44
+          #length-em</h4>
+
+          <p>A TTML transformation processor supports the <code>#length-em</code> feature
+          if it recognizes and is capable of transforming scalar values of the <a href=
+          "#style-value-length">&lt;length&gt;</a> style value expression that use
+          <code>em</code> (EM) units.</p>
+
+          <p>A TTML presentation processor supports the <code>#length-em</code> feature
+          if it implements presentation semantic support for scalar values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
+          use <code>em</code> (EM) units.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-em</code> does not, by itself, imply support for
+            <code>#length-integer</code>, <code>#length-real</code>,
+            <code>#length-positive</code>, or <code>#length-negative</code> features.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length-integer" name="feature-length-integer"></a>D.1.45
+          #length-integer</h4>
+
+          <p>A TTML transformation processor supports the <code>#length-integer</code>
+          feature if it recognizes and is capable of transforming integer values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
+
+          <p>A TTML presentation processor supports the <code>#length-integer</code>
+          feature if it implements presentation semantic support for integer values of
+          the <a href="#style-value-length">&lt;length&gt;</a> style value
+          expression.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-integer</code> does not, by itself, imply
+            support for <code>#length-positive</code> or <code>#length-negative</code>
+            features.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length-negative" name="feature-length-negative"></a>D.1.46
+          #length-negative</h4>
+
+          <p>A TTML transformation processor supports the <code>#length-negative</code>
+          feature if it recognizes and is capable of transforming negative values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
+
+          <p>A TTML presentation processor supports the <code>#length-negative</code>
+          feature if it implements presentation semantic support for negative values of
+          the <a href="#style-value-length">&lt;length&gt;</a> style value
+          expression.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-negative</code> does not, by itself, imply
+            support for <code>#length-integer</code> or <code>#length-real</code>
+            features.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length-percentage" name=
+          "feature-length-percentage"></a>D.1.47 #length-percentage</h4>
+
+          <p>A TTML transformation processor supports the <code>#length-percentage</code>
+          feature if it recognizes and is capable of transforming percentage values of
+          the <a href="#style-value-length">&lt;length&gt;</a> style value
+          expression.</p>
+
+          <p>A TTML presentation processor supports the <code>#length-percentage</code>
+          feature if it implements presentation semantic support for percentage values of
+          the <a href="#style-value-length">&lt;length&gt;</a> style value
+          expression.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-percentage</code> does not, by itself, imply
+            support for <code>#length-integer</code>, <code>#length-real</code>,
+            <code>#length-positive</code>, or <code>#length-negative</code> features.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length-pixel" name="feature-length-pixel"></a>D.1.48
+          #length-pixel</h4>
+
+          <p>A TTML transformation processor supports the <code>#length-pixel</code>
+          feature if it recognizes and is capable of transforming scalar values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
+          use <code>px</code> (pixel) units.</p>
+
+          <p>A TTML presentation processor supports the <code>#length-pixel</code>
+          feature if it implements presentation semantic support for scalar values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression that
+          use <code>px</code> (pixel) units.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-pixel</code> does not, by itself, imply support
+            for <code>#length-integer</code>, <code>#length-real</code>,
+            <code>#length-positive</code>, or <code>#length-negative</code> features.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length-positive" name="feature-length-positive"></a>D.1.49
+          #length-positive</h4>
+
+          <p>A TTML transformation processor supports the <code>#length-positive</code>
+          feature if it recognizes and is capable of transforming positive values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
+
+          <p>A TTML presentation processor supports the <code>#length-positive</code>
+          feature if it implements presentation semantic support for positive values of
+          the <a href="#style-value-length">&lt;length&gt;</a> style value
+          expression.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-positive</code> is intended to imply support for
+            zero valued <a href="#style-value-length">&lt;length&gt;</a> style value
+            expressions.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-positive</code> does not, by itself, imply
+            support for <code>#length-integer</code> or <code>#length-real</code>
+            features.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-length-real" name="feature-length-real"></a>D.1.50
+          #length-real</h4>
+
+          <p>A TTML transformation processor supports the <code>#length-real</code>
+          feature if it recognizes and is capable of transforming real values of the
+          <a href="#style-value-length">&lt;length&gt;</a> style value expression.</p>
+
+          <p>A TTML presentation processor supports the <code>#length-real</code> feature
+          if it implements presentation semantic support for real values of the <a href=
+          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-real</code> is intended to imply support for
+            integer valued <a href="#style-value-length">&lt;length&gt;</a> style value
+            expressions as well as real valued expressions.</p>
+          </div>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>Support for <code>#length-real</code> does not, by itself, imply support
+            for <code>#length-positive</code> or <code>#length-negative</code>
+            features.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-lineBreak-uax14" name="feature-lineBreak-uax14"></a>D.1.51
+          #lineBreak-uax14</h4>
+
+          <p>A TTML transformation processor supports the <code>#lineBreak-uax14</code>
+          feature if it recognizes and is capable of transforming requirements expressed
+          by <a href="#uax14">[UAX14]</a> into its target document space.</p>
+
+          <p>A TTML presentation processor supports the <code>#lineBreak-uax14</code>
+          feature if it implements presentation semantic support for <a href=
+          "#uax14">[UAX14]</a> as applies to line breaking.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-lineHeight" name="feature-lineHeight"></a>D.1.52
+          #lineHeight</h4>
+
+          <p>A TTML transformation processor supports the <code>#lineHeight</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-lineHeight"><code>tts:lineHeight</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#lineHeight</code> feature
+          if it implements presentation semantic support for the <a href=
+          "#style-attribute-lineHeight"><code>tts:lineHeight</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-markerMode" name="feature-markerMode"></a>D.1.53
+          #markerMode</h4>
+
+          <p>A TTML transformation processor supports the <code>#markerMode</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#markerMode</code> feature
+          if it implements presentation semantic support for the <a href=
+          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-markerMode-continuous" name=
+          "feature-markerMode-continuous"></a>D.1.54 #markerMode-continuous</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#markerMode-continuous</code> feature if it recognizes and is capable of
+          transforming the <code>continuous</code> value of the <a href=
+          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#markerMode-continuous</code> feature if it implements presentation
+          semantic support for the <code>continuous</code> value of the <a href=
+          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-markerMode-discontinuous" name=
+          "feature-markerMode-discontinuous"></a>D.1.55 #markerMode-discontinuous</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#markerMode-discontinuous</code> feature if it recognizes and is capable
+          of transforming the <code>discontinuous</code> value of the <a href=
+          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#markerMode-discontinuous</code> feature if it implements presentation
+          semantic support for the <code>discontinuous</code> value of the <a href=
+          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-metadata" name="feature-metadata"></a>D.1.56 #metadata</h4>
+
+          <p>A TTML transformation processor supports the <code>#metadata</code> feature
+          if it recognizes and is capable of transforming the following vocabulary
+          defined by <a href="#metadata"><b>12 Metadata</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#metadata-vocabulary-metadata"><code>metadata</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata-vocabulary-title"><code>ttm:title</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata-vocabulary-title"><code>ttm:desc</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata-vocabulary-title"><code>ttm:copyright</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata-vocabulary-title"><code>ttm:agent</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata-vocabulary-title"><code>ttm:name</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata-vocabulary-title"><code>ttm:actor</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata-attribute-agent">@<code>ttm:agent</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#metadata-attribute-role">@<code>ttm:role</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#metadata</code> feature if
+          it recognizes and is capable of presenting the information expressed by the
+          same vocabulary enumerated above.</p>
+
+          <div class="note">
+            <p class="prefix"><b>Note:</b></p>
+
+            <p>This specification does not define a standardized form for the
+            presentation of metadata information. The presentation or ability to present
+            metadata information is considered to be implementation dependent.</p>
+          </div>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-nested-div" name="feature-nested-div"></a>D.1.57
+          #nested-div</h4>
+
+          <p>A TTML transformation processor supports the <code>#nested-div</code>
+          feature if it recognizes and is capable of transforming nested <a href=
+          "#content-vocabulary-div"><code>div</code></a> elements.</p>
+
+          <p>A TTML presentation processor supports the <code>#nested-div</code> feature
+          if it implements presentation semantic support for nested <a href=
+          "#content-vocabulary-div"><code>div</code></a> elements.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-nested-span" name="feature-nested-span"></a>D.1.58
+          #nested-span</h4>
+
+          <p>A TTML transformation processor supports the <code>#nested-span</code>
+          feature if it recognizes and is capable of transforming nested <a href=
+          "#content-vocabulary-span"><code>span</code></a> elements.</p>
+
+          <p>A TTML presentation processor supports the <code>#nested-span</code> feature
+          if it implements presentation semantic support for nested <a href=
+          "#content-vocabulary-span"><code>span</code></a> elements.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-opacity" name="feature-opacity"></a>D.1.59 #opacity</h4>
+
+          <p>A TTML transformation processor supports the <code>#opacity</code> feature
+          if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-opacity"><code>tts:opacity</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#opacity</code> feature if
+          it (1) implements presentation semantic support for the <a href=
+          "#style-attribute-opacity"><code>tts:opacity</code></a> attribute and (2) is
+          capable of displaying or generating an output display signal that distinguishes
+          between at least eight (8) values of opacity.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-origin" name="feature-origin"></a>D.1.60 #origin</h4>
+
+          <p>A TTML transformation processor supports the <code>#origin</code> feature if
+          it recognizes and is capable of transforming the <a href=
+          "#style-attribute-origin"><code>tts:origin</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#origin</code> feature if
+          it implements presentation semantic support for the <a href=
+          "#style-attribute-origin"><code>tts:origin</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-overflow" name="feature-overflow"></a>D.1.61 #overflow</h4>
+
+          <p>A TTML transformation processor supports the <code>#overflow</code> feature
+          if it recognizes and is capable of transforming all defined values of the
+          <a href="#style-attribute-overflow"><code>tts:overflow</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#overflow</code> feature if
+          it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-overflow"><code>tts:overflow</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-overflow-visible" name="feature-overflow-visible"></a>D.1.62
+          #overflow-visible</h4>
+
+          <p>A TTML transformation processor supports the <code>#overflow-visible</code>
+          feature if it recognizes and is capable of transforming the
+          <code>visible</code> value of the <a href=
+          "#style-attribute-overflow"><code>tts:overflow</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#overflow-visible</code>
+          feature if it implements presentation semantic support for the
+          <code>visible</code> value of the <a href=
+          "#style-attribute-overflow"><code>tts:overflow</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-padding" name="feature-padding"></a>D.1.63 #padding</h4>
+
+          <p>A TTML transformation processor supports the <code>#padding</code> feature
+          if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#padding</code> feature if
+          it implements presentation semantic support for the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-padding-1" name="feature-padding-1"></a>D.1.64
+          #padding-1</h4>
+
+          <p>A TTML transformation processor supports the <code>#padding-1</code> feature
+          if it recognizes and is capable of transforming values of the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
+          of one <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
+
+          <p>A TTML presentation processor supports the <code>#padding-1</code> feature
+          if it implements presentation semantic support for values of the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
+          of one <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-padding-2" name="feature-padding-2"></a>D.1.65
+          #padding-2</h4>
+
+          <p>A TTML transformation processor supports the <code>#padding-2</code> feature
+          if it recognizes and is capable of transforming values of the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
+          of two <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
+
+          <p>A TTML presentation processor supports the <code>#padding-2</code> feature
+          if it implements presentation semantic support for values of the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
+          of two <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-padding-3" name="feature-padding-3"></a>D.1.66
+          #padding-3</h4>
+
+          <p>A TTML transformation processor supports the <code>#padding-3</code> feature
+          if it recognizes and is capable of transforming values of the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
+          of three <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
+
+          <p>A TTML presentation processor supports the <code>#padding-3</code> feature
+          if it implements presentation semantic support for values of the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
+          of three <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-padding-4" name="feature-padding-4"></a>D.1.67
+          #padding-4</h4>
+
+          <p>A TTML transformation processor supports the <code>#padding-4</code> feature
+          if it recognizes and is capable of transforming values of the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
+          of four <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
+
+          <p>A TTML presentation processor supports the <code>#padding-4</code> feature
+          if it implements presentation semantic support for values of the <a href=
+          "#style-attribute-padding"><code>tts:padding</code></a> attribute that consist
+          of four <a href="#style-value-length">&lt;length&gt;</a> specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-pixelAspectRatio" name="feature-pixelAspectRatio"></a>D.1.68
+          #pixelAspectRatio</h4>
+
+          <p>A TTML transformation processor supports the <code>#pixelAspectRatio</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#pixelAspectRatio</code>
+          feature if it implements presentation semantic support for the <a href=
+          "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-presentation" name="feature-presentation"></a>D.1.69
+          #presentation</h4>
+
+          <p>A TTML processor supports the <code>#presentation</code> feature if it (1)
+          satisfies the generic processor criteria defined by <a href=
+          "#conformance-generic-processor"><b>3.2.1 Generic Processor
+          Conformance</b></a>, (2) implements support for the region and line layout
+          semantics defined by <a href="#semantics-region-layout"><b>9.3 Region Layout
+          and Presentation</b></a> and <a href="#semantics-line-layout"><b>9.4 Line
+          Layout</b></a>, respectively, and (3) implements presentation semantics for the
+          following features:</p>
+
+          <ul>
+            <li>
+              <p><a href="#content"><code>#content</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-core"><code>#core</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-profile"><code>#profile</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-structure"><code>#structure</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-time-offset"><code>#time-offset</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#timing"><code>#timing</code></a></p>
+            </li>
+          </ul>
+
+          <p>In addition, a TTML processor that supports the <code>#presentation</code>
+          feature should satisfy the user agent accessibility guidelines specified by
+          <a href="#uaag">[UAAG]</a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-profile" name="feature-profile"></a>D.1.70 #profile</h4>
+
+          <p>A TTML transformation processor supports the <code>#profile</code> feature
+          if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-profile"><code>ttp:profile</code></a> attribute on the
+          <a href="#document-structure-vocabulary-tt"><code>tt</code></a> element and
+          transforming the following vocabulary defined by <a href=
+          "#parameter-element-vocabulary"><b>6.1 Parameter Element
+          Vocabulary</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#parameter-vocabulary-profile"><code>ttp:profile</code></a></p>
+            </li>
+
+            <li>
+              <p><a href=
+              "#parameter-vocabulary-features"><code>ttp:features</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#parameter-vocabulary-feature"><code>ttp:feature</code></a></p>
+            </li>
+
+            <li>
+              <p><a href=
+              "#parameter-vocabulary-extensions"><code>ttp:extensions</code></a></p>
+            </li>
+
+            <li>
+              <p><a href=
+              "#parameter-vocabulary-extension"><code>ttp:extension</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#profile</code> feature if
+          it implements presentation semantic support for the same vocabulary specified
+          above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-showBackground" name="feature-showBackground"></a>D.1.71
+          #showBackground</h4>
+
+          <p>A TTML transformation processor supports the <code>#showBackground</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href=
+          "#style-attribute-showBackground"><code>tts:showBackground</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#showBackground</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href=
+          "#style-attribute-showBackground"><code>tts:showBackground</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-structure" name="feature-structure"></a>D.1.72
+          #structure</h4>
+
+          <p>A TTML transformation processor supports the <code>#structure</code> feature
+          if it recognizes and is capable of transforming the following vocabulary
+          defined by <a href="#content"><b>7 Content</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#document-structure-vocabulary-tt"><code>tt</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#document-structure-vocabulary-head"><code>head</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#structure</code> feature
+          if it implements presentation semantic support for the same vocabulary
+          enumerated above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-styling" name="feature-styling"></a>D.1.73 #styling</h4>
+
+          <p>A TTML transformation processor supports the <code>#styling</code> feature
+          if it recognizes and is capable of transforming the following vocabulary
+          defined by <a href="#styling"><b>8 Styling</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#styling-vocabulary-styling"><code>styling</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#styling-vocabulary-style"><code>style</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#style-attribute-style">@<code>style</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#styling</code> feature if
+          it implements presentation semantic support for the same vocabulary enumerated
+          above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-styling-chained" name="feature-styling-chained"></a>D.1.74
+          #styling-chained</h4>
+
+          <p>A TTML transformation processor supports the <code>#styling-chained</code>
+          feature if it recognizes and is capable of transforming chained style
+          association as defined by <a href=
+          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
+          Referential Styling</b></a>.</p>
+
+          <p>A TTML presentation processor supports the <code>#styling-chained</code>
+          feature if it implements presentation semantic support for chained style
+          association as defined by <a href=
+          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
+          Referential Styling</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-styling-inheritance-content" name=
+          "feature-styling-inheritance-content"></a>D.1.75
+          #styling-inheritance-content</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#styling-inheritance</code> feature if it recognizes and is capable of
+          transforming content style inheritance as defined by <a href=
+          "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
+          Inheritance</b></a>.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#styling-inheritance-content</code> feature if it implements presentation
+          semantic support for content style inheritance as defined by <a href=
+          "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
+          Inheritance</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-styling-inheritance-region" name=
+          "feature-styling-inheritance-region"></a>D.1.76
+          #styling-inheritance-region</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#styling-inheritance</code> feature if it recognizes and is capable of
+          transforming region style inheritance as defined by <a href=
+          "#semantics-style-inheritance-region"><b>8.4.2.2 Region Style
+          Inheritance</b></a>.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#styling-inheritance-region</code> feature if it implements presentation
+          semantic support for region style inheritance as defined by <a href=
+          "#semantics-style-inheritance-region"><b>8.4.2.2 Region Style
+          Inheritance</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-styling-inline" name="feature-styling-inline"></a>D.1.77
+          #styling-inline</h4>
+
+          <p>A TTML transformation processor supports the <code>#styling-inline</code>
+          feature if it recognizes and is capable of transforming inline style
+          association as defined by <a href=
+          "#semantics-style-association-inline"><b>8.4.1.1 Inline Styling</b></a>.</p>
+
+          <p>A TTML presentation processor supports the <code>#styling-inline</code>
+          feature if it implements presentation semantic support for inline style
+          association as defined by <a href=
+          "#semantics-style-association-inline"><b>8.4.1.1 Inline Styling</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-styling-nested" name="feature-styling-nested"></a>D.1.78
+          #styling-nested</h4>
+
+          <p>A TTML transformation processor supports the <code>#styling-nested</code>
+          feature if it recognizes and is capable of transforming nested style
+          association as defined by <a href=
+          "#semantics-style-association-nested"><b>8.4.1.4 Nested Styling</b></a>.</p>
+
+          <p>A TTML presentation processor supports the <code>#styling-nested</code>
+          feature if it implements presentation semantic support for nested style
+          association as defined by <a href=
+          "#semantics-style-association-nested"><b>8.4.1.4 Nested Styling</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-styling-referential" name=
+          "feature-styling-referential"></a>D.1.79 #styling-referential</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#styling-referential</code> feature if it recognizes and is capable of
+          transforming referential style association as defined by <a href=
+          "#semantics-style-association-referential"><b>8.4.1.2 Referential
+          Styling</b></a>.</p>
+
+          <p>A TTML presentation processor supports the <code>#styling-referential</code>
+          feature if it implements presentation semantic support for referential style
+          association as defined by <a href=
+          "#semantics-style-association-referential"><b>8.4.1.2 Referential
+          Styling</b></a>.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-subFrameRate" name="feature-subFrameRate"></a>D.1.80
+          #subFrameRate</h4>
+
+          <p>A TTML transformation processor supports the <code>#subFrameRate</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#subFrameRate</code>
+          feature if it implements presentation semantic support for the <a href=
+          "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textAlign" name="feature-textAlign"></a>D.1.81
+          #textAlign</h4>
+
+          <p>A TTML transformation processor supports the <code>#textAlign</code> feature
+          if it recognizes and is capable of transforming all defined values of the
+          <a href="#style-attribute-textAlign"><code>tts:textAlign</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#textAlign</code> feature
+          if it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-textAlign"><code>tts:textAlign</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textAlign-absolute" name=
+          "feature-textAlign-absolute"></a>D.1.82 #textAlign-absolute</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#textAlign-absolute</code> feature if it recognizes and is capable of
+          transforming the <code>left</code>, <code>center</code>, and <code>right</code>
+          values of the <a href=
+          "#style-attribute-textAlign"><code>tts:textAlign</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#textAlign-absolute</code>
+          feature if it implements presentation semantic support for the
+          <code>left</code>, <code>center</code>, and <code>right</code> values of the
+          <a href="#style-attribute-textAlign"><code>tts:textAlign</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textAlign-relative" name=
+          "feature-textAlign-relative"></a>D.1.83 #textAlign-relative</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#textAlign-relative</code> feature if it recognizes and is capable of
+          transforming the <code>start</code>, <code>center</code>, and <code>end</code>
+          values of the <a href=
+          "#style-attribute-textAlign"><code>tts:textAlign</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#textAlign-relative</code>
+          feature if it implements presentation semantic support for the
+          <code>start</code>, <code>center</code>, and <code>end</code> values of the
+          <a href="#style-attribute-textAlign"><code>tts:textAlign</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textDecoration" name="feature-textDecoration"></a>D.1.84
+          #textDecoration</h4>
+
+          <p>A TTML transformation processor supports the <code>#textDecoration</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href=
+          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#textDecoration</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href=
+          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textDecoration-over" name=
+          "feature-textDecoration-over"></a>D.1.85 #textDecoration-over</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#textDecoration-over</code> feature if it recognizes and is capable of
+          transforming the <code>overline</code> and <code>noOverline</code> values of
+          the <a href=
+          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#textDecoration-over</code>
+          feature if it implements presentation semantic support for the
+          <code>overline</code> and <code>noOverline</code> values of the <a href=
+          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textDecoration-through" name=
+          "feature-textDecoration-through"></a>D.1.86 #textDecoration-through</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#textDecoration-through</code> feature if it recognizes and is capable of
+          transforming the <code>lineThrough</code> and <code>noLineThrough</code> values
+          of the <a href=
+          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#textDecoration-through</code> feature if it implements presentation
+          semantic support for the <code>lineThrough</code> and
+          <code>noLineThrough</code> values of the <a href=
+          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textDecoration-under" name=
+          "feature-textDecoration-under"></a>D.1.87 #textDecoration-under</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#textDecoration-under</code> feature if it recognizes and is capable of
+          transforming the <code>underline</code> and <code>noUnderline</code> values of
+          the <a href=
+          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#textDecoration-under</code> feature if it implements presentation
+          semantic support for the <code>underline</code> and <code>noUnderline</code>
+          values of the <a href=
+          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textOutline" name="feature-textOutline"></a>D.1.88
+          #textOutline</h4>
+
+          <p>A TTML transformation processor supports the <code>#textOutline</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#textOutline</code> feature
+          if it implements presentation semantic support for the <a href=
+          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textOutline-blurred" name=
+          "feature-textOutline-blurred"></a>D.1.89 #textOutline-blurred</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#textOutline-blurred</code> feature if it recognizes and is capable of
+          transforming values of the <a href=
+          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute that
+          includes a blur radius specification.</p>
+
+          <p>A TTML presentation processor supports the <code>#textOutline-blurred</code>
+          feature if it implements presentation semantic support for values of the
+          <a href="#style-attribute-textOutline"><code>tts:textOutline</code></a>
+          attribute that includes a blur radius specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-textOutline-unblurred" name=
+          "feature-textOutline-unblurred"></a>D.1.90 #textOutline-unblurred</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#textOutline-unblurred</code> feature if it recognizes and is capable of
+          transforming values of the <a href=
+          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute that
+          does not include a blur radius specification.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#textOutline-unblurred</code> feature if it implements presentation
+          semantic support for values of the <a href=
+          "#style-attribute-textOutline"><code>tts:textOutline</code></a> attribute that
+          does not include a blur radius specification.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-tickRate" name="feature-tickRate"></a>D.1.91 #tickRate</h4>
+
+          <p>A TTML transformation processor supports the <code>#tickRate</code> feature
+          if it recognizes and is capable of transforming the <a href=
+          "#parameter-attribute-tickRate"><code>ttp:tickRate</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#tickRate</code> feature if
+          it implements presentation semantic support for the <a href=
+          "#parameter-attribute-tickRate"><code>ttp:tickRate</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-timeBase-clock" name="feature-timeBase-clock"></a>D.1.92
+          #timeBase-clock</h4>
+
+          <p>A TTML transformation processor supports the <code>#timeBase-clock</code>
+          feature if it recognizes and is capable of transforming the <code>clock</code>
+          value of the <a href=
+          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute and if
+          it supports the <a href="#feature-clockMode"><code>#clockMode</code></a>
+          feature.</p>
+
+          <p>A TTML presentation processor supports the <code>#timeBase-clock</code>
+          feature if it implements presentation semantic support for the
+          <code>clock</code> value of the <a href=
+          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute and if
+          it supports the <a href="#feature-clockMode"><code>#clockMode</code></a>
+          feature.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-timeBase-media" name="feature-timeBase-media"></a>D.1.93
+          #timeBase-media</h4>
+
+          <p>A TTML transformation processor supports the <code>#timeBase-media</code>
+          feature if it recognizes and is capable of transforming the <code>media</code>
+          value of the <a href=
+          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#timeBase-media</code>
+          feature if it implements presentation semantic support for the
+          <code>media</code> value of the <a href=
+          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-timeBase-smpte" name="feature-timeBase-smpte"></a>D.1.94
+          #timeBase-smpte</h4>
+
+          <p>A TTML transformation processor supports the <code>#timeBase-smpte</code>
+          feature if it recognizes and is capable of transforming the <code>smpte</code>
+          value of the <a href=
+          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute and if
+          it supports the <a href="#feature-dropMode"><code>#dropMode</code></a>
+          feature.</p>
+
+          <p>A TTML presentation processor supports the <code>#timeBase-smpte</code>
+          feature if it implements presentation semantic support for the
+          <code>smpte</code> value of the <a href=
+          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a> attribute and if
+          it supports the <a href="#feature-dropMode"><code>#dropMode</code></a>
+          feature.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-timeContainer" name="feature-timeContainer"></a>D.1.95
+          #timeContainer</h4>
+
+          <p>A TTML transformation processor supports the <code>#timeContainer</code>
+          feature if it recognizes and is capable of transforming the <a href=
+          "#timing-attribute-timeContainer"><code>timeContainer</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#timeContainer</code>
+          feature if it implements presentation semantic support for the <a href=
+          "#timing-attribute-timeContainer"><code>timeContainer</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-time-clock" name="feature-time-clock"></a>D.1.96
+          #time-clock</h4>
+
+          <p>A TTML transformation processor supports the <code>#time-clock</code>
+          feature if it recognizes and is capable of transforming all values of the
+          <a href="#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy
+          the following subset of time expression syntax:</p>
+
+          <div class="exampleInner">
+            <pre>
+&lt;timeExpression&gt;
+  : hours ":" minutes ":" seconds ( fraction )?
+</pre>
+          </div>
+
+          <p>A TTML presentation processor supports the <code>#time-clock</code> feature
+          if it implements presentation semantic support for the same syntax specified
+          above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-time-clock-with-frames" name=
+          "feature-time-clock-with-frames"></a>D.1.97 #time-clock-with-frames</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#time-clock-with-frames</code> feature if it supports the <a href=
+          "#feature-frameRate"><code>#frameRate</code></a>, <a href=
+          "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a>, and
+          <a href="#feature-subFrameRate"><code>#subFrameRate</code></a> features and if
+          it recognizes and is capable of transforming all values of the <a href=
+          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy the
+          following subset of time expression syntax:</p>
+
+          <div class="exampleInner">
+            <pre>
+&lt;timeExpression&gt;
+  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?
+</pre>
+          </div>
+
+          <p>A TTML presentation processor supports the
+          <code>#time-clock-with-frames</code> feature if it implements presentation
+          semantic support for the same features and syntax specified above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-time-offset" name="feature-time-offset"></a>D.1.98
+          #time-offset</h4>
+
+          <p>A TTML transformation processor supports the <code>#time-offset</code>
+          feature if it recognizes and is capable of transforming all values of the
+          <a href="#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy
+          the following subset of time expression syntax:</p>
+
+          <div class="exampleInner">
+            <pre>
+&lt;timeExpression&gt;
+  : time-count fraction? ( "h" | "m" | "s" | "ms" )
+</pre>
+          </div>
+
+          <p>A TTML presentation processor supports the <code>#time-offset</code> feature
+          if it implements presentation semantic support for the same syntax specified
+          above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-time-offset-with-frames" name=
+          "feature-time-offset-with-frames"></a>D.1.99 #time-offset-with-frames</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#time-offset-with-frames</code> feature if it supports the <a href=
+          "#feature-frameRate"><code>#frameRate</code></a>, <a href=
+          "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a>, and
+          <a href="#feature-subFrameRate"><code>#subFrameRate</code></a> features and if
+          it recognizes and is capable of transforming all values of the <a href=
+          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy the
+          following subset of time expression syntax:</p>
+
+          <div class="exampleInner">
+            <pre>
+&lt;timeExpression&gt;
+  : time-count fraction? "f"
+</pre>
+          </div>
+
+          <p>A TTML presentation processor supports the
+          <code>#time-offset-with-frames</code> feature if it implements presentation
+          semantic support for the same features and syntax specified above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-time-offset-with-ticks" name=
+          "feature-time-offset-with-ticks"></a>D.1.100 #time-offset-with-ticks</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#time-offset-with-ticks</code> feature if it supports the <a href=
+          "#feature-tickRate"><code>#tickRate</code></a> feature and if it recognizes and
+          is capable of transforming all values of the <a href=
+          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that satisfy the
+          following subset of time expression syntax:</p>
+
+          <div class="exampleInner">
+            <pre>
+&lt;timeExpression&gt;
+  : time-count fraction? "t"
+</pre>
+          </div>
+
+          <p>A TTML presentation processor supports the
+          <code>#time-offset-with-ticks</code> feature if it implements presentation
+          semantic support for the same features and syntax specified above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-timing" name="feature-timing"></a>D.1.101 #timing</h4>
+
+          <p>A TTML transformation processor supports the <code>#timing</code> feature if
+          it recognizes and is capable of transforming the following vocabulary defined
+          by <a href="#timing"><b>10 Timing</b></a>:</p>
+
+          <ul>
+            <li>
+              <p><a href="#timing-attribute-begin">@<code>begin</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#timing-attribute-dur">@<code>dur</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#timing-attribute-end">@<code>end</code></a></p>
+            </li>
+          </ul>
+
+          <p>A TTML presentation processor supports the <code>#timing</code> feature if
+          it implements presentation semantic support for the same vocabulary enumerated
+          above.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-transformation" name="feature-transformation"></a>D.1.102
+          #transformation</h4>
+
+          <p>A TTML processor supports the <code>#transformation</code> feature if it (1)
+          satisfies the generic processor criteria defined by <a href=
+          "#conformance-generic-processor"><b>3.2.1 Generic Processor Conformance</b></a>
+          and (2) implements the transformation semantics of the following features:</p>
+
+          <ul>
+            <li>
+              <p><a href="#content"><code>#content</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-core"><code>#core</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-profile"><code>#profile</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-structure"><code>#structure</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#feature-time-offset"><code>#time-offset</code></a></p>
+            </li>
+
+            <li>
+              <p><a href="#timing"><code>#timing</code></a></p>
+            </li>
+          </ul>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-unicodeBidi" name="feature-unicodeBidi"></a>D.1.103
+          #unicodeBidi</h4>
+
+          <p>A TTML transformation processor supports the <code>#unicodeBidi</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#unicodeBidi</code> feature
+          if it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-visibility" name="feature-visibility"></a>D.1.104
+          #visibility</h4>
+
+          <p>A TTML transformation processor supports the <code>#visibility</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#visibility</code> feature
+          if it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-visibility-block" name=
+          "feature-visibility-block"></a>D.1.105 #visibility-block</h4>
+
+          <p>A TTML transformation processor supports the <code>#visibility-block</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
+          attribute when applied to a content element that would generate a block area
+          during presentation processing.</p>
+
+          <p>A TTML presentation processor supports the <code>#visibility-block</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
+          attribute when applied to a content element that generates a block area.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-visibility-inline" name=
+          "feature-visibility-inline"></a>D.1.106 #visibility-inline</h4>
+
+          <p>A TTML transformation processor supports the <code>#visibility-inline</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
+          attribute when applied to a content element that would generate an inline area
+          during presentation processing.</p>
+
+          <p>A TTML presentation processor supports the <code>#visibility-inline</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
+          attribute when applied to a content element that generates an inline area.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-visibility-region" name=
+          "feature-visibility-region"></a>D.1.107 #visibility-region</h4>
+
+          <p>A TTML transformation processor supports the <code>#visibility-region</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
+          attribute when applied to a <a href=
+          "#layout-vocabulary-region"><code>region</code></a> element.</p>
+
+          <p>A TTML presentation processor supports the <code>#visibility-region</code>
+          feature if it implements presentation semantic support for all defined values
+          of the <a href="#style-attribute-visibility"><code>tts:visibility</code></a>
+          attribute when applied to a <a href=
+          "#layout-vocabulary-region"><code>region</code></a> element.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-wrapOption" name="feature-wrapOption"></a>D.1.108
+          #wrapOption</h4>
+
+          <p>A TTML transformation processor supports the <code>#wrapOption</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-wrapOption"><code>tts:wrapOption</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#wrapOption</code> feature
+          if it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-wrapOption"><code>tts:wrapOption</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-writingMode" name="feature-writingMode"></a>D.1.109
+          #writingMode</h4>
+
+          <p>A TTML transformation processor supports the <code>#writingMode</code>
+          feature if it recognizes and is capable of transforming all defined values of
+          the <a href="#style-attribute-writingMode"><code>tts:writingMode</code></a>
+          attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#writingMode</code> feature
+          if it implements presentation semantic support for all defined values of the
+          <a href="#style-attribute-writingMode"><code>tts:writingMode</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-writingMode-vertical" name=
+          "feature-writingMode-vertical"></a>D.1.110 #writingMode-vertical</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#writingMode-vertical</code> feature if it recognizes and is capable of
+          transforming the <code>tbrl</code>, <code>tblr</code>, and <code>tb</code>
+          values of the <a href=
+          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#writingMode-vertical</code> feature if it implements presentation
+          semantic support for the <code>tbrl</code>, <code>tblr</code>, and
+          <code>tb</code> values of the <a href=
+          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-writingMode-horizontal" name=
+          "feature-writingMode-horizontal"></a>D.1.111 #writingMode-horizontal</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#writingMode-horizontal</code> feature if it recognizes and is capable of
+          transforming the <code>lrtb</code>, <code>rltb</code>, <code>lr</code> and
+          <code>rl</code> values of the <a href=
+          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#writingMode-horizontal</code> feature if it implements presentation
+          semantic support for the <code>lrtb</code>, <code>rltb</code>, <code>lr</code>
+          and <code>rl</code> values of the <a href=
+          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-writingMode-horizontal-lr" name=
+          "feature-writingMode-horizontal-lr"></a>D.1.112 #writingMode-horizontal-lr</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#writingMode-horizontal</code> feature if it recognizes and is capable of
+          transforming the <code>lrtb</code> and <code>lr</code> values of the <a href=
+          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#writingMode-horizontal-lr</code> feature if it implements presentation
+          semantic support for the <code>lrtb</code> and <code>lr</code> values of the
+          <a href="#style-attribute-writingMode"><code>tts:writingMode</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-writingMode-horizontal-rl" name=
+          "feature-writingMode-horizontal-rl"></a>D.1.113 #writingMode-horizontal-rl</h4>
+
+          <p>A TTML transformation processor supports the
+          <code>#writingMode-horizontal</code> feature if it recognizes and is capable of
+          transforming the <code>rltb</code> and <code>rl</code> values of the <a href=
+          "#style-attribute-writingMode"><code>tts:writingMode</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the
+          <code>#writingMode-horizontal-rl</code> feature if it implements presentation
+          semantic support for the <code>rltb</code> and <code>rl</code> values of the
+          <a href="#style-attribute-writingMode"><code>tts:writingMode</code></a>
+          attribute.</p>
+        </div>
+
+        <div class="div3">
+          <h4><a id="feature-zIndex" name="feature-zIndex"></a>D.1.114 #zIndex</h4>
+
+          <p>A TTML transformation processor supports the <code>#zIndex</code> feature if
+          it recognizes and is capable of transforming the <a href=
+          "#style-attribute-zIndex"><code>tts:zIndex</code></a> attribute.</p>
+
+          <p>A TTML presentation processor supports the <code>#zIndex</code> feature if
+          it implements presentation semantic support for the <a href=
+          "#style-attribute-zIndex"><code>tts:zIndex</code></a> attribute.</p>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="feature-support" name="feature-support"></a>D.2 Feature Support</h3>
+
+        <p>The following table, <a href="#feature-support-table"><b>Table D-1 – Feature
+        Support</b></a>, enumerates every defined feature designation (expressed without
+        the TT Feature Namespace), and, for each designated feature, specifies whether
+        the feature must be implemented, i.e., is mandatory (M), or may be implemented,
+        i.e., is optional (O), for transformation and presentation processors.</p><a id=
+        "feature-support-table" name="feature-support-table"></a>
+
+        <table class="common">
+          <caption>
+            Table D-1 – Feature Support
+          </caption>
+          <col width="60%" span="1">
+          <col width="20%" span="1">
+          <col width="20%" span="1">
+
+          <tbody>
+            <tr>
+              <td><span class="strong">Feature</span></td>
+
+              <td><span class="strong">Transformation</span></td>
+
+              <td><span class="strong">Presentation</span></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-animation"><code>#animation</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-backgroundColor"><code>#backgroundColor</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-backgroundColor-block"><code>#backgroundColor-block</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-backgroundColor-inline"><code>#backgroundColor-inline</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-backgroundColor-region"><code>#backgroundColor-region</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-bidi"><code>#bidi</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-cellResolution"><code>#cellResolution</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-clockMode"><code>#clockMode</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-clockMode-gps"><code>#clockMode-gps</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-clockMode-local"><code>#clockMode-local</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-clockMode-utc"><code>#clockMode-utc</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-color"><code>#color</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-content"><code>#content</code></a></td>
+
+              <td>M</td>
+
+              <td>M</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-core"><code>#core</code></a></td>
+
+              <td>M</td>
+
+              <td>M</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-direction"><code>#direction</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-display"><code>#display</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-display-block"><code>#display-block</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-display-inline"><code>#display-inline</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-display-region"><code>#display-region</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-displayAlign"><code>#displayAlign</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-dropMode"><code>#dropMode</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-dropMode-dropNTSC"><code>#dropMode-dropNTSC</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-dropMode-dropPAL"><code>#dropMode-dropPAL</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-dropMode-nonDrop"><code>#dropMode-nonDrop</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-extent"><code>#extent</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-extent-region"><code>#extent-region</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-extent-root"><code>#extent-root</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-fontFamily"><code>#fontFamily</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-fontFamily-generic"><code>#fontFamily-generic</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-fontFamily-non-generic"><code>#fontFamily-non-generic</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-fontSize"><code>#fontSize</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-fontSize-anamorphic"><code>#fontSize-anamorphic</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-fontSize-isomorphic"><code>#fontSize-isomorphic</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-fontStyle"><code>#fontStyle</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-fontStyle-italic"><code>#fontStyle-italic</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-fontStyle-oblique"><code>#fontStyle-oblique</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-fontWeight"><code>#fontWeight</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-fontWeight-bold"><code>#fontWeight-bold</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-frameRate"><code>#frameRate</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-layout"><code>#layout</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-length"><code>#length</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-length-cell"><code>#length-cell</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-length-em"><code>#length-em</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-length-integer"><code>#length-integer</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-length-negative"><code>#length-negative</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-length-percentage"><code>#length-percentage</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-length-pixel"><code>#length-pixel</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-length-positive"><code>#length-positive</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-length-real"><code>#length-real</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-lineBreak-uax14"><code>#lineBreak-uax14</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-lineHeight"><code>#lineHeight</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-markerMode"><code>#markerMode</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-markerMode-continuous"><code>#markerMode-continuous</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-markerMode-discontinuous"><code>#markerMode-discontinuous</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-metadata"><code>#metadata</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-nested-div"><code>#nested-div</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-nested-span"><code>#nested-span</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-opacity"><code>#opacity</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-origin"><code>#origin</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-overflow"><code>#overflow</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-overflow-visible"><code>#overflow-visible</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-padding"><code>#padding</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-padding-1"><code>#padding-1</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-padding-2"><code>#padding-2</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-padding-3"><code>#padding-3</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-padding-4"><code>#padding-4</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-pixelAspectRatio"><code>#pixelAspectRatio</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-presentation"><code>#presentation</code></a></td>
+
+              <td>O</td>
+
+              <td>M</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-profile"><code>#profile</code></a></td>
+
+              <td>M</td>
+
+              <td>M</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-showBackground"><code>#showBackground</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-structure"><code>#structure</code></a></td>
+
+              <td>M</td>
+
+              <td>M</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-styling"><code>#styling</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-styling-chained"><code>#styling-chained</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-styling-inheritance-content"><code>#styling-inheritance-content</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-styling-inheritance-region"><code>#styling-inheritance-region</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-styling-inline"><code>#styling-inline</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-styling-nested"><code>#styling-nested</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-styling-referential"><code>#styling-referential</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-subFrameRate"><code>#subFrameRate</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-textAlign"><code>#textAlign</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-textAlign-absolute"><code>#textAlign-absolute</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-textAlign-relative"><code>#textAlign-relative</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-textDecoration"><code>#textDecoration</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-textDecoration-over"><code>#textDecoration-over</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-textDecoration-through"><code>#textDecoration-through</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-textDecoration-under"><code>#textDecoration-under</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-textOutline"><code>#textOutline</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-textOutline-blurred"><code>#textOutline-blurred</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-textOutline-unblurred"><code>#textOutline-unblurred</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-tickRate"><code>#tickRate</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-timeBase-clock"><code>#timeBase-clock</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-timeBase-media"><code>#timeBase-media</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-timeBase-smpte"><code>#timeBase-smpte</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-timeContainer"><code>#timeContainer</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-time-clock"><code>#time-clock</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-time-clock-with-frames"><code>#time-clock-with-frames</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-time-offset"><code>#time-offset</code></a></td>
+
+              <td>M</td>
+
+              <td>M</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-time-offset-with-frames"><code>#time-offset-with-frames</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-time-offset-with-ticks"><code>#time-offset-with-ticks</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-timing"><code>#timing</code></a></td>
+
+              <td>M</td>
+
+              <td>M</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-transformation"><code>#transformation</code></a></td>
+
+              <td>M</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-unicodeBidi"><code>#unicodeBidi</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-visibility"><code>#visibility</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-visibility-block"><code>#visibility-block</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-visibility-inline"><code>#visibility-inline</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-visibility-region"><code>#visibility-region</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-wrapOption"><code>#wrapOption</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-writingMode"><code>#writingMode</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-writingMode-vertical"><code>#writingMode-vertical</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-writingMode-horizontal"><code>#writingMode-horizontal</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-writingMode-horizontal-lr"><code>#writingMode-horizontal-lr</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#feature-writingMode-horizontal-rl"><code>#writingMode-horizontal-rl</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-zIndex"><code>#zIndex</code></a></td>
+
+              <td>O</td>
+
+              <td>O</td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>For the sake of convenience, the following table, <a href=
+        "#feature-transformation-mandatory-table"><b>Table D-2 – Mandatory Features -
+        Transformation</b></a>, enumerates all mandatory features for a TTML
+        Transformation Processor, providing additional comments to summarize the context
+        of usage or the nature of the feature. The <em>Profile Definition Document</em>
+        that defines the corresponding DFXP Transformation Profile is specified in
+        <a href="#profile-dfxp-transformation"><b>F.1 DFXP Transformation
+        Profile</b></a>.</p><a id="feature-transformation-mandatory-table" name=
+        "feature-transformation-mandatory-table"></a>
+
+        <table class="common">
+          <caption>
+            Table D-2 – Mandatory Features - Transformation
+          </caption>
+          <col width="60%" span="1">
+          <col width="40%" span="1">
+
+          <tbody>
+            <tr>
+              <td><span class="strong">Feature</span></td>
+
+              <td><span class="strong">Comments</span></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-content"><code>#content</code></a></td>
+
+              <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
+              <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
+              "#content-vocabulary-p"><code>p</code></a>, <a href=
+              "#content-vocabulary-span"><code>span</code></a>, <a href=
+              "#content-vocabulary-br"><code>br</code></a></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-core"><code>#core</code></a></td>
+
+              <td><a href="#content-attribute-id">@<code>xml:id</code></a>, <a href=
+              "#content-attribute-id">@<code>xml:lang</code></a>, <a href=
+              "#content-attribute-id">@<code>xml:space</code></a></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-profile"><code>#profile</code></a></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-structure"><code>#structure</code></a></td>
+
+              <td><a href="#document-structure-vocabulary-tt"><code>tt</code></a>,
+              <a href="#document-structure-vocabulary-head"><code>head</code></a></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-time-offset"><code>#time-offset</code></a></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-timing"><code>#timing</code></a></td>
+
+              <td><a href="#timing-attribute-begin">@<code>begin</code></a>, <a href=
+              "#timing-attribute-dur">@<code>dur</code></a>, <a href=
+              "#timing-attribute-end">@<code>end</code></a></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-transformation"><code>#transformation</code></a></td>
+
+              <td></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>For the sake of convenience, the following table, <a href=
+        "#feature-presentation-mandatory-table"><b>Table D-3 – Mandatory Features -
+        Presentation</b></a>, enumerates all mandatory features for a TTML Presentation
+        Processor, providing additional comments to summarize the context of usage or the
+        nature of the feature. The <em>Profile Definition Document</em> that defines the
+        corresponding DFXP Presentation Profile is specified in <a href=
+        "#profile-dfxp-presentation"><b>F.2 DFXP Presentation Profile</b></a>.</p><a id=
+        "feature-presentation-mandatory-table" name=
+        "feature-presentation-mandatory-table"></a>
+
+        <table class="common">
+          <caption>
+            Table D-3 – Mandatory Features - Presentation
+          </caption>
+          <col width="60%" span="1">
+          <col width="40%" span="1">
+
+          <tbody>
+            <tr>
+              <td><span class="strong">Feature</span></td>
+
+              <td><span class="strong">Comments</span></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-content"><code>#content</code></a></td>
+
+              <td><a href="#document-structure-vocabulary-body"><code>body</code></a>,
+              <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
+              "#content-vocabulary-p"><code>p</code></a>, <a href=
+              "#content-vocabulary-span"><code>span</code></a>, <a href=
+              "#content-vocabulary-br"><code>br</code></a></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-core"><code>#core</code></a></td>
+
+              <td><a href="#content-attribute-id">@<code>xml:id</code></a>, <a href=
+              "#content-attribute-id">@<code>xml:lang</code></a>, <a href=
+              "#content-attribute-id">@<code>xml:space</code></a></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-profile"><code>#profile</code></a></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-presentation"><code>#presentation</code></a></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-structure"><code>#structure</code></a></td>
+
+              <td><a href="#document-structure-vocabulary-tt"><code>tt</code></a>,
+              <a href="#document-structure-vocabulary-head"><code>head</code></a></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-time-offset"><code>#time-offset</code></a></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#feature-timing"><code>#timing</code></a></td>
+
+              <td><a href="#timing-attribute-begin">@<code>begin</code></a>, <a href=
+              "#timing-attribute-dur">@<code>dur</code></a>, <a href=
+              "#timing-attribute-end">@<code>end</code></a></td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="extensions" name="extensions"></a>E Extensions</h2>
+
+      <p><em>This appendix is normative.</em></p>
+
+      <p>This appendix specifies the syntactic form of extension designations, which are
+      used to express authorial intent regarding the support for extension mechanisms in
+      a TTML processor.</p>
+
+      <div class="div2">
+        <h3><a id="extension-designations" name="extension-designations"></a>E.1
+        Extension Designations</h3>
+
+        <p>An extension designation is expressed as a string that adheres to the
+        following form:</p>
+
+        <div class="exampleInner">
+          <pre>
+extension-designation
+  : extension-namespace designation
+
+extension-namespace
+  : <em>TT Extension Namespace</em>                  // http://www.w3.org/ns/ttml/extension/
+  | <em>Other Extension Namespace</em>               // expressed as an absolute URI
+
+designation
+  : "#" token-char+
+
+token-char
+  : { XML NameChar }                        // XML 1.1 Production [4a]
+</pre>
+        </div>
+
+        <p>If the extension namespace of an extension designation is the TT Extension
+        Namespace, then all values of the following <code>designation</code> token are
+        reserved for future standardization.</p>
+
+        <p>If the extension namespace of an extension designation is not the TT Extension
+        Namespace, i.e., is an <em>Other Extension Namespace</em>, then the extension
+        namespace must be expressed as an absolute URI capable of serving as a base URI
+        used in combination with a <code>designation</code> token that takes the form of
+        a fragment identifier.</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="profiles" name="profiles"></a>F Profiles</h2>
+
+      <p><em>This appendix is normative.</em></p>
+
+      <p>This appendix specifies the following standard TTML profiles:</p>
+
+      <ul>
+        <li>
+          <p><a href="#profile-dfxp-transformation"><b>F.1 DFXP Transformation
+          Profile</b></a></p>
+        </li>
+
+        <li>
+          <p><a href="#profile-dfxp-presentation"><b>F.2 DFXP Presentation
+          Profile</b></a></p>
+        </li>
+
+        <li>
+          <p><a href="#profile-dfxp-full"><b>F.3 DFXP Full Profile</b></a></p>
+        </li>
+      </ul>
+
+      <p>The SDP US profile is defined in <a href=
+      "http://www.w3.org/TR/ttml10-sdp-us/">TTML Simple Delivery Profile for Closed
+      Captions (US)</a>.</p>
+
+      <p>Each TTML profile is defined in terms of a <em>Profile Definition Document</em>,
+      which is expressed as an XML document wherein the root element adheres to <a href=
+      "#parameter-vocabulary-profile"><b>6.1.1 ttp:profile</b></a>.</p>
+
+      <div class="div2">
+        <h3><a id="profile-dfxp-transformation" name=
+        "profile-dfxp-transformation"></a>F.1 DFXP Transformation Profile</h3>
+
+        <p>The DFXP Transformation Profile is intended to be used to express minimum
+        compliance for transformation processing.</p>
+
+        <div class="exampleInner">
+          <pre>
+&lt;?xml version="1.0" encoding="utf-8"?&gt;
+&lt;!-- this file defines the "dfxp-transformation" profile of ttml --&gt;
+&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
+  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
+    &lt;!-- required (mandatory) feature support --&gt;
+    &lt;feature value="required"&gt;#content&lt;/feature&gt;
+    &lt;feature value="required"&gt;#core&lt;/feature&gt;
+    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
+    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
+    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
+    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
+    &lt;feature value="required"&gt;#transformation&lt;/feature&gt;
+    &lt;!-- optional (voluntary) feature support --&gt;
+    &lt;feature value="optional"&gt;#animation&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#backgroundColor-block&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#backgroundColor-inline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#backgroundColor-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#backgroundColor&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#bidi&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#cellResolution&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#clockMode-gps&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#clockMode-local&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#clockMode-utc&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#clockMode&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#color&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#direction&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#display-block&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#display-inline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#display-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#display&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#displayAlign&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#dropMode-dropNTSC&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#dropMode-dropPAL&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#dropMode-nonDrop&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#dropMode&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#extent-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#extent-root&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#extent&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontFamily-generic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontFamily-non-generic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontFamily&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontSize-anamorphic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontSize-isomorphic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontSize&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontStyle-italic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontStyle-oblique&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontStyle&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontWeight-bold&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontWeight&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#frameRate&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#frameRateMultiplier&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#layout&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-cell&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-em&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-integer&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-negative&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-percentage&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-pixel&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-positive&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-real&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#lineBreak-uax14&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#lineHeight&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#markerMode-continuous&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#markerMode-discontinuous&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#markerMode&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#metadata&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#nested-div&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#nested-span&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#opacity&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#origin&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#overflow-visible&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#overflow&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding-1&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding-2&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding-3&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding-4&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#pixelAspectRatio&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#presentation&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#showBackground&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-chained&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-inheritance-content&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-inheritance-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-inline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-nested&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-referential&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#subFrameRate&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textAlign-absolute&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textAlign-relative&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textAlign&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textDecoration-over&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textDecoration-through&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textDecoration-under&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textDecoration&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textOutline-blurred&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textOutline-unblurred&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textOutline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#tickRate&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#time-clock-with-frames&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#time-clock&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#time-offset-with-frames&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#time-offset-with-ticks&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#timeBase-clock&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#timeBase-media&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#timeBase-smpte&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#timeContainer&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#unicodeBidi&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#visibility-block&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#visibility-inline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#visibility-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#visibility&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#wrapOption&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode-horizontal&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode-vertical&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#zIndex&lt;/feature&gt;
+  &lt;/features&gt;
+  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
+    &lt;!-- required (mandatory) extension support --&gt;
+    &lt;!-- optional (voluntary) extension support --&gt;
+  &lt;/extensions&gt;
+&lt;/profile&gt;
+
+</pre>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="profile-dfxp-presentation" name="profile-dfxp-presentation"></a>F.2
+        DFXP Presentation Profile</h3>
+
+        <p>The DFXP Presentation Profile is intended to be used to express minimum
+        compliance for presentation processing.</p>
+
+        <div class="exampleInner">
+          <pre>
+&lt;?xml version="1.0" encoding="utf-8"?&gt;
+&lt;!-- this file defines the "dfxp-presentation" profile of ttml --&gt;
+&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
+  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
+    &lt;!-- required (mandatory) feature support --&gt;
+    &lt;feature value="required"&gt;#content&lt;/feature&gt;
+    &lt;feature value="required"&gt;#core&lt;/feature&gt;
+    &lt;feature value="required"&gt;#presentation&lt;/feature&gt;
+    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
+    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
+    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
+    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
+    &lt;!-- optional (voluntary) feature support --&gt;
+    &lt;feature value="optional"&gt;#animation&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#backgroundColor-block&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#backgroundColor-inline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#backgroundColor-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#backgroundColor&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#bidi&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#cellResolution&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#clockMode-gps&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#clockMode-local&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#clockMode-utc&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#clockMode&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#color&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#direction&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#display-block&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#display-inline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#display-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#display&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#displayAlign&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#dropMode-dropNTSC&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#dropMode-dropPAL&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#dropMode-nonDrop&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#dropMode&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#extent-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#extent-root&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#extent&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontFamily-generic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontFamily-non-generic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontFamily&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontSize-anamorphic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontSize-isomorphic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontSize&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontStyle-italic&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontStyle-oblique&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontStyle&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontWeight-bold&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#fontWeight&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#frameRate&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#frameRateMultiplier&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#layout&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-cell&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-em&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-integer&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-negative&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-percentage&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-pixel&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-positive&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length-real&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#length&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#lineBreak-uax14&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#lineHeight&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#markerMode-continuous&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#markerMode-discontinuous&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#markerMode&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#metadata&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#nested-div&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#nested-span&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#opacity&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#origin&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#overflow-visible&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#overflow&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding-1&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding-2&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding-3&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding-4&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#padding&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#pixelAspectRatio&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#showBackground&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-chained&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-inheritance-content&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-inheritance-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-inline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-nested&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling-referential&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#styling&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#subFrameRate&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textAlign-absolute&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textAlign-relative&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textAlign&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textDecoration-over&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textDecoration-through&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textDecoration-under&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textDecoration&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textOutline-blurred&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textOutline-unblurred&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#textOutline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#tickRate&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#time-clock-with-frames&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#time-clock&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#time-offset-with-frames&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#time-offset-with-ticks&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#timeBase-clock&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#timeBase-media&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#timeBase-smpte&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#timeContainer&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#transformation&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#unicodeBidi&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#visibility-block&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#visibility-inline&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#visibility-region&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#visibility&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#wrapOption&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode-horizontal&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode-vertical&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#writingMode&lt;/feature&gt;
+    &lt;feature value="optional"&gt;#zIndex&lt;/feature&gt;
+  &lt;/features&gt;
+  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
+    &lt;!-- required (mandatory) extension support --&gt;
+    &lt;!-- optional (voluntary) extension support --&gt;
+  &lt;/extensions&gt;
+&lt;/profile&gt;
+
+</pre>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="profile-dfxp-full" name="profile-dfxp-full"></a>F.3 DFXP Full
+        Profile</h3>
+
+        <p>The DFXP Full Profile is intended to be used to express maximum compliance for
+        both transformation and presentation processing.</p>
+
+        <div class="exampleInner">
+          <pre>
+&lt;?xml version="1.0" encoding="utf-8"?&gt;
+&lt;!-- this file defines the "dfxp-full" profile of ttml --&gt;
+&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
+  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
+    &lt;!-- required (mandatory) feature support --&gt;
+    &lt;feature value="required"&gt;#animation&lt;/feature&gt;
+    &lt;feature value="required"&gt;#backgroundColor-block&lt;/feature&gt;
+    &lt;feature value="required"&gt;#backgroundColor-inline&lt;/feature&gt;
+    &lt;feature value="required"&gt;#backgroundColor-region&lt;/feature&gt;
+    &lt;feature value="required"&gt;#backgroundColor&lt;/feature&gt;
+    &lt;feature value="required"&gt;#bidi&lt;/feature&gt;
+    &lt;feature value="required"&gt;#cellResolution&lt;/feature&gt;
+    &lt;feature value="required"&gt;#clockMode-gps&lt;/feature&gt;
+    &lt;feature value="required"&gt;#clockMode-local&lt;/feature&gt;
+    &lt;feature value="required"&gt;#clockMode-utc&lt;/feature&gt;
+    &lt;feature value="required"&gt;#clockMode&lt;/feature&gt;
+    &lt;feature value="required"&gt;#color&lt;/feature&gt;
+    &lt;feature value="required"&gt;#content&lt;/feature&gt;
+    &lt;feature value="required"&gt;#core&lt;/feature&gt;
+    &lt;feature value="required"&gt;#direction&lt;/feature&gt;
+    &lt;feature value="required"&gt;#display-block&lt;/feature&gt;
+    &lt;feature value="required"&gt;#display-inline&lt;/feature&gt;
+    &lt;feature value="required"&gt;#display-region&lt;/feature&gt;
+    &lt;feature value="required"&gt;#display&lt;/feature&gt;
+    &lt;feature value="required"&gt;#displayAlign&lt;/feature&gt;
+    &lt;feature value="required"&gt;#dropMode-dropNTSC&lt;/feature&gt;
+    &lt;feature value="required"&gt;#dropMode-dropPAL&lt;/feature&gt;
+    &lt;feature value="required"&gt;#dropMode-nonDrop&lt;/feature&gt;
+    &lt;feature value="required"&gt;#dropMode&lt;/feature&gt;
+    &lt;feature value="required"&gt;#extent-region&lt;/feature&gt;
+    &lt;feature value="required"&gt;#extent-root&lt;/feature&gt;
+    &lt;feature value="required"&gt;#extent&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontFamily-generic&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontFamily-non-generic&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontFamily&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontSize-anamorphic&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontSize-isomorphic&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontSize&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontStyle-italic&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontStyle-oblique&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontStyle&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontWeight-bold&lt;/feature&gt;
+    &lt;feature value="required"&gt;#fontWeight&lt;/feature&gt;
+    &lt;feature value="required"&gt;#frameRate&lt;/feature&gt;
+    &lt;feature value="required"&gt;#frameRateMultiplier&lt;/feature&gt;
+    &lt;feature value="required"&gt;#layout&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length-cell&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length-em&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length-integer&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length-negative&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length-percentage&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length-pixel&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length-positive&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length-real&lt;/feature&gt;
+    &lt;feature value="required"&gt;#length&lt;/feature&gt;
+    &lt;feature value="required"&gt;#lineBreak-uax14&lt;/feature&gt;
+    &lt;feature value="required"&gt;#lineHeight&lt;/feature&gt;
+    &lt;feature value="required"&gt;#markerMode-continuous&lt;/feature&gt;
+    &lt;feature value="required"&gt;#markerMode-discontinuous&lt;/feature&gt;
+    &lt;feature value="required"&gt;#markerMode&lt;/feature&gt;
+    &lt;feature value="required"&gt;#metadata&lt;/feature&gt;
+    &lt;feature value="required"&gt;#nested-div&lt;/feature&gt;
+    &lt;feature value="required"&gt;#nested-span&lt;/feature&gt;
+    &lt;feature value="required"&gt;#opacity&lt;/feature&gt;
+    &lt;feature value="required"&gt;#origin&lt;/feature&gt;
+    &lt;feature value="required"&gt;#overflow-visible&lt;/feature&gt;
+    &lt;feature value="required"&gt;#overflow&lt;/feature&gt;
+    &lt;feature value="required"&gt;#padding-1&lt;/feature&gt;
+    &lt;feature value="required"&gt;#padding-2&lt;/feature&gt;
+    &lt;feature value="required"&gt;#padding-3&lt;/feature&gt;
+    &lt;feature value="required"&gt;#padding-4&lt;/feature&gt;
+    &lt;feature value="required"&gt;#padding&lt;/feature&gt;
+    &lt;feature value="required"&gt;#pixelAspectRatio&lt;/feature&gt;
+    &lt;feature value="required"&gt;#presentation&lt;/feature&gt;
+    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
+    &lt;feature value="required"&gt;#showBackground&lt;/feature&gt;
+    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
+    &lt;feature value="required"&gt;#styling-chained&lt;/feature&gt;
+    &lt;feature value="required"&gt;#styling-inheritance-content&lt;/feature&gt;
+    &lt;feature value="required"&gt;#styling-inheritance-region&lt;/feature&gt;
+    &lt;feature value="required"&gt;#styling-inline&lt;/feature&gt;
+    &lt;feature value="required"&gt;#styling-nested&lt;/feature&gt;
+    &lt;feature value="required"&gt;#styling-referential&lt;/feature&gt;
+    &lt;feature value="required"&gt;#styling&lt;/feature&gt;
+    &lt;feature value="required"&gt;#subFrameRate&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textAlign-absolute&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textAlign-relative&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textAlign&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textDecoration-over&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textDecoration-through&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textDecoration-under&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textDecoration&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textOutline-blurred&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textOutline-unblurred&lt;/feature&gt;
+    &lt;feature value="required"&gt;#textOutline&lt;/feature&gt;
+    &lt;feature value="required"&gt;#tickRate&lt;/feature&gt;
+    &lt;feature value="required"&gt;#time-clock-with-frames&lt;/feature&gt;
+    &lt;feature value="required"&gt;#time-clock&lt;/feature&gt;
+    &lt;feature value="required"&gt;#time-offset-with-frames&lt;/feature&gt;
+    &lt;feature value="required"&gt;#time-offset-with-ticks&lt;/feature&gt;
+    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
+    &lt;feature value="required"&gt;#timeBase-clock&lt;/feature&gt;
+    &lt;feature value="required"&gt;#timeBase-media&lt;/feature&gt;
+    &lt;feature value="required"&gt;#timeBase-smpte&lt;/feature&gt;
+    &lt;feature value="required"&gt;#timeContainer&lt;/feature&gt;
+    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
+    &lt;feature value="required"&gt;#transformation&lt;/feature&gt;
+    &lt;feature value="required"&gt;#unicodeBidi&lt;/feature&gt;
+    &lt;feature value="required"&gt;#visibility-block&lt;/feature&gt;
+    &lt;feature value="required"&gt;#visibility-inline&lt;/feature&gt;
+    &lt;feature value="required"&gt;#visibility-region&lt;/feature&gt;
+    &lt;feature value="required"&gt;#visibility&lt;/feature&gt;
+    &lt;feature value="required"&gt;#wrapOption&lt;/feature&gt;
+    &lt;feature value="required"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
+    &lt;feature value="required"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
+    &lt;feature value="required"&gt;#writingMode-horizontal&lt;/feature&gt;
+    &lt;feature value="required"&gt;#writingMode-vertical&lt;/feature&gt;
+    &lt;feature value="required"&gt;#writingMode&lt;/feature&gt;
+    &lt;feature value="required"&gt;#zIndex&lt;/feature&gt;
+    &lt;!-- optional (voluntary) feature support --&gt;
+  &lt;/features&gt;
+  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
+    &lt;!-- required (mandatory) extension support --&gt;
+    &lt;!-- optional (voluntary) extension support --&gt;
+  &lt;/extensions&gt;
+&lt;/profile&gt;
+
+</pre>
+        </div>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="references" name="references"></a>G References</h2>
+
+      <p><em>This appendix is normative.</em></p>
+
+      <dl>
+        <dt class="label"><a id="css2" name="css2"></a>CSS2</dt>
+
+        <dd>Bert Bos et al., <a href=
+        "http://www.w3.org/TR/2011/REC-CSS2-20110607/"><cite>Cascading Style Sheets,
+        Level 2 Revision 1</cite></a>, W3C Recommendation, 07 June 2011. (See <a href=
+        "http://www.w3.org/TR/2011/REC-CSS2-20110607/">http://www.w3.org/TR/2011/REC-CSS2-20110607/</a>.)</dd>
+
+        <dt class="label"><a id="css3-color" name="css3-color"></a>CSS3 Color</dt>
+
+        <dd>Tantek Çelik and Chris Lilley, <a href=
+        "http://www.w3.org/TR/2011/REC-css3-color-20110607/"><cite>CSS Color Module Level
+        3</cite></a>, W3C Recommendation, 07 June 2011. (See <a href=
+        "http://www.w3.org/TR/2011/REC-css3-color-20110607/">http://www.w3.org/TR/2011/REC-css3-color-20110607/</a>.)</dd>
+
+        <dt class="label"><a id="gps" name="gps"></a>GPS</dt>
+
+        <dd><a href="http://tycho.usno.navy.mil/gpsinfo.html"><cite>Global Positioning
+        System</cite></a>, US Naval Observatory. (See <a href=
+        "http://tycho.usno.navy.mil/gpsinfo.html">http://tycho.usno.navy.mil/gpsinfo.html</a>.)</dd>
+
+        <dt class="label"><a id="media-types" name="media-types"></a>Media Types</dt>
+
+        <dd>Ned Freed and Nathaniel Borenstein, <a href=
+        "http://www.rfc-editor.org/rfc/rfc2046.txt"><cite>Multipurpose Internet Mail
+        Extensions (MIME) Part Two: Media Types</cite></a>, RFC 2046, November 1996,
+        IETF.(See <a href=
+        "http://www.rfc-editor.org/rfc/rfc2046.txt">http://www.rfc-editor.org/rfc/rfc2046.txt</a>.)</dd>
+
+        <dt class="label"><a id="rng" name="rng"></a>RELAX NG</dt>
+
+        <dd>ISO/IEC 19757-2, <a href="http://www.iso.org/"><cite>Information technology –
+        Document Schema Definition Language (DSDL) – Part 2: Regular-grammar-based
+        validation – RELAX NG</cite></a>, International Organization for Standardization
+        (ISO).</dd>
+
+        <dt class="label"><a id="smil21" name="smil21"></a>SMIL 2.1</dt>
+
+        <dd>Dick Bultermann, et al., <a href=
+        "http://www.w3.org/TR/2005/REC-SMIL2-20051213/"><cite>Synchronized Multimedia
+        Integration Language (SMIL 2.1)</cite></a>, W3C Recommendation, 13 December 2005.
+        (See <a href=
+        "http://www.w3.org/TR/2005/REC-SMIL2-20051213/">http://www.w3.org/TR/2005/REC-SMIL2-20051213/</a>.)</dd>
+
+        <dt class="label"><a id="smpte12m" name="smpte12m"></a>SMPTE 12M</dt>
+
+        <dd>ANSI/SMPTE 12M, <a href="https://www.smpte.org/"><cite>Television, Audio and
+        Film – Time and Control Code</cite></a>, SMPTE Standard.</dd>
+
+        <dt class="label"><a id="srgb" name="srgb"></a>SRGB</dt>
+
+        <dd>IEC 61966-2-1, <a href="http://www.iec.ch/"><cite>Multimedia systems and
+        equipment – Colour measurement and management – Part 2-1: Colour management –
+        Default RGB colour space – sRGB</cite></a>, International Electrotechnical
+        Commission (IEC).</dd>
+
+        <dt class="label"><a id="uaag" name="uaag"></a>UAAG</dt>
+
+        <dd>Ian Jacobs, Jon Gunderson, and Eric Hansen, Eds., <a href=
+        "http://www.w3.org/TR/2002/REC-UAAG10-20021217/"><cite>User Agent Accessibility
+        Guidelines 1.0</cite></a>, W3C Recommendation, 17 December 2002. (See <a href=
+        "http://www.w3.org/TR/2002/REC-UAAG10-20021217/">http://www.w3.org/TR/2002/REC-UAAG10-20021217/</a>.)</dd>
+
+        <dt class="label"><a id="uax14" name="uax14"></a>UAX14</dt>
+
+        <dd>Asmus Freytag, <a href=
+        "http://www.unicode.org/reports/tr14/tr14-17.html"><cite>Line Breaking
+        Properties</cite></a>, Unicode Consortium, 29 August 2005. (See <a href=
+        "http://www.unicode.org/reports/tr14/tr14-17.html">http://www.unicode.org/reports/tr14/tr14-17.html</a>.)</dd>
+
+        <dt class="label"><a id="utc" name="utc"></a>UTC</dt>
+
+        <dd>Recommendation TF.460, <a href="http://www.itu.int/"><cite>Standard-Frequency
+        and Time-Signal Emissions</cite></a>, International Telecommunciations Union,
+        Radio Sector (ITU-R).</dd>
+
+        <dt class="label"><a id="wcag" name="wcag"></a>WCAG</dt>
+
+        <dd>Ben Caldwell, et al., Eds., <a href=
+        "http://www.w3.org/TR/2008/REC-WCAG20-20081211/"><cite>Web Content Accessibility
+        Guidelines (WCAG) 2.0</cite></a>, W3C Recommendation, 11 December 2008. (See
+        <a href=
+        "http://www.w3.org/TR/2008/REC-WCAG20-20081211/">http://www.w3.org/TR/2008/REC-WCAG20-20081211/</a>.)</dd>
+
+        <dt class="label"><a id="xml10" name="xml10"></a>XML 1.0</dt>
+
+        <dd>Tim Bray, et al. <a href=
+        "http://www.w3.org/TR/2008/REC-xml-20081126/"><cite>Extensible Markup Language
+        (XML) 1.0 (Fifth Edition)</cite></a>, W3C Recommendation, 26 November 2008. (See
+        <a href=
+        "http://www.w3.org/TR/2008/REC-xml-20081126/">http://www.w3.org/TR/2008/REC-xml-20081126/</a>.)</dd>
+
+        <dt class="label"><a id="xml11" name="xml11"></a>XML 1.1</dt>
+
+        <dd>Tim Bray, et al. <a href=
+        "http://www.w3.org/TR/2006/REC-xml11-20060816/"><cite>Extensible Markup Language
+        (XML) 1.1 (Second Edition)</cite></a>, W3C Recommendation, 16 August 2006, edited
+        in place 29 September 2006. (See <a href=
+        "http://www.w3.org/TR/2006/REC-xml11-20060816/">http://www.w3.org/TR/2006/REC-xml11-20060816/</a>.)</dd>
+
+        <dt class="label"><a id="xmlbase" name="xmlbase"></a>XML Base</dt>
+
+        <dd>Jonathan Marsh and Richard Tobin, Eds., <a href=
+        "http://www.w3.org/TR/2009/REC-xmlbase-20090128/"><cite>XML Base (Second
+        Edition)</cite></a>, W3C Recommendation, 28 January 2009. (See <a href=
+        "http://www.w3.org/TR/2009/REC-xmlbase-20090128/">http://www.w3.org/TR/2009/REC-xmlbase-20090128/</a>.)</dd>
+
+        <dt class="label"><a id="xmlid" name="xmlid"></a>XML ID</dt>
+
+        <dd>Jonathan Marsh, Daniel Veillard, Norman Walsh, Eds., <a href=
+        "http://www.w3.org/TR/2005/REC-xml-id-20050909/"><cite>xml:id Version
+        1.0</cite></a>, W3C Recommendation, 09 September 2005. (See <a href=
+        "http://www.w3.org/TR/2005/REC-xml-id-20050909/">http://www.w3.org/TR/2005/REC-xml-id-20050909/</a>.)</dd>
+
+        <dt class="label"><a id="infoset" name="infoset"></a>XML InfoSet</dt>
+
+        <dd>John Cowan and Richard Tobin, Eds., <a href=
+        "http://www.w3.org/TR/2004/REC-xml-infoset-20040204/"><cite>XML Information Set
+        (Second Edition)</cite></a>, W3C Recommendation, 04 February 2004. (See <a href=
+        "http://www.w3.org/TR/2004/REC-xml-infoset-20040204/">http://www.w3.org/TR/2004/REC-xml-infoset-20040204/</a>.)</dd>
+
+        <dt class="label"><a id="xml-media" name="xml-media"></a>XML Media Types</dt>
+
+        <dd>Makato Murata, Simon St. Laurent, Kan Khon, Eds., <a href=
+        "http://www.rfc-editor.org/rfc/rfc3023.txt"><cite>XML Media Types</cite></a>, RFC
+        3023, January 2001, IETF.(See <a href=
+        "http://www.rfc-editor.org/rfc/rfc3023.txt">http://www.rfc-editor.org/rfc/rfc3023.txt</a>.)</dd>
+
+        <dt class="label"><a id="xmlns10" name="xmlns10"></a>XML Namespaces 1.0</dt>
+
+        <dd>Tim Bray, et al. <a href=
+        "http://www.w3.org/TR/2009/REC-xml-names-20091208/"><cite>Namespaces in XML 1.0
+        (Third Edition)</cite></a>, W3C Recommendation, 8 December 2009. (See <a href=
+        "http://www.w3.org/TR/2009/REC-xml-names-20091208/">http://www.w3.org/TR/2009/REC-xml-names-20091208/</a>.)</dd>
+
+        <dt class="label"><a id="xsd-1" name="xsd-1"></a>XML Schema Part 1</dt>
+
+        <dd>Henry S. Thompson, David Beech, Murray Maloney, Noah Mendelsohn, Eds.,
+        <a href="http://www.w3.org/TR/xmlschema-1/"><cite>XML Schema Part 1:
+        Structures</cite></a>, W3C Recommendation, 28 October 2004. (See <a href=
+        "http://www.w3.org/TR/xmlschema-1/">http://www.w3.org/TR/xmlschema-1/</a>.)</dd>
+
+        <dt class="label"><a id="xsd-2" name="xsd-2"></a>XML Schema Part 2</dt>
+
+        <dd>Paul Biron and Ashok Malhotra, <a href=
+        "http://www.w3.org/TR/xmlschema-2/"><cite>XML Schema Part 2:
+        Datatypes</cite></a>, W3C Recommendation, 28 October 2004. (See <a href=
+        "http://www.w3.org/TR/xmlschema-2/">http://www.w3.org/TR/xmlschema-2/</a>.)</dd>
+
+        <dt class="label"><a id="xsl11" name="xsl11"></a>XSL 1.1</dt>
+
+        <dd>Anders Berglund, <a href=
+        "http://www.w3.org/TR/2006/REC-xsl11-20061205/"><cite>Extensible Stylesheet
+        Language (XSL) Version 1.1</cite></a>, W3C Recommendation, 05 December 2006. (See
+        <a href=
+        "http://www.w3.org/TR/2006/REC-xsl11-20061205/">http://www.w3.org/TR/2006/REC-xsl11-20061205/</a>.)</dd>
+      </dl>
+    </div>
+
+    <div class="div1">
+      <h2><a id="other-references" name="other-references"></a>H Other References
+      (Non-Normative)</h2>
+
+      <dl>
+        <dt class="label"><a id="ccreq" name="ccreq"></a>CC-DECODER-REQ</dt>
+
+        <dd><a href=
+        "http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml">
+        <cite>Closed Caption Decoder Requirements for Analog Television</cite></a>,
+        United States Code of Federal Regulations, Title 47, Volume 1, Part 15, § 15.119.
+        (See <a href=
+        "http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml">
+        http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml</a>.)</dd>
+
+        <dt class="label"><a id="cea608c" name="cea608c"></a>CEA-608-C</dt>
+
+        <dd>EIA/CEA-608-C, <a href="http://www.ce.org/"><cite>Line 21 Data
+        Services</cite></a>, EIA/CEA Standard, Consumer Electronics Association
+        (CEA).</dd>
+
+        <dt class="label"><a id="cea708d" name="cea708d"></a>CEA-708-D</dt>
+
+        <dd>CEA-708-D, <a href="http://www.ce.org/"><cite>Digital Television (DTV) Closed
+        Captioning</cite></a>, CEA Standard, Consumer Electronics Association (CEA).</dd>
+
+        <dt class="label"><a id="dcmes" name="dcmes"></a>DCMES 1.1</dt>
+
+        <dd>Dublin Core Metadata Initiative, <a href=
+        "http://dublincore.org/documents/dces/"><cite>Dublin Core Metadata Element Set,
+        Version 1.1: Reference Description</cite></a>. (See <a href=
+        "http://dublincore.org/documents/dces/">http://dublincore.org/documents/dces/</a>.)</dd>
+
+        <dt class="label"><a id="mpeg7-5" name="mpeg7-5"></a>MPEG7-5</dt>
+
+        <dd>ISO/IEC 15938-5, <a href="http://www.iso.org/"><cite>Information technology –
+        Multimedia content description interface – Part 5: Multimedia description
+        schemes</cite></a>, International Organization for Standardization (ISO).</dd>
+
+        <dt class="label"><a id="nsstate" name="nsstate"></a>NSState</dt>
+
+        <dd>Norman Walsh, Ed., <a href=
+        "http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09.html"><cite>The
+        Disposition of Names in an XML Namespace</cite></a>, TAG Finding, 9 January 2006.
+        (See <a href=
+        "http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09.html">http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09</a>.)</dd>
+
+        <dt class="label"><a id="qaf-sg" name="qaf-sg"></a>QAF SG</dt>
+
+        <dd>Karl Dubost, et al., <a href=
+        "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/"><cite>QA Framework:
+        Specifications Guidelines</cite></a>, W3C Recommendation, 17 August 2005. (See
+        <a href=
+        "http://www.w3.org/TR/qaframe-spec/">http://www.w3.org/TR/qaframe-spec/</a>.)</dd>
+
+        <dt class="label"><a id="smpte170m" name="smpte170m"></a>SMPTE 170M</dt>
+
+        <dd>ANSI/SMPTE 170M, <a href="http://www.smpte.org/"><cite>Television – Composite
+        Analog Video Signal – NTSC for Studio Applications</cite></a>, SMPTE
+        Standard.</dd>
+
+        <dt class="label"><a id="smpte2052" name="smpte2052"></a>SMPTE 2052-11</dt>
+
+        <dd>SMPTE 2052-11, <a href="http://www.smpte.org/"><cite>Conversion from CEA-708
+        Caption Data to SMPTE-TT</cite></a>, SMPTE Recommended Practice.</dd>
+
+        <dt class="label"><a id="svg11" name="svg11"></a>SVG 1.1</dt>
+
+        <dd>Jon Ferraiolo, Jun Fujisawa, Dean Jackson, Eds., <a href=
+        "http://www.w3.org/TR/2003/REC-SVG11-20030114/"><cite>Scalable Vector Graphics
+        (SVG) 1.1 Specification</cite></a>, W3C Recommendation, 14 January 2003. (See
+        <a href=
+        "http://www.w3.org/TR/2003/REC-SVG11-20030114/">http://www.w3.org/TR/2003/REC-SVG11-20030114/</a>.)</dd>
+
+        <dt class="label"><a id="ttaf1-req" name="ttaf1-req"></a>TTAF1-REQ</dt>
+
+        <dd>Glenn Adams, Ed., <a href=
+        "http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/"><cite>Timed Text (TT)
+        Authoring Format 1.0 Use Cases and Requirements</cite></a>, W3C Working Group
+        Note, 27 April 2006. (See <a href=
+        "http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/">http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/</a>.)</dd>
+
+        <dt class="label"><a id="xhtml10" name="xhtml10"></a>XHTML 1.0</dt>
+
+        <dd>Steven Pemberton, et al., <a href=
+        "http://www.w3.org/TR/2002/REC-xhtml1-20020801/"><cite>XHTML™ 1.0, The Extensible
+        Hypertext Markup Language (Second Edition)</cite></a>, W3C Recommendation, 01
+        August 2002. (See <a href=
+        "http://www.w3.org/TR/2002/REC-xhtml1-20020801/">http://www.w3.org/TR/2002/REC-xhtml1-20020801/</a>.)</dd>
+      </dl>
+    </div>
+
+    <div class="div1">
+      <h2><a id="requirements" name="requirements"></a>I Requirements
+      (Non-Normative)</h2>
+
+      <p>The Timed Text Markup Language (TTML), also known as the Distribution Format
+      Exchange Profile (DFXP) of the Timed Text Authoring Format (TTAF), satisfies a
+      subset of the requirements established by <a href="#ttaf1-req">[TTAF1-REQ]</a>. The
+      following table enumerates these requirements and indicates the extent to which
+      they are satisfied by this specification, where <em>S</em> denotes a requirement is
+      satisfied, <em>P</em> denotes a requirement is partially satisfied, and <em>N</em>
+      denotes a requirement is not satisfied.</p><a id="requirements-table" name=
+      "requirements-table"></a>
+
+      <table class="common">
+        <caption>
+          Table I-1 – Requirement Satisfaction
+        </caption>
+        <col width="10%" span="1">
+        <col width="40%" span="1">
+        <col width="10%" span="1">
+        <col span="1">
+
+        <tbody>
+          <tr>
+            <th>ID</th>
+
+            <th>Name</th>
+
+            <th>Status</th>
+
+            <th>Comments</th>
+          </tr>
+
+          <tr>
+            <td>R100</td>
+
+            <td>Specification Format</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R101</td>
+
+            <td>Specification Modularity</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R102</td>
+
+            <td>Specification Organization</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R103</td>
+
+            <td>Core and Periphery</td>
+
+            <td>S</td>
+
+            <td>TT extension namespaces</td>
+          </tr>
+
+          <tr>
+            <td>R104</td>
+
+            <td>Evolution of Core</td>
+
+            <td>S</td>
+
+            <td>TT extension namespaces</td>
+          </tr>
+
+          <tr>
+            <td>R105</td>
+
+            <td>Ownership of Core</td>
+
+            <td>S</td>
+
+            <td>TT namespaces</td>
+          </tr>
+
+          <tr>
+            <td>R106</td>
+
+            <td>Surjection of Core</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R107</td>
+
+            <td>Evolution of Periphery</td>
+
+            <td>S</td>
+
+            <td>TT extension namespaces</td>
+          </tr>
+
+          <tr>
+            <td>R108</td>
+
+            <td>Ownership of Periphery</td>
+
+            <td>S</td>
+
+            <td>Non-TT namespaces</td>
+          </tr>
+
+          <tr>
+            <td>R109</td>
+
+            <td>Transformation</td>
+
+            <td>S</td>
+
+            <td>Supports 3GPP, QText, RealText, SAMI</td>
+          </tr>
+
+          <tr>
+            <td>R110</td>
+
+            <td>Streamable Transformation</td>
+
+            <td>S</td>
+
+            <td>Progressive decoding</td>
+          </tr>
+
+          <tr>
+            <td>R111</td>
+
+            <td>Accessibility – Content</td>
+
+            <td>S</td>
+
+            <td>Alternative document instances</td>
+          </tr>
+
+          <tr>
+            <td>R112</td>
+
+            <td>Accessibility – Authoring System</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R200</td>
+
+            <td>Authorability</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R201</td>
+
+            <td>Multiple Natural Languages</td>
+
+            <td>S</td>
+
+            <td>Alternative document instances</td>
+          </tr>
+
+          <tr>
+            <td>R202</td>
+
+            <td>Natural Language Coverage</td>
+
+            <td>S</td>
+
+            <td>Unicode 4.0</td>
+          </tr>
+
+          <tr>
+            <td>R203</td>
+
+            <td>Natural Language Association Granularity</td>
+
+            <td>S</td>
+
+            <td>See <code>xml:lang</code></td>
+          </tr>
+
+          <tr>
+            <td>R204</td>
+
+            <td>Minimum Character Representability</td>
+
+            <td>S</td>
+
+            <td>Unicode 4.0</td>
+          </tr>
+
+          <tr>
+            <td>R205</td>
+
+            <td>Intrinsic and Extrinsic Text Content</td>
+
+            <td>P</td>
+
+            <td>Intrinsic only</td>
+          </tr>
+
+          <tr>
+            <td>R206</td>
+
+            <td>Markup Association</td>
+
+            <td>P</td>
+
+            <td>Intrinsic only</td>
+          </tr>
+
+          <tr>
+            <td>R207</td>
+
+            <td>Conditional Content</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R208</td>
+
+            <td>Flowed Text</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R209</td>
+
+            <td>Logical Flowed Text Vocabulary</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R210</td>
+
+            <td>Presentational Flowed Text Vocabulary</td>
+
+            <td>S</td>
+
+            <td>Implied mapping from logical flowed text.</td>
+          </tr>
+
+          <tr>
+            <td>R211</td>
+
+            <td>Flowed Text Vocabulary Relationship</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R212</td>
+
+            <td>Flowed Text Vocabulary Separation</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R213</td>
+
+            <td>Non-Flowed Text</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R214</td>
+
+            <td>Non-Flowed Text Vocabulary</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R215</td>
+
+            <td>Hybrid Flowed and Non-Flowed Text</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R216</td>
+
+            <td>Hyperlinking</td>
+
+            <td>N</td>
+
+            <td>Can support via XLink</td>
+          </tr>
+
+          <tr>
+            <td>R217</td>
+
+            <td>Embedded Graphics</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R218</td>
+
+            <td>Non-Embedded Graphics</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R219</td>
+
+            <td>Embedded Fonts</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R220</td>
+
+            <td>Non-Embedded Fonts</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R221</td>
+
+            <td>Descriptive Vocabulary</td>
+
+            <td>S</td>
+
+            <td>See <code>ttm:agent</code>, <code>ttm:role</code></td>
+          </tr>
+
+          <tr>
+            <td>R222</td>
+
+            <td>Embedded Audio</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R223</td>
+
+            <td>Non-Embedded Audio</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R290</td>
+
+            <td>Markup Format</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R291</td>
+
+            <td>Markup Format and Unicode Interaction</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R292</td>
+
+            <td>Extrinsic Resource References</td>
+
+            <td>N</td>
+
+            <td>No extrinsic references</td>
+          </tr>
+
+          <tr>
+            <td>R293</td>
+
+            <td>Schema Validity Specification</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R300</td>
+
+            <td>Inline Styling</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R301</td>
+
+            <td>Inline Styling Form</td>
+
+            <td>P</td>
+
+            <td>Inline and referential styling</td>
+          </tr>
+
+          <tr>
+            <td>R301</td>
+
+            <td>Out-of-Line Styling</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R301</td>
+
+            <td>Out-of-Line Styling Form</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R304</td>
+
+            <td>Styling Prioritization</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R305</td>
+
+            <td>Style Parameters – Aural</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R306</td>
+
+            <td>Style Parameters – Visual</td>
+
+            <td>P</td>
+
+            <td>Supports absolute position, background color, color, display none,
+            display alignment, font family, font size, font style, font weight, height,
+            line height, origin, opacity, overflow, padding (before, after, start, end),
+            text alignment, text shadow (as outline), visibility, width, writing mode,
+            z-index</td>
+          </tr>
+
+          <tr>
+            <td>R390</td>
+
+            <td>Style Parameter Symmetry</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R391</td>
+
+            <td>Style Parameter Definitions</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R392</td>
+
+            <td>Style Parameter Shorthands</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R401</td>
+
+            <td>Inline Timing</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R402</td>
+
+            <td>Out-of-Line Timing</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R403</td>
+
+            <td>Synchronization Parameters</td>
+
+            <td>P</td>
+
+            <td>Supports begin, end, dur</td>
+          </tr>
+
+          <tr>
+            <td>R404</td>
+
+            <td>Synchronization Parameter Value Spaces</td>
+
+            <td>P</td>
+
+            <td>Supports offset values, media marker values (SMPTE 12M), wall-clock
+            values</td>
+          </tr>
+
+          <tr>
+            <td>R405</td>
+
+            <td>Time Containment Semantics</td>
+
+            <td>P</td>
+
+            <td>Supports sequential, parallel</td>
+          </tr>
+
+          <tr>
+            <td>R500</td>
+
+            <td>Animation Modes</td>
+
+            <td>P</td>
+
+            <td>Supports discrete</td>
+          </tr>
+
+          <tr>
+            <td>R502</td>
+
+            <td>Highlight Animation</td>
+
+            <td>S</td>
+
+            <td><code>&lt;set tts:backgroundColor="..."/&gt;</code></td>
+          </tr>
+
+          <tr>
+            <td>R503</td>
+
+            <td>Fade Transition Animation</td>
+
+            <td>S</td>
+
+            <td><code>&lt;set tts:opacity="..."/&gt;</code></td>
+          </tr>
+
+          <tr>
+            <td>R504</td>
+
+            <td>Animated Style Parameters – Aural</td>
+
+            <td>N</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R505</td>
+
+            <td>Animated Style Parameters – Visual</td>
+
+            <td>P</td>
+
+            <td>Supports animating background color, color, display, opacity, origin,
+            visibility</td>
+          </tr>
+
+          <tr>
+            <td>N506</td>
+
+            <td>Animated Content</td>
+
+            <td>S</td>
+
+            <td></td>
+          </tr>
+
+          <tr>
+            <td>R600</td>
+
+            <td>Metadata Item Association</td>
+
+            <td>S</td>
+
+            <td>See <code>metadata</code>, <code>Metadata.class</code></td>
+          </tr>
+
+          <tr>
+            <td>R601</td>
+
+            <td>Metadata Item Constituents</td>
+
+            <td>P</td>
+
+            <td>Supports name, value</td>
+          </tr>
+
+          <tr>
+            <td>R602</td>
+
+            <td>Metadata Item Value Representation</td>
+
+            <td>P</td>
+
+            <td>See <code>metadata</code></td>
+          </tr>
+
+          <tr>
+            <td>R603</td>
+
+            <td>Metadata Item Extensibility</td>
+
+            <td>S</td>
+
+            <td>See <code>metadata</code></td>
+          </tr>
+
+          <tr>
+            <td>R604</td>
+
+            <td>Metadata Item Validation</td>
+
+            <td>S</td>
+
+            <td>See <code>metadata</code></td>
+          </tr>
+
+          <tr>
+            <td>R690</td>
+
+            <td>Dublin Core Preference</td>
+
+            <td>N</td>
+
+            <td>Uses <code>ttm:copyright</code>, <code>ttm:desc</code>,
+            <code>ttm:title</code></td>
+          </tr>
+        </tbody>
+      </table>
+    </div>
+
+    <div class="div1">
+      <h2><a id="derivation" name="derivation"></a>J Vocabulary Derivation
+      (Non-Normative)</h2>
+
+      <p>This appendix provides information about the derivation of TTML vocabulary,
+      separately describing derivation of elements and attributes.</p>
+
+      <div class="div2">
+        <h3><a id="d3e18678" name="d3e18678"></a>J.1 Element Derivation</h3>
+
+        <p>The first column of <a href="#element-vocab-derivation-table"><b>Table J-1 –
+        Elements</b></a> specifies a TTML element vocabulary item; the second column
+        specifies the syntactic and/or semantic model on which the vocabulary item is
+        based; the third column specifies the reference that defines the model (if a
+        model is indicated); the fourth column specifies details about the derivation;
+        the last column refers to additional notes describing the nature of the
+        derivation.</p>
+
+        <p>In the fourth column, which describes details of derivation, a notation is use
+        to indicate the addition or removal of an attribute. For example, in the
+        derivation of the <code>tt:div</code> element, the details column includes
+        "-@class", which denotes that the <code>class</code> attribute that is specified
+        for use with the <code>xhtml:div</code> model element is not specified for use
+        with the corresponding TTML element; in contrast, the details column includes
+        "+@begin", which denotes that a <code>begin</code> attribute is added that is not
+        specified for use with the <code>xhtml:div</code> model element.</p><a id=
+        "element-vocab-derivation-table" name="element-vocab-derivation-table"></a>
+
+        <table class="common">
+          <caption>
+            Table J-1 – Elements
+          </caption>
+          <col width="20%" span="1">
+          <col width="17%" span="1">
+          <col width="13%" align="center" span="1">
+          <col width="40%" span="1">
+          <col width="10%" align="center" span="1">
+
+          <tbody>
+            <tr>
+              <td><span class="strong">Element</span></td>
+
+              <td><span class="strong">Model</span></td>
+
+              <td><span class="strong">Reference</span></td>
+
+              <td><span class="strong">Details</span></td>
+
+              <td><span class="strong">Notes</span></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#document-structure-vocabulary-body"><code>tt:body</code></a></td>
+
+              <td><code>xhtml:body</code></td>
+
+              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
+
+              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end,
+              +@region, +@timeContainer, +@ttm:*, +@tts:*; content model subsetted to
+              zero or more division (div) children, and supersetted by optional metadata
+              and animation children</td>
+
+              <td>1,2</td>
+            </tr>
+
+            <tr>
+              <td><a href="#content-vocabulary-br"><code>tt:br</code></a></td>
+
+              <td><code>xhtml:br</code></td>
+
+              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
+
+              <td>-@class, -@title; +@ttm:*, +@tts:*, +@xml:lang, +@xml:space; content
+              model supersetted by optional metadata and animation children for congruity
+              with other content vocabulary</td>
+
+              <td>1,2</td>
+            </tr>
+
+            <tr>
+              <td><a href="#content-vocabulary-div"><code>tt:div</code></a></td>
+
+              <td><code>xhtml:div</code></td>
+
+              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
+
+              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end,
+              +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model
+              subsetted to zero or more paragraph (p) children, and supersetted by
+              optional metadata and animation children</td>
+
+              <td>1,2,3</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#document-structure-vocabulary-head"><code>tt:head</code></a></td>
+
+              <td><code>xhtml:head</code></td>
+
+              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
+
+              <td>-@dir, -@lang, -@profile; +@id, +@xml:space; content model changed to
+              optional metadata children, followed by optional styling child, followed by
+              optional layout child</td>
+
+              <td>1,3</td>
+            </tr>
+
+            <tr>
+              <td><a href="#layout-vocabulary-layout"><code>tt:layout</code></a></td>
+
+              <td><code>fo:simple-page-master</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>4</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#metadata-vocabulary-metadata"><code>tt:metadata</code></a></td>
+
+              <td><code>svg:metadata</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>-@xml:base; +@ttm:*, +@xml:lang, +@xml:space; content model subsetted
+              to foreign namespace element content only (no #PCDATA)</td>
+
+              <td>3,5</td>
+            </tr>
+
+            <tr>
+              <td><a href="#content-vocabulary-p"><code>tt:p</code></a></td>
+
+              <td><code>xhtml:p</code></td>
+
+              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
+
+              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end,
+              +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model
+              subsetted to zero or more span children, and supersetted by optional
+              metadata and animation children</td>
+
+              <td>1,2,3</td>
+            </tr>
+
+            <tr>
+              <td><a href="#layout-vocabulary-region"><code>tt:region</code></a></td>
+
+              <td><code>fo:region-*</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>4</td>
+            </tr>
+
+            <tr>
+              <td><a href="#animation-vocabulary-set"><code>tt:set</code></a></td>
+
+              <td><code>svg:set</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>-@* except begin, dur, end; +@tts:*, +@xml:lang, +@xml:space</td>
+
+              <td>3,6</td>
+            </tr>
+
+            <tr>
+              <td><a href="#content-vocabulary-span"><code>tt:span</code></a></td>
+
+              <td><code>xhtml:span</code></td>
+
+              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
+
+              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end,
+              +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model
+              subsetted to zero or more #PCDATA or break (br) children, and supersetted
+              by optional metadata and animation children</td>
+
+              <td>1,2,3</td>
+            </tr>
+
+            <tr>
+              <td><a href="#styling-vocabulary-style"><code>tt:style</code></a></td>
+
+              <td><em>style specification</em></td>
+
+              <td><a href="#css2">[CSS2]</a></td>
+
+              <td>XML representation of identified set of pairs of style property name
+              and value, with optional inclusion of other styles by reference to other
+              style elements</td>
+
+              <td>7</td>
+            </tr>
+
+            <tr>
+              <td><a href="#styling-vocabulary-styling"><code>tt:styling</code></a></td>
+
+              <td><code>xhtml:style</code></td>
+
+              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
+
+              <td>XML representation of a set of style specifications sets, each
+              represented by a style child element</td>
+
+              <td>1,7</td>
+            </tr>
+
+            <tr>
+              <td><a href="#document-structure-vocabulary-tt"><code>tt:tt</code></a></td>
+
+              <td><code>xhtml:html</code></td>
+
+              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
+
+              <td>-@dir, -@lang; +@id, +@ttp:*, +@xml:space; content model subsetted by
+              permitting body and/or head to be optional</td>
+
+              <td>1,8</td>
+            </tr>
+
+            <tr>
+              <td><a href="#metadata-vocabulary-actor"><code>ttm:actor</code></a></td>
+
+              <td><code>mpeg7:Creator</code></td>
+
+              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>4</td>
+            </tr>
+
+            <tr>
+              <td><a href="#metadata-vocabulary-agent"><code>ttm:agent</code></a></td>
+
+              <td><code>mpeg7:Agent</code></td>
+
+              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>4</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#metadata-vocabulary-copyright"><code>ttm:copyright</code></a></td>
+
+              <td><code>mpeg7:CopyrightString</code></td>
+
+              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>4</td>
+            </tr>
+
+            <tr>
+              <td><a href="#metadata-vocabulary-desc"><code>ttm:desc</code></a></td>
+
+              <td><code>svg:desc</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>-@class, -@style, -@xml:base</td>
+
+              <td>2,5,9</td>
+            </tr>
+
+            <tr>
+              <td><a href="#metadata-vocabulary-name"><code>ttm:name</code></a></td>
+
+              <td><code>mpeg7:Name</code></td>
+
+              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>4</td>
+            </tr>
+
+            <tr>
+              <td><a href="#metadata-vocabulary-title"><code>ttm:title</code></a></td>
+
+              <td><code>svg:title</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>-@class, -@style, -@xml:base</td>
+
+              <td>2,5,9</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-vocabulary-extension"><code>ttp:extension</code></a></td>
+
+              <td><code>@requiredExtensions</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>10</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-vocabulary-extensions"><code>ttp:extensions</code></a></td>
+
+              <td><code>@requiredExtensions</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>10</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-vocabulary-feature"><code>ttp:feature</code></a></td>
+
+              <td><code>@requiredFeatures</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>10</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-vocabulary-features"><code>ttp:features</code></a></td>
+
+              <td><code>@requiredFeatures</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>10</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-vocabulary-profile"><code>ttp:profile</code></a></td>
+
+              <td><code>@baseProfile</code></td>
+
+              <td><a href="#svg11">[SVG 1.1]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td>11</td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <ol class="enumar">
+            <li>
+              <p>Derivation is indicated with respect to the strict DTD defined by
+              <a href="#xhtml10">[XHTML 1.0]</a>, §A.1.</p>
+            </li>
+
+            <li>
+              <p>The <code>class</code> attribute is effectively replaced by the
+              <code>style</code> attribute, which, instead of specifying an inline style,
+              refers indirectly to one or more <a href=
+              "#styling-vocabulary-style"><code>style</code></a> elements that define a
+              set of style specification sets.</p>
+            </li>
+
+            <li>
+              <p>The <code>xml:lang</code> and <code>xml:space</code> attributes are
+              defined for all element types in order to support their inheritance
+              semantics to operate in the context of foreign namespace elements.</p>
+            </li>
+
+            <li>
+              <p>Derivation is conceptual (notional) only.</p>
+            </li>
+
+            <li>
+              <p>The <code>xml:base</code> attribute is not used since there are no
+              external references from core vocabulary.</p>
+            </li>
+
+            <li>
+              <p>The <code>attributeName</code> and <code>to</code> attributes of
+              <code>svg:set</code> are replaced by the direct expression of the target
+              attribute name and value by use of a <code>tts:*</code> attribute.</p>
+            </li>
+
+            <li>
+              <p>CSS style specification syntax is mapped to XML by use of attributes
+              defined in the TT Style Namespace.</p>
+            </li>
+
+            <li>
+              <p>The <code>xml:id</code> attribute is defined for use on all element
+              types.</p>
+            </li>
+
+            <li>
+              <p>The <code>style</code> attribute is supported only on content
+              elements.</p>
+            </li>
+
+            <li>
+              <p>Derived from the use of <code>@requiredExtensions</code> and
+              <code>@requiredFeatures</code> on the <code>svg:svg</code> element, but
+              extended to support distinct specification of optionality.</p>
+            </li>
+
+            <li>
+              <p>Derived from the use of <code>@baseProfile</code> and
+              <code>@version</code> on the <code>svg:svg</code> element.</p>
+            </li>
+          </ol>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="d3e19157" name="d3e19157"></a>J.2 Attribute Derivation</h3>
+
+        <p>The first column of <a href="#attribute-vocab-derivation-table"><b>Table J-2 –
+        Attributes</b></a> specifies a TTML attribute vocabulary item; the second column
+        specifies the syntactic and/or semantic model on which the vocabulary item is
+        based; the third column specifies the reference that defines the model (if a
+        model is indicated); the fourth column specifies details about the derivation;
+        the last column refers to additional notes describing the nature of the
+        derivation.</p>
+
+        <p>In the fourth column, which describes details of derivation, a notation is use
+        to indicate the addition or removal of an attribute value. For example, in the
+        derivation of the <code>timeContainer</code> attribute, the details column
+        includes "-excl", which denotes that the <code>excl</code> value that is
+        specified for use with the <code>timeContainer</code> model attribute is not
+        specified for use with the corresponding TTML attribute; similarly, an
+        "+<em>value</em>" in the details column indicates that the attribute's values
+        have been extended to include <em>value</em>.</p>
+
+        <p>Only those attributes that are specified for use on more than one TTML element
+        type are listed below. Those per-element namespace attributes that are uniquely
+        defined for a specific TTML element type are not listed below, but are considered
+        to be part of the specific element type's derivation described in <a href=
+        "#element-vocab-derivation-table"><b>Table J-1 – Elements</b></a>
+        above.</p><a id="attribute-vocab-derivation-table" name=
+        "attribute-vocab-derivation-table"></a>
+
+        <table class="common">
+          <caption>
+            Table J-2 – Attributes
+          </caption>
+          <col width="20%" span="1">
+          <col width="17%" span="1">
+          <col width="13%" align="center" span="1">
+          <col width="40%" span="1">
+          <col width="10%" align="center" span="1">
+
+          <tbody>
+            <tr>
+              <td><span class="strong">Attribute</span></td>
+
+              <td><span class="strong">Model</span></td>
+
+              <td><span class="strong">Reference</span></td>
+
+              <td><span class="strong">Details</span></td>
+
+              <td><span class="strong">Notes</span></td>
+            </tr>
+
+            <tr>
+              <td><a href="#timing-attribute-begin"><code>begin</code></a></td>
+
+              <td><code>begin</code></td>
+
+              <td><a href="#smil21">[SMIL 2.1]</a></td>
+
+              <td>see notes</td>
+
+              <td>2,3,4</td>
+            </tr>
+
+            <tr>
+              <td><a href="#timing-attribute-dur"><code>dur</code></a></td>
+
+              <td><code>dur</code></td>
+
+              <td><a href="#smil21">[SMIL 2.1]</a></td>
+
+              <td>see notes</td>
+
+              <td>2,3,4</td>
+            </tr>
+
+            <tr>
+              <td><a href="#timing-attribute-end"><code>end</code></a></td>
+
+              <td><code>end</code></td>
+
+              <td><a href="#smil21">[SMIL 2.1]</a></td>
+
+              <td>see notes</td>
+
+              <td>2,3,4</td>
+            </tr>
+
+            <tr>
+              <td><a href="#layout-attribute-region"><code>region</code></a></td>
+
+              <td><code>master-reference</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td>conceptual derivation</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-style"><code>style</code></a></td>
+
+              <td><code>class</code></td>
+
+              <td><a href="#css2">[CSS2]</a></td>
+
+              <td>dereferences style specification(s) directly</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#timing-attribute-timeContainer"><code>timeContainer</code></a></td>
+
+              <td><code>timeContainer</code></td>
+
+              <td><a href="#smil21">[SMIL 2.1]</a></td>
+
+              <td>-excl, -none; no default attribute value</td>
+
+              <td>5</td>
+            </tr>
+
+            <tr>
+              <td><a href="#metadata-attribute-agent"><code>ttm:agent</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>used to attribute agent of content</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#metadata-attribute-role"><code>ttm:role</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>used to attribute role of content</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>expresses uniform grid resolution for cell based coordinates</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>determines how to interpret time expressions</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>expresses integral frame rate</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>used to express non-integral, rational frame rates</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>expresses marker continuity semantics</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>expresses pixel aspect ratio of related media</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-profile"><code>ttp:profile</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>expresses profile of TTML used by a <em>Document Instance</em></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>expresses frame counting (drop) modes</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>expresses sub-frame rate</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-tickRate"><code>ttp:tickRate</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>used to interpret tick based time expressions</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a></td>
+
+              <td><em>none</em></td>
+
+              <td></td>
+
+              <td>used to interpret semantics of time expressions</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a></td>
+
+              <td><code>background-color</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>1,6</td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-color"><code>tts:color</code></a></td>
+
+              <td><code>color</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>6</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-direction"><code>tts:direction</code></a></td>
+
+              <td><code>direction</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-display"><code>tts:display</code></a></td>
+
+              <td><code>display</code></td>
+
+              <td><a href="#css2">[CSS2]</a></td>
+
+              <td>only <code>auto</code>, <code>none</code></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-displayAlign"><code>tts:displayAlign</code></a></td>
+
+              <td><code>display-align</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-extent"><code>tts:extent</code></a></td>
+
+              <td><code>width</code>, <code>height</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td>shorthand property</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-fontFamily"><code>tts:fontFamily</code></a></td>
+
+              <td><code>font-family</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code>, extends generic family names</td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-fontSize"><code>tts:fontSize</code></a></td>
+
+              <td><code>font-size</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>1,7</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-fontStyle"><code>tts:fontStyle</code></a></td>
+
+              <td><code>font-style</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code>, <code>-backslant</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-fontWeight"><code>tts:fontWeight</code></a></td>
+
+              <td><code>font-weight</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code>, <code>-bolder</code>, <code>-lighter</code>,
+              <code>-&lt;number&gt;</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-lineHeight"><code>tts:lineHeight</code></a></td>
+
+              <td><code>line-height</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code>, <code>-&lt;number&gt;</code>,
+              <code>-&lt;space&gt;</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-opacity"><code>tts:opacity</code></a></td>
+
+              <td><code>opacity</code></td>
+
+              <td><a href="#css3-color">[CSS3 Color]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-origin"><code>tts:origin</code></a></td>
+
+              <td><code>top</code>, <code>left</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td>shorthand property</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-overflow"><code>tts:overflow</code></a></td>
+
+              <td><code>overflow</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code>, <code>-auto</code>,
+              <code>-error-if-overflow</code></td>
+
+              <td>8</td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-padding"><code>tts:padding</code></a></td>
+
+              <td><code>padding</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>9</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-showBackground"><code>tts:showBackground</code></a></td>
+
+              <td><code>showBackground</code></td>
+
+              <td><a href="#smil21">[SMIL 2.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-textAlign"><code>tts:textAlign</code></a></td>
+
+              <td><code>text-align</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-textDecoration"><code>tts:textDecoration</code></a></td>
+
+              <td><code>text-decoration</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>1,10,13</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-textOutline"><code>tts:textOutline</code></a></td>
+
+              <td><code>text-shadow</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>11,13</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a></td>
+
+              <td><code>unicode-bidi</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-visibility"><code>tts:visibility</code></a></td>
+
+              <td><code>visibility</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code>, <code>-collapse</code></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-wrapOption"><code>tts:wrapOption</code></a></td>
+
+              <td><code>wrap-option</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "#style-attribute-writingMode"><code>tts:writingMode</code></a></td>
+
+              <td><code>writing-mode</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code>, <code>+tblr</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href="#style-attribute-zIndex"><code>tts:zIndex</code></a></td>
+
+              <td><code>z-index</code></td>
+
+              <td><a href="#xsl11">[XSL 1.1]</a></td>
+
+              <td><code>-inherit</code></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href="#content-attribute-id"><code>xml:id</code></a></td>
+
+              <td><code>xml:id</code></td>
+
+              <td><a href="#xmlid">[XML ID]</a></td>
+
+              <td>complies with model</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#content-attribute-lang"><code>xml:lang</code></a></td>
+
+              <td><code>xml:lang</code></td>
+
+              <td><a href="#xml10">[XML 1.0]</a></td>
+
+              <td>complies with model</td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href="#content-attribute-space"><code>xml:space</code></a></td>
+
+              <td><code>xml:space</code></td>
+
+              <td><a href="#xml10">[XML 1.0]</a></td>
+
+              <td>see notes</td>
+
+              <td>12</td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <ol class="enumar">
+            <li>
+              <p>Attribute name and/or value(s) are normalized to use
+              <em>lowerCamelCase</em> naming convention.</p>
+            </li>
+
+            <li>
+              <p>Restricted to expressing a clock value that denotes one of the following
+              in accordance to whether the parameter expressed by the
+              <code>ttp:timeBase</code> attribute is <code>media</code>,
+              <code>smpte</code>, or <code>clock</code>, respectively: (1) an offset from
+              an implicit syncbase that is linked to a media time line, (2) an event time
+              that represents the occurrence of an implicit media marker, or (3) a
+              wall-clock time.</p>
+            </li>
+
+            <li>
+              <p>Syntactically subsets and supersets the <a href="#smil21">[SMIL
+              2.1]</a>&nbsp;<code>Clock-value</code> syntax as follows: (1) requires
+              non-negative <code>Full-clock-value</code> or <code>Timecount-value</code>;
+              (2) if <code>Full-clock-value</code> then <em>hours</em> must be two or
+              more digits; (3) if <code>Timecount-value</code>, then <em>metric</em> must
+              be specified; (4) uses <code>m</code> as alias for <code>min</code> metric
+              to denote minutes; (5) adds <code>f</code> and <code>t</code> metrics
+              denoting frames and ticks, respectively; (6) adds alternative expression of
+              optional <code>Fraction</code> in <code>Full-clock-value</code> by
+              specifying frame count or frame count with subframe count.</p>
+            </li>
+
+            <li>
+              <p>Interpretation of time expression is further constrained by parameters
+              expressed by <code>ttp:clockMode</code>, <code>ttp:dropMode</code>,
+              <code>ttp:frameRate</code>, <code>ttp:frameRateMultiplier</code>,
+              <code>ttp:markerMode</code>, <code>ttp:subFrameRate</code>,
+              <code>ttp:tickRate</code>, and <code>ttp:timeBase</code> attributes.</p>
+            </li>
+
+            <li>
+              <p>Uses subset of named colors from model to which two aliases are added as
+              follows: <code>magenta</code> as <code>fuchsia</code>, and
+              <code>cyan</code> as <code>aqua</code>.</p>
+            </li>
+
+            <li>
+              <p>If not specified, then parallel (par) container semantics apply to the
+              element types specified by <a href=
+              "#timing-attribute-timeContainer"><b>10.2.4 timeContainer</b></a>.</p>
+            </li>
+
+            <li>
+              <p>Restricts size to length specification which can be a percentage; adds
+              optional second length (or percentage) for specifying separate horizontal
+              and vertical scaling of glyph's EM square.</p>
+            </li>
+
+            <li>
+              <p>Expressed in terms of writing mode relative padding properties rather
+              than absolute padding properties.</p>
+            </li>
+
+            <li>
+              <p>Excludes <code>blink</code> and <code>no-blink</code> values.</p>
+            </li>
+
+            <li>
+              <p>Uses only one length specification instead of two, where one length
+              defines distance of outline effect from nominal edge of glyph contour
+              outline perpendicular to point of glyph contour. Percentage lengths are
+              also added to express outline effect in relative to font size. Outline
+              effects are intended to be drawn both outside of outer closed contours and
+              inside of inner closed contours.</p>
+            </li>
+
+            <li>
+              <p>On root element, default attribute value specified as
+              <code>default</code>, which is defined in terms of whitespace
+              normalization. Semantics of preservation and default normalization are
+              defined in terms of presentation semantics by <a href=
+              "#content-attribute-space"><b>7.2.3 xml:space</b></a>.</p>
+            </li>
+
+            <li>
+              <p>Defined to be inheritable.</p>
+            </li>
+          </ol>
+        </div>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="qa" name="qa"></a>K QA Framework Compliance (Non-Normative)</h2>
+
+      <p>This appendix specifies the compliance of this specification with the
+      requirements and guidelines defined by <a href=
+      "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/">QA Framework Specifications
+      Guidelines</a>&nbsp;<a href="#qaf-sg">[QAF SG]</a>.</p>
+
+      <div class="div2">
+        <h3><a id="d3e20043" name="d3e20043"></a>K.1 Requirements</h3><a id=
+        "qa-framework-requirements-table" name="qa-framework-requirements-table"></a>
+
+        <table class="common">
+          <caption>
+            Table K-1 – QA Framework Requirements Checklist
+          </caption>
+          <col width="76%" span="1">
+          <col width="6%" align="center" span="1">
+          <col width="6%" align="center" span="1">
+          <col width="6%" align="center" span="1">
+          <col width="6%" align="center" span="1">
+
+          <tbody>
+            <tr>
+              <td><span class="strong">Requirement</span></td>
+
+              <td><span class="strong">YES</span></td>
+
+              <td><span class="strong">NO</span></td>
+
+              <td><span class="strong">N/A</span></td>
+
+              <td><span class="strong">Notes</span></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#include-conformance-clause-principle">
+              Requirement 01: Include a conformance clause</a></td>
+
+              <td><a href="#conformance">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-scope-principle">
+              Requirement 02: Define the scope.</a></td>
+
+              <td><a href="#intro">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#implement-principle">Requirement
+              03: Identify who or what will implement the specification.</a></td>
+
+              <td><a href="#conformance">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-norm-principle">Requirement
+              04: Make a list of normative references.</a></td>
+
+              <td><a href="#references">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-principle">
+              Requirement 05: Define the terms used in the normative parts of the
+              specification.</a></td>
+
+              <td><a href="#definitions">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conf-label-principle">
+              Requirement 06: Create conformance labels for each part of the conformance
+              model.</a></td>
+
+              <td><a href="#conformance">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#consistent-style-principle">
+              Requirement 07: Use a consistent style for conformance requirements and
+              explain how to distinguish them.</a></td>
+
+              <td><a href="#conventions">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#req-opt-conf-principle">
+              Requirement 08: Indicate which conformance requirements are mandatory,
+              which are recommended, and which are optional.</a></td>
+
+              <td><a href="#conventions">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-mandatory-principle">
+              Requirement 09: If the technology is subdivided, then indicate which
+              subdivisions are mandatory for conformance.</a></td>
+
+              <td><a href="#conformance">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdiv-constraints-principle">
+              Requirement 10: If the technology is subdivided, then address subdivision
+              constraints.</a></td>
+
+              <td><a href="#conformance">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#likehood-extension-principle">
+              Requirement 11: Address Extensibility.</a></td>
+
+              <td><a href="#doctypes">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#deprecated-feature-principle">
+              Requirement 12: Identify deprecated features.</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td>N/A</td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#degree-support-principle">
+              Requirement 13: Define how each class of product handles each deprecated
+              feature.</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td>N/A</td>
+
+              <td>1</td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <ol class="enumar">
+            <li>
+              <p>No feature is deprecated by this version of this specification.</p>
+            </li>
+          </ol>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="d3e20207" name="d3e20207"></a>K.2 Guidelines</h3><a id=
+        "qa-framework-guidelines-table" name="qa-framework-guidelines-table"></a>
+
+        <table class="common">
+          <caption>
+            Table K-2 – QA Framework Guidelines Checklist
+          </caption>
+          <col width="76%" span="1">
+          <col width="6%" align="center" span="1">
+          <col width="6%" align="center" span="1">
+          <col width="6%" align="center" span="1">
+          <col width="6%" align="center" span="1">
+
+          <tbody>
+            <tr>
+              <td><span class="strong">Guideline</span></td>
+
+              <td><span class="strong">YES</span></td>
+
+              <td><span class="strong">NO</span></td>
+
+              <td><span class="strong">N/A</span></td>
+
+              <td><span class="strong">Notes</span></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-model-gp">
+              Good Practice 01: Define the specification's conformance model in the
+              conformance clause.</a></td>
+
+              <td><a href="#conformance">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#norm-informative-gp">Good
+              Practice 02: Specify in the conformance clause how to distinguish normative
+              from informative content.</a></td>
+
+              <td><a href="#conventions">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-claim-gp">
+              Good Practice 03: Provide the wording for conformance claims.</a></td>
+
+              <td><a href="#claims">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-gp">Good Practice
+              04: Provide an Implementation Conformance Statement Pro Forma.</a></td>
+
+              <td></td>
+
+              <td>NO</td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-claim-gp">Good
+              Practice 05: Require an Implementation Conformance Statement as part of
+              valid conformance claims.</a></td>
+
+              <td><a href="#claims">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#use-example-gp">Good
+              Practice 06: Provide examples, use cases, and graphics.</a></td>
+
+              <td><a href="#example">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-sample-gp">Good
+              Practice 07: Write sample code or tests.</a></td>
+
+              <td>YES</td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-define-practice">Good
+              Practice 08: When imposing requirements by normative references, address
+              conformance dependencies.</a></td>
+
+              <td><a href="#references">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td>1</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-inline-gp">
+              Good Practice 09: Define unfamiliar terms in-line and consolidate the
+              definitions in a glossary section.</a></td>
+
+              <td><a href="#definitions">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#reuse-terms-gp">Good
+              Practice 10: Use terms already defined without changing their
+              definition.</a></td>
+
+              <td><a href="#definitions">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td>2</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#formal-language-gp">Good
+              Practice 11: Use formal languages when possible.</a></td>
+
+              <td><a href="#schemas">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-assertion-gp">Good
+              Practice 12: Write Test Assertions.</a></td>
+
+              <td></td>
+
+              <td>NO</td>
+
+              <td></td>
+
+              <td>3</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-foster-gp">Good
+              Practice 13: Create subdivisions of the technology when warranted.</a></td>
+
+              <td><a href="#conformance">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#rules-profiles-gp">Good
+              Practice 14: If the technology is profiled, define rules for creating new
+              profiles.</a></td>
+
+              <td><a href="#vocabulary-profiles">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#need-option-gp">Good
+              Practice 15:Use optional features as warranted.</a></td>
+
+              <td>YES</td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#label-options-gp">Good
+              Practice 16: Clearly identify optional features.</a></td>
+
+              <td>YES</td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#constraints-gp">Good
+              Practice 17: Indicate any limitations or constraints on optional
+              features.</a></td>
+
+              <td>YES</td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#extensions-prohibited-gp">
+              Good Practice 18: If extensibility is allowed, define an extension
+              mechanism.</a></td>
+
+              <td><a href="#extension-vocabulary-overview">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#breaking-conformance-gp">
+              Good Practice 19: Warn extension creators to create extensions that do not
+              interfere with conformance.</a></td>
+
+              <td><a href="#extension-vocabulary-overview">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-error-gp">Good
+              Practice 20: Define error-handling for unknown extensions.</a></td>
+
+              <td><a href="#conformance-processor">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td>4</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#workaround-gp">Good
+              Practice 21: Explain how to avoid using a deprecated feature.</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td>N/A</td>
+
+              <td>5</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#obsolete-gp">Good
+              Practice 22: Identify obsolete features.</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td>N/A</td>
+
+              <td>5</td>
+            </tr>
+
+            <tr>
+              <td><a href=
+              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#error-handling-gp">Good
+              Practice 23: Define an error handling mechanism.</a></td>
+
+              <td><a href="#reduced-infoset">YES</a></td>
+
+              <td></td>
+
+              <td></td>
+
+              <td></td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <ol class="enumar">
+            <li>
+              <p>When making normative references to external specifications, specific
+              clauses or sections are cited.</p>
+            </li>
+
+            <li>
+              <p>See also <a href="#derivation"><b>J Vocabulary Derivation</b></a>.</p>
+            </li>
+
+            <li>
+              <p>Test assertions and test suites will be provided prior to entering
+              Proposed Recommendation (PR) phase.</p>
+            </li>
+
+            <li>
+              <p>See criterion #3 in <a href="#conformance-processor"><b>3.2 Processor
+              Conformance</b></a> and definition of TTML <a href="#doctypes">Abstract
+              Document Instance</a>.</p>
+            </li>
+
+            <li>
+              <p>No feature is deprecated or obsoleted by this version of this
+              specification.</p>
+            </li>
+          </ol>
+        </div>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="streaming" name="streaming"></a>L Streaming TTML Content
+      (Non-Normative)</h2>
+
+      <p>TTML Content is designed to support streamability by implementing the following
+      properties:</p>
+
+      <ul>
+        <li>
+          <p>can be progressively encoded (i.e., does not require computing subsequent
+          data prior to sending current data);</p>
+        </li>
+
+        <li>
+          <p>can be progressively decoded (i.e., does not require forward references, but
+          uses only reverse references when necessary);</p>
+        </li>
+
+        <li>
+          <p>does not require dereferencing (and subsequent loading) of any resources
+          other than TTML Content (i.e., no embedded URIs);</p>
+        </li>
+
+        <li>
+          <p>does not support alternative content forms (e.g., different language,
+          graphics formats, time bases) in a single document;</p>
+        </li>
+
+        <li>
+          <p>has timing structure compiled into inline format that makes possible a
+          temporal ordering of content that follows temporal presentation order;</p>
+        </li>
+
+        <li>
+          <p>constrains content models to prevent arbitrary nested content
+          structures;</p>
+        </li>
+      </ul>
+
+      <p>One possible means by which TTML Content may be streamed is to partition a
+      <em>Document Instance</em>'s information set into non-overlapping fragments, where
+      one particular fragment, call it the <em>root fragment</em>, represents the front
+      matter (head) of the <em>Document Instance</em> as well as its top level structural
+      elements, and other fragments represent content whose time intervals are expected
+      to be active in parallel.</p>
+
+      <p>In applications that require arbitrary (random) entry into a stream, i.e., the
+      property of being able to start reading data at an arbitrary data access unit, the
+      root fragment will be repetitively transmitted (inserted) into the stream in order
+      to permit a decoder to resynchronize and acquire sufficient structural information
+      in the information set in order to interpret subsequent content fragments.</p>
+
+      <p>An example of such a fragmentation of a <em>Document Instance</em> is shown in
+      <a href="#fragment-streaming-graphic"><b>Figure 3 – Fragment
+      Streaming</b></a>.</p><a id="fragment-streaming-graphic" name=
+      "fragment-streaming-graphic"></a>
+
+      <table class="example-images">
+        <caption>
+          Figure 3 – Fragment Streaming
+        </caption>
+        <col span="1">
+
+        <tbody>
+          <tr>
+            <td><img src="images/streaming.png" alt="Fragment Streaming"></td>
+          </tr>
+        </tbody>
+      </table>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>This specification does not define a transport buffer model or a decoder
+        capabilities model.</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="concrete-encoding" name="concrete-encoding"></a>M Concrete Encoding
+      (Non-Normative)</h2>
+
+      <p>In the absence of other requirements, it is recommended that a <em>Document
+      Instance</em> be concretely encoded as a well-formed XML 1.0 <a href="#xml10">[XML
+      1.0]</a> document using the UTF-8 character encoding.</p>
+    </div>
+
+    <div class="div1">
+      <h2><a id="time-expression-semantics" name="time-expression-semantics"></a>N Time
+      Expression Semantics (Non-Normative)</h2>
+
+      <p>This appendix describes the intended semantics for interpreting time expressions
+      in <em>Document Instances</em>.</p>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>It is expected that the information in this appendix will be elevated to
+        normative status in a future revision of this specification.</p>
+      </div>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>The phrase <em>local real time</em> as used below is intended to model a
+        virtual real time clock in the document processing context, where <em>local</em>
+        means in the immediate proximity of the implementation of this processing
+        context. The intent of defining relationships with this virtual clock is to
+        establish a locally valid physical realization of time for didactic purposes.</p>
+      </div>
+
+      <div class="note">
+        <p class="prefix"><b>Note:</b></p>
+
+        <p>The phrase <em>play rate</em> as used below is intended to model a (possibly
+        variable) parameter in the document processing context wherein the rate of
+        playback (or interpretation) of time may artificially dilated or narrowed, for
+        example, when slowing down or speeding up the rate of playback of a <em>Related
+        Media Object</em>. Without loss of generality, the following discussion assumes a
+        fixed play(back) rate. In the case of variable play rates, appropriate
+        adjustments may need to be made to the resulting computations.</p>
+      </div>
+
+      <div class="div2">
+        <h3><a id="time-expression-semantics-clock" name=
+        "time-expression-semantics-clock"></a>N.1 Clock Time Base</h3>
+
+        <p>When operating with the <code>clock</code> time base, the following semantics
+        should be applied for interpreting time expressions, as defined by <a href=
+        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their relationship
+        to media time and local real time.</p>
+
+        <p>The clock time base <span class="strong"><code>C</code></span> is related to
+        local real time <span class="strong"><code>R</code></span> expressed in an
+        arbitrary (implementation defined) epoch <span class=
+        "strong"><code>E</code></span> as follows:</p><a id="clock-time-and-real-time"
+        name="clock-time-and-real-time"></a>
+
+        <table class="semantics">
+          <caption>
+            TTML Semantics – Clock Time and Real Time Relationship
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <blockquote>
+                  <p><br>
+                  <code>R = C + epochOffset + discontinuityOffset</code><br>
+                  <br>
+                  where <code>C ∈ ℜ</code>, <code>0 ≤ C &lt; ∞</code>, <code>C</code> in
+                  seconds since the most immediately prior midnight of the reference
+                  clock base;<br>
+                  <br>
+                  <code>epochOffset ∈ ℜ</code>, <code>0 ≤ epochOffset &lt; ∞</code>,
+                  <code>epochOffset</code> in seconds, with 0 being the beginning of
+                  epoch <code>E</code>, and where the value of <code>epochOffset</code>
+                  is determined from the computed value of the <code>ttp:clockMode</code>
+                  parameter as follows:<br>
+                  <br>
+                  (1) if <code>local</code>, then the difference between the local real
+                  time at the most immediately prior local midnight and the local real
+                  time at the beginning of epoch <code>E</code>, expressed in
+                  seconds;<br>
+                  <br>
+                  (2) if <code>gps</code>, then the difference between the GPS time at
+                  the most immediately prior GPS midnight and the GPS time at the
+                  beginning of epoch <code>E</code>, expressed in seconds;<br>
+                  <br>
+                  (3) if <code>utc</code>, then the difference between the UTC time at
+                  the most immediately prior UTC midnight and the UTC time at the
+                  beginning of epoch <code>E</code>, expressed in seconds;<br>
+                  <br>
+                  <code>discontinuityOffset ∈ ℜ</code>, <code>−∞ &lt; discontinuityOffset
+                  &lt; ∞</code>, <code>discontinuityOffset</code> in seconds, and where
+                  the value of <code>discontinuityOffset</code> is equal to the sum of
+                  leap seconds (and fractions thereof) that have been added (or
+                  subtracted) since the most immediately prior midnight in the reference
+                  clock base;<br>
+                  <br>
+                  and <code>epochOffset</code> and <code>discontinuityOffset</code> are
+                  determined once and only once prior to the beginning of the <em>Root
+                  Temporal Extent</em> such that during the period between value
+                  determination and the beginning of the <em>Root Temporal Extent</em>
+                  there occurs no local midnight or reference clock base
+                  discontinuity.<br></p>
+                </blockquote>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>Time value expressions, as denoted by a <a href=
+        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, are related to clock
+        time <span class="strong"><code>C</code></span> as follows:</p><a id=
+        "time-expressions-and-clock-time" name="time-expressions-and-clock-time"></a>
+
+        <table class="semantics">
+          <caption>
+            TTML Semantics – Time Expressions and Clock Time Relationship
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <blockquote>
+                  <p><br>
+                  If a time expression uses the <em>clock-time</em> form or an
+                  <em>offset-time</em> form that doesn't use the ticks (<code>t</code>)
+                  metric, then:<br>
+                  <br>
+                  <code>C = 3600 * hours + 60 * minutes + seconds</code><br>
+                  <br>
+                  where <code>hours</code>, <code>minutes</code>, <code>seconds</code>
+                  components are extracted from time expression if present, or zero if
+                  not present.<br>
+                  <br>
+                  Otherwise, if a time expression uses an <em>offset-time</em> form that
+                  uses the ticks (<code>t</code>) metric, then:<br>
+                  <br>
+                  <code>C = ticks / tickRate</code><br></p>
+                </blockquote>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>The <em>frames</em> and <em>sub-frames</em> terms and the frames
+          (<code>f</code>) metric of time expressions do not apply when using the
+          <code>clock</code> time base.</p>
+        </div>
+
+        <p>The clock time base <span class="strong"><code>C</code></span> is independent
+        of media time <span class="strong"><code>M</code></span>:</p><a id=
+        "clock-time-and-media-time" name="clock-time-and-media-time"></a>
+
+        <table class="semantics">
+          <caption>
+            TTML Semantics – Clock Time and Media Time Relationship
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <blockquote>
+                  <p><br>
+                  <code>M ¬∝ C</code><br></p>
+                </blockquote>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>That is to say, timing is disconnected from (not necessarily proportional
+          to) media time when the <code>clock</code> time base is used. For example, if
+          the media play rate is zero (0), media playback is suspended; however, timing
+          coordinates will continue to advance according to the natural progression of
+          clock time in direct proportion to the reference clock base. Furthermore, if
+          the media play rate changes during playback, presentation timing is not
+          affected.</p>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="time-expression-semantics-media" name=
+        "time-expression-semantics-media"></a>N.2 Media Time Base</h3>
+
+        <p>When operating with the <code>media</code> time base, the following semantics
+        should be applied for interpreting time expressions, as defined by <a href=
+        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their relationship
+        to media time and local real time.</p>
+
+        <p>The media time base <span class="strong"><code>M</code></span> is related to
+        local real time <span class="strong"><code>R</code></span> expressed in an
+        arbitrary (implementation defined) epoch <span class=
+        "strong"><code>E</code></span> as follows:</p><a id="media-time-and-real-time"
+        name="media-time-and-real-time"></a>
+
+        <table class="semantics">
+          <caption>
+            TTML Semantics – Media Time and Real Time Relationship
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <blockquote>
+                  <p><br>
+                  <code>R = playRate * M + epochOffset</code><br>
+                  <br>
+                  where <code>M ∈ ℜ</code>, <code>0 ≤ M &lt; ∞</code>, <code>M</code> in
+                  seconds, with 0 corresponding to the beginning of the <em>Root Temporal
+                  Extent</em>;<br>
+                  <br>
+                  <code>playRate ∈ ℜ</code>, <code>−∞ &lt; playRate &lt; ∞</code>,
+                  <code>playRate</code> is unit-less, and where the value of
+                  <code>playRate</code> is determined by the document processing
+                  context;<br>
+                  <br>
+                  and <code>epochOffset ∈ ℜ</code>, <code>0 ≤ epochOffset &lt; ∞</code>,
+                  <code>epochOffset</code> in seconds, with 0 corresponding to the
+                  beginning of an epoch <code>E</code>, and where the value of
+                  <code>epochOffset</code> is the difference between the local real time
+                  at the beginning of the <em>Root Temporal Extent</em> and the local
+                  real time at the the beginning of epoch <code>E</code>, expressed in
+                  seconds.</p>
+                </blockquote>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>Time value expressions, as denoted by a <a href=
+        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, are related to media
+        time <span class="strong"><code>M</code></span> in accordance to the
+        <code>ttp:frameRate</code>, <code>ttp:subFrameRate</code>, and
+        <code>ttp:frameRateMultipler</code> parameters as follows:</p><a id=
+        "time-expressions-and-media-time" name="time-expressions-and-media-time"></a>
+
+        <table class="semantics">
+          <caption>
+            TTML Semantics – Time Expressions and Media Time Relationship
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <blockquote>
+                  <p><br>
+                  If a time expression uses a <em>clock-time</em> form or an
+                  <em>offset-time</em> form that doesn't use the ticks (<code>t</code>)
+                  metric, then:<br>
+                  <br>
+                  <code>M = referenceBegin + 3600 * hours + 60 * minutes + seconds +
+                  ((frames + (subFrames / subFrameRate)) / effectiveFrameRate)</code><br>
+                  <br>
+                  where <code>referenceBegin</code> is determined according to whether
+                  the nearest ancestor time container employs parallel (<code>par</code>)
+                  or sequential (<code>seq</code>) semantics: if parallel or if
+                  sequential and no prior sibling timed element exists, then
+                  <code>referenceBegin</code> is the media time that corresponds to the
+                  beginning of the nearest ancestor time container or zero (0) if this
+                  time container is the <em>Root Temporal Extent</em>; otherwise, if
+                  sequential and a prior sibling timed element exists, then
+                  <code>referenceBegin</code> is the media time that corresponds to the
+                  active end of the immediate prior sibling timed element;<br>
+                  <br>
+                  the <code>hours</code>, <code>minutes</code>, <code>seconds</code>,
+                  <code>frames</code>, <code>subFrames</code> components are extracted
+                  from time expression if present, or zero if not present;<br>
+                  <br>
+                  <code>subFrameRate</code> is the computed value of the
+                  <code>ttp:subFrameRate</code> parameter;<br>
+                  <br>
+                  and <code>effectiveFrameRate</code> (in frames per second) is
+                  <code>frameRate * frameRateMultipler</code> where
+                  <code>frameRate</code> is the computed value of the
+                  <code>ttp:frameRate</code> parameter and
+                  <code>frameRateMultipler</code> is the computed value of the
+                  <code>ttp:frameRateMultiplier</code> parameter.<br>
+                  <br>
+                  Otherwise, if a time expression uses an <em>offset-time</em> form that
+                  uses the ticks (<code>t</code>) metric, then:<br>
+                  <br>
+                  <code>M = referenceBegin + ticks / tickRate</code><br>
+                  <br>
+                  where <code>referenceBegin</code> is as described above;<br>
+                  <br>
+                  the <code>ticks</code> component is extracted from time expression;<br>
+                  <br>
+                  and <code>tickRate</code> is the computed value of the
+                  <code>ttp:tickRate</code> parameter;<br></p>
+                </blockquote>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>If the computed <code>frameRateMultipler</code> ratio is not integral, then
+          <code>effectiveFrameRate</code> will be a non-integral rational.</p>
+        </div>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>The above formalisms assumes that the <em>Root Temporal Extent</em>
+          corresponds with the beginning of a related media object. If this assumption
+          doesn't hold, then an additional offset that accounts for the difference may be
+          introduced when computing media time <code>M</code>.</p>
+        </div>
+      </div>
+
+      <div class="div2">
+        <h3><a id="time-expression-semantics-smpte" name=
+        "time-expression-semantics-smpte"></a>N.3 SMPTE Time Base</h3>
+
+        <p>When operating with the <code>smpte</code> time base, the following semantics
+        should be applied for interpreting time expressions, as defined by <a href=
+        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their relationship
+        to media time and local real time.</p>
+
+        <p>If the computed value of the <code>ttp:markerMode</code> parameter is
+        <code>discontinuous</code>, then there is no direct relationship between time
+        expressions and media time <span class="strong"><code>M</code></span> or local
+        real time <span class="strong"><code>R</code></span>. In this case, time
+        expressions refer to synchronization events (markers) emitted by the <em>Document
+        Processing Context</em> when <em>SMPTE Time Codes</em> are encountered in the
+        <em>Related Media Object</em>.</p>
+
+        <p>Otherwise, if the computed value of the <code>ttp:markerMode</code> parameter
+        is <code>continuous</code>, then the relationships between time expressions and
+        local real time and media time are as described below in terms of a <em>Synthetic
+        SMPTE Document Syncbase</em>, here referred to as the SMPTE time base
+        <span class="strong"><code>S</code></span>.</p><a id=
+        "time-expressions-and-smpte-time" name="time-expressions-and-smpte-time"></a>
+
+        <table class="semantics">
+          <caption>
+            TTML Semantics – Time Expressions and SMPTE Time Relationship
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <blockquote>
+                  <p><br>
+                  <code>S = (countedFrames - droppedFrames + (subFrames / subFrameRate))
+                  / effectiveFrameRate</code><br>
+                  <br>
+                  where<br>
+                  <br>
+                  <code>countedFrames = (3600 * hours + 60 * minutes + seconds) *
+                  frameRate + frames</code><br>
+                  <br>
+                  <code>hours</code>, <code>minutes</code>, <code>seconds</code>,
+                  <code>frames</code>, <code>subFrames</code> components are extracted
+                  from time expression if present, or zero if not present;<br>
+                  <br>
+                  <code>droppedFrames</code> is computed as follows:<br>
+                  <br>
+                  1. let <em>dropMode</em> be the computed value of the
+                  <code>ttp:dropMode</code> parameter;<br>
+                  <br>
+                  2. if <em>dropMode</em> is <code>dropNTSC</code>, let
+                  <code>droppedFrames = (hours * 54 + floor(minutes - minutes/10)) *
+                  2</code>;<br>
+                  <br>
+                  3. otherwise, if <em>dropMode</em> is <code>dropPAL</code>, let
+                  <code>droppedFrames = (hours * 27 + floor(minutes/2 - minutes/20)) *
+                  4</code>;<br>
+                  <br>
+                  4. otherwise, let <code>droppedFrames = 0</code>;<br>
+                  <br>
+                  <code>frameRate</code> is the computed value of the
+                  <code>ttp:frameRate</code> parameter;<br>
+                  <br>
+                  <code>subFrameRate</code> is the computed value of the
+                  <code>ttp:subFrameRate</code> parameter;<br>
+                  <br>
+                  and <code>effectiveFrameRate</code> (in frames per second) is
+                  <code>frameRate * frameRateMultipler</code> where
+                  <code>frameRate</code> is the computed value of the
+                  <code>ttp:frameRate</code> parameter and
+                  <code>frameRateMultipler</code> is the computed value of the
+                  <code>ttp:frameRateMultiplier</code> parameter.<br>
+                  <br>
+                  Notwithstanding the above, if a time expression contains a frame code
+                  that is designated as dropped according to <a href=
+                  "#parameter-attribute-dropMode"><b>6.2.3 ttp:dropMode</b></a>, then
+                  that time expression should be considered to be invalid for purposes of
+                  validation assessment.<br></p>
+                </blockquote>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>The SMPTE time base <span class="strong"><code>S</code></span> is related to
+        the media time base <span class="strong"><code>M</code></span> as
+        follows:</p><a id="smpte-time-and-media-time" name=
+        "smpte-time-and-media-time"></a>
+
+        <table class="semantics">
+          <caption>
+            TTML Semantics – SMPTE Time and Media Time Relationship
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <blockquote>
+                  <p><br>
+                  <code>M = referenceBegin + S</code><br>
+                  <br>
+                  where <code>referenceBegin</code> is determined according to whether
+                  the nearest ancestor time container employs parallel (<code>par</code>)
+                  or sequential (<code>seq</code>) semantics: if parallel or if
+                  sequential and no prior sibling timed element exists, then
+                  <code>referenceBegin</code> is the SMPTE time that corresponds to the
+                  beginning of the nearest ancestor time container or zero (0) if this
+                  time container is the <em>Root Temporal Extent</em>; otherwise, if
+                  sequential and a prior sibling timed element exists, then
+                  <code>referenceBegin</code> is the SMPTE time that corresponds to the
+                  active end of the immediate prior sibling timed element;<br></p>
+                </blockquote>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+
+        <p>Given the derived media time base as described above, then media time base
+        <span class="strong"><code>M</code></span> is related to the local real time
+        <span class="strong"><code>R</code></span> as described in <a href=
+        "#time-expression-semantics-media"><b>N.2 Media Time Base</b></a> above.</p>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="common-styling" name="common-styling"></a>O Common Caption Style
+      Examples (Non-Normative)</h2>
+
+      <p>This section provides examples of the following common caption styles using TTML
+      Content to obtain the desired behavior:</p>
+
+      <ul>
+        <li>
+          <p>Pop-On Captions</p>
+        </li>
+
+        <li>
+          <p>Roll-Up Captions</p>
+        </li>
+
+        <li>
+          <p>Paint-On Captions</p>
+        </li>
+      </ul>
+
+      <div class="div2">
+        <h3><a id="pop-on-example" name="pop-on-example"></a>O.1 Pop-On Caption
+        Example</h3>
+
+        <p>An example of paint-on captions. In this example, two regions are targeted
+        with alternating, paint-on content, where content is timed using explicit
+        sequential time containment rules. Each paragraph is non-overlapping in time and
+        appears in the same single row of its targeted region.</p><a id=
+        "pop-on-example-1-s" name="pop-on-example-1-s"></a>
+
+        <table class="example">
+          <caption>
+            Example – Pop-On Captions
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
+  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;head&gt;
+    &lt;layout&gt;
+      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 1c"/&gt;
+      &lt;region xml:id="r2" tts:color="yellow" tts:origin="10c 8c" tts:extent="40c 1c"/&gt;
+    &lt;/layout&gt;
+  &lt;/head&gt;
+  &lt;body&gt;
+    &lt;div timeContainer="seq"&gt;
+      &lt;p region="r1" dur="4s"&gt;Lorem ipsum dolor sit&lt;/p
+      &lt;p region="r2" dur="4s"&gt;Amet consectetur adipiscing elit&lt;/p&gt;
+      &lt;p region="r1" dur="6s"&gt;Sed do eiusmod tempor incididunt labore&lt;/p&gt;
+      &lt;p region="r2" dur="4s"&gt;et dolore magna aliqua&lt;/p&gt;
+      &lt;p region="r1" dur="7s"&gt;Ut enim ad minim veniam quis, nostrud&lt;/p&gt;
+    &lt;/div&gt;
+  &lt;/body&gt;
+&lt;/tt&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+
+      <div class="div2">
+        <h3><a id="roll-up-example" name="roll-up-example"></a>O.2 Roll-Up Caption
+        Example</h3>
+
+        <p>An example of roll-up captions. Roll-up effects are achieved by using
+        overlapped time intervals, where zero, one, or two paragraphs appear in the
+        region at a given time. Each paragraph consumes a single row (line) of the region
+        since no wrapping occurs. Depending on whether a presentation processor supports
+        <a href="#semantics-smooth-scrolling-recommendation">smooth scrolling between
+        adjacent synchronic intermediate document instances</a>, the transitions, i.e.,
+        moving an old paragraph (line) out and a new paragraph (line) in, will be either
+        smooth or discrete.</p><a id="roll-up-example-1-s" name=
+        "roll-up-example-1-s"></a>
+
+        <table class="example">
+          <caption>
+            Example – Roll-Up Captions
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
+  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;head&gt;
+    &lt;layout&gt;
+      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 2c"/&gt;
+    &lt;/layout&gt;
+  &lt;/head&gt;
+  &lt;body&gt;
+    &lt;div region="r1"&gt;
+      &lt;p begin="0s" end="8s"&gt;Lorem ipsum dolor sit&lt;/p
+      &lt;p begin="4s" end="12s"&gt;Amet consectetur adipiscing elit&lt;/p&gt;
+      &lt;p begin="8s" end="18s"&gt;Sed do eiusmod tempor incididunt labore&lt;/p&gt;
+      &lt;p begin="14s" end="25s"&gt;et dolore magna aliqua&lt;/p&gt;
+      &lt;p begin="18s" end="29s"&gt;Ut enim ad minim veniam quis, nostrud&lt;/p&gt;
+    &lt;/div&gt;
+  &lt;/body&gt;
+&lt;/tt&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+
+      <div class="div2">
+        <h3><a id="paint-on-example" name="paint-on-example"></a>O.3 Paint-On Caption
+        Example</h3>
+
+        <p>An example of paint-on captions. Paint-on effects are achieved by using timed
+        <code>span</code> elements in order to expose (paint) inline text units, e.g.,
+        words, over some time interval. Here, five paragraphs have their individual words
+        sequentially timed in order to paint one new word every second. The end of the
+        active duration of each inline element coincides with the end of the
+        <code>div</code> element's parallel time container, so that once a word is
+        painted, it remains in the region (on its rendered line) until the
+        <code>div</code> element's active time interval lapses.</p><a id=
+        "paint-on-example-1-s" name="paint-on-example-1-s"></a>
+
+        <table class="example">
+          <caption>
+            Example – Paint-On Captions
+          </caption>
+
+          <tbody>
+            <tr>
+              <td>
+                <div class="exampleInner">
+                  <pre>
+&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
+  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
+  &lt;head&gt;
+    &lt;layout&gt;
+      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 5c"/&gt;
+    &lt;/layout&gt;
+  &lt;/head&gt;
+  &lt;body&gt;
+    &lt;div begin="0s" end="25s"&gt;
+      &lt;p&gt;
+        &lt;span begin="0s"&gt;Lorem&lt;/span&gt;
+        &lt;span begin="1s"&gt;ipsum&lt;/span&gt;
+        &lt;span begin="2s"&gt;dolor&lt;/span&gt;
+        &lt;span begin="3s"&gt;sit&lt;/span&gt;
+      &lt;/p&gt;
+      &lt;p&gt;
+        &lt;span begin="4s"&gt;Amet&lt;/span&gt;                
+        &lt;span begin="5s"&gt;consectetur&lt;/span&gt;
+        &lt;span begin="6s"&gt;adipiscing&lt;/span&gt;
+        &lt;span begin="7s"&gt;elit&lt;/span&gt;
+      &lt;/p&gt;
+      &lt;p&gt;
+        &lt;span begin="8s"&gt;Sed&lt;/span&gt;
+        &lt;span begin="9s"&gt;do&lt;/span&gt;
+        &lt;span begin="10s"&gt;eiusmod&lt;/span&gt;
+        &lt;span begin="11s"&gt;tempor&lt;/span&gt;
+        &lt;span begin="12s"&gt;incididunt &lt;/span&gt;
+        &lt;span begin="13s"&gt;labore&lt;/span&gt;
+     &lt;/p&gt;
+     &lt;p&gt;
+        &lt;span begin="14s"&gt;et&lt;/span&gt;
+        &lt;span begin="15s"&gt;dolore&lt;/span&gt;
+        &lt;span begin="16s"&gt;magna&lt;/span&gt;
+        &lt;span begin="17s"&gt;aliqua&lt;/span&gt;
+      &lt;/p&gt;
+      &lt;p&gt;
+        &lt;span begin="18s"&gt;Ut&lt;/span&gt;
+        &lt;span begin="19s"&gt;enim&lt;/span&gt;
+        &lt;span begin="20s"&gt;ad&lt;/span&gt;
+        &lt;span begin="21s"&gt;minim&lt;/span&gt;
+        &lt;span begin="22s"&gt;veniam&lt;/span&gt;
+        &lt;span begin="23s"&gt;quis,&lt;/span&gt;
+        &lt;span begin="24s"&gt;nostrud&lt;/span&gt;
+      &lt;/p&gt;
+    &lt;/div&gt;
+  &lt;/body&gt;
+&lt;/tt&gt;
+</pre>
+                </div>
+              </td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+    </div>
+
+    <div class="div1">
+      <h2><a id="acknowledgments" name="acknowledgments"></a>P Acknowledgments
+      (Non-Normative)</h2>
+
+      <p>The editor acknowledges the current and former members of the Timed Text Working
+      Group, the members of other W3C Working Groups, and industry experts in other
+      forums who have contributed directly or indirectly to the process or content of
+      this document as follows:</p>
+
+      <p>Glenn Adams, Thomas Bause-Mason, John Birch, Kees Blom, Bert Bos, Brad Botkin,
+      Dick Bulterman, Frans de Jong, Mike Dolan, Martin Dürst, Donald Evans, Geoff Freed,
+      Al Gilman, Giles Godart-Brown, Markus Gylling, Markku Hakkinen, Sean Hayes, Erik
+      Hodge, Philipp Hoschka, Suzi Hyun, Michael Jordan, Masahiko Kaneko, Courtney
+      Kennedy, George Kerscher, David Kirby, Andrew Kirkpatrick, Philippe Le Hégaret,
+      Chris Lilley, Pierre-Anthony Lemieux, Jason Livingston, Monica Martin, Thierry
+      Michel, Matthew May, Frank Olivier, Soohong Daniel Park, Silvia Pfeiffer, Brian
+      Raymor, David Ronca, Patrick Schmitz, David Singer, Craig Smithpeters, Andreas Tai,
+      and Mohamed Zergaoui.</p>
+
+      <p>The editor wishes to especially acknowledge the following contributions by
+      members: Micheal Dolan (SMPTE time codes, streaming; SMPTE liaison), David Kirby
+      (introductory example document; SMPTE time codes, descriptive metadata; EBU/AAF
+      liaison), Geoff Freed (styling and example images of style properties), Sean Hayes
+      (advanced profile concepts, including applicative timing), Eric Hodge (timing),
+      Thierry Michel (metadata), and Dave Singer (animation, scrolling).</p>
+
+      <p>The Working Group dedicates this specification to our colleague David Kirby.</p>
+    </div>
+  </div>
+</body>
+</html>
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-  "http://www.w3.org/StyleSheets/TR/W3C-PER.css">
-</head>
-
-<body>
-  <div class="head">
-    <p><a href="http://www.w3.org/"><img src="http://www.w3.org/Icons/w3c_home"
-    alt="W3C" height="48" width="72"></a></p>
-
-    <h1><a id="title" name="title"></a>Timed Text Markup Language (TTML) 1.0
-    (Second Edition)</h1>
-
-    <h2><a id="w3c-doctype" name="w3c-doctype"></a>W3C Proposed Edited
-    Recommendation DD July 2013</h2>
-
-    <dl>
-      <dt>This version:</dt>
-
-      <dd><a href=
-      "http://www.w3.org/TR/2013/PER-ttaf1-dfxp-201307DD/">http://www.w3.org/TR/2013/PER-ttaf1-dfxp-201307DD/</a></dd>
-
-      <dt>Latest version:</dt>
-
-      <dd><a href=
-      "http://www.w3.org/TR/ttaf1-dfxp/">http://www.w3.org/TR/ttaf1-dfxp/</a></dd>
-
-      <dt>Previous version:</dt>
-
-      <dd><a href=
-      "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/</a></dd>
-
-      <dt>Editor:</dt>
-
-      <dd>Glenn Adams, Cox Communications, Inc.</dd>
-
-      <dt>Contributing Authors:</dt>
-
-      <dd>Mike Dolan, Invited Expert</dd>
-
-      <dd>Geoff Freed, WGBH National Center for Accessible Media</dd>
-
-      <dd>Sean Hayes, Microsoft</dd>
-
-      <dd>Erik Hodge, RealNetworks</dd>
-
-      <dd>David Kirby, British Broadcasting Corporation (BBC)</dd>
-
-      <dd>Thierry Michel, W3C</dd>
-
-      <dd>Dave Singer, Apple Computer</dd>
-    </dl>
-
-    <p>Please refer to the <a href=
-    "https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttml-issues.html">
-    errata</a> for this document, which may include normative corrections.</p>
-
-    <p>See also <a href=
-    "http://www.w3.org/2003/03/Translations/byTechnology?technology=ttaf1-dfxp">
-    <strong>translations</strong></a>.</p>
-
-    <p class="copyright"><a href=
-    "http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>&nbsp;©&nbsp;2013&nbsp;<a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup>
-    (<a href="http://www.csail.mit.edu/"><acronym title=
-    "Massachusetts Institute of Technology">MIT</acronym></a>, <a href=
-    "http://www.ercim.eu/"><acronym title=
-    "European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>,
-    <a href="http://www.keio.ac.jp/">Keio</a>, <a href=
-    "http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a href=
-    "http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
-    <a href=
-    "http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
-    and <a href=
-    "http://www.w3.org/Consortium/Legal/copyright-documents">document use</a>
-    rules apply.</p>
-  </div>
-  <hr>
-
-  <div>
-    <h2><a id="abstract" name="abstract"></a>Abstract</h2>
-
-    <p>This document specifies the Timed Text Markup Language (TTML) in terms
-    of a vocabulary and semantics thereof.</p>
-
-    <p>The Timed Text Markup Language is a content type that represents timed
-    text media for the purpose of interchange among authoring systems. Timed
-    text is textual information that is intrinsically or extrinsically
-    associated with timing information.</p>
-
-    <p>It is intended to be used for the purpose of transcoding or exchanging
-    timed text information among legacy distribution content formats presently
-    in use for subtitling and captioning functions.</p>
-
-    <p>In addition to being used for interchange among legacy distribution
-    content formats, TTML Content may be used directly as a distribution
-    format, for example, providing a standard content format to reference from
-    a <code>&lt;track&gt;</code> element in an HTML5 document, or a
-    <code>&lt;text&gt;</code> or <code>&lt;textstream&gt;</code> media element
-    in a <a href="#smil21">[SMIL 2.1]</a> document.</p>
-  </div>
-
-  <div>
-    <h2><a id="status" name="status"></a>Status of this Document</h2>
-
-    <p><em>This section describes the status of this document at the time of
-    its publication. Other documents may supersede this document. A list of
-    current W3C publications and the latest revision of this technical report
-    can be found in the <a href="http://www.w3.org/TR/">W3C technical reports
-    index</a> at http://www.w3.org/TR/.</em></p>
-
-    <p>This document, published on DD July 2013, is a <a href=
-    "http://www.w3.org/2005/10/Process-20051014/tr.html#ProposedEditedRec">Proposed
-    Edited Recommendation</a> of the W3C. This second edition is not a new
-    version of this specification; its purpose is to clarify a number of issues
-    that have become apparent since the first edition was published.</p>
-
-    <p>This document has been produced by the <a href=
-    "http://www.w3.org/AudioVideo/TT/">Timed Text (TT) Working Group</a> as
-    part of the W3C <a href="http://www.w3.org/2008/WebVideo/">Video in the Web
-    Activity</a>, following the procedures set out for the W3C <a href=
-    "http://www.w3.org/Consortium/Process/">Process</a>. The authors of this
-    document are listed in the header of this document.</p>
-
-    <p>Publication as a Proposed Edited Recommendation does not imply
-    endorsement by the W3C Membership. This is a draft document and may be
-    updated, replaced or obsoleted by other documents at any time. It is
-    inappropriate to cite this document as other than work in progress.</p>
-
-    <p>W3C Advisory Committee Members are invited to send formal review
-    comments on this Proposed Edited Recommendation to the W3C Team until DD
-    August 2013. Members of the W3C Advisory Committee will find the
-    appropriate review form for this document by consulting their <a href=
-    "http://www.w3.org/2002/09/wbs/myQuestionnaires">list of WBS
-    questionnaires</a>.</p>
-
-    <p>This document incorporates changes made against the <a href=
-    "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">Recommendation</a> of
-    18 November 2010 that resolve all errata known at the date of publication.
-    A list of the errata that have been applied is provided in <a href=
-    "https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttml-changes.html#change-history-rec-to-2e-per">
-    Changes from Recommendation to Proposed Edited Recommendation (2nd
-    Ed.)</a>.</p>
-
-    <p>Please report errors in and submit comments on this document to the W3C
-    Timed Text public comments mailing list, <a href=
-    "mailto:public-tt-comments@w3.org">public-tt-comments@w3.org</a>. Please
-    include the string <code>[ttml10se]</code> at the beginning of the subject
-    line of your report. Each email message should contain only one error
-    report. Archives of the comments and responses are available at <a href=
-    "http://lists.w3.org/Archives/Public/public-tt-comments/">http://lists.w3.org/Archives/Public/public-tt-comments/</a>.</p>
-
-    <p>An updated <a href=
-    "http://www.w3.org/2009/05/dfxp-results.html">implementation report</a>
-    will be made available, but the decision of the Director to transition this
-    document to Proposed Edited Recommendation did not depend on the existence
-    of that report.</p>
-
-    <p>The Timed Text Working Group plans to submit this specification for
-    consideration as a W3C Recommendation (Second Edition) as soon as the
-    Working Group has responded formally to all issues raised during the PER
-    period against this document.</p>
-
-    <p>This document was produced by a group operating under the <a href=
-    "http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 W3C
-    Patent Policy</a>. W3C maintains a <a href=
-    "http://www.w3.org/2004/01/pp-impl/34314/status#disclosures" rel=
-    "disclosure">public list of any patent disclosures</a> made in connection
-    with the deliverables of the group; that page also includes instructions
-    for disclosing a patent. An individual who has actual knowledge of a patent
-    which the individual believes contains <a href=
-    "http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
-    Claim(s)</a> must disclose the information in accordance with <a href=
-    "http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
-    6 of the W3C Patent Policy</a>.</p>
-  </div>
-
-  <div class="toc">
-    <h2><a id="contents" name="contents"></a>Table of Contents</h2>
-
-    <p class="toc">1 <a href="#intro">Introduction</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;1.1 <a href="#model">System Model</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;1.2 <a href="#example">Document Example</a><br>
-    2 <a href="#definitions">Definitions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;2.1 <a href="#acronyms">Acronyms</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;2.2 <a href="#terms">Terminology</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;2.3 <a href="#conventions">Documentation
-    Conventions</a><br>
-    3 <a href="#conformance">Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;3.1 <a href="#conformance-content">Content
-    Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;3.2 <a href="#conformance-processor">Processor
-    Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.1 <a href=
-    "#conformance-generic-processor">Generic Processor Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.2 <a href=
-    "#conformance-transformation-processor">Transformation Processor
-    Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2.3 <a href=
-    "#conformance-presentation-processor">Presentation Processor
-    Conformance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;3.3 <a href="#claims">Claims</a><br>
-    4 <a href="#doctypes">Document Types</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;4.1 <a href="#ttml-content-doctype">TTML
-    Content</a><br>
-    5 <a href="#vocabulary">Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;5.1 <a href=
-    "#vocabulary-namespaces">Namespaces</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;5.2 <a href="#vocabulary-profiles">Profiles</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;5.3 <a href="#vocabulary-overview">Catalog</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.3.1 <a href=
-    "#core-vocabulary-overview">Core Catalog</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.3.2 <a href=
-    "#extension-vocabulary-overview">Extension Catalog</a><br>
-    6 <a href="#parameters">Parameters</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;6.1 <a href=
-    "#parameter-element-vocabulary">Parameter Element Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.1 <a href=
-    "#parameter-vocabulary-profile">ttp:profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.2 <a href=
-    "#parameter-vocabulary-features">ttp:features</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.3 <a href=
-    "#parameter-vocabulary-feature">ttp:feature</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.4 <a href=
-    "#parameter-vocabulary-extensions">ttp:extensions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1.5 <a href=
-    "#parameter-vocabulary-extension">ttp:extension</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;6.2 <a href=
-    "#parameter-attribute-vocabulary">Parameter Attribute Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.1 <a href=
-    "#parameter-attribute-cellResolution">ttp:cellResolution</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.2 <a href=
-    "#parameter-attribute-clockMode">ttp:clockMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.3 <a href=
-    "#parameter-attribute-dropMode">ttp:dropMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.4 <a href=
-    "#parameter-attribute-frameRate">ttp:frameRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.5 <a href=
-    "#parameter-attribute-frameRateMultiplier">ttp:frameRateMultiplier</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.6 <a href=
-    "#parameter-attribute-markerMode">ttp:markerMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.7 <a href=
-    "#parameter-attribute-pixelAspectRatio">ttp:pixelAspectRatio</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.8 <a href=
-    "#parameter-attribute-profile">ttp:profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.9 <a href=
-    "#parameter-attribute-subFrameRate">ttp:subFrameRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.10 <a href=
-    "#parameter-attribute-tickRate">ttp:tickRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2.11 <a href=
-    "#parameter-attribute-timeBase">ttp:timeBase</a><br>
-    7 <a href="#content">Content</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;7.1 <a href="#content-element-vocabulary">Content
-    Element Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.1 <a href=
-    "#document-structure-vocabulary-tt">tt</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.2 <a href=
-    "#document-structure-vocabulary-head">head</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.3 <a href=
-    "#document-structure-vocabulary-body">body</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.4 <a href=
-    "#content-vocabulary-div">div</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.5 <a href=
-    "#content-vocabulary-p">p</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.6 <a href=
-    "#content-vocabulary-span">span</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.1.7 <a href=
-    "#content-vocabulary-br">br</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;7.2 <a href="#content-attribute-vocabulary">Content
-    Attribute Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.1 <a href=
-    "#content-attribute-id">xml:id</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.2 <a href=
-    "#content-attribute-lang">xml:lang</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;7.2.3 <a href=
-    "#content-attribute-space">xml:space</a><br>
-    8 <a href="#styling">Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;8.1 <a href="#styling-element-vocabulary">Styling
-    Element Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.1.1 <a href=
-    "#styling-vocabulary-styling">styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.1.2 <a href=
-    "#styling-vocabulary-style">style</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;8.2 <a href="#styling-attribute-vocabulary">Styling
-    Attribute Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.1 <a href=
-    "#style-attribute-style">style</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.2 <a href=
-    "#style-attribute-backgroundColor">tts:backgroundColor</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.3 <a href=
-    "#style-attribute-color">tts:color</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.4 <a href=
-    "#style-attribute-direction">tts:direction</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.5 <a href=
-    "#style-attribute-display">tts:display</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.6 <a href=
-    "#style-attribute-displayAlign">tts:displayAlign</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.7 <a href=
-    "#style-attribute-extent">tts:extent</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.8 <a href=
-    "#style-attribute-fontFamily">tts:fontFamily</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.9 <a href=
-    "#style-attribute-fontSize">tts:fontSize</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.10 <a href=
-    "#style-attribute-fontStyle">tts:fontStyle</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.11 <a href=
-    "#style-attribute-fontWeight">tts:fontWeight</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.12 <a href=
-    "#style-attribute-lineHeight">tts:lineHeight</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.13 <a href=
-    "#style-attribute-opacity">tts:opacity</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.14 <a href=
-    "#style-attribute-origin">tts:origin</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.15 <a href=
-    "#style-attribute-overflow">tts:overflow</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.16 <a href=
-    "#style-attribute-padding">tts:padding</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.17 <a href=
-    "#style-attribute-showBackground">tts:showBackground</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.18 <a href=
-    "#style-attribute-textAlign">tts:textAlign</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.19 <a href=
-    "#style-attribute-textDecoration">tts:textDecoration</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.20 <a href=
-    "#style-attribute-textOutline">tts:textOutline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.21 <a href=
-    "#style-attribute-unicodeBidi">tts:unicodeBidi</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.22 <a href=
-    "#style-attribute-visibility">tts:visibility</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.23 <a href=
-    "#style-attribute-wrapOption">tts:wrapOption</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.24 <a href=
-    "#style-attribute-writingMode">tts:writingMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.2.25 <a href=
-    "#style-attribute-zIndex">tts:zIndex</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;8.3 <a href=
-    "#styling-style-value-expressions">Style Value Expressions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.1 <a href=
-    "#style-value-alpha">&lt;alpha&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.2 <a href=
-    "#style-value-color">&lt;color&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.3 <a href=
-    "#style-value-digit">&lt;digit&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.4 <a href=
-    "#style-value-duration">Deleted</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.5 <a href=
-    "#style-value-familyName">&lt;familyName&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.6 <a href=
-    "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.7 <a href=
-    "#style-value-hexDigit">&lt;hexDigit&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.8 <a href=
-    "#style-value-integer">&lt;integer&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.9 <a href=
-    "#style-value-length">&lt;length&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.10 <a href=
-    "#style-value-namedColor">&lt;namedColor&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.11 <a href=
-    "#style-value-quotedString">Deleted</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.3.12 <a href=
-    "#style-value-string">Deleted</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;8.4 <a href="#semantics-style-resolution">Style
-    Resolution</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1 <a href=
-    "#semantics-style-association">Style Association</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.1
-    <a href="#semantics-style-association-inline">Inline Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.2
-    <a href="#semantics-style-association-referential">Referential
-    Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.3
-    <a href="#semantics-style-association-chained-referential">Chained
-    Referential Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.1.4
-    <a href="#semantics-style-association-nested">Nested Styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2 <a href=
-    "#semantics-style-inheritance">Style Inheritance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2.1
-    <a href="#semantics-style-inheritance-content">Content Style
-    Inheritance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.2.2
-    <a href="#semantics-style-inheritance-region">Region Style
-    Inheritance</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3 <a href=
-    "#semantics-style-resolution-value-categories">Style Resolution Value
-    Categories</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.1
-    <a href="#semantics-style-resolved-value-category-specified">Specified
-    Values</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.2
-    <a href="#semantics-style-resolved-value-category-computed">Computed
-    Values</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.3.3
-    <a href="#semantics-style-resolved-value-category-actual">Actual
-    Values</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4 <a href=
-    "#semantics-style-resolution-processing">Style Resolution
-    Processing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.1
-    <a href="#semantics-style-resolution-processing-definitions">Conceptual
-    Definitions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.2
-    <a href="#semantics-style-resolution-processing-sss">Specified Style Set
-    Processing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.3
-    <a href="#semantics-style-resolution-processing-css">Computed Style Set
-    Processing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;8.4.4.4
-    <a href="#semantics-style-resolution-process-overall">Style Resolution
-    Process</a><br>
-    9 <a href="#layout">Layout</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;9.1 <a href="#layout-element-vocabulary">Layout
-    Element Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.1.1 <a href=
-    "#layout-vocabulary-layout">layout</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.1.2 <a href=
-    "#layout-vocabulary-region">region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;9.2 <a href="#layout-attribute-vocabulary">Layout
-    Attribute Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.2.1 <a href=
-    "#layout-attribute-region">region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;9.3 <a href="#semantics-region-layout">Region
-    Layout and Presentation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.1 <a href=
-    "#semantics-default-region">Default Region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.2 <a href=
-    "#semantics-region-layout-step-1">Intermediate Synchronic Document
-    Construction</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.3 <a href=
-    "#semantics-region-layout-step-2">Synchronic Flow Processing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9.3.4 <a href=
-    "#semantics-region-layout-example">Elaborated Example (Informative)</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;9.4 <a href="#semantics-line-layout">Line
-    Layout</a><br>
-    10 <a href="#timing">Timing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;10.1 <a href="#timing-element-vocabulary">Timing
-    Element Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;10.2 <a href="#timing-attribute-vocabulary">Timing
-    Attribute Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.1 <a href=
-    "#timing-attribute-begin">begin</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.2 <a href=
-    "#timing-attribute-end">end</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.3 <a href=
-    "#timing-attribute-dur">dur</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.2.4 <a href=
-    "#timing-attribute-timeContainer">timeContainer</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;10.3 <a href="#timing-time-value-expressions">Time
-    Value Expressions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;10.3.1 <a href=
-    "#timing-value-timeExpression">&lt;timeExpression&gt;</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;10.4 <a href="#timing-time-intervals">Time
-    Intervals</a><br>
-    11 <a href="#animation">Animation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;11.1 <a href=
-    "#animation-element-vocabulary">Animation Element Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;11.1.1 <a href=
-    "#animation-vocabulary-set">set</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;11.2 <a href=
-    "#animation-attribute-vocabulary">Animation Attribute Vocabulary</a><br>
-    12 <a href="#metadata">Metadata</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;12.1 <a href=
-    "#metadata-element-vocabulary">Metadata Element Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.1 <a href=
-    "#metadata-vocabulary-metadata">metadata</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.2 <a href=
-    "#metadata-vocabulary-title">ttm:title</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.3 <a href=
-    "#metadata-vocabulary-desc">ttm:desc</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.4 <a href=
-    "#metadata-vocabulary-copyright">ttm:copyright</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.5 <a href=
-    "#metadata-vocabulary-agent">ttm:agent</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.6 <a href=
-    "#metadata-vocabulary-name">ttm:name</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.1.7 <a href=
-    "#metadata-vocabulary-actor">ttm:actor</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;12.2 <a href=
-    "#metadata-attribute-vocabulary">Metadata Attribute Vocabulary</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.2.1 <a href=
-    "#metadata-attribute-agent">ttm:agent</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;12.2.2 <a href=
-    "#metadata-attribute-role">ttm:role</a><br></p>
-
-    <h3><a id="appendices" name="appendices"></a>Appendices</h3>
-
-    <p class="toc">A <a href="#reduced-infoset">Reduced XML Infoset</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;A.1 <a href="#reduced-infoset-document">Document
-    Information Item</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;A.2 <a href="#reduced-infoset-element">Element
-    Information Item</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;A.3 <a href="#reduced-infoset-attribute">Attribute
-    Information Item</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;A.4 <a href="#reduced-infoset-character">Character
-    Information Item</a><br>
-    B <a href="#schemas">Schemas</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;B.1 <a href="#ttml-schema-rnc">Relax NG Compact
-    (RNC) Schema</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;B.2 <a href="#ttml-schema-xsd">XML Schema
-    Definition (XSD) Schema</a><br>
-    C <a href="#media-types-registration">Media Type Registration</a><br>
-    D <a href="#features">Features</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;D.1 <a href="#feature-designations">Feature
-    Designations</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.1 <a href=
-    "#feature-animation">#animation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.2 <a href=
-    "#feature-backgroundColor">#backgroundColor</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.3 <a href=
-    "#feature-backgroundColor-block">#backgroundColor-block</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.4 <a href=
-    "#feature-backgroundColor-inline">#backgroundColor-inline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.5 <a href=
-    "#feature-backgroundColor-region">#backgroundColor-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.6 <a href=
-    "#feature-bidi">#bidi</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.7 <a href=
-    "#feature-cellResolution">#cellResolution</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.8 <a href=
-    "#feature-clockMode">#clockMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.9 <a href=
-    "#feature-clockMode-gps">#clockMode-gps</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.10 <a href=
-    "#feature-clockMode-local">#clockMode-local</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.11 <a href=
-    "#feature-clockMode-utc">#clockMode-utc</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.12 <a href=
-    "#feature-color">#color</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.13 <a href=
-    "#feature-content">#content</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.14 <a href=
-    "#feature-core">#core</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.15 <a href=
-    "#feature-direction">#direction</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.16 <a href=
-    "#feature-display">#display</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.17 <a href=
-    "#feature-display-block">#display-block</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.18 <a href=
-    "#feature-display-inline">#display-inline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.19 <a href=
-    "#feature-display-region">#display-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.20 <a href=
-    "#feature-displayAlign">#displayAlign</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.21 <a href=
-    "#feature-dropMode">#dropMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.22 <a href=
-    "#feature-dropMode-dropNTSC">#dropMode-dropNTSC</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.23 <a href=
-    "#feature-dropMode-dropPAL">#dropMode-dropPAL</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.24 <a href=
-    "#feature-dropMode-nonDrop">#dropMode-nonDrop</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.25 <a href=
-    "#feature-extent">#extent</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.26 <a href=
-    "#feature-extent-region">#extent-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.27 <a href=
-    "#feature-extent-root">#extent-root</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.28 <a href=
-    "#feature-fontFamily">#fontFamily</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.29 <a href=
-    "#feature-fontFamily-generic">#fontFamily-generic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.30 <a href=
-    "#feature-fontFamily-non-generic">#fontFamily-non-generic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.31 <a href=
-    "#feature-fontSize">#fontSize</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.32 <a href=
-    "#feature-fontSize-anamorphic">#fontSize-anamorphic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.33 <a href=
-    "#feature-fontSize-isomorphic">#fontSize-isomorphic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.34 <a href=
-    "#feature-fontStyle">#fontStyle</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.35 <a href=
-    "#feature-fontStyle-italic">#fontStyle-italic</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.36 <a href=
-    "#feature-fontStyle-oblique">#fontStyle-oblique</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.37 <a href=
-    "#feature-fontWeight">#fontWeight</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.38 <a href=
-    "#feature-fontWeight-bold">#fontWeight-bold</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.39 <a href=
-    "#feature-frameRate">#frameRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.40 <a href=
-    "#feature-frameRateMultiplier">#frameRateMultiplier</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.41 <a href=
-    "#feature-layout">#layout</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.42 <a href=
-    "#feature-length">#length</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.43 <a href=
-    "#feature-length-cell">#length-cell</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.44 <a href=
-    "#feature-length-em">#length-em</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.45 <a href=
-    "#feature-length-integer">#length-integer</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.46 <a href=
-    "#feature-length-negative">#length-negative</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.47 <a href=
-    "#feature-length-percentage">#length-percentage</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.48 <a href=
-    "#feature-length-pixel">#length-pixel</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.49 <a href=
-    "#feature-length-positive">#length-positive</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.50 <a href=
-    "#feature-length-real">#length-real</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.51 <a href=
-    "#feature-lineBreak-uax14">#lineBreak-uax14</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.52 <a href=
-    "#feature-lineHeight">#lineHeight</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.53 <a href=
-    "#feature-markerMode">#markerMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.54 <a href=
-    "#feature-markerMode-continuous">#markerMode-continuous</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.55 <a href=
-    "#feature-markerMode-discontinuous">#markerMode-discontinuous</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.56 <a href=
-    "#feature-metadata">#metadata</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.57 <a href=
-    "#feature-nested-div">#nested-div</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.58 <a href=
-    "#feature-nested-span">#nested-span</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.59 <a href=
-    "#feature-opacity">#opacity</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.60 <a href=
-    "#feature-origin">#origin</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.61 <a href=
-    "#feature-overflow">#overflow</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.62 <a href=
-    "#feature-overflow-visible">#overflow-visible</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.63 <a href=
-    "#feature-padding">#padding</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.64 <a href=
-    "#feature-padding-1">#padding-1</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.65 <a href=
-    "#feature-padding-2">#padding-2</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.66 <a href=
-    "#feature-padding-3">#padding-3</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.67 <a href=
-    "#feature-padding-4">#padding-4</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.68 <a href=
-    "#feature-pixelAspectRatio">#pixelAspectRatio</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.69 <a href=
-    "#feature-presentation">#presentation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.70 <a href=
-    "#feature-profile">#profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.71 <a href=
-    "#feature-showBackground">#showBackground</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.72 <a href=
-    "#feature-structure">#structure</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.73 <a href=
-    "#feature-styling">#styling</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.74 <a href=
-    "#feature-styling-chained">#styling-chained</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.75 <a href=
-    "#feature-styling-inheritance-content">#styling-inheritance-content</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.76 <a href=
-    "#feature-styling-inheritance-region">#styling-inheritance-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.77 <a href=
-    "#feature-styling-inline">#styling-inline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.78 <a href=
-    "#feature-styling-nested">#styling-nested</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.79 <a href=
-    "#feature-styling-referential">#styling-referential</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.80 <a href=
-    "#feature-subFrameRate">#subFrameRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.81 <a href=
-    "#feature-textAlign">#textAlign</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.82 <a href=
-    "#feature-textAlign-absolute">#textAlign-absolute</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.83 <a href=
-    "#feature-textAlign-relative">#textAlign-relative</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.84 <a href=
-    "#feature-textDecoration">#textDecoration</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.85 <a href=
-    "#feature-textDecoration-over">#textDecoration-over</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.86 <a href=
-    "#feature-textDecoration-through">#textDecoration-through</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.87 <a href=
-    "#feature-textDecoration-under">#textDecoration-under</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.88 <a href=
-    "#feature-textOutline">#textOutline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.89 <a href=
-    "#feature-textOutline-blurred">#textOutline-blurred</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.90 <a href=
-    "#feature-textOutline-unblurred">#textOutline-unblurred</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.91 <a href=
-    "#feature-tickRate">#tickRate</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.92 <a href=
-    "#feature-timeBase-clock">#timeBase-clock</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.93 <a href=
-    "#feature-timeBase-media">#timeBase-media</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.94 <a href=
-    "#feature-timeBase-smpte">#timeBase-smpte</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.95 <a href=
-    "#feature-timeContainer">#timeContainer</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.96 <a href=
-    "#feature-time-clock">#time-clock</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.97 <a href=
-    "#feature-time-clock-with-frames">#time-clock-with-frames</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.98 <a href=
-    "#feature-time-offset">#time-offset</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.99 <a href=
-    "#feature-time-offset-with-frames">#time-offset-with-frames</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.100 <a href=
-    "#feature-time-offset-with-ticks">#time-offset-with-ticks</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.101 <a href=
-    "#feature-timing">#timing</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.102 <a href=
-    "#feature-transformation">#transformation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.103 <a href=
-    "#feature-unicodeBidi">#unicodeBidi</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.104 <a href=
-    "#feature-visibility">#visibility</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.105 <a href=
-    "#feature-visibility-block">#visibility-block</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.106 <a href=
-    "#feature-visibility-inline">#visibility-inline</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.107 <a href=
-    "#feature-visibility-region">#visibility-region</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.108 <a href=
-    "#feature-wrapOption">#wrapOption</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.109 <a href=
-    "#feature-writingMode">#writingMode</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.110 <a href=
-    "#feature-writingMode-vertical">#writingMode-vertical</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.111 <a href=
-    "#feature-writingMode-horizontal">#writingMode-horizontal</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.112 <a href=
-    "#feature-writingMode-horizontal-lr">#writingMode-horizontal-lr</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.113 <a href=
-    "#feature-writingMode-horizontal-rl">#writingMode-horizontal-rl</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;D.1.114 <a href=
-    "#feature-zIndex">#zIndex</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;D.2 <a href="#feature-support">Feature
-    Support</a><br>
-    E <a href="#extensions">Extensions</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;E.1 <a href="#extension-designations">Extension
-    Designations</a><br>
-    F <a href="#profiles">Profiles</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;F.1 <a href="#profile-dfxp-transformation">DFXP
-    Transformation Profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;F.2 <a href="#profile-dfxp-presentation">DFXP
-    Presentation Profile</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;F.3 <a href="#profile-dfxp-full">DFXP Full
-    Profile</a><br>
-    G <a href="#references">References</a><br>
-    H <a href="#other-references">Other References</a> (Non-Normative)<br>
-    I <a href="#requirements">Requirements</a> (Non-Normative)<br>
-    J <a href="#derivation">Vocabulary Derivation</a> (Non-Normative)<br>
-    &nbsp;&nbsp;&nbsp;&nbsp;J.1 <a href="#d3e18638">Element Derivation</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;J.2 <a href="#d3e19117">Attribute
-    Derivation</a><br>
-    K <a href="#qa">QA Framework Compliance</a> (Non-Normative)<br>
-    &nbsp;&nbsp;&nbsp;&nbsp;K.1 <a href="#d3e20003">Requirements</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;K.2 <a href="#d3e20167">Guidelines</a><br>
-    L <a href="#streaming">Streaming TTML Content</a> (Non-Normative)<br>
-    M <a href="#concrete-encoding">Concrete Encoding</a> (Non-Normative)<br>
-    N <a href="#time-expression-semantics">Time Expression Semantics</a>
-    (Non-Normative)<br>
-    &nbsp;&nbsp;&nbsp;&nbsp;N.1 <a href=
-    "#time-expression-semantics-clock">Clock Time Base</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;N.2 <a href=
-    "#time-expression-semantics-media">Media Time Base</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;N.3 <a href=
-    "#time-expression-semantics-smpte">SMPTE Time Base</a><br>
-    O <a href="#common-styling">Common Caption Style Examples</a>
-    (Non-Normative)<br>
-    &nbsp;&nbsp;&nbsp;&nbsp;O.1 <a href="#pop-on-example">Pop-On Caption
-    Example</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;O.2 <a href="#roll-up-example">Roll-Up Caption
-    Example</a><br>
-    &nbsp;&nbsp;&nbsp;&nbsp;O.3 <a href="#paint-on-example">Paint-On Caption
-    Example</a><br>
-    P <a href="#acknowledgments">Acknowledgments</a> (Non-Normative)<br></p>
-  </div>
-  <hr>
-
-  <div class="body">
-    <div class="div1">
-      <h2><a id="intro" name="intro"></a>1 Introduction</h2>
-
-      <p><em>Unless specified otherwise, this section and its sub-sections are
-      non-normative.</em></p>
-
-      <p>The Timed Text Markup Language (TTML) 1.0 provides a standardized
-      representation of a particular subset of textual information with which
-      stylistic, layout, and timing semantics are associated by an author or an
-      authoring system for the purpose of interchange and processing.</p>
-
-      <p>TTML is expressly designed to meet only a limited set of requirements
-      established by <a href="#ttaf1-req">[TTAF1-REQ]</a>, and summarized in
-      <a href="#requirements"><b>I Requirements</b></a>. In particular, only
-      those requirements which service the need of performing interchange with
-      existing, legacy distribution systems are satisfied.</p>
-
-      <p>In addition to being used for interchange among legacy distribution
-      content formats, TTML Content may be used directly as a distribution
-      format (as implied by the acronym DFXP), providing, for example, a
-      standard content format to reference from a <code>&lt;track&gt;</code>
-      element in an HTML5 document, or a <code>&lt;text&gt;</code> or
-      <code>&lt;textstream&gt;</code> media element in a <a href=
-      "#smil21">[SMIL 2.1]</a> document. Certain properties of TTML support
-      streamability of content, as described in <a href="#streaming"><b>L
-      Streaming TTML Content</b></a>.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>While TTML was not expressly designed for direct (embedded)
-        integration into an HTML or a SMIL document instance, such integration
-        is not precluded.</p>
-      </div>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>In some contexts of use, it may be appropriate to employ animated
-        content to depict sign language representations of the same content as
-        expressed by a Timed Text <em>Document Instance</em>. This use case is
-        not explicitly addressed by TTML mechanisms, but may be addressed by
-        some external multimedia integration technology, such as SMIL.</p>
-      </div>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>In previous drafts of this specification, TTML was referred to as
-        DFXP (Distribution Format Exchange Profile). This latter term is
-        retained for historical reasons in certain contexts, such as profile
-        names and designators, and the short name <code>ttaf1-dfxp</code> used
-        in URLs to refer to this specification.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="model" name="model"></a>1.1 System Model</h3>
-
-        <p>Use of TTML is intended to function in a wider context of Timed Text
-        Authoring and Distribution mechanisms that are based upon the system
-        model depicted in <a href="#model-graphic"><b>Figure 1 – System
-        Model</b></a>, wherein the Timed Text Markup Language serves as a
-        bidirectional interchange format among a heterogeneous collection of
-        authoring systems, and as a unidirectional interchange format to a
-        heterogeneous collection of distribution formats after undergoing
-        transcoding or compilation to the target distribution formats as
-        required, and where one particular distribution format is TTML (labeled
-        as "DFXP" in the figure).</p><a id="model-graphic" name=
-        "model-graphic"></a>
-
-        <table class="example-images">
-          <caption>
-            Figure 1 – System Model
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/model.png" alt="System Model"></td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-
-      <div class="div2">
-        <h3><a id="example" name="example"></a>1.2 Document Example</h3>
-
-        <p>A TTML <em>Document Instance</em> consists of a <code>tt</code>
-        document element that contains a header and a body, where the header
-        specifies document level metadata, styling definitions and layout
-        definitions, and the body specifies text content intermixed with
-        references to style and layout information and inline styling and
-        timing information.</p><a id="ttml-example-document-structure" name=
-        "ttml-example-document-structure"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Document Structure
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
-  &lt;head&gt;
-    &lt;metadata/&gt;
-    &lt;styling/&gt;
-    &lt;layout/&gt;
-  &lt;/head&gt;
-  &lt;body/&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Document level metadata may specify a document title, description,
-        and copyright information. In addition, arbitrary metadata drawn from
-        other namespaces may be specified.</p><a id="ttml-example-metadata"
-        name="ttml-example-metadata"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Metadata
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
-  &lt;ttm:title&gt;Timed Text TTML Example&lt;/ttm:title&gt;
-  &lt;ttm:copyright&gt;The Authors (c) 2006&lt;/ttm:copyright&gt;
-&lt;/metadata&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Styling information may be specified in the form of style
-        specification definitions that are referenced by layout and content
-        information, specified inline with content information, or both.</p>
-
-        <p>In <a href="#ttml-example-styling"><b>Example Fragment – TTML
-        Styling</b></a>, four style sets of specifications are defined, with
-        one set serving as a collection of default styles.</p><a id=
-        "ttml-example-styling" name="ttml-example-styling"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Styling
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;styling xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;!-- s1 specifies default color, font, and text alignment --&gt;
-  &lt;style xml:id="s1"
-    tts:color="white"
-    tts:fontFamily="proportionalSansSerif"
-    tts:fontSize="22px"
-    tts:textAlign="center"
-  /&gt;
-  &lt;!-- alternative using yellow text but otherwise the same as style s1 --&gt;
-  &lt;style xml:id="s2" style="s1" tts:color="yellow"/&gt;
-  &lt;!-- a style based on s1 but justified to the right --&gt;
-  &lt;style xml:id="s1Right" style="s1" tts:textAlign="end" /&gt;     
-  &lt;!-- a style based on s2 but justified to the left --&gt;
-  &lt;style xml:id="s2Left" style="s2" tts:textAlign="start" /&gt;
-&lt;/styling&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Layout information defines one or more regions into which content is
-        intended to be presented. A region definition may reference one or more
-        sets of style specifications in order to permit content flowed in the
-        region to inherit from these styles. In <a href=
-        "#ttml-example-layout"><b>Example Fragment – TTML Layout</b></a>, the
-        region definition makes reference to style specification
-        <code>s1</code> augmented by specific inline styles which, together,
-        allow content flowed into the region to inherit from the region's
-        styles (in the case that a style is not already explicitly specified on
-        content or inherited via the content hierarchy.)</p><a id=
-        "ttml-example-layout" name="ttml-example-layout"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Layout
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;layout xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;region xml:id="subtitleArea"
-    style="s1"
-    tts:extent="560px 62px"
-    tts:padding="5px 3px"
-    tts:backgroundColor="black"
-    tts:displayAlign="after"
-  /&gt;
-&lt;/layout&gt;  
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The content of a <em>Document Instance</em> is expressed in its
-        body, which is organized in terms of block and inline text elements.
-        The hierarchical organization of content elements serves a primary role
-        in determining both spatial and temporal relationships. For example, in
-        <a href="#ttml-example-body"><b>Example Fragment – TTML Body</b></a>,
-        each paragraph (<code>p</code> element) is flowed into its target
-        region in the specified lexical order; furthermore, the active time
-        interval of each paragraph is timed in accordance to its parent or
-        sibling according to the applicable time containment semantics — in
-        this case, the division parent is interpreted (by default) as a
-        parallel time container.</p><a id="ttml-example-body" name=
-        "ttml-example-body"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – TTML Body
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;body region="subtitleArea"&gt;
-  &lt;div&gt;
-    &lt;p xml:id="subtitle1" begin="0.76s" end="3.45s"&gt;
-      It seems a paradox, does it not,
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle2" begin="5.0s" end="10.0s"&gt;
-      that the image formed on&lt;br/&gt;
-      the Retina should be inverted?
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle3" begin="10.0s" end="16.0s" style="s2"&gt;
-      It is puzzling, why is it&lt;br/&gt;
-      we do not see things upside-down?
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle4" begin="17.2s" end="23.0s"&gt;
-      You have never heard the Theory,&lt;br/&gt;
-      then, that the Brain also is inverted?
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle5" begin="23.0s" end="27.0s" style="s2"&gt;
-      No indeed! What a beautiful fact!
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle6a" begin="28.0s" end="34.6s" style="s2Left"&gt;
-      But how is it proved?
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle6b" begin="28.0s" end="34.6s" style="s1Right"&gt;
-      Thus: what we call
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle7" begin="34.6s" end="45.0s" style="s1Right"&gt;
-      the vertex of the Brain&lt;br/&gt;
-      is really its base
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle8" begin="45.0s" end="52.0s" style="s1Right"&gt;
-      and what we call its base&lt;br/&gt;
-      is really its vertex,
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle9a" begin="53.5s" end="58.7s"&gt;
-      it is simply a question of nomenclature.
-    &lt;/p&gt;
-    &lt;p xml:id="subtitle9b" begin="53.5s" end="58.7s" style="s2"&gt;
-      How truly delightful!
-    &lt;/p&gt;
-  &lt;/div&gt;    
-&lt;/body&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The first subtitle <a href="#ttml-example-subtitle-1"><b>Subtitle 1
-        – Time Interval [0.76, 3.45)</b></a> is presented during the time
-        interval 0.76 to 3.45 seconds. This subtitle inherits its font family,
-        font size, foreground color, and text alignment from the region into
-        which it is presented. Since no region is explicitly specified on the
-        paragraph, the nearest ancestor that specifies a region determines the
-        targeted region. Note also that content is presented at the bottom
-        (after edge) of the containing region due to the
-        <code>tts:displayAlign="after"</code> being specified on the region
-        definition.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The notation "[<em>X</em>,<em>Y</em>]" denotes a closed interval
-          from <em>X</em> to <em>Y</em>, including <em>X</em> and <em>Y</em>;
-          "[<em>X</em>,<em>Y</em>)" denotes a right half-open interval from
-          <em>X</em> to <em>Y</em>, including <em>X</em> but not including
-          <em>Y</em>; "(<em>X</em>,<em>Y</em>]" denotes a left half-open
-          interval from <em>X</em> to <em>Y</em>, not including <em>X</em> but
-          including <em>Y</em>; "(<em>X</em>,<em>Y</em>)" denotes an open
-          interval from <em>X</em> to <em>Y</em>, not including <em>X</em> or
-          <em>Y</em>.</p>
-        </div><a id="ttml-example-subtitle-1" name=
-        "ttml-example-subtitle-1"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 1 – Time Interval [0.76, 3.45)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle1.png" alt="Subtitle 1"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The second subtitle continues with the default style, except that it
-        contains two lines of text with an intervening author-specified line
-        break. Note the effects of the use of
-        <code>tts:textAlign="center"</code> to specify the paragraph's
-        alignment in the inline progression direction.</p><a id=
-        "ttml-example-subtitle-2" name="ttml-example-subtitle-2"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 2 – Time Interval [5.0, 10.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle2.png" alt="Subtitle 2"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The third subtitle continues, using a variant style which overrides
-        the default style's foreground color with a different color.</p><a id=
-        "ttml-example-subtitle-3" name="ttml-example-subtitle-3"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 3 – Time Interval [10.0, 16.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle3.png" alt="Subtitle 3"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The fourth subtitle reverts to the default style.</p><a id=
-        "ttml-example-subtitle-4" name="ttml-example-subtitle-4"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 4 – Time Interval [17.2, 23.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle4.png" alt="Subtitle 4"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The fifth subtitle continues, again using a variant style which
-        overrides the default style's foreground color with a different
-        color.</p><a id="ttml-example-subtitle-5" name=
-        "ttml-example-subtitle-5"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 5 – Time Interval [23.0, 27.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle5.png" alt="Subtitle 5"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>During the next active time interval, two distinct subtitles are
-        simultaneously active, with the paragraphs expressing each subtitle
-        using different styles that override color and paragraph text alignment
-        of the default style. Note that the flow order is determined by the
-        lexical order of elements as they appear in the content
-        hierarchy.</p><a id="ttml-example-subtitle-6" name=
-        "ttml-example-subtitle-6"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitles 6a and 6b – Time Interval [28.0, 34.6)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle6.png" alt=
-              "Subtitles 6a and 6b"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The next subtitle is specified in a similar manner using a style
-        override to give the paragraph right (end) justification in the inline
-        progression direction.</p><a id="ttml-example-subtitle-7" name=
-        "ttml-example-subtitle-7"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 7 – Time Interval [34.6, 45.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle7.png" alt=
-              "Subtitles 7a and 7b"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The eighth subtitle uses the same style override as the previous
-        subtitle in order to maintain the right (end) justification of the
-        paragraph.</p><a id="ttml-example-subtitle-8" name=
-        "ttml-example-subtitle-8"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitle 8 – Time Interval [47.3, 49.0)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle8.png" alt="Subtitle 8"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>During the final (ninth) active time interval, two distinct
-        subtitles are again simultaneously active, but with a different style
-        applied to the second paragraph to override the default color. Note
-        that the flow order is determined by the lexical order of elements as
-        they appear in the content hierarchy.</p><a id=
-        "ttml-example-subtitle-9" name="ttml-example-subtitle-9"></a>
-
-        <table class="example-images">
-          <caption>
-            Subtitles 9a and 9b – Time Interval [53.5, 58.7)
-          </caption>
-
-          <tbody>
-            <tr>
-              <td><img src="images/subtitle9.png" alt=
-              "Subtitles 9a and 9b"></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The examples shown above demonstrate the primary types of
-        information that may be authored using TTML: metadata, styling, layout,
-        timing, and content. In typical cases, styling and layout information
-        are separately specified in a <em>Document Instance</em>. Content
-        information is expressed in a hierarchical fashion that embodies the
-        organization of both spatial (flow) and timing information. Content
-        makes direct or indirect references to styling and layout information
-        and may specify inline overrides to styling.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="definitions" name="definitions"></a>2 Definitions</h2>
-
-      <div class="div2">
-        <h3><a id="acronyms" name="acronyms"></a>2.1 Acronyms</h3>
-
-        <table class="acronyms" summary="Glossary List">
-          <tr>
-            <td class="label"><b>DFXP</b></td>
-
-            <td class="def">
-              <p>Distribution Format Exchange Profile</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TT</b></td>
-
-            <td class="def">
-              <p>Timed Text</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TTML</b></td>
-
-            <td class="def">
-              <p>Timed Text Markup Language</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TTAF</b></td>
-
-            <td class="def">
-              <p>Timed Text Authoring Format</p>
-            </td>
-          </tr>
-
-          <tr>
-            <td class="label"><b>TTWG</b></td>
-
-            <td class="def">
-              <p>Timed Text Working Group</p>
-            </td>
-          </tr>
-        </table>
-      </div>
-
-      <div class="div2">
-        <h3><a id="terms" name="terms"></a>2.2 Terminology</h3>
-
-        <dl>
-          <dt class="label">Abstract Document Instance</dt>
-
-          <dd>
-            <p>An instance of an abstract data set as represented by a
-            <em>Reduced XML Infoset</em>.</p>
-          </dd>
-
-          <dt class="label">Abstract Document Type</dt>
-
-          <dd>
-            <p>A set of constraints that defines a class of <em>XML Information
-            Sets</em> <a href="#infoset">[XML InfoSet]</a>.</p>
-          </dd>
-
-          <dt class="label">Attribute Information Item</dt>
-
-          <dd>
-            <p>Each specified or defaulted attribute of an XML document
-            corresponds with an attribute information item as defined by
-            <a href="#infoset">[XML InfoSet]</a>, §2.3.</p>
-          </dd>
-
-          <dt class="label">Character Information Item</dt>
-
-          <dd>
-            <p>Each data character appearing in an XML document corresponds
-            with a character information item as defined by <a href=
-            "#infoset">[XML InfoSet]</a>, §2.6.</p>
-          </dd>
-
-          <dt class="label">Computed Cell Size</dt>
-
-          <dd>
-            <p>The size (extent) of a cell computed by dividing the width of
-            the <em>Root Container Region</em> (in pixels) by the column count,
-            i.e., the number of cells in the horizontal axis, and by dividing
-            the height of the <em>Root Container Region</em> (in pixels) by the
-            row count, i.e., the number of cells in the vertical axis, where
-            the column and row counts are determined by the
-            <code>ttp:cellResolution</code> parameter attribute.</p>
-          </dd>
-
-          <dt class="label">Content Processor</dt>
-
-          <dd>
-            <p>A processing system capable of importing (receiving) Timed Text
-            Markup Language content for the purpose of transforming,
-            presenting, or otherwise processing the content.</p>
-          </dd>
-
-          <dt class="label">Content Profile</dt>
-
-          <dd>
-            <p>A collection of features and extensions that are (or may be)
-            employed by Timed Text Markup Language content.</p>
-          </dd>
-
-          <dt class="label">Content Region</dt>
-
-          <dd>
-            <p>A logical region into which rendered content is placed when
-            modeling or performing presentation processing.</p>
-          </dd>
-
-          <dt class="label">Document Instance</dt>
-
-          <dd>
-            <p>A concrete realization of a Timed Text Markup Language document,
-            where the concrete form is specific to the context of reference.
-            For example, a sequence of bytes that represents an XML
-            serialization of a Timed Text document, an internal, parsed
-            representation of such a Timed Text document, etc.</p>
-          </dd>
-
-          <dt class="label">Document Interchange Context</dt>
-
-          <dd>
-            <p>The implied context or environment external to a <em>Content
-            Processor</em> in which document interchange occurs, and in which
-            out-of-band protocols or specifications may define certain
-            behavioral defaults, such as an implied <em>Content
-            Profile</em>.</p>
-          </dd>
-
-          <dt class="label">Document Processing Context</dt>
-
-          <dd>
-            <p>The implied context or environment internal to a <em>Content
-            Processor</em> in which document processing occurs, and in which
-            out-of-band protocols or specifications may define certain
-            behavioral defaults, such as the establishment or creation of a
-            <em>Synthetic Document Syncbase</em>.</p>
-          </dd>
-
-          <dt class="label">Element Information Item</dt>
-
-          <dd>
-            <p>Each element appearing in an XML document corresponds with an
-            element information item as defined by <a href="#infoset">[XML
-            InfoSet]</a>, §2.2.</p>
-          </dd>
-
-          <dt class="label">Exchange Profile</dt>
-
-          <dd>
-            <p>A content profile that serves a set of needs for content
-            interchange.</p>
-          </dd>
-
-          <dt class="label">Extension</dt>
-
-          <dd>
-            <p>A syntactic or semantic expression or capability that is defined
-            and labeled (using a extension designation) in another (public or
-            private) specification.</p>
-          </dd>
-
-          <dt class="label">Feature</dt>
-
-          <dd>
-            <p>A syntactic or semantic expression or capability that is defined
-            and labeled (using a feature designation) in this specification (or
-            a future revision of this specification).</p>
-          </dd>
-
-          <dt class="label">Presentation Processor</dt>
-
-          <dd>
-            <p>A <em>Content Processor</em> which purpose is to layout, format,
-            and render, i.e., to present, <em>Timed Text Markup Language</em>
-            content by applying the presentation semantics defined in this
-            specification.</p>
-          </dd>
-
-          <dt class="label">Processor</dt>
-
-          <dd>
-            <p>See <em>Content Processor</em>.</p>
-          </dd>
-
-          <dt class="label">Processor Profile</dt>
-
-          <dd>
-            <p>A collection of features and extensions that must or may be
-            implemented (supported) by a content processor.</p>
-          </dd>
-
-          <dt class="label">Profile Definition Document</dt>
-
-          <dd>
-            <p>A document that defines a specific collection of features and
-            extensions for which support is required or optional in a recipient
-            content processor.</p>
-          </dd>
-
-          <dt class="label">Region</dt>
-
-          <dd>
-            <p>A logical construct that models authorial intention regarding
-            desired or potential presentation processing, and which is
-            represented as a rectangular area of a presentation surface into
-            which content is composed and rendered during presentation
-            processing.</p>
-          </dd>
-
-          <dt class="label">Reduced XML Infoset</dt>
-
-          <dd>
-            <p>An XML Information Set <a href="#infoset">[XML InfoSet]</a> that
-            satisfies the constraints specify by <a href=
-            "#reduced-infoset"><b>A Reduced XML Infoset</b></a>.</p>
-          </dd>
-
-          <dt class="label">Related Media Object</dt>
-
-          <dd>
-            <p>A (possibly null) media object associated with or otherwise
-            related to a <em>Document Instance</em>. For example, an aggregate
-            audio/video media object for which a <em>Document Instance</em>
-            provides caption or subtitle information, and with which that
-            <em>Document Instance</em> is associated.</p>
-          </dd>
-
-          <dt class="label">Related Media Object Region</dt>
-
-          <dd>
-            <p>When a non-null <em>Related Media Object</em> exists, the region
-            in which a presentation processor presents this media object.</p>
-          </dd>
-
-          <dt class="label">Root Container Region</dt>
-
-          <dd>
-            <p>A logical region that establishes a coordinate system into which
-            <em>Document Instance</em> content regions are placed and
-            optionally clipped.</p>
-          </dd>
-
-          <dt class="label">Root Temporal Extent</dt>
-
-          <dd>
-            <p>The temporal extent (interval) defined by the temporal beginning
-            and ending of a <em>Document Instance</em> in relationship with
-            some external application or presentation context.</p>
-          </dd>
-
-          <dt class="label">SMPTE Time Code</dt>
-
-          <dd>
-            <p>A time code whose format and semantics are established by
-            <a href="#smpte12m">[SMPTE 12M]</a>, which may be embedded into or
-            otherwise associated with media content, such as a broadcast
-            audio/video stream.</p>
-          </dd>
-
-          <dt class="label">Synthetic Document Syncbase</dt>
-
-          <dd>
-            <p>A document level <a href=
-            "http://www.w3.org/TR/2005/REC-SMIL2-20051213/smil-timing.html#Timing-Syncbases">
-            syncbase</a> <a href="#smil21">[SMIL 2.1]</a>, § 10.7.1,
-            synthesized or otherwise established by the <em>Document Processing
-            Context</em> in accordance with the <em>Related Media Object</em>
-            or other processing criteria.</p>
-          </dd>
-
-          <dt class="label">Synthetic SMPTE Document Syncbase</dt>
-
-          <dd>
-            <p>A <em>Synthetic Document Syncbase</em> constructed from
-            <em>SMPTE Time Code</em> values embedded in or associated with the
-            <em>Related Media Object</em> or otherwise determined by the
-            <em>Document Processing Context</em>.</p>
-          </dd>
-
-          <dt class="label">Timed Text</dt>
-
-          <dd>
-            <p>Textual information that is intrinsically or extrinsically
-            associated with timing information.</p>
-          </dd>
-
-          <dt class="label">Timed Text Markup Language</dt>
-
-          <dd>
-            <p>A content type that represents timed text media for the purpose
-            of interchange among authoring systems.</p>
-          </dd>
-
-          <dt class="label">Timed Text Authoring System</dt>
-
-          <dd>
-            <p>A content authoring system capable of importing and exporting
-            Timed Text Markup Language content.</p>
-          </dd>
-
-          <dt class="label">Transformation Processor</dt>
-
-          <dd>
-            <p>A <em>Content Processor</em> which purpose is to transform or
-            otherwise rewrite <em>Timed Text Markup Language</em> content to
-            either <em>Timed Text Markup Language</em> or to another
-            (arbitrary) content format. An example of the first is a processor
-            that removes or rewrites TTML features so as to conform to a
-            profile of TTML. An example of the latter is a processor that
-            translates TTML into a completely different timed text format.
-            Because this specification does not otherwise define a target
-            profile or format for transformation processing, no further
-            transformation semantics are defined by this specification.</p>
-          </dd>
-
-          <dt class="label">Valid Abstract Document Instance</dt>
-
-          <dd>
-            <p>An <em>Abstract Document Instance</em> which has been assessed
-            for validity and found to be valid as defined by <a href=
-            "#doctypes"><b>4 Document Types</b></a>.</p>
-          </dd>
-        </dl>
-      </div>
-
-      <div class="div2">
-        <h3><a id="conventions" name="conventions"></a>2.3 Documentation
-        Conventions</h3>
-
-        <p>Within normative prose in this specification, the words
-        <em>may</em>, <em>should</em>, and <em>must</em> are defined as
-        follows:</p>
-
-        <dl class="conformance-keywords">
-          <dt class="label">may</dt>
-
-          <dd>
-            <p>Conforming documents and/or TTML processors are permitted to,
-            but need not behave as described.</p>
-          </dd>
-
-          <dt class="label">should</dt>
-
-          <dd>
-            <p>Conforming documents and/or TTML processors are strongly
-            recommended to, but need not behave as described.</p>
-          </dd>
-
-          <dt class="label">must</dt>
-
-          <dd>
-            <p>Conforming documents and/or TTML processors are required to
-            behave as described; otherwise, they are in error.</p>
-          </dd>
-        </dl>
-
-        <p>If normative specification language takes an imperative form, then
-        it is to be treated as if the term <span class="strong">must</span>
-        applies. Furthermore, if normative language takes a declarative form,
-        and this language is governed by <span class="strong">must</span>, then
-        it is also to be treated as if the term <span class=
-        "strong">must</span> applies.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>For example, the phrases "treat X as an error" and "consider X as
-          an error" are to be read as mandatory requirements in the context of
-          use. Similarly, if the specification prose is "X must apply", "X
-          applies", or "X is mandatory", and "X" is further defined as "X is Y
-          and Z", then, by transitive closure, this last declarative phrase is
-          to be read as "Y is mandatory" and "Z is mandatory" in the context of
-          use.</p>
-        </div>
-
-        <p>All normative syntactic definitions of XML representations and other
-        related terms are depicted with a light yellow-orange background color
-        and labeled as "XML Representation" or "Syntax Representation", such as
-        in the following:</p><a id="elt-syntax-example" name=
-        "elt-syntax-example"></a>
-
-        <table class="syntax">
-          <caption>
-            XML Representation – Element Information Item: example
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;example
-  <span class="reqattr">count</span> = integer
-  size = (<em>large</em>|<em>medium</em>|<em>small</em>) : medium&gt;
-  <em>Content:</em> (all | any*)
-&lt;/example&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>In an XML representation, bold-face attribute names (e.g.
-        <span class="strong">count</span> above) indicate a required attribute
-        information item, and the rest are optional. Where an attribute
-        information item has an enumerated type definition, the values are
-        shown separated by vertical bars, as for <code>size</code> above; if
-        there is a default value, it is shown following a colon. Where an
-        attribute information item has a built-in simple type definition
-        defined in <a href="#xsd-2">[XML Schema Part 2]</a>, a hyperlink to its
-        definition therein is given.</p>
-
-        <p>The allowed content of the information item is shown as a grammar
-        fragment, using the Kleene operators <code>?</code>, <code>*</code> and
-        <code>+</code>. Each element name therein is a hyperlink to its own
-        illustration.</p>
-
-        <p>The term linear white-space (LWSP) is to be interpreted as a
-        non-empty sequence of SPACE (U+0020), TAB (U+0009), CARRIAGE RETURN
-        (U+000D), or LINE FEED (U+000A), which corresponds to production [3]
-        <code>S</code> as defined by <a href="#xml10">[XML 1.0]</a>.</p>
-
-        <p>All content of this specification that is not explicitly marked as
-        non-normative is considered to be normative. If a section or appendix
-        header contains the expression "Non-Normative", then the entirety of
-        the section or appendix is considered non-normative.</p>
-
-        <p>All paragraphs marked as a <span class="strong">Note</span> are
-        considered non-normative.</p>
-
-        <p>Example code fragments are depicted with a light blue-green
-        background color and labeled as "Example Fragment", such as in the
-        following:</p><a id="example-fragment-1" name="example-fragment-1"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – Sample
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
-  &lt;head&gt;
-    &lt;metadata/&gt;
-    &lt;styling/&gt;
-    &lt;layout/&gt;
-  &lt;/head&gt;
-  &lt;body/&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="conformance" name="conformance"></a>3 Conformance</h2>
-
-      <p>This section specifies the general conformance requirements for TTML
-      Content and processors.</p>
-
-      <div class="div2">
-        <h3><a id="conformance-content" name="conformance-content"></a>3.1
-        Content Conformance</h3>
-
-        <p>A TTML <em>Document Instance</em> conforms to this specification if
-        the following criteria are satisfied:</p>
-
-        <ol class="enumar">
-          <li>
-            <p>When transporting a <em>Document Instance</em> in a <em>Document
-            Interchange Context</em> in which a Media Type <a href=
-            "#media-types">[Media Types]</a> identifies the content type of the
-            interchanged <em>Document Instance</em>, then the specified media
-            type is <code>application/ttml+xml</code> in conformance with
-            <a href="#xml-media">[XML Media Types]</a> § 7, with which an
-            optional <code>profile</code> parameter may appear, the value of
-            which conforms to a profile designator as defined by <a href=
-            "#vocabulary-profiles"><b>5.2 Profiles</b></a>.</p>
-          </li>
-
-          <li>
-            <p>The <em>Document Instance</em> is or can be represented as a
-            Reduced XML Infoset as defined by <a href="#reduced-infoset"><b>A
-            Reduced XML Infoset</b></a>.</p>
-          </li>
-
-          <li>
-            <p>The Reduced XML Infoset that corresponds to the <em>Document
-            Instance</em> is or can be associated with one of the <em>Abstract
-            Document Types</em> defined by <a href="#doctypes"><b>4 Document
-            Types</b></a>.</p>
-          </li>
-
-          <li>
-            <p>The <em>Reduced XML Infoset</em> that corresponds to the
-            <em>Document Instance</em> is a <em>Valid Abstract Document
-            Instance</em> of the associated <em>Abstract Document
-            Type</em>.</p>
-          </li>
-
-          <li>
-            <p>The <em>Reduced XML Infoset</em> satisfies all additional
-            mandatory syntactic and semantic constraints defined by this
-            specification. In addition, this Infoset should satisfy the web
-            content accessibility guidelines specified by <a href=
-            "#wcag">[WCAG]</a>.</p>
-          </li>
-        </ol>
-      </div>
-
-      <div class="div2">
-        <h3><a id="conformance-processor" name="conformance-processor"></a>3.2
-        Processor Conformance</h3>
-
-        <div class="div3">
-          <h4><a id="conformance-generic-processor" name=
-          "conformance-generic-processor"></a>3.2.1 Generic Processor
-          Conformance</h4>
-
-          <p>A TTML <em>Content Processor</em> conforms to this specification
-          if the following generic processor criteria are satisfied:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>The processor provides at least one mechanism for notionally
-              instantiating a Reduced XML Infoset representation of a
-              conformant <em>Document Instance</em>.</p>
-            </li>
-
-            <li>
-              <p>If a process does or can perform validation of a candidate
-              <em>Document Instance</em>, then it provides at least one
-              mechanism to implicitly or explicitly associate the <em>Reduced
-              XML Infoset</em> representation of a conformant <em>Document
-              Instance</em> with one of the <em>Abstract Document Types</em>
-              defined by <a href="#doctypes"><b>4 Document Types</b></a>.</p>
-            </li>
-
-            <li>
-              <p>The processor does not <em>a priori</em> reject or abort the
-              processing of a conformant <em>Document Instance</em> unless the
-              processor does not support some required (mandatory) feature
-              specified or implied by a TTML Content profile declared to apply
-              to the <em>Document Instance</em>.</p>
-            </li>
-
-            <li>
-              <p>The processor supports all mandatory processing semantics
-              defined by this specification.</p>
-
-              <div class="note">
-                <p class="prefix"><b>Note:</b></p>
-
-                <p>The phrase <em>mandatory semantics</em> refers to all
-                explicit use of the conformance key phrases <span class=
-                "strong">must</span> and <span class="strong">must not</span>
-                as well as any declarative statement that can be reasonably
-                inferred from such key phrases. For example, these mandatory
-                semantics include support for all features marked as mandatory
-                in <a href="#feature-support"><b>D.2 Feature
-                Support</b></a>.</p>
-              </div>
-            </li>
-
-            <li>
-              <p>If the processor supports some optional processing semantics
-              defined by this specification, then it does so in a manner
-              consistent with the defined semantics.</p>
-
-              <div class="note">
-                <p class="prefix"><b>Note:</b></p>
-
-                <p>The phrase <em>optional semantics</em> refers to all
-                explicit use of the conformance key phrases <span class=
-                "strong">should</span>, <span class="strong">should not</span>,
-                <span class="strong">may</span>, and <span class="strong">may
-                not</span>, as well as any declarative statement that can be
-                reasonably inferred from such key phrases. For example, these
-                optional semantics include support for all features marked as
-                optional in <a href="#feature-support"><b>D.2 Feature
-                Support</b></a>.</p>
-              </div>
-            </li>
-          </ol>
-        </div>
-
-        <div class="div3">
-          <h4><a id="conformance-transformation-processor" name=
-          "conformance-transformation-processor"></a>3.2.2 Transformation
-          Processor Conformance</h4>
-
-          <p>A TTML <em>Content Processor</em> is a conformant TTML
-          <em>Transformation Processor</em> if the following criteria are
-          satisfied:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>The processor satisfies all requirements specified by <a href=
-              "#conformance-generic-processor"><b>3.2.1 Generic Processor
-              Conformance</b></a>.</p>
-            </li>
-
-            <li>
-              <p>The processor supports the DFXP Transformation profile as
-              specified by <a href="#profile-dfxp-transformation"><b>F.1 DFXP
-              Transformation Profile</b></a>.</p>
-            </li>
-          </ol>
-        </div>
-
-        <div class="div3">
-          <h4><a id="conformance-presentation-processor" name=
-          "conformance-presentation-processor"></a>3.2.3 Presentation Processor
-          Conformance</h4>
-
-          <p>A TTML <em>Content Processor</em> is a conformant TTML
-          <em>Presentation Processor</em> if the following criteria are
-          satisfied:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>The processor satisfies all requirements specified by <a href=
-              "#conformance-generic-processor"><b>3.2.1 Generic Processor
-              Conformance</b></a>.</p>
-            </li>
-
-            <li>
-              <p>The processor supports the DFXP Presentation profile as
-              specified by <a href="#profile-dfxp-presentation"><b>F.2 DFXP
-              Presentation Profile</b></a>.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="claims" name="claims"></a>3.3 Claims</h3>
-
-        <p>Any claim of compliance with respect to the conformance of a TTML
-        <em>Document Instance</em> or <em>Content Processor</em> must make
-        reference to an implementation compliance statement (ICS).</p>
-
-        <p>An implementation compliance statement must identify all mandatory
-        and optional features of this specification that are satisfied by the
-        document instance or the content processor implementation. In
-        particular, the statement must identify the utilized or supported TTML
-        vocabulary profile(s) as defined by <a href=
-        "#vocabulary-profiles"><b>5.2 Profiles</b></a>, and, if a subset or
-        superset profile is used or supported, then what features are excluded
-        or included in the subset or superset profile.</p>
-
-        <p>A <em>Document Instance</em> for which a compliance claim is made
-        must specify either (1) a <code>ttp:profile</code> attribute on its
-        root <code>tt</code> element as defined by <a href=
-        "#parameter-attribute-profile"><b>6.2.8 ttp:profile</b></a> or (2) a
-        <code>ttp:profile</code> element as a child of the <code>head</code>
-        element as defined by <a href="#parameter-vocabulary-profile"><b>6.1.1
-        ttp:profile</b></a>.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="doctypes" name="doctypes"></a>4 Document Types</h2>
-
-      <p>This section defines the following TTML <em>Abstract Document
-      Types</em>:</p>
-
-      <ul>
-        <li>
-          <p><a href="#ttml-content-doctype"><b>4.1 TTML Content</b></a></p>
-        </li>
-      </ul>
-
-      <p>Each <em>Abstract Document Type</em> consists of the following
-      constraints:</p>
-
-      <ul>
-        <li>
-          <p>a non-empty collection of element types, where each element type
-          consists of a name, a (possibly empty) collection of attributes, and
-          a content specification</p>
-        </li>
-
-        <li>
-          <p>a non-empty collection of element types that may appear as the
-          document element</p>
-        </li>
-      </ul>
-
-      <p>An <em>Abstract Document Instance</em> may be assessed in terms of
-      validity, and is considered to be a <em>Valid Abstract Document
-      Instance</em> if it satisfies the following condition: if after</p>
-
-      <ol class="enumar">
-        <li>
-          <p>pruning all element information items whose names are not members
-          of the collection of element types defined by the associated
-          <em>Abstract Document Type</em>, then</p>
-        </li>
-
-        <li>
-          <p>pruning character information item children from any remaining
-          element in case that all character children of the element denote XML
-          whitespace characters and the element's type is defined as empty in
-          the associated <em>Abstract Document Type</em>, and then</p>
-        </li>
-
-        <li>
-          <p>pruning all attribute information items having expanded names such
-          that the namespace URI of the expanded names are not listed in
-          <a href="#namespace-vocab-table"><b>Table 1 – Namespaces</b></a>,</p>
-        </li>
-      </ol>
-
-      <p>then the document element is one of the document element types
-      permitted by the associated <em>Abstract Document Type</em>, the
-      descendants of the document element satisfy their respective element
-      type's content specifications, all required attributes are present, and
-      the declared value of each attribute satisfies the type declared by the
-      associated <em>Abstract Document Type</em>.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>While a conformant processor may not <em>a priori</em> reject a
-        conformant <em>Document Instance</em> that adheres to a supported
-        content profile, a given <em>Document Instance</em> may be constrained
-        by the author or authoring tool to satisfy a more restrictive
-        definition of validity.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="ttml-content-doctype" name="ttml-content-doctype"></a>4.1
-        TTML Content</h3>
-
-        <p>TTML Content is an <em>Abstract Document Type</em> of a profile of
-        the Timed Text Markup Language intended to be used for interchange
-        among distribution systems. This document type is defined in terms of
-        the element and attribute vocabulary specified in <a href=
-        "#vocabulary"><b>5 Vocabulary</b></a>.</p>
-
-        <p>This specification references two types of schemas that may be used
-        to validate a superset/subset of conformant TTML Content <em>Document
-        Instances</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#ttml-schema-rnc"><b>B.1 Relax NG Compact (RNC)
-            Schema</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#ttml-schema-xsd"><b>B.2 XML Schema Definition (XSD)
-            Schema</b></a></p>
-          </li>
-        </ul>
-
-        <p>The (root) document element of a TTML Content <em>Document
-        Instance</em> must be a <code>tt</code> element, as defined by <a href=
-        "#document-structure-vocabulary-tt"><b>7.1.1 tt</b></a>.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The schemas referenced by this specification do not validate all
-          syntactic constraints defined by this specification, and, as such,
-          represent a superset of conformant TTML Content. In particular,
-          performing validation with one of the above referenced schemas may
-          result in a <em>false positive</em> indication of validity. For
-          example, both the RNC and XSD schemas specify that a
-          <code>tts:fontFamily</code> attribute must satisfy the
-          <code>xs:string</code> XSD data type; however, this data type is a
-          superset of the values permitted to be used with the
-          <code>tts:fontFamily</code> attribute.</p>
-
-          <p>In addition, the RNC schema may produce a <em>false negative</em>
-          indication of validity when using the <code>xml:id</code> attribute
-          with an element in a foreign namespace, thus representing a subset of
-          conformant TTML Content. This is due to a specific limitation in
-          expressing wildcard patterns involving <code>xsd:ID</code> typed
-          attributes in Relax NG schemas. Note that this specification defines
-          the formal validity of a <em>Document Instance</em> to be based on an
-          <em>Abstract Document Instance</em> from which all foreign namespace
-          elements and attributes have been removed. Therefore, the exceptional
-          reporting of this false negative does not impact the formal
-          assessment of <em>Document Instance</em> validity.</p>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="vocabulary" name="vocabulary"></a>5 Vocabulary</h2>
-
-      <p>This section defines the namespaces, profiles, and vocabulary (as an
-      element and attribute catalog) of the Timed Text Markup Language (TTML)
-      as follows:</p>
-
-      <ul>
-        <li>
-          <p><a href="#vocabulary-namespaces"><b>5.1 Namespaces</b></a></p>
-        </li>
-
-        <li>
-          <p><a href="#vocabulary-profiles"><b>5.2 Profiles</b></a></p>
-        </li>
-
-        <li>
-          <p><a href="#vocabulary-overview"><b>5.3 Catalog</b></a></p>
-        </li>
-      </ul>
-
-      <div class="div2">
-        <h3><a id="vocabulary-namespaces" name="vocabulary-namespaces"></a>5.1
-        Namespaces</h3>
-
-        <p>The Timed Text Markup Language (TTML) employs a number of XML
-        Namespaces <a href="#xmlns10">[XML Namespaces 1.0]</a> for elements and
-        certain global attributes. The following table specifies this set of
-        namespaces and indicates the default prefix used within this
-        specification and the normative URI that denotes each namespace.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>In a specific <em>Document Instance</em>, it is not required that
-          the default prefixes shown below are used. Any prefix or namespace
-          binding that satisfies the constraints of XML Namespaces <a href=
-          "#xmlns10">[XML Namespaces 1.0]</a> may be used that is associated
-          with the specified namespace URI.</p>
-        </div><a id="namespace-vocab-table" name="namespace-vocab-table"></a>
-
-        <table class="common">
-          <caption>
-            Table 1 – Namespaces
-          </caption>
-          <col width="30%" span="1">
-          <col span="1">
-          <col span="1">
-
-          <tbody>
-            <tr>
-              <th>Name</th>
-
-              <th>Prefix</th>
-
-              <th>Value</th>
-            </tr>
-
-            <tr>
-              <td>TT</td>
-
-              <td><code>tt:</code></td>
-
-              <td><code>http://www.w3.org/ns/ttml</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Parameter</td>
-
-              <td><code>ttp:</code></td>
-
-              <td><code>http://www.w3.org/ns/ttml#parameter</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Style</td>
-
-              <td><code>tts:</code></td>
-
-              <td><code>http://www.w3.org/ns/ttml#styling</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Metadata</td>
-
-              <td><code>ttm:</code></td>
-
-              <td><code>http://www.w3.org/ns/ttml#metadata</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Profile</td>
-
-              <td><em>none</em></td>
-
-              <td><code>http://www.w3.org/ns/ttml/profile/</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Feature</td>
-
-              <td><em>none</em></td>
-
-              <td><code>http://www.w3.org/ns/ttml/feature/</code></td>
-            </tr>
-
-            <tr>
-              <td>TT Extension</td>
-
-              <td><em>none</em></td>
-
-              <td><code>http://www.w3.org/ns/ttml/extension/</code></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>If a reference to an element type is used in this specification
-          and the name of the element type is not namespace qualified, then the
-          TT Namespace applies.</p>
-
-          <p>For certain namespaces defined above, the default prefix is
-          specified as <em>none</em> if no XML vocabulary is defined in the
-          namespace by this specification (nor expected to be defined in a
-          future version of this specification). In such cases, the use of the
-          namespace URI is for purposes other than defining XML vocabulary,
-          e.g., for designating profiles, features, extensions and for
-          dereferencing standard profile definitions.</p>
-        </div>
-
-        <p>All TTML Namespaces are <a href=
-        "http://www.w3.org/2001/tag/doc/namespaceState#namespacedef"><em>mutable</em></a>
-        <a href="#nsstate">[NSState]</a>; all undefined names in these
-        namespaces are reserved for future standardization by the W3C.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="vocabulary-profiles" name="vocabulary-profiles"></a>5.2
-        Profiles</h3>
-
-        <p>The Timed Text Markup Language (TTML) employs a number of standard,
-        predefined profiles of its vocabulary and associated semantics. The
-        following table specifies this set of profiles, indicating a normative
-        name and designator for each predefined profile, and where each of
-        these profiles is formally elaborated in <a href="#profiles"><b>F
-        Profiles</b></a> or in another TTWG specification.</p><a id=
-        "profile-vocab-table" name="profile-vocab-table"></a>
-
-        <table class="common">
-          <caption>
-            Table 2 – Profiles
-          </caption>
-          <col width="25%" span="1">
-          <col span="1">
-
-          <tbody>
-            <tr>
-              <th>Name</th>
-
-              <th>Designator</th>
-            </tr>
-
-            <tr>
-              <td>DFXP Transformation</td>
-
-              <td>
-              <code>http://www.w3.org/ns/ttml/profile/dfxp-transformation</code></td>
-            </tr>
-
-            <tr>
-              <td>DFXP Presentation</td>
-
-              <td>
-              <code>http://www.w3.org/ns/ttml/profile/dfxp-presentation</code></td>
-            </tr>
-
-            <tr>
-              <td>DFXP Full</td>
-
-              <td><code>http://www.w3.org/ns/ttml/profile/dfxp-full</code></td>
-            </tr>
-
-            <tr>
-              <td>SDP US</td>
-
-              <td><code>http://www.w3.org/ns/ttml/profile/sdp-us</code></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>A profile designator must adhere to the <code>xsd:anyURI</code> data
-        type defined by <a href="#xsd-2">[XML Schema Part 2]</a>, §3.2.17. If
-        the profile designator is expressed as a relative URI, then it must be
-        absolutized by using the TT Profile Namespace value as the base
-        URI.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>For example, if a profile designator is expressed as
-          <code>dfxp-presentation</code>, then the absolutized profile
-          designator would be
-          <code>http://www.w3.org/ns/ttml/profile/dfxp-presentation</code>.</p>
-        </div>
-
-        <p>All profile designators which have the TT Profile Namespace as a
-        prefix but are otherwise not listed in <a href=
-        "#profile-vocab-table"><b>Table 2 – Profiles</b></a> are reserved for
-        future standardization, and must not be appear in a conformant
-        <em>Document Instance</em>. Nothwithstanding this constraint, a profile
-        designator is not restricted to the set of designators enumerated in
-        <a href="#profile-vocab-table"><b>Table 2 – Profiles</b></a>, but may
-        be any URI that feasibly dereferences a TTML <em>Profile Definition
-        Document</em> provided it does not use the TT Profile Namespace as a
-        prefix.</p>
-
-        <p>The profile of TTML that must be supported by a TTML <em>Content
-        Processor</em> in order to process a <em>Document Instance</em> is
-        determined either (1) by specifying a <code>ttp:profile</code>
-        attribute on the root <code>tt</code> element, as defined by <a href=
-        "#parameter-attribute-profile"><b>6.2.8 ttp:profile</b></a>, or (2) by
-        including one or more <code>ttp:profile</code> elements in the
-        <code>head</code> element, in accordance with <a href=
-        "#parameter-vocabulary-profile"><b>6.1.1 ttp:profile</b></a>.</p>
-
-        <p>If a <code>ttp:profile</code> element appears as a descendant of the
-        <code>tt</code> element, then the <a href=
-        "#parameter-attribute-profile"><code>ttp:profile</code></a> attribute
-        should not be specified on the <code>tt</code> element. If both a
-        <code>ttp:profile</code> element and a <code>ttp:profile</code>
-        attribute are present (in a given <em>Document Instance</em>), then the
-        <code>ttp:profile</code> attribute must be ignored for the purpose of
-        determining the declared profile requirements.</p>
-
-        <p>If more than one <code>ttp:profile</code> element appears in a
-        <em>Document Instance</em>, then all specified profiles apply
-        simultaneously. In such a case, if some feature or some extension is
-        specified by one profile to be used (mandatory and enabled) and by
-        another profile to be required (mandatory) or optional (voluntary),
-        then that feature or extension must be considered to be used (mandatory
-        and enabled); if some feature or some extension is specified by one
-        profile to be merely required (mandatory) and by another profile to be
-        optional (voluntary), then that feature or extension must be considered
-        to be required (mandatory).</p>
-
-        <p>If neither <a href=
-        "#parameter-attribute-profile"><code>ttp:profile</code></a> attribute
-        nor <a href=
-        "#parameter-vocabulary-profile"><code>ttp:profile</code></a> element is
-        present in a <em>Document Instance</em>, and if the <em>Document
-        Interchange Context</em> does not make an implicit or explicit
-        reference to a pre-defined Content Profile or does not specify a
-        <em>Profile Definition Document</em> or another equivalent set of
-        feature designations, then the DFXP Transformation profile applies.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>It is not a requirement on a conformant <em>Document Instance</em>
-          that a <em>Content Profile</em> be internally defined by use of a
-          <code>ttp:profile</code> element or internally referenced by a
-          <code>ttp:profile</code> attribute. More specifically, it is
-          permitted that the <em>Document Interchange Context</em> determines
-          the applicable <em>Content Profile</em> through private agreement,
-          out-of-band protocol, or common use (between sender and receiver) of
-          a profile defined by an external specification.</p>
-        </div>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>It is intended that the <code>ttp:profile</code> attribute be used
-          when the author wishes to reference one of the standard, predefined
-          profiles of TTML Content, and does not wish to modify (by
-          supersetting or subsetting) that profile. This attribute may also be
-          used by an author to indicate the use of a non-standard profile, in
-          which case the specified profile designator expresses a URI that
-          denotes an externally defined <em>Profile Definition Document</em>.
-          However, it is not required that a conformant TTML Content processor
-          be able to dereference such an externally specified profile
-          definition.</p>
-
-          <p>In contrast, it is intended that the <code>ttp:profile</code>
-          element be used when the author wishes to make use of a modified
-          predefined profile or wishes to include in the <em>Document
-          Instance</em> a non-standard profile definition not based upon one of
-          the predefined profiles.</p>
-
-          <p>A predefined profile is supersetted by specifying some feature or
-          extension to be required (mandatory) that was either not specified in
-          the underlying, baseline profile or was specified as optional
-          (voluntary) in the baseline profile. A predefined profile is
-          subsetted by specifying some feature or extension to be optional
-          (voluntary) that was specified as required in the underlying,
-          baseline profile.</p>
-
-          <p>When a baseline profile is modified by subsetting, the resulting,
-          derived profile is referred to as a <em>subtractive</em> profile;
-          when modified by supersetting, the result is referred to as an
-          <em>additive</em> profile. It is also possible to define a derived
-          profile that is simultaneously subtractive and additive.</p>
-        </div>
-
-        <p>If a <em>Document Instance</em> makes use of a feature defined by
-        <a href="#feature-designations"><b>D.1 Feature Designations</b></a> and
-        if the intended use of the document requires the recognition and
-        processing of that feature, then the document must include a
-        <em>required feature</em> or a <em>used feature</em> specification in
-        one of its declared or referenced profiles. If a <em>Document
-        Instance</em> makes use of an extension designatable by <a href=
-        "#extension-designations"><b>E.1 Extension Designations</b></a> and if
-        the intended use of the document requires the recognition and
-        processing of that extension, then the document must include a
-        <em>required extension</em> or a <em>used extension</em> specification
-        in one of its declared or referenced profiles.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>A required or used feature specification is expressed directly (or
-          indirectly by referring to a profile) by means of a <a href=
-          "#parameter-vocabulary-feature"><code>ttp:feature</code></a> element
-          where the value of its <code>value</code> attribute is
-          <code>required</code> or <code>use</code>, respectively. A required
-          or used extension specification is expressed directly (or indirectly
-          by referring to a profile) by means of a <a href=
-          "#parameter-vocabulary-extension"><code>ttp:extension</code></a>
-          element where the value of its <code>value</code> attribute is
-          <code>required</code> or <code>use</code>, respectively.</p>
-        </div>
-
-        <p>An example of an author defined additive, derived profile of the
-        DFXP Presentation profile is shown below in <a href=
-        "#ttml-example-sub-profile"><b>Example Fragment – DFXP Additive
-        Profile</b></a>.</p><a id="ttml-example-sub-profile" name=
-        "ttml-example-sub-profile"></a>
-
-        <table class="example">
-          <caption>
-            Example Fragment – DFXP Additive Profile
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
- &lt;head&gt;
-   &lt;profile use="dfxp-presentation" xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
-     &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-       &lt;feature value="required"&gt;#fontStyle-italic&lt;/feature&gt;
-     &lt;/features&gt;
-   &lt;/profile&gt;
- &lt;/head&gt;
- &lt;body/&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>In the above example, the baseline profile is declared to be the
-          DFXP Presentation profile, which is then additively modified by
-          making the <code>#fontStyle-italic</code> feature required (rather
-          than optional as it is defined in <a href=
-          "#profile-dfxp-presentation"><b>F.2 DFXP Presentation
-          Profile</b></a>). Note also the resetting of the default XMLNS
-          binding on the <code>profile</code> element to the TT Parameter
-          Namespace.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="vocabulary-overview" name="vocabulary-overview"></a>5.3
-        Catalog</h3>
-
-        <p>The vocabulary of the Timed Text Markup Language (TTML) is defined
-        in the following major catalogs (divisions of vocabulary):</p>
-
-        <ul>
-          <li>
-            <p><a href="#core-vocabulary-overview"><b>5.3.1 Core
-            Catalog</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#extension-vocabulary-overview"><b>5.3.2 Extension
-            Catalog</b></a></p>
-          </li>
-        </ul>
-
-        <p>The core catalog defines the baseline, core vocabulary of TTML, and,
-        in particular, the vocabulary of TTML Content. The extension catalog
-        serves as a placeholder for extensions to the core vocabulary defined
-        by TTML.</p>
-
-        <div class="div3">
-          <h4><a id="core-vocabulary-overview" name=
-          "core-vocabulary-overview"></a>5.3.1 Core Catalog</h4>
-
-          <p>The core vocabulary catalog is intended to satisfy the needs of
-          TTML while providing a baseline vocabulary for future profiles. This
-          vocabulary is divided into distinct categories, specified in detail
-          in the following sections:</p>
-
-          <ul>
-            <li>
-              <p><a href="#parameters"><b>6 Parameters</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content"><b>7 Content</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#styling"><b>8 Styling</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#layout"><b>9 Layout</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing"><b>10 Timing</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#animation"><b>11 Animation</b></a></p>
-            </li>
-
-            <li>
-              <p><a href="#metadata"><b>12 Metadata</b></a></p>
-            </li>
-          </ul>
-
-          <p>The core element vocabulary specified for use with a <em>Document
-          Instance</em> is enumerated in <a href=
-          "#element-vocab-table"><b>Table 3 – Element
-          Vocabulary</b></a>.</p><a id="element-vocab-table" name=
-          "element-vocab-table"></a>
-
-          <table class="common">
-            <caption>
-              Table 3 – Element Vocabulary
-            </caption>
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <th>Module</th>
-
-                <th>Elements</th>
-              </tr>
-
-              <tr>
-                <td>Animation</td>
-
-                <td><a href="#animation-vocabulary-set">set</a></td>
-              </tr>
-
-              <tr>
-                <td>Content</td>
-
-                <td><a href="#document-structure-vocabulary-body">body</a>,
-                <a href="#content-vocabulary-div">div</a>, <a href=
-                "#content-vocabulary-p">p</a>, <a href=
-                "#content-vocabulary-span">span</a>, <a href=
-                "#content-vocabulary-br">br</a></td>
-              </tr>
-
-              <tr>
-                <td>Document</td>
-
-                <td><a href="#document-structure-vocabulary-tt">tt</a></td>
-              </tr>
-
-              <tr>
-                <td>Head</td>
-
-                <td><a href="#document-structure-vocabulary-head">head</a></td>
-              </tr>
-
-              <tr>
-                <td>Layout</td>
-
-                <td><a href="#layout-vocabulary-layout">layout</a>, <a href=
-                "#layout-vocabulary-region">region</a></td>
-              </tr>
-
-              <tr>
-                <td>Metadata</td>
-
-                <td><a href="#metadata-vocabulary-metadata">metadata</a></td>
-              </tr>
-
-              <tr>
-                <td>Metadata Items</td>
-
-                <td><a href="#metadata-vocabulary-actor">ttm:actor</a>,
-                <a href="#metadata-vocabulary-agent">ttm:agent</a>, <a href=
-                "#metadata-vocabulary-copyright">ttm:copyright</a>, <a href=
-                "#metadata-vocabulary-desc">ttm:desc</a>, <a href=
-                "#metadata-vocabulary-name">ttm:name</a>, <a href=
-                "#metadata-vocabulary-title">ttm:title</a></td>
-              </tr>
-
-              <tr>
-                <td>Parameter Items</td>
-
-                <td><a href="#parameter-vocabulary-profile">ttp:profile</a>,
-                <a href="#parameter-vocabulary-features">ttp:features</a>,
-                <a href="#parameter-vocabulary-feature">ttp:feature</a>,
-                <a href="#parameter-vocabulary-extensions">ttp:extensions</a>,
-                <a href=
-                "#parameter-vocabulary-extension">ttp:extension</a></td>
-              </tr>
-
-              <tr>
-                <td>Styling</td>
-
-                <td><a href="#styling-vocabulary-styling">styling</a>, <a href=
-                "#styling-vocabulary-style">style</a></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>Element vocabulary groups that are used in defining content models
-          for TTML element types are enumerated in <a href=
-          "#element-vocab-group-table"><b>Table 4 – Element Vocabulary
-          Groups</b></a>.</p><a id="element-vocab-group-table" name=
-          "element-vocab-group-table"></a>
-
-          <table class="common">
-            <caption>
-              Table 4 – Element Vocabulary Groups
-            </caption>
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <th>Group</th>
-
-                <th>Elements</th>
-              </tr>
-
-              <tr>
-                <td>Animation.class</td>
-
-                <td><a href="#animation-vocabulary-set">set</a></td>
-              </tr>
-
-              <tr>
-                <td>Block.class</td>
-
-                <td><a href="#content-vocabulary-div">div</a> | <a href=
-                "#content-vocabulary-p">p</a></td>
-              </tr>
-
-              <tr>
-                <td>Inline.class</td>
-
-                <td><a href="#content-vocabulary-span">span</a> | <a href=
-                "#content-vocabulary-span">br</a> | <code>#PCDATA</code></td>
-              </tr>
-
-              <tr>
-                <td>Metadata.class</td>
-
-                <td><a href="#metadata-vocabulary-metadata">metadata</a> |
-                <a href="#metadata-vocabulary-copyright">ttm:agent</a> |
-                <a href="#metadata-vocabulary-copyright">ttm:copyright</a> |
-                <a href="#metadata-vocabulary-desc">ttm:desc</a> | <a href=
-                "#metadata-vocabulary-title">ttm:title</a></td>
-              </tr>
-
-              <tr>
-                <td>Parameters.class</td>
-
-                <td><a href=
-                "#parameter-vocabulary-profile">ttp:profile</a></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The attribute vocabulary specified for use with the core
-          vocabulary catalog is enumerated in <a href=
-          "#attribute-vocab-table"><b>Table 5 – Attribute
-          Vocabulary</b></a>.</p><a id="attribute-vocab-table" name=
-          "attribute-vocab-table"></a>
-
-          <table class="common">
-            <caption>
-              Table 5 – Attribute Vocabulary
-            </caption>
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <th>Module</th>
-
-                <th>Attributes</th>
-              </tr>
-
-              <tr>
-                <td>Core Attributes</td>
-
-                <td><a href="#content-attribute-id">xml:id</a>, <a href=
-                "#content-attribute-lang">xml:lang</a>, <a href=
-                "#content-attribute-space">xml:space</a></td>
-              </tr>
-
-              <tr>
-                <td>Layout</td>
-
-                <td><a href="#layout-attribute-region">region</a></td>
-              </tr>
-
-              <tr>
-                <td>Metadata Attributes</td>
-
-                <td><a href="#metadata-attribute-agent">ttm:agent</a>, <a href=
-                "#metadata-attribute-role">ttm:role</a></td>
-              </tr>
-
-              <tr>
-                <td>Parameter Attributes</td>
-
-                <td><a href=
-                "#parameter-attribute-cellResolution">ttp:cellResolution</a>,
-                <a href="#parameter-attribute-clockMode">ttp:clockMode</a>,
-                <a href="#parameter-attribute-dropMode">ttp:dropMode</a>,
-                <a href="#parameter-attribute-frameRate">ttp:frameRate</a>,
-                <a href=
-                "#parameter-attribute-frameRateMultiplier">ttp:frameRateMultipler</a>,
-                <a href="#parameter-attribute-markerMode">ttp:markerMode</a>,
-                <a href=
-                "#parameter-attribute-pixelAspectRatio">ttp:pixelAspectRatio</a>,
-                <a href="#parameter-attribute-profile">ttp:profile</a>,
-                <a href="#parameter-attribute-subFrameRate">ttp:subFrameRate</a>,
-                <a href="#parameter-attribute-tickRate">ttp:tickRate</a>,
-                <a href="#parameter-attribute-timeBase">ttp:timeBase</a></td>
-              </tr>
-
-              <tr>
-                <td>Styling</td>
-
-                <td><a href="#style-attribute-style">style</a></td>
-              </tr>
-
-              <tr>
-                <td>Styling Attributes</td>
-
-                <td><a href=
-                "#style-attribute-backgroundColor">tts:backgroundColor</a>,
-                <a href="#style-attribute-color">tts:color</a>, <a href=
-                "#style-attribute-direction">tts:direction</a>, <a href=
-                "#style-attribute-display">tts:display</a>, <a href=
-                "#style-attribute-displayAlign">tts:displayAlign</a>, <a href=
-                "#style-attribute-extent">tts:extent</a>, <a href=
-                "#style-attribute-fontFamily">tts:fontFamily</a>, <a href=
-                "#style-attribute-fontSize">tts:fontSize</a>, <a href=
-                "#style-attribute-fontStyle">tts:fontStyle</a>, <a href=
-                "#style-attribute-fontWeight">tts:fontWeight</a>, <a href=
-                "#style-attribute-lineHeight">tts:lineHeight</a>, <a href=
-                "#style-attribute-opacity">tts:opacity</a>, <a href=
-                "#style-attribute-origin">tts:origin</a>, <a href=
-                "#style-attribute-overflow">tts:overflow</a>, <a href=
-                "#style-attribute-padding">tts:padding</a>, <a href=
-                "#style-attribute-showBackground">tts:showBackground</a>,
-                <a href="#style-attribute-textAlign">tts:textAlign</a>,
-                <a href="#style-attribute-textDecoration">tts:textDecoration</a>,
-                <a href="#style-attribute-textOutline">tts:textOutline</a>,
-                <a href="#style-attribute-unicodeBidi">tts:unicodeBidi</a>,
-                <a href="#style-attribute-visibility">tts:visibility</a>,
-                <a href="#style-attribute-wrapOption">tts:wrapOption</a>,
-                <a href="#style-attribute-writingMode">tts:writingMode</a>,
-                <a href="#style-attribute-zIndex">tts:zIndex</a></td>
-              </tr>
-
-              <tr>
-                <td>Timing Attributes</td>
-
-                <td><a href="#timing-attribute-begin">begin</a>, <a href=
-                "#timing-attribute-dur">dur</a>, <a href=
-                "#timing-attribute-end">end</a>, <a href=
-                "#timing-attribute-timeContainer">timeContainer</a></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Only those attributes defined as either (1) global, i.e.,
-            namespace qualified, or (2) shared element-specific, i.e., not
-            namespace qualified but shared across multiple element types, are
-            listed in <a href="#attribute-vocab-table"><b>Table 5 – Attribute
-            Vocabulary</b></a> above.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>All vocabulary defined by TTML consistently makes use of the
-            so-called <em>lowerCamelCase</em> naming convention. In some cases,
-            this results in the change of a name when the name was based upon
-            another specification that used a different naming convention.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="extension-vocabulary-overview" name=
-          "extension-vocabulary-overview"></a>5.3.2 Extension Catalog</h4>
-
-          <p>The extension vocabulary catalog is intended for use by future
-          profiles of TTML, and is not further defined by this version of this
-          specification.</p>
-
-          <p>In addition to standardized extension vocabulary, a conforming
-          <em>Document Instance</em> may contain arbitrary namespace qualified
-          elements that reside in any namespace other than those namespaces
-          defined for use with this specification. Furthermore, a conforming
-          <em>Document Instance</em> may contain arbitrary namespace qualified
-          attributes on TTML defined vocabulary where such attributes reside in
-          any namespace other than those defined for use with this
-          specification.</p>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="parameters" name="parameters"></a>6 Parameters</h2>
-
-      <p>This section specifies the <em>parameters</em> matter of the core
-      vocabulary catalog, where parameters are to be understood as information
-      that is either (1) essential or (2) of significant importance for the
-      purpose of interpreting the semantics of other types of information
-      expressed by core vocabulary items or for establishing a <em>Document
-      Processing Context</em> by means of which TTML Content can be related to
-      an external environment.</p>
-
-      <div class="div2">
-        <h3><a id="parameter-element-vocabulary" name=
-        "parameter-element-vocabulary"></a>6.1 Parameter Element
-        Vocabulary</h3>
-
-        <p>The following elements, all defined in the TT Parameter Namespace,
-        specify parametric information that applies to a <em>Document
-        Instance</em> or <em>Content Processor</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#parameter-vocabulary-profile"><b>6.1.1
-            ttp:profile</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-vocabulary-features"><b>6.1.2
-            ttp:features</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-vocabulary-feature"><b>6.1.3
-            ttp:feature</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-vocabulary-extensions"><b>6.1.4
-            ttp:extensions</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-vocabulary-extension"><b>6.1.5
-            ttp:extension</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-profile" name=
-          "parameter-vocabulary-profile"></a>6.1.1 ttp:profile</h4>
-
-          <p>The <code>ttp:profile</code> element is used to specify a
-          collection of used (mandatory and enabled), required (mandatory), and
-          optional (voluntary) features and extensions that must or may be
-          supported by a <em>Content Processor</em> in order to process a
-          <em>Document Instance</em> that makes (or may make) use of such
-          features and extensions.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The difference between a <em>feature</em> and an
-            <em>extension</em> is where it is defined and how it is labeled: if
-            defined in this specification (or a future revision thereof) and
-            labeled with a feature designation in <a href="#features"><b>D
-            Features</b></a>, then it is considered to be a feature; if defined
-            in another specification and labeled there with an extension
-            designation, then it is considered to be an extension. In general,
-            features are expected to be defined by the W3C standards process,
-            while extensions are expected to be defined by third parties.</p>
-          </div>
-
-          <p>This specification defines two distinct uses of the
-          <code>ttp:profile</code> element:</p>
-
-          <ul>
-            <li>
-              <p>as a child of the <code>head</code> element within a TTML
-              <em>Document Instance</em>;</p>
-            </li>
-
-            <li>
-              <p>as the root element of a TTML <em>Profile Definition
-              Document</em> instance;</p>
-            </li>
-          </ul>
-
-          <p>When a <code>tt:profile</code> element appears within a TTML
-          <em>Document Instance</em>, its purpose is to express authorial
-          intentions about which features and extensions must or may be
-          supported by a recipient content processor. In addition, the element
-          indirectly expresses information about the set of features or
-          extensions that are (or may expected to be) used by the <em>Document
-          Instance</em>.</p>
-
-          <p>When a <code>tt:profile</code> element is used by a TTML
-          <em>Profile Definition Document</em> instance, it serves to publish a
-          machine readable specification of a specific TTML Content profile, of
-          which this specification defines three such <em>Profile Definition
-          Documents</em> in <a href="#profiles"><b>F Profiles</b></a>.</p>
-
-          <p>The <code>ttp:profile</code> element accepts as its children zero
-          or more elements in the <code>Metadata.class</code> element group,
-          followed by zero or more <code>ttp:features</code> elements, followed
-          by zero or more <code>ttp:extensions</code> elements.</p><a id=
-          "elt-syntax-parameter-profile" name=
-          "elt-syntax-parameter-profile"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:profile
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:profile
-  use = string
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#parameter-vocabulary-features">ttp:features</a>*, <a href=
-"#parameter-vocabulary-extensions">ttp:extensions</a>*
-&lt;/ttp:profile&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If specified, the <code>use</code> attribute must adhere to the
-          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML
-          Schema Part 2]</a>, §3.2.17, and, furthermore, must denote a profile
-          designator in accordance with <a href="#vocabulary-profiles"><b>5.2
-          Profiles</b></a>. In this case, the profile designator must refer to
-          (1) a standard, predefined <em>Profile Definition Document</em> as
-          defined by <a href="#profiles"><b>F Profiles</b></a>, or (2) a
-          feasibly dereferenceable resource representing a valid <em>Profile
-          Definition Document</em> instance. In either case, the referenced
-          profile serves as the baseline profile of the specifying
-          <code>ttp:profile</code> element.</p>
-
-          <p>If the <code>use</code> attribute is not specified, then the
-          baseline profile of the <code>ttp:profile</code> element must be
-          considered to be the empty (null) profile, i.e., a profile definition
-          containing no feature or extension specifications.</p>
-
-          <p>The collection of features and extensions of a profile are
-          determined according to the following ordered rules:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>initialize the features and extensions of the profile to the
-              empty set;</p>
-            </li>
-
-            <li>
-              <p>if a <code>use</code> attribute is present, then augment the
-              profile with the set of features and extensions specified by the
-              referenced baseline profile;</p>
-            </li>
-
-            <li>
-              <p>for each <code>ttp:feature</code> and
-              <code>ttp:extension</code> element descendant of the
-              <code>ttp:profile</code> element, using a post-order traversal,
-              merge the specified feature or extension with the features and
-              extensions of the profile, where merging a feature or extension
-              entails replacing an existing feature or extension specification,
-              if it already exists, or adding a new feature or extension
-              specification, if it does not yet exist in the profile;</p>
-            </li>
-          </ol>
-
-          <p>A conformant TTML processor is not required to be able to
-          dereference a <em>Profile Definition Document</em> that is not one of
-          the standard, predefined profiles defined by <a href="#profiles"><b>F
-          Profiles</b></a>. Furthermore, a conformant TTML processor may make
-          use of a built-in, static form of each standard, predefined profile
-          so as not to require dereferencing a network resource.</p>
-
-          <p>If a TTML processor is unable to dereference a non-standard
-          <em>Profile Definition Document</em>, then it must not further
-          process the document without the presence of an explicit override
-          from an end-user or some implementation specific parameter traceable
-          to an end-user or to a user or system configuration setting. If a
-          TTML processor aborts processing of a <em>Document Instance</em> due
-          to the inability to reference a non-standard <em>Profile Definition
-          Document</em>, then some end-user notification should be given unless
-          the end-user or system has disabled such a notification, or if the
-          processor does not permit or entail the intervention of an
-          end-user.</p>
-
-          <p>The <code>ttp:profile</code> element is illustrated by the
-          following example.</p><a id="parameter-vocabulary-profile-example-1"
-          name="parameter-vocabulary-profile-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – ttp:profile
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:profile use="dfxp-presentation"&gt;
-  &lt;ttp:features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    &lt;ttp:feature&gt;#text-outline&lt;/ttp:feature&gt;
-  &lt;/ttp:features&gt;
-&lt;/ttp:profile&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the DFXP presentation profile is used as
-            the baseline profile. This baseline profile is then supersetted
-            (thus creating an additive derived profile) by requiring support
-            for <code>#text-outline</code> feature.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-features" name=
-          "parameter-vocabulary-features"></a>6.1.2 ttp:features</h4>
-
-          <p>The <code>ttp:features</code> element is a container element used
-          to group infomation about feature support requirements.</p>
-
-          <p>The <code>ttp:features</code> element accepts as its children zero
-          or more elements in the <code>Metadata.class</code> element group,
-          followed by zero or more <code>ttp:feature</code> elements.</p><a id=
-          "elt-syntax-parameter-features" name=
-          "elt-syntax-parameter-features"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:features
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:features
-  xml:base = string : <em>TT Feature Namespace</em>
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#parameter-vocabulary-feature">ttp:feature</a>*
-&lt;/ttp:features&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If specified, the <code>xml:base</code> attribute must (1) adhere
-          to the <code>xsd:anyURI</code> data type defined by <a href=
-          "#xsd-2">[XML Schema Part 2]</a>, §3.2.17, (2) express an absolute
-          URI that adheres to <a href="#xmlbase">[XML Base]</a> and, (3)
-          express a feature namespace as defined by <a href=
-          "#feature-designations"><b>D.1 Feature Designations</b></a>. If not
-          specified, the <code>xml:base</code> attribute's default value
-          applies, which is the TT Feature Namespace.</p>
-
-          <p>The <code>xml:base</code> attribute is used to permit the
-          abbreviation of feature designation URIs expressed by child
-          <code>ttp:feature</code> elements.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-feature" name=
-          "parameter-vocabulary-feature"></a>6.1.3 ttp:feature</h4>
-
-          <p>The <code>ttp:feature</code> element is used to specify infomation
-          about support requirements for a particular feature.</p>
-
-          <p>The children of the <code>ttp:feature</code> element must express
-          a non-empty sequence of character information items that adheres to
-          the <code>xsd:anyURI</code> data type defined by <a href=
-          "#xsd-2">[XML Schema Part 2]</a>, §3.2.17.</p><a id=
-          "elt-syntax-parameter-feature" name=
-          "elt-syntax-parameter-feature"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:feature
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:feature
-  value = (optional|required|use) : required
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttp:feature&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the URI expressed by the content of the
-          <code>ttp:feature</code> element is a relative URI, then, when
-          combined with the feature namespace value expressed by the
-          <code>xml:base</code> attribute of the nearest ancestor
-          <code>ttp:features</code> element, it must express an absolute URI.
-          In either case (original absolute URI or resulting absolutized URI),
-          the URI expressed by the <code>ttp:feature</code> element must
-          further adhere to the syntax of a feature designation as defined by
-          <a href="#feature-designations"><b>D.1 Feature Designations</b></a>,
-          and, furthermore, the specific designation that appears in this URI,
-          i.e., the portion of the feature designation that starts with the
-          fragment identifier separator '#', must be defined by this
-          specification or some published version thereof (that has achieved
-          REC status).</p>
-
-          <p>If the URI expressed by the content of the
-          <code>ttp:feature</code> element is a relative URI, then an
-          <code>xml:base</code> attribute should be specified on the nearest
-          ancestor <code>ttp:features</code> element.</p>
-
-          <p>The <code>value</code> attribute specifies whether a conforming
-          TTML processor must or may implement the designated feature in order
-          to process the document. If the value of the <code>value</code>
-          attribute is <code>optional</code>, then the processor need not
-          implement or otherwise support the feature in order to process the
-          document; if the value is <code>required</code>, then the processor
-          must implement or otherwise support the feature, irrespective of
-          whether the feature is enabled or disabled, in order to process the
-          document; if the value is <code>use</code>, then the processor must
-          both (1) implement or otherwise support the feature and (2) have
-          enabled (activated) use of the feature.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The default value of the <code>value</code> attribute is
-            <code>required</code>, as indicated in the above element
-            information item definition. Therefore, if a <code>value</code>
-            attribute is not specified on a <code>ttp:feature</code> element,
-            it is equivalent to specifying that support for the feature is
-            required.</p>
-          </div>
-
-          <p>If the value of the <code>value</code> attribute is
-          <code>required</code> or <code>use</code> and the TTML processor
-          implementation does not support the feature, or if the
-          <code>value</code> attribute is <code>use</code> and the TTML
-          processor implementation supports but has disabled that feature, then
-          it must not further process the document without the presence of an
-          explicit override from an end-user or some implementation specific
-          parameter traceable to an end-user or to a user or system
-          configuration setting. If a TTML processor aborts processing of a
-          <em>Document Instance</em> due to the specification of a required,
-          but unsupported feature by this element, then some end-user
-          notification should be given unless the end-user or system has
-          disabled such a notification, or if the processor does not permit or
-          entail the intervention of an end-user.</p>
-
-          <p>If the value of the <code>value</code> attribute is
-          <code>optional</code>, and if the TTML processor implementation does
-          not support the feature, then it may further process the document
-          even in the case that some use of the feature is present in the
-          document. In the case of actual use of a feature designated as
-          optional, the default semantics associated with that feature apply;
-          that is, the processor may behave as if the feature were not actually
-          used or referenced by the document. Notwithstanding the above, the
-          syntactic presence or reference to an optional feature by a document
-          must not be considered to be a violation of document validity or a
-          barrier to further processing if the syntactic expression is
-          well-formed and valid.</p>
-
-          <p>If some defined (i.e., standardized) or otherwise well known
-          feature is not specified by a <code>ttp:feature</code> element in a
-          given profile, then it must be interpreted as if the feature were
-          specified with the <code>value</code> attribute equal to
-          <code>optional</code>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In particular, if some feature is not present in a profile
-            definition, then it is not to be interpreted as meaning the use of
-            that feature (in a <em>Document Instance</em>) is disallowed or
-            otherwise prohibited.</p>
-          </div>
-
-          <p>The <code>ttp:feature</code> element is illustrated by the
-          following example.</p><a id="parameter-vocabulary-feature-example-1"
-          name="parameter-vocabulary-feature-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – ttp:feature
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-presentation"&gt;
-  &lt;ttp:features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    <span class=
-"strong">&lt;ttp:feature value="required"&gt;#fontStyle-italic&lt;/ttp:feature&gt;</span>
-    <span class=
-"strong">&lt;ttp:feature value="required"&gt;#textDecoration-under&lt;/ttp:feature&gt;</span>
-  &lt;/ttp:features&gt;
-&lt;/ttp:profile&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the DFXP presentation profile is used as
-            the baseline profile. This baseline profile is then modified by two
-            <code>ttp:feature</code> elements in order to superset the baseline
-            profile (since neither <code>#fontStyle-italic</code> nor
-            <code>#textDecoration-under</code> are required by the DFXP
-            presentation profile).</p>
-
-            <p>The effect of this example is to express authorial intentions
-            that italic font style and text underlining must be supported.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-extensions" name=
-          "parameter-vocabulary-extensions"></a>6.1.4 ttp:extensions</h4>
-
-          <p>The <code>ttp:extensions</code> element is a container element
-          used to group infomation about extension support requirements.</p>
-
-          <p>The <code>ttp:extensions</code> element accepts as its children
-          zero or more elements in the <code>Metadata.class</code> element
-          group, followed by zero or more <code>ttp:extension</code>
-          elements.</p><a id="elt-syntax-parameter-extensions" name=
-          "elt-syntax-parameter-extensions"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:extensions
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:extensions
-  xml:base = string : <em>TT Extension Namespace</em>
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#parameter-vocabulary-extension">ttp:extension</a>*
-&lt;/ttp:extensions&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If specified, the <code>xml:base</code> attribute must (1) adhere
-          to the <code>xsd:anyURI</code> data type defined by <a href=
-          "#xsd-2">[XML Schema Part 2]</a>, §3.2.17, (2) express an absolute
-          URI that adheres to <a href="#xmlbase">[XML Base]</a> and, (3)
-          express an extension namespace as defined by <a href=
-          "#extension-designations"><b>E.1 Extension Designations</b></a>. If
-          not specified, the <code>xml:base</code> attribute's default value
-          applies, which is the TT Extension Namespace.</p>
-
-          <p>The <code>xml:base</code> attribute is used to permit the
-          abbreviation of feature designation URIs expressed by child
-          <code>ttp:extension</code> elements.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-vocabulary-extension" name=
-          "parameter-vocabulary-extension"></a>6.1.5 ttp:extension</h4>
-
-          <p>The <code>ttp:extension</code> element is used to specify
-          infomation about support requirements for a particular extension.</p>
-
-          <p>The children of the <code>ttp:extension</code> element must
-          express a non-empty sequence of character information items that
-          adheres to the <code>xsd:anyURI</code> data type defined by <a href=
-          "#xsd-2">[XML Schema Part 2]</a>, §3.2.17.</p><a id=
-          "elt-syntax-parameter-extension" name=
-          "elt-syntax-parameter-extension"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttp:extension
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:extension
-  value = (optional|required|use) : required
-  <a href="#content-attribute-id">xml:id</a> = ID
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttp:extension&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the URI expressed by the content of the
-          <code>ttp:extension</code> element is a relative URI, then, when
-          combined with the extension namespace value expressed by the
-          <code>xml:base</code> attribute of the nearest ancestor
-          <code>ttp:extensions</code> element, it must express an absolute URI.
-          In either case (original absolute URI or resulting absolutized URI),
-          the URI expressed by the <code>ttp:extension</code> element must
-          further adhere to the syntax of an extension designation as defined
-          by <a href="#extension-designations"><b>E.1 Extension
-          Designations</b></a>.</p>
-
-          <p>If the URI expressed by the content of the
-          <code>ttp:feature</code> element is a relative URI, then an
-          <code>xml:base</code> attribute should be specified on the nearest
-          ancestor <code>ttp:extensions</code> element.</p>
-
-          <p>The <code>value</code> attribute specifies whether a conforming
-          TTML processor must or may implement the designated extension in
-          order to process the document. If the value of the <code>value</code>
-          attribute is <code>optional</code>, then the processor need not
-          implement or otherwise support the extension in order to process the
-          document; if the value is <code>required</code>, then the processor
-          must implement or otherwise support the extension in order to process
-          the document; if the value is <code>use</code>, then the processor
-          must both (1) implement or otherwise support the extension and (2)
-          enable (activate) use of the extension.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The default value of the <code>value</code> attribute is
-            <code>required</code>, as indicated in the above element
-            information item definition. Therefore, if a <code>value</code>
-            attribute is not specified on a <code>ttp:extension</code> element,
-            it is equivalent to specifying that support for the extension is
-            required.</p>
-          </div>
-
-          <p>If the value of the <code>value</code> attribute is
-          <code>required</code> or <code>use</code> and the TTML processor
-          implementation does not support the extension, or if the
-          <code>value</code> attribute is <code>use</code> and the TTML
-          processor implementation supports but has disabled that extension,
-          then it must not further process the document without the presence of
-          an explicit override from an end-user or some implementation specific
-          parameter traceable to an end-user or to a user or system
-          configuration setting. If a TTML processor aborts processing of a
-          <em>Document Instance</em> due to the specification of a required,
-          but unsupported extension by this element, then some end-user
-          notification should be given unless the end-user or system has
-          disabled such a notification, or if the processor does not permit or
-          entail the intervention of an end-user.</p>
-
-          <p>If the value of the <code>value</code> attribute is
-          <code>optional</code>, and if the TTML processor implementation does
-          not support the extension, then it may further process the document
-          even in the case that some use of the extension is present in the
-          document. In the case of actual use of an extension designated as
-          optional, the default semantics associated with that extension apply;
-          that is, the processor may behave as if the extension were not
-          actually used or referenced by the document. Notwithstanding the
-          above, the syntactic presence or reference to an optional extension
-          by a document must not be considered to be a violation of document
-          validity or a barrier to further processing if the syntactic
-          expression is well-formed and valid.</p>
-
-          <p>If some well known extension is not specified by a
-          <code>ttp:extension</code> element in a given profile, then it must
-          be interpreted as if the extension were specified with the
-          <code>value</code> attribute equal to <code>optional</code>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In particular, if some extension is not present in a profile
-            definition, then it is not to be interpreted as meaning the use of
-            that extension (in a <em>Document Instance</em>) is disallowed or
-            otherwise prohibited.</p>
-          </div>
-
-          <p>The <code>ttp:extension</code> element is illustrated by the
-          following example.</p><a id=
-          "parameter-vocabulary-extension-example-1" name=
-          "parameter-vocabulary-extension-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – ttp:extension
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-transformation"&gt;
-  &lt;ttp:extensions xml:base="http://example.org/ttml/extension/"&gt;
-    <span class=
-"strong">&lt;ttp:extension value="use"&gt;#prefilter-by-language&lt;/ttp:extension&gt;</span>
-  &lt;/ttp:extensions&gt;
-&lt;/ttp:profile&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the DFXP transformation profile is used as
-            the baseline profile. This baseline profile is then supersetted by
-            specifying that support and use is required for a private extension
-            defined in a third party namespace.</p>
-
-            <p>The effect of this example is to express authorial intentions
-            that a recipient processor must support the DFXP transformation
-            profile and must also support and enable an extension defined by a
-            third party.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="parameter-attribute-vocabulary" name=
-        "parameter-attribute-vocabulary"></a>6.2 Parameter Attribute
-        Vocabulary</h3>
-
-        <p>The following attributes are defined in the TT Parameter
-        Namespace.</p>
-
-        <ul>
-          <li>
-            <p><a href="#parameter-attribute-cellResolution"><b>6.2.1
-            ttp:cellResolution</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-clockMode"><b>6.2.2
-            ttp:clockMode</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-dropMode"><b>6.2.3
-            ttp:dropMode</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-frameRate"><b>6.2.4
-            ttp:frameRate</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-frameRateMultiplier"><b>6.2.5
-            ttp:frameRateMultiplier</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-markerMode"><b>6.2.6
-            ttp:markerMode</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-pixelAspectRatio"><b>6.2.7
-            ttp:pixelAspectRatio</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-profile"><b>6.2.8
-            ttp:profile</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-subFrameRate"><b>6.2.9
-            ttp:subFrameRate</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-tickRate"><b>6.2.10
-            ttp:tickRate</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#parameter-attribute-timeBase"><b>6.2.11
-            ttp:timeBase</b></a></p>
-          </li>
-        </ul>
-
-        <p>Unless explicitly stated otherwise, linear white-space (LWSP) must
-        appear between adjacent non-terminal components of a TT Parameter value
-        unless some other delimiter is permitted and used.</p>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-cellResolution" name=
-          "parameter-attribute-cellResolution"></a>6.2.1
-          ttp:cellResolution</h4>
-
-          <p>The <code>ttp:cellResolution</code> attribute may be used by an
-          author to express the number of horizontal and vertical cells into
-          which the <em>Root Container Region</em> area is divided for the
-          purpose of expressing presentation semantics in terms of a uniform
-          grid.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id=
-          "parameter-attribute-cellResolution-syntax" name=
-          "parameter-attribute-cellResolution-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:cellResolution
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:cellResolution
-  : columns rows                            // <em>columns</em> != 0; <em>rows</em> != 0
-
-columns | rows
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If not specified, the number of columns and rows must be
-          considered to be 32 and 15, respectively. If specified, then columns
-          or rows must not be zero (0).</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The choice of values 32 and 15 are based on this being the
-            maximum number of columns and rows defined by <a href=
-            "#cea608c">[CEA-608-C]</a>.</p>
-          </div>
-
-          <p>A <code>ttp:cellResolution</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The use of a uniform grid is employed only for the purpose of
-            measuring lengths and expressing coordinates. In particular, it is
-            not assumed that the presentation of text or the alignment of
-            individual glyph areas is coordinated with this grid. Such
-            alignment is possible, but requires the use of a monospaced font
-            and a font size whose EM square exactly matches the cell size.</p>
-          </div>
-
-          <p>Except where indicated otherwise, when a <a href=
-          "#style-value-length">&lt;length&gt;</a> expressed in cells denotes a
-          dimension parallel to the inline or block progression dimension, the
-          cell's dimension in the inline or block progression dimension
-          applies, respectively.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>For example, if padding (on all four edges) is specified as
-            0.1c, the cell resolution is 20 by 10, and the extent of the
-            <em>Root Container Region</em> is 640 by 480, then, assuming top to
-            bottom, left to right writing mode, the start and end padding will
-            be (640 / 20) * 0.1 pixels and the before and after padding will be
-            (480 / 10) * 0.1 pixels.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-clockMode" name=
-          "parameter-attribute-clockMode"></a>6.2.2 ttp:clockMode</h4>
-
-          <p>The <code>ttp:clockMode</code> attribute is used to specify the
-          interpretation of time expressions as real-time time coordinates when
-          operating with time base of <code>clock</code> as defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#timing-time-value-expressions"><b>10.3 Time Value
-            Expressions</b></a> for the specification of time expression syntax
-            and semantics.</p>
-          </div>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id="parameter-attribute-clockMode-syntax"
-          name="parameter-attribute-clockMode-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:clockMode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:clockMode
-  : "local"
-  | "gps"
-  | "utc"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the time base, defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is
-          designated as <code>clock</code>, then this parameter applies as
-          follows: if the parameter's value is <code>local</code>, then time
-          expressions are interpreted as local wall-clock time coordinates; if
-          <code>utc</code>, then time expressions are interpreted as UTC time
-          coordinates <a href="#utc">[UTC]</a>; if <code>gps</code>, then time
-          expressions are interpreted as GPS time coordinates <a href=
-          "#gps">[GPS]</a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The primary difference between GPS time and UTC time is that GPS
-            time is not adjusted for leap seconds, while UTC time is adjusted
-            as follows: UTC = TAI (<em>Temp Atomique International</em>) +
-            <em>leap seconds accumulated since 1972</em>. TAI is maintained by
-            the <em>Bureau International des Poids et Mesures</em> (BIPM) in
-            Sevres, France. The GPS system time is steered to a Master Clock
-            (MC) at the US Naval Observatory which is kept within a close but
-            unspecified tolerance of TAI.</p>
-          </div>
-
-          <p>If not specified, the value of this parameter must be considered
-          to be <code>utc</code>.</p>
-
-          <p>A <code>ttp:clockMode</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-dropMode" name=
-          "parameter-attribute-dropMode"></a>6.2.3 ttp:dropMode</h4>
-
-          <p>The <code>ttp:dropMode</code> attribute is used to specify
-          constraints on the interpretation and use of frame counts that
-          correspond with <a href="#smpte12m">[SMPTE 12M]</a> time coordinates
-          when operating with time base of <code>smpte</code> as defined by
-          <a href="#parameter-attribute-timeBase"><b>6.2.11
-          ttp:timeBase</b></a>.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id="parameter-attribute-dropMode-syntax"
-          name="parameter-attribute-dropMode-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:dropMode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:dropMode
-  : "dropNTSC"
-  | "dropPAL"
-  | "nonDrop"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the time base, defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is
-          designated as <code>smpte</code>, then this parameter applies as
-          follows: if the parameter's value is <code>nonDrop</code>, then,
-          within any given second of a time expression, frames count from 0 to
-          <em>N−1</em>, where <em>N</em> is the value specified by the
-          <code>ttp:frameRate</code> parameter, but while ignoring any value
-          specified by the <code>ttp:frameRateMultiplier</code> parameter.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When operating in <code>nonDrop</code> mode, a second of a time
-            expression may or may not be equal to a second of real time during
-            normal (1x speed) forward playback. If the
-            <code>ttp:frameRateMultiplier</code> parameter is specified and is
-            not equal to 1:1, then a second of a time expression will either be
-            shorter or longer than a second of elapsed play in real time.</p>
-          </div>
-
-          <p>If this parameter's value is <code>dropNTSC</code>, then, within
-          any given second of a time expression except the second
-          <code>00</code>, frames count from 0 to <em>N−1</em>, where
-          <em>N</em> is the value specified by the <code>ttp:frameRate</code>
-          parameter, but while ignoring any value specified by the
-          <code>ttp:frameRateMultiplier</code> parameter. If the second of a
-          time expression is <code>00</code> and the minute of the time
-          expression is not <code>00</code>, <code>10</code>, <code>20</code>,
-          <code>30</code>, <code>40</code>, or <code>50</code>, then frame
-          codes <code>00</code> and <code>01</code> are dropped during that
-          second; otherwise, these frame codes are not dropped.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>For example, when operating in <code>dropNTSC</code> mode with
-            <code>ttp:frameRate</code> of <code>30</code>, a discontinuity in
-            frame count occurs between consecutive frames as shown in the
-            following sequence of time expressions: <code>01:08:59:28</code>,
-            <code>01:08:59:29</code>, <code>01:09:00:02</code>,
-            <code>01:09:00:03</code>.</p>
-          </div>
-
-          <p>If this parameter's value is <code>dropPAL</code>, then, within
-          any given second of a time expression except the second
-          <code>00</code>, frames count from 0 to <em>N−1</em>, where
-          <em>N</em> is the value specified by the <code>ttp:frameRate</code>
-          parameter, but while ignoring any value specified by the
-          <code>ttp:frameRateMultiplier</code> parameter. If the second of a
-          time expression is <code>00</code> and the minute of the time
-          expression is even but not <code>00</code>, <code>20</code>, or
-          <code>40</code>, then frame codes <code>00</code> through
-          <code>03</code> are dropped during that second; otherwise, these
-          frame codes are not dropped.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>For example, when operating in <code>dropPAL</code> mode with
-            <code>ttp:frameRate</code> of <code>30</code>, a discontinuity in
-            frame count occurs between consecutive frames as shown in the
-            following sequence of time expressions: <code>01:09:59:28</code>,
-            <code>01:09:59:29</code>, <code>01:10:00:04</code>,
-            <code>01:10:00:05</code>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The <code>dropPAL</code> mode is also known as the
-            <em>M/PAL</em> or <em>PAL (M)</em> drop-frame code, which uses PAL
-            modulation with the NTSC frame rate of ~29.97 frames/second. The
-            M/PAL system is used primarily in Brazil.</p>
-          </div>
-
-          <p>If not specified, then <code>nonDrop</code> must be assumed to
-          apply.</p>
-
-          <p>A <code>ttp:dropMode</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-frameRate" name=
-          "parameter-attribute-frameRate"></a>6.2.4 ttp:frameRate</h4>
-
-          <p>The <code>ttp:frameRate</code> attribute is used to specify the
-          frame rate of a related media object or the intrinsic frame rate of a
-          <em>Document Instance</em> in case it is intended to function as an
-          independent media object.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id="parameter-attribute-frameRate-syntax"
-          name="parameter-attribute-frameRate-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:frameRate
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:frameRate
-  : <a href=
-"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The frame rate that applies to a <em>Document Instance</em> is
-          used to interpret time expressions that are expressed in
-          <em>frames</em> as defined by <a href=
-          "#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>If the <code>media</code> time base applies and the effective
-          frame rate is integral, then a frame is interpreted as a division of
-          a second of media time, such that if the frame rate is specified as
-          <em>F</em>, then a second of media time is divided into <em>F</em>
-          intervals of equal duration, where each interval is labeled as frame
-          <em>f</em>, with <em>f</em> ∈ [0…<em>F−1</em>].</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
-            Base</b></a> for further details on the interpretation of time
-            expressions for the <code>media</code> time base.</p>
-          </div>
-
-          <p>If not specified, the frame rate must be considered to be equal to
-          some application defined frame rate, or if no application defined
-          frame rate applies, then thirty (30) frames per second. If specified,
-          then the frame rate must be greater than zero (0).</p>
-
-          <p>A <code>ttp:frameRate</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-frameRateMultiplier" name=
-          "parameter-attribute-frameRateMultiplier"></a>6.2.5
-          ttp:frameRateMultiplier</h4>
-
-          <p>The <code>ttp:frameRateMultiplier</code> attribute is used to
-          specify a multiplier to be applied to the frame rate specified by a
-          <code>ttp:frameRate</code> attribute in order to compute the
-          effective frame rate.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id=
-          "parameter-attribute-frameRateMultiplier-syntax" name=
-          "parameter-attribute-frameRateMultiplier-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:frameRateMultiplier
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:frameRateMultiplier
-  : numerator denominator                   // <em>numerator</em> != 0; <em>denominator</em> != 0
-
-numerator | denominator
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>A frame rate multiplier is used when the desired frame rate cannot
-          be expressed as an integral number of frames per second.</p>
-
-          <p>If not specified, the frame rate multiplier must be considered to
-          be equal to one (1:1). Both numerator and denominator must be
-          non-zero.</p>
-
-          <p>A <code>ttp:frameRateMultiplier</code> attribute is considered to
-          be significant only when specified on the <code>tt</code>
-          element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The frame rate multiplier used for synchronizing with NTSC
-            <a href="#smpte170m">[SMPTE 170M]</a> formatted video objects at 30
-            frames per second is nominally 1000:1001. The nominal frame rate of
-            NTSC video is defined as the chrominance sub-carrier frequency of
-            3,579,545.45…Hz (= 5.0MHz × 63/88) times the ratio 2/455 divided by
-            the number of horizontal lines per frame of 525, which yields a
-            frame rate of 29.970029970029… (= 30 × 1000/1001) frames per
-            second. Other frame rate multipliers apply to different regions of
-            usage and video format standards.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Except in the case of PAL/M, the frame rate multiplier used for
-            synchronizing with PAL formatted video objects at 25 frames per
-            second is nominally 1:1.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-markerMode" name=
-          "parameter-attribute-markerMode"></a>6.2.6 ttp:markerMode</h4>
-
-          <p>The <code>ttp:markerMode</code> attribute is used to specify
-          constraints on the interpretation and use of time expressions that
-          correspond with <a href="#smpte12m">[SMPTE 12M]</a> time coordinates
-          when operating with time base of <code>smpte</code> as defined by
-          <a href="#parameter-attribute-timeBase"><b>6.2.11
-          ttp:timeBase</b></a>.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id="parameter-attribute-markerMode-syntax"
-          name="parameter-attribute-markerMode-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:markerMode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:markerMode
-  : "continuous"
-  | "discontinuous"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the time base, defined by <a href=
-          "#parameter-attribute-timeBase"><b>6.2.11 ttp:timeBase</b></a>, is
-          designated as <code>smpte</code>, then this parameter applies as
-          follows: if the parameter's value is <code>continuous</code>, then
-          <a href="#smpte12m">[SMPTE 12M]</a> time coordinates may be assumed
-          to be linear and either monotonically increasing or decreasing;
-          however, if <code>discontinuous</code>, then any assumption must not
-          be made regarding linearity or monotonicity of time coordinates.</p>
-
-          <p>If not specified, the value of this parameter must be considered
-          to be <code>discontinuous</code>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The default value for this parameter was originally specified
-            (in <a href=
-            "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">TTML 1.0 First
-            Edition</a>) as <code>continuous</code>; however, further
-            evaluation of the state of the industry indicates this choice was
-            incorrect, and that the most common default is
-            <code>discontinuous</code>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Due to lack of industry consensus on the utility and
-            interpretation of the <code>continuous</code> marker mode, authors
-            are advised to avoid its use. Furthermore, the
-            <code>ttp:markerMode</code> is being considered for deprecation in
-            the next revision of this specification.</p>
-          </div>
-
-          <p>A <code>ttp:markerMode</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-
-          <p>If a value of <code>continuous</code> applies, then time
-          expressions may be converted to real time coordinates by taking into
-          account the computed frame rate and drop mode as expressed by the
-          <code>ttp:dropMode</code> parameter. In this case, the <em>Content
-          Processor</em> must create and maintain a <em>Synthetic SMPTE
-          Document Syncbase</em> within which these time expressions are
-          interpreted as further described in <a href=
-          "#timing-time-intervals"><b>10.4 Time Intervals</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When operating with <code>smpte</code> time base and
-            <code>continuous</code> marker mode, there is an implied time
-            coordinate space, the <em>Synthetic SMPTE Document Syncbase</em>,
-            defined by the monotonically increasing (or decreasing) <a href=
-            "#smpte12m">[SMPTE 12M]</a> time coordinates, while taking into
-            account the computed frame rate and drop mode. All time expressions
-            are interpreted in relationship to this time coordinate space based
-            upon <em>SMPTE Time Code</em> synchronization events (markers),
-            where the <em>Document Processing Context</em> emits these events
-            with implied constraints regarding time coordinate monoticity and
-            resynchronization in the presence of dropped frames.</p>
-
-            <p>Use of <code>continuous</code> marker mode with the
-            <code>smpte</code> time base is different from using the
-            <code>media</code> time base because (1) the semantics of the
-            <code>ttp:dropMode</code> parameter apply to the former, but not
-            the latter, and (2) <a href="#smpte12m">[SMPTE 12M]</a> time
-            coordinates may be applied monotonically to media which has been
-            subjected to dilation in time, constriction in time, or reversal in
-            time.</p>
-          </div>
-
-          <p>If a value of <code>discontinuous</code> applies, then time
-          expressions must not be converted to real time coordinates,
-          arithmetical operators (addition, multiplication) are not defined on
-          time expressions, and, consequently, any (well-formed) expression of
-          a duration must be considered to be invalid.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When operating with <code>smpte</code> time base and
-            <code>discontinuous</code> marker mode, there is no effective time
-            coordinate space; rather, all time expressions are interpreted as
-            labeled synchronization events (markers), where the <em>Document
-            Processing Context</em> emits these events, which, when they
-            correspond with time expressions that denote the same label, cause
-            a temporal interval to begin or end accordingly.</p>
-
-            <p>An additional side-effect of operating in
-            <code>discontinuous</code> mode is that time expressions of
-            children have no necessary relationship with time expressions of
-            their temporal container; that is, temporal containers and children
-            of these containers are temporally activated and inactivated
-            independently based on the occurrence of a labeled synchronization
-            (marker) event.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The notion of marker discontinuity as captured by this parameter
-            is logically independent from the method used to count frames as
-            expressed by the <code>ttp:dropMode</code> parameter. In
-            particular, even if the <code>ttp:dropMode</code> parameter is
-            specified as <code>dropNTSC</code> or <code>dropPAL</code>, the
-            marker mode may be specified as <code>continuous</code>, even in
-            the presence of frame count discontinuities induced by the frame
-            counting method, unless there were some other non-linearity or
-            discontinuity in marker labeling, for example, two consecutive
-            frames labeled as <code>10:00:00:00</code> and
-            <code>10:00:01:00</code>.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-pixelAspectRatio" name=
-          "parameter-attribute-pixelAspectRatio"></a>6.2.7
-          ttp:pixelAspectRatio</h4>
-
-          <p>The <code>ttp:pixelAspectRatio</code> attribute may be used by a
-          content author to express the aspect ratio of non-square pixels in
-          the production of content that makes use of pixel coordinates.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id=
-          "parameter-attribute-pixelAspectRatio-syntax" name=
-          "parameter-attribute-pixelAspectRatio-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:pixelAspectRatio
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:pixelAspectRatio
-  : width height                            // <em>width</em> != 0; <em>height</em> != 0
-
-width | height
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If not specified, then square pixels (i.e., aspect ratio 1:1) must
-          be assumed to apply. If specified, then both width and height must be
-          non-zero.</p>
-
-          <p>A <code>ttp:pixelAspectRatio</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>This parameter may be used by a content transcoder or translator
-            in order to convert pixel measurements between different pixel
-            aspect ratios while still maintaining authorial layout
-            intentions.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-profile" name=
-          "parameter-attribute-profile"></a>6.2.8 ttp:profile</h4>
-
-          <p>The <code>ttp:profile</code> attribute may be used by a content
-          author to express the profile of the Timed Text Markup Language
-          (TTML) used in a <em>Document Instance</em>.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          <code>xsd:anyURI</code> data type defined by <a href="#xsd-2">[XML
-          Schema Part 2]</a>, §3.2.17, and, further, must specify a profile
-          designator in accordance with <a href="#vocabulary-profiles"><b>5.2
-          Profiles</b></a>.</p>
-
-          <p>A <code>ttp:profile</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-subFrameRate" name=
-          "parameter-attribute-subFrameRate"></a>6.2.9 ttp:subFrameRate</h4>
-
-          <p>The <code>ttp:subFrameRate</code> attribute is used to specify the
-          sub-frame rate of a related media object or the intrinsic sub-frame
-          rate of a <em>Document Instance</em> in case it is intended to
-          function as an independent media object.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id="parameter-attribute-subFrameRate-syntax"
-          name="parameter-attribute-subFrameRate-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:subFrameRate
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:subFrameRate
-  : <a href=
-"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The sub-frame rate that applies to a <em>Document Instance</em> is
-          used to interpret time expressions that are expressed in
-          <em>sub-frames</em> as defined by <a href=
-          "#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>If the <code>media</code> time base applies and the effective
-          frame rate is integral, a sub-frame is interpreted as a division of a
-          frame of media time, such that if the sub-frame rate is specified as
-          <em>S</em>, then a frame of media time is divided into <em>S</em>
-          intervals of equal duration, where each interval is labeled as
-          sub-frame <em>s</em>, with <em>s</em> ∈ [0…<em>S−1</em>].</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
-            Base</b></a> for further details on the interpretation of time
-            expressions for the <code>media</code> time base.</p>
-          </div>
-
-          <p>If not specified, the sub-frame rate must be considered to be
-          equal to one (1). If specified, then the sub-frame rate must be
-          greater than zero (0).</p>
-
-          <p>A <code>ttp:subFrameRate</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The sub-frame is sometimes referred to as a <em>field</em> in
-            the context of synchronization with an interlaced video media
-            object.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-tickRate" name=
-          "parameter-attribute-tickRate"></a>6.2.10 ttp:tickRate</h4>
-
-          <p>The <code>ttp:tickRate</code> attribute is used to specify the
-          tick rate of a related media object or the intrinsic tick rate of
-          content of a <em>Document Instance</em> in case it is intended to
-          function as an independent media object.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id="parameter-attribute-tickRate-syntax"
-          name="parameter-attribute-tickRate-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:tickRate
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:tickRate
-  : <a href=
-"#style-value-digit">&lt;digit&gt;</a>+                                // <em>value</em> &gt; 0
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The tick rate that applies to a <em>Document Instance</em> is used
-          to interpret time expressions that are expressed in <em>ticks</em> by
-          using the <code>t</code> metric as defined by <a href=
-          "#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>If the <code>media</code> time base applies, a tick is interpreted
-          as an integral division of a second of media time, such that if the
-          tick rate is specified as <em>T</em>, then a second of media time is
-          divided into <em>T</em> intervals of equal duration, where each
-          interval is labeled as tick <em>t</em>, with <em>t</em> ∈
-          [0…<em>T−1</em>].</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#time-expression-semantics-media"><b>N.2 Media Time
-            Base</b></a> for further details on the interpretation of time
-            expressions for the <code>media</code> time base.</p>
-          </div>
-
-          <p>If not specified, then if a frame rate is specified, the tick rate
-          must be considered to be the effective frame rate multiplied by the
-          sub-frame rate (i.e., ticks are interpreted as sub-frames); or, if no
-          frame rate is specified, the tick rate must be considered to be one
-          (1) tick per second of media time. If specified, then the tick rate
-          must not be zero (0).</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>There is no predefined relationship between ticks and frames or
-            sub-frames. Ticks are an arbitrary division of seconds that permit
-            use of fixed point arithmetic rather than fractional (and
-            potentially inexact) expressions of seconds.</p>
-          </div>
-
-          <p>A <code>ttp:tickRate</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="parameter-attribute-timeBase" name=
-          "parameter-attribute-timeBase"></a>6.2.11 ttp:timeBase</h4>
-
-          <p>The <code>ttp:timeBase</code> attribute is used to specify the
-          temporal coordinate system by means of which time expressions are
-          interpreted in a <em>Document Instance</em>.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax:</p><a id="parameter-attribute-timeBase-syntax"
-          name="parameter-attribute-timeBase-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttp:timeBase
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttp:timeBase
-  : "media"
-  | "smpte"
-  | "clock"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the time base is designated as <code>media</code>, then a time
-          expression denotes a coordinate in some media object's time line,
-          where the media object may be an external media object with which the
-          content of a <em>Document Instance</em> is to be synchronized, or it
-          may be the content of a <em>Document Instance</em> itself in a case
-          where the timed text content is intended to establish an independent
-          time line.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When using a media time base, if that time base is paused or
-            scaled positively or negatively, i.e., the media play rate is not
-            unity, then it is expected that the presentation of associated
-            Timed Text content will be similarly paused, accelerated, or
-            decelerated, respectively. The means for controlling an external
-            media time base is outside the scope of this specification.</p>
-          </div>
-
-          <p>If the time base is designated as <code>smpte</code>, then a time
-          expression denotes a <a href="#smpte12m">[SMPTE 12M]</a> time
-          coordinate with which the content of a <em>Document Instance</em> is
-          to be synchronized. In this case, the value of the
-          <code>ttp:markerMode</code> and <code>ttp:dropMode</code> parameters
-          apply, as defined by <a href=
-          "#parameter-attribute-markerMode"><b>6.2.6 ttp:markerMode</b></a> and
-          <a href="#parameter-attribute-dropMode"><b>6.2.3
-          ttp:dropMode</b></a>, respectively.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When the time base is designated as <code>smpte</code>, every
-            time expression denotes a media marker value akin to that defined
-            by <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, except instead of
-            using an opaque marker name, a structured <a href=
-            "#smpte12m">[SMPTE 12M]</a> time coordinate serves as the marker
-            name.</p>
-          </div>
-
-          <p>If the time base is designated as <code>clock</code>, then the
-          time expression denotes a coordinate in some real-world time line as
-          established by some real-time clock, such as the local wall-clock
-          time or UTC (Coordinated Universal Time) or GPS (Global Positioning
-          System) time lines.</p>
-
-          <p>If not specified, the default time base must be considered to be
-          <code>media</code>.</p>
-
-          <p>A <code>ttp:timeBase</code> attribute is considered to be
-          significant only when specified on the <code>tt</code> element.</p>
-
-          <p>When operating with either <code>media</code> or
-          <code>smpte</code> time bases, a diachronic presentation of a
-          <em>Document Instance</em> may be subject to transformations of the
-          controlling time line, such as temporal reversal, dilation
-          (expansion), or constriction (compression); however, when operating
-          with the <code>clock</code> time base, no transformations are
-          permitted, and diachronic presentation proceeds on a linear,
-          monotonically increasing time line based on the passage of real
-          time.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Due to there being only one time base parameter that applies to
-            a given <em>Document Instance</em>, the interpretation of time
-            expressions is uniform throughout the <em>Document
-            Instance</em>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#time-expression-semantics"><b>N Time Expression
-            Semantics</b></a> for further details on the interpretation of time
-            expressions according to the designated time base.</p>
-          </div>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="content" name="content"></a>7 Content</h2>
-
-      <p>This section specifies the <em>content</em> matter of the core
-      vocabulary catalog.</p>
-
-      <div class="div2">
-        <h3><a id="content-element-vocabulary" name=
-        "content-element-vocabulary"></a>7.1 Content Element Vocabulary</h3>
-
-        <p>The following elements specify the structure and principal content
-        aspects of a <em>Document Instance</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#document-structure-vocabulary-tt"><b>7.1.1
-            tt</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#document-structure-vocabulary-head"><b>7.1.2
-            head</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#document-structure-vocabulary-body"><b>7.1.3
-            body</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-vocabulary-div"><b>7.1.4 div</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-vocabulary-p"><b>7.1.5 p</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-vocabulary-span"><b>7.1.6 span</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-vocabulary-br"><b>7.1.7 br</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="document-structure-vocabulary-tt" name=
-          "document-structure-vocabulary-tt"></a>7.1.1 tt</h4>
-
-          <p>The <code>tt</code> element serves as the root document element of
-          a <em>Document Instance</em>.</p>
-
-          <p>The <code>tt</code> element accepts as its children zero or one
-          <code>head</code> element followed by zero or one <code>body</code>
-          element.</p><a id="elt-syntax-tt" name="elt-syntax-tt"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: tt
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt
-  <a href="#style-attribute-extent">tts:extent</a> = string
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang"><span class=
-"reqattr">xml:lang</span></a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>) : default
-  {<em>any attribute in TT Parameter namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#document-structure-vocabulary-head">head</a>?, <a href=
-"#document-structure-vocabulary-body">body</a>?
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The <em>Root Temporal Extent</em>, i.e., the time interval over
-          which a <em>Document Instance</em> is active, has an implicit
-          duration that is equal to the implicit duration of the
-          <code>body</code> element of the document, if the <code>body</code>
-          element is present, or zero, if the <code>body</code> element is
-          absent.</p>
-
-          <p>If the <code>tts:extent</code> attribute is specified on the
-          <code>tt</code> element, then it must adhere to <a href=
-          "#style-attribute-extent"><b>8.2.7 tts:extent</b></a>, in which case
-          it specifies the spatial extent of the <em>Root Container Region</em>
-          in which content regions are located and presented. If no
-          <code>tts:extent</code> attribute is specified, then the spatial
-          extent of the <em>Root Container Region</em> is considered to be
-          determined by the <em>Document Processing Context</em>. The origin of
-          the <em>Root Container Region</em> is determined by the <em>Document
-          Processing Context</em>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the absence of other requirements, and if a <em>Related Media
-            Object</em> exists, then it is recommended that the <em>Document
-            Processing Context</em> determine that:</p>
-
-            <ul>
-              <li>
-                <p>if no <code>tts:extent</code> is specified on the root
-                <code>tt</code> element, the extent of the <em>Root Container
-                Region</em> be established as equal to the extent of the
-                <em>Related Media Object Region</em>; and</p>
-              </li>
-
-              <li>
-                <p>the origin of the <em>Root Container Region</em> be
-                established so that this region is centered in the <em>Related
-                Media Object Region</em>.</p>
-              </li>
-            </ul>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>If an author desires to signal the (storage or image) aspect
-            ratio of the <em>Root Container Region</em> without specifying its
-            resolution, then this may be accomplished by using metadata
-            specified in an external namespace, such as
-            <code>m708:aspectRatio</code> as defined in <a href=
-            "#smpte2052">[SMPTE 2052-11]</a>, §5.4.4. This would permit, for
-            example, the interchange of information that reflects the the
-            semantics of <a href="#cea708d">[CEA-708-D]</a> , §4.5 “Caption
-            Service Metadata”, “ASPECT RATIO”.</p>
-          </div>
-
-          <p>An <code>xml:lang</code> attribute must be specified on the
-          <code>tt</code> element. If the attribute value is empty, it
-          signifies that there is no default language that applies to the text
-          contained within the <em>Document Instance</em>.</p>
-
-          <p>If no <code>xml:space</code> attribute is specified upon the
-          <code>tt</code> element, then it must be considered as if the
-          attribute had been specified with a value of
-          <code>default</code>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="document-structure-vocabulary-head" name=
-          "document-structure-vocabulary-head"></a>7.1.2 head</h4>
-
-          <p>The <code>head</code> element is a container element used to group
-          header matter, including metadata, profile, styling, and layout
-          information.</p>
-
-          <p>The <code>head</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed
-          by zero or more elements in the <code>Parameters.class</code> element
-          group, followed by zero or one <code>styling</code> element, followed
-          by zero or one <code>layout</code> element.</p>
-
-          <p>Any metadata specified by children in the
-          <code>Metadata.class</code> element group applies semantically to the
-          <em>Document Instance</em> as a whole, and not just the
-          <code>head</code> element.</p>
-
-          <p>Any parameters specified by children in the
-          <code>Parameters.class</code> element group applies semantically to
-          the <em>Document Instance</em> as a whole, and not just the
-          <code>head</code> element.</p>
-
-          <p>A <code>styling</code> child element is used to specify style
-          constructs that are referenced from other style constructs, by layout
-          constructs, and by content elements.</p>
-
-          <p>A <code>layout</code> child element is used to specify layout
-          constructs that are referenced by content elements.</p><a id=
-          "elt-syntax-head" name="elt-syntax-head"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: head
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;head
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Parameters.class</a>*, <a href=
-"#styling-vocabulary-styling">styling</a>?, <a href=
-"#layout-vocabulary-layout">layout</a>?
-&lt;/head&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>To the extent that time semantics apply to the content of the
-          <code>head</code> element, the implied time interval of this element
-          is defined to be coterminous with the <em>Root Temporal
-          Extent</em>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="document-structure-vocabulary-body" name=
-          "document-structure-vocabulary-body"></a>7.1.3 body</h4>
-
-          <p>The <code>body</code> element functions as a logical container and
-          a temporal structuring element for a sequence of textual content
-          units represented as logical divisions.</p>
-
-          <p>The <code>body</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed
-          by zero or more elements in the <code>Animation.class</code> element
-          group, followed by zero or more <code>div</code> elements.</p>
-
-          <p>Any metadata specified by children in the
-          <code>Metadata.class</code> element group applies semantically to the
-          <code>body</code> element and its descendants as a whole.</p>
-
-          <p>Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>body</code> element.</p><a id="elt-syntax-body" name=
-          "elt-syntax-body"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: body
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;body
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#layout-attribute-region">region</a> = IDREF
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#content-vocabulary-div">div</a>*
-&lt;/body&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An author may specify a temporal interval for a <code>body</code>
-          element using the <code>begin</code>, <code>dur</code>, and
-          <code>end</code> attributes. If the begin point of this interval
-          remains unspecified, then the begin point is interpreted as the
-          beginning point of the <em>Root Temporal Extent</em>. Similarly, if
-          the end point of this interval remains unspecified, then the end
-          point is interpreted as the ending point of the <em>Root Temporal
-          Extent</em>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>A <em>Document Instance</em> referenced from a SMIL presentation
-            is expected to follow the same timing rules as apply to other SMIL
-            media objects.</p>
-          </div>
-
-          <p>If relative begin or end times are specified on the
-          <code>body</code> element, then these times are resolved by reference
-          to the beginning and ending time of the <em>Root Temporal
-          Extent</em>.</p>
-
-          <p>If the <em>Root Temporal Extent</em> is shorter than the computed
-          duration of the <code>body</code> element, then the active time
-          interval of a <code>body</code> element is truncated to the active
-          end point of the <em>Root Temporal Extent</em>.</p>
-
-          <p>An author may associate a set of style properties with a
-          <code>body</code> element by means of either the <code>style</code>
-          attribute or inline style attributes or a combination thereof.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Style properties that are associated with a <code>body</code>
-            element in a <em>Document Instance</em> are available for style
-            inheritance by descendant content elements such as
-            <code>div</code>, <code>p</code>, <code>span</code> and
-            <code>br</code>.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>body</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-vocabulary-div" name=
-          "content-vocabulary-div"></a>7.1.4 div</h4>
-
-          <p>The <code>div</code> element functions as a logical container and
-          a temporal structuring element for a sequence of textual content
-          units represented as logical sub-divisions or paragraphs.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When rendered on a continuous (non-paged) visual presentation
-            medium, a <code>div</code> element is expected to generate one or
-            more block areas that contain zero or more child block areas
-            generated by the <code>div</code> element's descendant
-            <code>p</code> elements.</p>
-
-            <p>If some block area generated by a <code>div</code> element does
-            not contain any child areas, then it is not expected to be
-            presented.</p>
-          </div>
-
-          <p>The <code>div</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed
-          by zero or more elements in the <code>Animation.class</code> element
-          group, followed by zero or more <code>div</code> or <code>p</code>
-          elements.</p>
-
-          <p>Any metadata specified by children in the
-          <code>Metadata.class</code> element group applies semantically to the
-          <code>div</code> element and its descendants as a whole.</p>
-
-          <p>Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>div</code> element.</p><a id="elt-syntax-div" name=
-          "elt-syntax-div"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: div
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;div
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#layout-attribute-region">region</a> = IDREF
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#element-vocab-group-table">Block.class</a>*
-&lt;/div&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An author may associate a set of style properties with a
-          <code>div</code> element by means of either the <code>style</code>
-          attribute or inline style attributes or a combination thereof.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Style properties that are associated with a <code>div</code>
-            element in a <em>Document Instance</em> are available for style
-            inheritance by descendant content elements such as
-            <code>div</code>, <code>p</code>, <code>span</code>, and
-            <code>br</code>.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>div</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-vocabulary-p" name=
-          "content-vocabulary-p"></a>7.1.5 p</h4>
-
-          <p>A <code>p</code> element represents a logical paragraph, serving
-          as a transition between block level and inline level formatting
-          semantics.</p>
-
-          <p>The <code>p</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed
-          by zero or more elements in the <code>Animation.class</code> element
-          group, followed by zero or more intermixed <code>span</code>
-          elements, <code>br</code> elements, or text nodes interpreted as an
-          anonymous spans.</p>
-
-          <p>Any metadata specified by children in the
-          <code>Metadata.class</code> element group applies semantically to the
-          <code>p</code> element and its descendants as a whole.</p>
-
-          <p>Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>p</code> element.</p><a id="elt-syntax-p" name=
-          "elt-syntax-p"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: p
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;p
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#layout-attribute-region">region</a> = IDREF
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#element-vocab-group-table">Inline.class</a>*
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An author may associate a set of style properties with a
-          <code>p</code> element by means of either the <code>style</code>
-          attribute or inline style attributes or a combination thereof.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Style properties that are associated with a <code>p</code>
-            element in a <em>Document Instance</em> are available for style
-            inheritance by descendant content elements such as
-            <code>span</code> and <code>br</code>.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>p</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-
-          <p>If a sequence of children of a <code>p</code> element consists
-          solely of character information items, then that sequence must be
-          considered to be an <em>anonymous span</em> for the purpose of
-          applying style properties that apply to <code>span</code>
-          elements.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The presentation semantics of TTML effectively implies that a
-            <code>p</code> element constitutes a line break. In particular, it
-            is associated with a block-stacking constraint both before the
-            first generated line area and after the last generated line area.
-            See <a href="#semantics-region-layout-step-2"><b>9.3.3 Synchronic
-            Flow Processing</b></a> for further details.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-vocabulary-span" name=
-          "content-vocabulary-span"></a>7.1.6 span</h4>
-
-          <p>The <code>span</code> element functions as a logical container and
-          a temporal structuring element for a sequence of textual content
-          units having inline level formatting semantics.</p>
-
-          <p>When presented on a visual medium, a <code>span</code> element is
-          intended to generate a sequence of inline areas, each containing one
-          or more glyph areas.</p>
-
-          <p>The <code>span</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group, followed
-          by zero or more elements in the <code>Animation.class</code> element
-          group, followed by zero or more intermixed <code>span</code>
-          elements, <code>br</code> elements, or text nodes interpreted as
-          anonymous spans.</p>
-
-          <p>Any metadata specified by children in the
-          <code>Metadata.class</code> element group applies semantically to the
-          <code>span</code> element and its descendants as a whole.</p>
-
-          <p>Any animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>span</code> element.</p><a id="elt-syntax-span" name=
-          "elt-syntax-span"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: span
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;span
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#layout-attribute-region">region</a> = IDREF
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#element-vocab-group-table">Inline.class</a>*
-&lt;/span&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An author may associate a set of style properties with a
-          <code>span</code> element by means of either the <code>style</code>
-          attribute or inline style attributes or a combination thereof.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Style properties that are associated with a <code>span</code>
-            element in a <em>Document Instance</em> are available for style
-            inheritance by descendant content elements such as
-            <code>span</code> and <code>br</code>.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>span</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-vocabulary-br" name=
-          "content-vocabulary-br"></a>7.1.7 br</h4>
-
-          <p>The <code>br</code> element denotes an explicit line
-          break.</p><a id="elt-syntax-br" name="elt-syntax-br"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: br
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;br
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*
-&lt;/br&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>When presented on a visual medium, the presence of a
-          <code>br</code> element must be interpreted as a forced line
-          break.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The visual presentation of a <code>br</code> element is intended
-            to produce the same effect as the control character <code>CR</code>
-            (U+000D) followed by the control code <code>LF</code> (U+000A) when
-            presented on a teletype device. Therefore, two <code>br</code>
-            elements in sequence will produce a different effect than a single
-            <code>br</code> element.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="content-attribute-vocabulary" name=
-        "content-attribute-vocabulary"></a>7.2 Content Attribute
-        Vocabulary</h3>
-
-        <p>This section defines the following common attributes used with many
-        or all element types in the core vocabulary catalog:</p>
-
-        <ul>
-          <li>
-            <p><a href="#content-attribute-id"><b>7.2.1 xml:id</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-attribute-lang"><b>7.2.2 xml:lang</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#content-attribute-space"><b>7.2.3
-            xml:space</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="content-attribute-id" name=
-          "content-attribute-id"></a>7.2.1 xml:id</h4>
-
-          <p>The <code>xml:id</code> attribute is used as defined by <a href=
-          "#xmlid">[XML ID]</a>.</p>
-
-          <p>The <code>xml:id</code> attribute may be used with any element in
-          the core vocabulary catalog.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-attribute-lang" name=
-          "content-attribute-lang"></a>7.2.2 xml:lang</h4>
-
-          <p>The <code>xml:lang</code> attribute is used as defined by <a href=
-          "#xml10">[XML 1.0]</a>, §2.12, <em>Language Identification</em>.</p>
-
-          <p>The <code>xml:lang</code> attribute must be specified on the
-          <code>tt</code> element and may be specified by an instance of any
-          other element type in the core vocabulary catalog except parameter
-          vocabulary.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="content-attribute-space" name=
-          "content-attribute-space"></a>7.2.3 xml:space</h4>
-
-          <p>The <code>xml:space</code> attribute is used as defined by
-          <a href="#xml10">[XML 1.0]</a>, §2.10, <em>White Space
-          Handling</em>.</p>
-
-          <p>The <code>xml:space</code> attribute may be used with any element
-          in the core vocabulary catalog except parameter vocabulary.</p>
-
-          <p>The semantics of the value <code>default</code> are fixed to mean
-          that when performing presentation processing of a <em>Document
-          Instance</em> as described by <a href=
-          "#semantics-region-layout-step-2"><b>9.3.3 Synchronic Flow
-          Processing</b></a>, processing must occur as if the following
-          properties were specified on the affected elements of an equivalent
-          intermediate XSL-FO document:</p>
-
-          <ul>
-            <li>
-              <p><code>suppress-at-line-break="auto"</code></p>
-            </li>
-
-            <li>
-              <p><code>linefeed-treatment="treat-as-space"</code></p>
-            </li>
-
-            <li>
-              <p><code>white-space-collapse="true"</code></p>
-            </li>
-
-            <li>
-              <p>
-              <code>white-space-treatment="ignore-if-surrounding-linefeed"</code></p>
-            </li>
-          </ul>
-
-          <p>Similarly, the semantics of the value <code>preserve</code> are
-          fixed to mean that when performing presentation processing,
-          processing must occur as if the following properties were specified
-          on the affected elements of an equivalent intermediate XSL-FO
-          document:</p>
-
-          <ul>
-            <li>
-              <p><code>suppress-at-line-break="retain"</code></p>
-            </li>
-
-            <li>
-              <p><code>linefeed-treatment="preserve"</code></p>
-            </li>
-
-            <li>
-              <p><code>white-space-collapse="false"</code></p>
-            </li>
-
-            <li>
-              <p><code>white-space-treatment="preserve"</code></p>
-            </li>
-          </ul>
-
-          <p>When performing other types of processing intended to eventually
-          result in a visual presentation by means other than those described
-          in this specification, the semantics of space collapsing and
-          preservation as described above should be respected. For other types
-          of processing, the treatment of the <code>xml:space</code> attribute
-          is processor dependent, but should respect the semantics described
-          above if possible.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the above four cited XSL-FO properties are
-            defined by by <a href="#xsl11">[XSL 1.1]</a>, § 7.17.3, 7.16.7,
-            7.16.12, and 7.16.8, respectively.</p>
-          </div>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="styling" name="styling"></a>8 Styling</h2>
-
-      <p>This section specifies the <em>styling</em> matter of the core
-      vocabulary catalog, where styling is to be understood as a separable
-      layer of information that applies to content and that denotes authorial
-      intentions about the presentation of that content.</p>
-
-      <p>Styling attributes are included in TTML to enable authorial intent of
-      presentation to be included within a self-contained document. This
-      section describes the semantics of style presentation in terms of a
-      standard processing model. TTML Processors are not required to present
-      <em>Document Instances</em> in any particular way; but an implementation
-      of this model by a TTML Presentation Processor that provides externally
-      observable results that are consistent with this model is likely to lead
-      to a user experience that closely resembles the experience intended by
-      the documents' authors.</p>
-
-      <p>The semantics of TTML style presentation are described in terms of the
-      model in <a href="#xsl11">[XSL 1.1]</a>. The effects of the attributes in
-      this section are intended to be compatible with the layout and formatting
-      model of XSL; however, Presentation agents may use any technology to
-      satisfy the authorial intent of the document. In particular since
-      <a href="#css2">[CSS2]</a> is a subset of this model, a CSS processor may
-      be used for the features that the models have in common.</p>
-
-      <p>No normative use of an <code>&lt;?xml-stylesheet ... ?&gt;</code>
-      processing instruction is defined by this specification.</p>
-
-      <div class="div2">
-        <h3><a id="styling-element-vocabulary" name=
-        "styling-element-vocabulary"></a>8.1 Styling Element Vocabulary</h3>
-
-        <p>The following elements specify the structure and principal styling
-        aspects of a <em>Document Instance</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#styling-vocabulary-styling"><b>8.1.1
-            styling</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#styling-vocabulary-style"><b>8.1.2 style</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="styling-vocabulary-styling" name=
-          "styling-vocabulary-styling"></a>8.1.1 styling</h4>
-
-          <p>The <code>styling</code> element is a container element used to
-          group styling matter, including metadata that applies to styling
-          matter.</p>
-
-          <p>The <code>styling</code> element accepts as its children zero or
-          more elements in the <code>Metadata.class</code> element group,
-          followed by zero or more <code>style</code> elements.</p><a id=
-          "elt-syntax-styling" name="elt-syntax-styling"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: styling
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;styling
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#styling-vocabulary-style">style</a>*
-&lt;/styling&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>To the extent that time semantics apply to the content of the
-          <code>styling</code> element, the implied time interval of this
-          element is defined to be coterminous with the <em>Root Temporal
-          Extent</em>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="styling-vocabulary-style" name=
-          "styling-vocabulary-style"></a>8.1.2 style</h4>
-
-          <p>The <code>style</code> element is used to define a set of style
-          specifications expressed as a specified style set in accordance with
-          <a href="#semantics-style-resolution-processing-sss"><b>8.4.4.2
-          Specified Style Set Processing</b></a>.</p>
-
-          <p>The <code>style</code> element accepts as its children zero or
-          more <code>metadata</code> elements.</p><a id="elt-syntax-style"
-          name="elt-syntax-style"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: style
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;style
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
- <em>Content:</em> EMPTY
-&lt;/style&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a <code>style</code> element appears as a descendant of a
-          <code>region</code> element, then the <code>style</code> element must
-          be ignored for the purpose of computing referential styles as defined
-          by <a href="#semantics-style-association-referential"><b>8.4.1.2
-          Referential Styling</b></a> and <a href=
-          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
-          Referential Styling</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>That is to say, when referential styling is used by an element
-            to refer to a <code>style</code> element, then the referenced
-            <code>style</code> element must appear as a descendant of the
-            <code>styling</code> element, and not in any other context.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="styling-attribute-vocabulary" name=
-        "styling-attribute-vocabulary"></a>8.2 Styling Attribute
-        Vocabulary</h3>
-
-        <p>This section defines the <a href="#style-attribute-style"><b>8.2.1
-        style</b></a> attribute used with both style definition elements as
-        well as content elements.</p>
-
-        <p>In addition, this section specifies the following attributes in the
-        TT Style Namespace for use with style definition elements, certain
-        layout elements, and content elements that support inline style
-        specifications:</p>
-
-        <ul>
-          <li>
-            <p><a href="#style-attribute-backgroundColor"><b>8.2.2
-            tts:backgroundColor</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-color"><b>8.2.3 tts:color</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-direction"><b>8.2.4
-            tts:direction</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-display"><b>8.2.5
-            tts:display</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-displayAlign"><b>8.2.6
-            tts:displayAlign</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-extent"><b>8.2.7
-            tts:extent</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-fontFamily"><b>8.2.8
-            tts:fontFamily</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-fontSize"><b>8.2.9
-            tts:fontSize</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-fontStyle"><b>8.2.10
-            tts:fontStyle</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-fontWeight"><b>8.2.11
-            tts:fontWeight</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-lineHeight"><b>8.2.12
-            tts:lineHeight</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-opacity"><b>8.2.13
-            tts:opacity</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-origin"><b>8.2.14
-            tts:origin</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-overflow"><b>8.2.15
-            tts:overflow</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-padding"><b>8.2.16
-            tts:padding</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-showBackground"><b>8.2.17
-            tts:showBackground</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-textAlign"><b>8.2.18
-            tts:textAlign</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-textDecoration"><b>8.2.19
-            tts:textDecoration</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-textOutline"><b>8.2.20
-            tts:textOutline</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-unicodeBidi"><b>8.2.21
-            tts:unicodeBidi</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-visibility"><b>8.2.22
-            tts:visibility</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-wrapOption"><b>8.2.23
-            tts:wrapOption</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-writingMode"><b>8.2.24
-            tts:writingMode</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-attribute-zIndex"><b>8.2.25
-            tts:zIndex</b></a></p>
-          </li>
-        </ul>
-
-        <p>Unless explicitly stated otherwise, linear white-space (LWSP) must
-        appear between adjacent non-terminal components of a value of a TT
-        Style or TT Style Extension Property value unless some other delimiter
-        is permitted and used.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>This specification makes use of <em>lowerCamelCased</em> local
-          names for style attributes that are based upon like-named properties
-          defined by <a href="#xsl11">[XSL 1.1]</a>. This convention is
-          likewise extended to token values of such properties.</p>
-        </div>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>A style property may be expressed as a specified attribute on any
-          content element type independently of whether the property applies to
-          that element type. This capability permits the expression of an
-          inheritable style property on ancestor elements to which the property
-          does not apply.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-style" name=
-          "style-attribute-style"></a>8.2.1 style</h4>
-
-          <p>The <code>style</code> attribute is used by referential style
-          association to reference one or more <code>style</code> elements each
-          of which define a style (property) set.</p>
-
-          <p>The <code>style</code> attribute may be specified by an instance
-          of the following element types:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#document-structure-vocabulary-body"><code>body</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#layout-vocabulary-region"><code>region</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#styling-vocabulary-style"><code>style</code></a></p>
-            </li>
-          </ul>
-
-          <p>If specified, the value of a <code>style</code> attribute must
-          adhere to the <code>IDREFS</code> data type defined by <a href=
-          "#xsd-2">[XML Schema Part 2]</a>, § 3.3.10, and, furthermore, each
-          IDREF must reference a <code>style</code> element which has a
-          <code>styling</code> element as an ancestor.</p>
-
-          <p>If the same IDREF, <em>ID<sub>1</sub></em>, appears more than one
-          time in the value of a <code>style</code> attribute, then there
-          should be an intervening IDREF, <em>ID<sub>2</sub></em>, where
-          <em>ID<sub>2</sub></em> is not equal to <em>ID<sub>1</sub></em>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>This constraint is intended to discourage the use of redundant
-            referential styling while still allowing the same style to be
-            referenced multiple times in order to potentially override prior
-            referenced styles, e.g., when an intervening, distinct style is
-            referenced in the IDREFS list.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See the specific element type definitions that permit use of the
-            <code>style</code> attribute, as well as <a href=
-            "#semantics-style-association-referential"><b>8.4.1.2 Referential
-            Styling</b></a> and <a href=
-            "#semantics-style-association-chained-referential"><b>8.4.1.3
-            Chained Referential Styling</b></a>, for further information on its
-            semantics.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-backgroundColor" name=
-          "style-attribute-backgroundColor"></a>8.2.2 tts:backgroundColor</h4>
-
-          <p>The <code>tts:backgroundColor</code> attribute is used to specify
-          a style property that defines the background color of a region or an
-          area generated by content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id=
-          "style-property-details-backgroundColor" name=
-          "style-property-details-backgroundColor"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-color">&lt;color&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>transparent</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#document-structure-vocabulary-body"><code>body</code></a>,
-                <a href="#content-vocabulary-div"><code>div</code></a>,
-                <a href="#content-vocabulary-p"><code>p</code></a>, <a href=
-                "#layout-vocabulary-region"><code>region</code></a>, <a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>The <code>tts:backgroundColor</code> style is illustrated by the
-          following example.</p><a id=
-          "style-attribute-backgroundColor-example-1" name=
-          "style-attribute-backgroundColor-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Background Color
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="306px 114px"/&gt;
-  &lt;style <span class="strong">tts:backgroundColor="red"</span>/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:padding="3px 40px"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1" <span class=
-"strong">tts:backgroundColor="purple"</span> tts:textAlign="center"&gt;
-  Twinkle, twinkle, little bat!&lt;br/&gt;
-  How &lt;span <span class=
-"strong">tts:backgroundColor="green"</span>&gt;I wonder&lt;/span&gt; where you're at!
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-backgroundColor-example-1-images"
-          name="style-attribute-backgroundColor-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Background Color
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/backgroundColor.png" alt=
-                "TTML backgroundColor style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.8.2.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-color" name=
-          "style-attribute-color"></a>8.2.3 tts:color</h4>
-
-          <p>The <code>tts:color</code> attribute is used to specify a style
-          property that defines the foreground color of marks associated with
-          an area generated by content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-color" name=
-          "style-property-details-color"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-color">&lt;color&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td>see prose</td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>The initial value of the <code>tts:color</code> property is
-          considered to be implementation dependent. In the absence of end-user
-          preference information, a conformant presentation processor should
-          use an initial value that is highly contrastive to the background
-          color of the <em>Root Container Region</em>.</p>
-
-          <p>The <code>tts:color</code> style is illustrated by the following
-          example.</p><a id="style-attribute-color-example-1" name=
-          "style-attribute-color-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Color
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style <span class="strong">tts:color="white"</span>/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  In spring, when woods are &lt;span <span class=
-"strong">tts:color="green"</span>&gt;getting green&lt;/span&gt;,&lt;br/&gt;
-  I'll try and tell you what I mean.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-color-example-1-images" name=
-          "style-attribute-color-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Color
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/color.png" alt=
-                "TTML color style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.18.1.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-direction" name=
-          "style-attribute-direction"></a>8.2.4 tts:direction</h4>
-
-          <p>The <code>tts:direction</code> attribute is used to specify a
-          style property that defines the directionality of an embedding or
-          override according to the Unicode bidirectional algorithm.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-direction"
-          name="style-property-details-direction"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>ltr</code> | <code>rtl</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>ltr</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-p"><code>p</code></a>,
-                <a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must ignore the attribute.</p>
-
-          <p>The <code>tts:direction</code> style is illustrated by the
-          following example.</p><a id="style-attribute-direction-example-1"
-          name="style-attribute-direction-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Direction
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="265px 84px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  Little birds are playing&lt;br/&gt;
-  Bagpipes on the shore,&lt;br/&gt;
-  &lt;span tts:unicodeBidi="bidiOverride" <span class=
-"strong">tts:direction="rtl"</span>&gt;where the tourists snore.&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-direction-example-1-images" name=
-          "style-attribute-direction-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Direction
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/direction.png" alt=
-                "TTML direction style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.29.1.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-display" name=
-          "style-attribute-display"></a>8.2.5 tts:display</h4>
-
-          <p>The <code>tts:display</code> attribute is used to specify a style
-          property that defines whether an element is a candidate for layout
-          and composition in a region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-display" name=
-          "style-property-details-display"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>auto</code> | <code>none</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>auto</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#document-structure-vocabulary-body"><code>body</code></a>,
-                <a href="#content-vocabulary-div"><code>div</code></a>,
-                <a href="#content-vocabulary-p"><code>p</code></a>, <a href=
-                "#layout-vocabulary-region"><code>region</code></a>, <a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>If the value of this attribute is <code>auto</code>, then the
-          affected element is a candidate for region layout and presentation;
-          however, if the value is <code>none</code>, then the affected element
-          and its descendants must be considered ineligible for region layout
-          and presentation.</p>
-
-          <p>The <code>tts:display</code> style is illustrated by the following
-          example.</p><a id="style-attribute-display-example-1" name=
-          "style-attribute-display-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Display
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="369px 119px"
-            tts:backgroundColor="black"
-            tts:color="white"
-            tts:displayAlign="before"
-            tts:textAlign="start"/&gt;
-&lt;/region&gt;
-...
-&lt;div region="r1"&gt;
-  &lt;p dur="5s"&gt;
-    [[[
-    &lt;span <span class="strong">tts:display="none"</span>&gt;
-      &lt;set begin="1s" dur="1s" <span class=
-"strong">tts:display="auto"</span>/&gt;
-      Beautiful soup,
-    &lt;/span&gt;
-    &lt;span <span class="strong">tts:display="none"</span>&gt;
-      &lt;set begin="2s" dur="1s" <span class=
-"strong">tts:display="auto"</span>/&gt;
-      so rich and green,
-    &lt;/span&gt;
-    &lt;span <span class="strong">tts:display="none"</span>&gt;
-      &lt;set begin="3s" dur="1s" <span class=
-"strong">tts:display="auto"</span>/&gt;
-      waiting in a hot tureen!
-    &lt;/span&gt;
-    ]]]
-  &lt;/p&gt;
-&lt;/div&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-display-example-1-images" name=
-          "style-attribute-display-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Display
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/display_0.png" alt=
-                "TTML display style property - [0,1)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/display_1.png" alt=
-                "TTML display style property - [1,2)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/display_2.png" alt=
-                "TTML display style property - [2,3)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/display_3.png" alt=
-                "TTML display style property - [3,4)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/display_4.png" alt=
-                "TTML display style property - [4,5)"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href=
-            "#css2">[CSS2]</a>, § 9.2.4.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-displayAlign" name=
-          "style-attribute-displayAlign"></a>8.2.6 tts:displayAlign</h4>
-
-          <p>The <code>tts:displayAlign</code> attribute is used to specify a
-          style property that defines the alignment of block areas in the block
-          progression direction.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-displayAlign"
-          name="style-property-details-displayAlign"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>before</code> | <code>center</code> |
-                <code>after</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>before</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>before</code> were specified.</p>
-
-          <p>The <code>tts:displayAlign</code> style is illustrated by the
-          following example.</p><a id="style-attribute-displayAlign-example-1"
-          name="style-attribute-displayAlign-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Display Align
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="128px 66px" tts:origin="0px 0px"
-       tts:backgroundColor="black" tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:displayAlign="before"</span>/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:extent="192px 66px" tts:origin="128px 66px"/&gt;
-       tts:backgroundColor="green" tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:displayAlign="after"</span>/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r3"&gt;
-  &lt;style tts:extent="128px 66px"/&gt; style tts:origin="0px 132px"
-       tts:backgroundColor="black" tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:displayAlign="before"</span>/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r4"&gt;
-  &lt;style tts:extent="192px 66px" tts:origin="128px 198px"/&gt;
-       tts:backgroundColor="green" tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:displayAlign="after"</span>/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-...
-&lt;div&gt;
-  &lt;p region="r1"&gt;I sent a message to the fish:&lt;/p&gt;
-  &lt;p region="r2"&gt;I told them&lt;br/&gt; "This is what I wish."&lt;/p&gt;
-  &lt;p region="r3"&gt;The little fishes of the sea,&lt;/p&gt;
-  &lt;p region="r4"&gt;They sent an&lt;br/&gt; answer back to me.&lt;/p&gt;
-&lt;/div&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-displayAlign-example-1-images" name=
-          "style-attribute-displayAlign-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Display Align
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/displayAlign.png" alt=
-                "TTML displayAlign style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.14.4.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-extent" name=
-          "style-attribute-extent"></a>8.2.7 tts:extent</h4>
-
-          <p>The <code>tts:extent</code> attribute is used to specify the
-          <em>width</em> and <em>height</em> of a region area (which may be the
-          <em>Root Container Region</em>).</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-extent" name=
-          "style-property-details-extent"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>auto</code> | <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>auto</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#document-structure-vocabulary-tt"><code>tt</code></a>,
-                <a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to width and height of <em>Root Container
-                Region</em></td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute consists of two <a href=
-          "#style-value-length">&lt;length&gt;</a> specifications, then they
-          must be interpreted as <em>width</em> and <em>height</em>, where the
-          first specification is the <em>width</em>, and the second
-          specification is the <em>height</em>.</p>
-
-          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used
-          to express extent must be non-negative.</p>
-
-          <p>If the value of this attribute is <code>auto</code>, then the
-          initial value of the style property must be considered to be the same
-          as the extent of the <em>Root Container Region</em>.</p>
-
-          <p>The extent of the <em>Root Container Region</em> is determined
-          either by a <code>tts:extent</code> specified on the <code>tt</code>
-          element, if present, or as described by <a href=
-          "#document-structure-vocabulary-tt"><b>7.1.1 tt</b></a> if not
-          present. If <code>tts:extent</code> is specified on the
-          <code>tt</code> element, then the width and height must be expressed
-          in terms of two <a href="#style-value-length">&lt;length&gt;</a>
-          specifications, and these specifications must be expressed as
-          non-percentage, definite lengths using pixel units.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>auto</code> were specified.</p>
-
-          <p>The <code>tts:extent</code> style is illustrated by the following
-          example.</p><a id="style-attribute-extent-example-1" name=
-          "style-attribute-extent-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Extent
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style <span class="strong">tts:extent="330px 122px"</span>/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  'Tis the voice of the Lobster:&lt;br/&gt;
-  I heard him declare,&lt;br/&gt;
-  "You have baked me too brown,&lt;br/&gt;
-  I must sugar my hair."
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-extent-example-1-images" name=
-          "style-attribute-extent-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Extent
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/extent.png" alt=
-                "TTML extent style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-fontFamily" name=
-          "style-attribute-fontFamily"></a>8.2.8 tts:fontFamily</h4>
-
-          <p>The <code>tts:fontFamily</code> attribute is used to specify a
-          style property that defines the font family from which glyphs are
-          selected for glyph areas generated by content flowed into a
-          region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-fontFamily"
-          name="style-property-details-fontFamily"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td>(<a href="#style-value-familyName">&lt;familyName&gt;</a> |
-                <a href=
-                "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a>)
-                (<code>","</code> &nbsp;(<a href=
-                "#style-value-familyName">&lt;familyName&gt;</a> | <a href=
-                "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a>))*</td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>default</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The initial value, <code>default</code>, is a generic font
-            family name, and is further described in <a href=
-            "#style-value-genericFamilyName"><b>8.3.6
-            &lt;genericFamilyName&gt;</b></a> below.</p>
-          </div>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>If a specified font family is not available, then a presentation
-          processor must attempt to map the specified font family to an
-          available font family that has similar typographic characteristics,
-          or, in the absence of such a mapping, it must interpret the font
-          family as if the value <code>default</code> were specified.</p>
-
-          <p>The <code>tts:fontFamily</code> style is illustrated by the
-          following example.</p><a id="style-attribute-fontFamily-example-1"
-          name="style-attribute-fontFamily-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Font Family
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="474px 146px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-  &lt;style <span class=
-"strong">tts:fontFamily="proportionalSansSerif"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;div region="r1"&gt;
-  &lt;p&gt;
-    "The time has come," the Walrus said,&lt;br/&gt;
-    "to talk of many things:
-  &lt;/p&gt;
-  &lt;p tts:textAlign="end" <span class=
-"strong">tts:fontFamily="monospaceSerif"</span>&gt;
-    Of shoes, and ships, and sealing wax,&lt;br/&gt;
-    Of cabbages and kings,
-  &lt;/p&gt;
-  &lt;p&gt;
-    And why the sea is boiling hot,&lt;br/&gt;
-    and whether pigs have wings."
-  &lt;/p&gt;
-&lt;/div&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-fontFamily-example-1-images" name=
-          "style-attribute-fontFamily-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Font Family
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/fontFamily.png" alt=
-                "TTML fontFamily style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.9.2.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-fontSize" name=
-          "style-attribute-fontSize"></a>8.2.9 tts:fontSize</h4>
-
-          <p>The <code>tts:fontSize</code> attribute is used to specify a style
-          property that defines the font size for glyphs that are selected for
-          glyph areas generated by content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-fontSize" name=
-          "style-property-details-fontSize"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a>?</td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>1c</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to parent element's font size, or if no parent
-                element, then relative to the <em>Computed Cell Size</em></td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a single <a href="#style-value-length">&lt;length&gt;</a> value
-          is specified, then this length applies equally to horizontal and
-          vertical scaling of a glyph's EM square; if two <a href=
-          "#style-value-length">&lt;length&gt;</a> values are specified, then
-          the first expresses the horizontal scaling and the second expresses
-          vertical scaling.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Use of independent horizontal and vertical font sizes is
-            expected to be used with cell based units in order to denote fonts
-            that are two rows in height and one column in width.</p>
-          </div>
-
-          <p>If horizontal and vertical sizes are expressed independently, then
-          the units of the <a href="#style-value-length">&lt;length&gt;</a>
-          values must be the same.</p>
-
-          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used
-          to express font size must be non-negative.</p>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the closest
-          supported value were specified.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The expression <code>1c</code> means one cell, where
-            <code>'c'</code> expresses the <em>cell</em> length unit as defined
-            by <a href="#style-value-length"><b>8.3.9 &lt;length&gt;</b></a>.
-            When a single &lt;length&gt; is expressed using cell units, then it
-            refers to the height of the <em>Computed Cell Size</em>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>As specified above, the use of percentage units to express font
-            size are interpreted as relative to <em>Computed Cell Size</em>
-            when there is no parent element. For example, if cell resolution is
-            32 by 15, and the extent of the <em>Root Container Region</em> is
-            640 by 480, then the <em>Computed Cell Size</em> is [20px, 32px],
-            i.e., 640px/32 (width) and 480px/15 (height). Consequently, if
-            <code>tts:fontSize</code> were specified as 75% on the root
-            <code>tt</code> element, then this would be equivalent to
-            specifying 24px, i.e., 32px cell height * 75%. If two length
-            expressions (independent horizontal and vertical font scaling) were
-            specified, e.g., "80% 75%", then this would be equivalent to
-            specifying "16px 24px", i.e., 80% of 20px cell width is 16px, and
-            75% of 32px cell height is 24px.</p>
-          </div>
-
-          <p>The <code>tts:fontSize</code> style is illustrated by the
-          following example.</p><a id="style-attribute-fontSize-example-1"
-          name="style-attribute-fontSize-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Font Size
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="299px 97px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style <span class="strong">tts:fontSize="18px"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  Then fill up the glasses&lt;br/&gt;
-  with treacle and ink,&lt;br/&gt;
-  Or anything else&lt;br/&gt;
-  that is &lt;span <span class=
-"strong">tts:fontSize="24px"</span>&gt;pleasant&lt;/span&gt; to drink.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-fontSize-example-1-images" name=
-          "style-attribute-fontSize-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Font Size
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/fontSize.png" alt=
-                "TTML fontSize style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.9.4. The addition of a second length component to
-            permit specifying font width and height independently is an
-            extension introduced by TTML.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-fontStyle" name=
-          "style-attribute-fontStyle"></a>8.2.10 tts:fontStyle</h4>
-
-          <p>The <code>tts:fontStyle</code> attribute is used to specify a
-          style property that defines the font style to apply to glyphs that
-          are selected for glyph areas generated by content flowed into a
-          region, where the mapping from font style value to specific font face
-          or style parameterization is not determined by this
-          specification.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-fontStyle"
-          name="style-property-details-fontStyle"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>normal</code> | <code>italic</code> |
-                <code>oblique</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>normal</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>Use of the value <code>oblique</code> denotes a shear
-          transformation (at an unspecified angle) in the inline progression
-          dimension.</p>
-
-          <p>If a specified font style is not available, then a presentation
-          processor must attempt to map the specified font style to an
-          available font style that has similar typographic characteristics,
-          or, in the absence of such a mapping, it must interpret the font
-          style as if the value <code>normal</code> were specified.</p>
-
-          <p>The <code>tts:fontStyle</code> style is illustrated by the
-          following example.</p><a id="style-attribute-fontStyle-example-1"
-          name="style-attribute-fontStyle-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Font Style
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="331px 84px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  In autumn, when the leaves are brown,&lt;br/&gt;
-  Take pen and ink, and &lt;span <span class=
-"strong">tts:fontStyle="italic"</span>&gt;write it down.&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-fontStyle-example-1-images" name=
-          "style-attribute-fontStyle-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Font Style
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/fontStyle.png" alt=
-                "TTML fontStyle style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.9.7.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-fontWeight" name=
-          "style-attribute-fontWeight"></a>8.2.11 tts:fontWeight</h4>
-
-          <p>The <code>tts:fontWeight</code> attribute is used to specify a
-          style property that defines the font weight to apply to glyphs that
-          are selected for glyph areas generated by content flowed into a
-          region, where the mapping from font weight value to specific font
-          face or weight parameterization is not determined by this
-          specification.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-fontWeight"
-          name="style-property-details-fontWeight"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>normal</code> | <code>bold</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>normal</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>If a specified font weight is not available, then a presentation
-          processor must attempt to map the specified font weight to an
-          available font weight that has similar typographic characteristics,
-          or, in the absence of such a mapping, it must interpret the font
-          weight as if the value <code>normal</code> were specified.</p>
-
-          <p>The <code>tts:fontWeight</code> style is illustrated by the
-          following example.</p><a id="style-attribute-fontWeight-example-1"
-          name="style-attribute-fontWeight-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Font Weight
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="376px 95px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  They told me you had been to her,&lt;br/&gt;
-  &lt;span <span class=
-"strong">tts:fontWeight="bold"</span>&gt;and mentioned me to him:&lt;/span&gt;&lt;br/&gt;
-  She gave me a good character&lt;br/&gt;
-  &lt;span <span class=
-"strong">tts:fontWeight="bold"</span>&gt;but said I could not swim.&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-fontWeight-example-1-images" name=
-          "style-attribute-fontWeight-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Font Weight
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/fontWeight.png" alt=
-                "TTML fontWeight style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.9.9.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-lineHeight" name=
-          "style-attribute-lineHeight"></a>8.2.12 tts:lineHeight</h4>
-
-          <p>The <code>tts:lineHeight</code> attribute is used to specify a
-          style property that defines the inter-baseline separation between
-          line areas generated by content flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-lineHeight"
-          name="style-property-details-lineHeight"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>normal</code> | <a href=
-                "#style-value-length">&lt;length&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>normal</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-p"><code>p</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to this element's font size</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute is <code>normal</code>, then the
-          initial value of the style property must be considered to be the same
-          as the largest font size that applies to any descendant element.</p>
-
-          <p>If specified as a <a href=
-          "#style-value-length">&lt;length&gt;</a>, then the length must be
-          non-negative.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>normal</code> were specified.</p>
-
-          <p>The <code>tts:lineHeight</code> style is illustrated by the
-          following example.</p><a id="style-attribute-lineHeight-example-1"
-          name="style-attribute-lineHeight-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Line Height
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="255px 190px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style tts:fontSize="16px"/&gt;
-  &lt;style <span class="strong">tts:lineHeight="32px"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  He thought he saw an elephant,&lt;br/&gt;
-  That practised on a fife:&lt;br/&gt;
-  He looked again, and found it was&lt;br/&gt;
-  A letter from his wife.&lt;br/&gt;
-  "At length I realise," he said,&lt;br/&gt;
-  "The bitterness of Life.
-"&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-lineHeight-example-1-images" name=
-          "style-attribute-lineHeight-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Line Height
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/lineHeight.png" alt=
-                "TTML lineHeight style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.16.4. Furthermore, it is the intention of this
-            specification that the allocation rectangle of a line be consistent
-            with the <span class="strong">per-inline-height-rectangle</span> as
-            defined by <a href="#xsl11">[XSL 1.1]</a>, § 4.5, i.e., that a
-            CSS-style line box stacking strategy be used.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-opacity" name=
-          "style-attribute-opacity"></a>8.2.13 tts:opacity</h4>
-
-          <p>The <code>tts:opacity</code> attribute is used to specify a style
-          property that defines the opacity (or conversely, the transparency)
-          of marks associated with a region.</p>
-
-          <p>When presented onto a visual medium, the opacity of the region is
-          applied uniformly and on a linear scale to all marks produced by
-          content targeted to the region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-opacity" name=
-          "style-property-details-opacity"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-alpha">&lt;alpha&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>1.0</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The <code>tts:opacity</code> style is illustrated by the following
-          example.</p><a id="style-attribute-opacity-example-1" name=
-          "style-attribute-opacity-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Opacity
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1" dur="5s"&gt;
-  &lt;set begin="0s" dur="1s" <span class=
-"strong">tts:opacity="1.00"</span>/&gt;
-  &lt;set begin="1s" dur="1s" <span class=
-"strong">tts:opacity="0.75"</span>/&gt;
-  &lt;set begin="2s" dur="1s" <span class=
-"strong">tts:opacity="0.50"</span>/&gt;
-  &lt;set begin="3s" dur="1s" <span class=
-"strong">tts:opacity="0.25"</span>/&gt;
-  &lt;set begin="4s" dur="1s" <span class=
-"strong">tts:opacity="0.00"</span>/&gt;
-  &lt;style tts:extent="304px 77px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  The sun was shining on the sea
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-opacity-example-1-images" name=
-          "style-attribute-opacity-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Opacity
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/opacity_0.png" alt=
-                "TTML opacity style property - [0,1)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/opacity_1.png" alt=
-                "TTML opacity style property - [1,2)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/opacity_2.png" alt=
-                "TTML opacity style property - [2,3)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/opacity_3.png" alt=
-                "TTML opacity style property - [3,4)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/opacity_4.png" alt=
-                "TTML opacity style property - [4,5)"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href=
-            "#css3-color">[CSS3 Color]</a>, § 3.2.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-origin" name=
-          "style-attribute-origin"></a>8.2.14 tts:origin</h4>
-
-          <p>The <code>tts:origin</code> attribute is used to specify the
-          <em>x</em> and <em>y</em> coordinates of the origin of a region area
-          with respect to the origin of the <em>Root Container Region</em>.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-origin" name=
-          "style-property-details-origin"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>auto</code> | <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>auto</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to width and height of <em>Root Container
-                Region</em></td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute consists of two <a href=
-          "#style-value-length">&lt;length&gt;</a> specifications, then they
-          must be interpreted as <em>x</em> and <em>y</em> coordinates, where
-          the first specification is the <em>x</em> coordinate, and the second
-          specification is the <em>y</em> coordinate.</p>
-
-          <p>If the value of this attribute is <code>auto</code>, then the
-          initial value of the style property must be considered to be the same
-          as the origin of the <em>Root Container Region</em>.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>auto</code> were specified.</p>
-
-          <p>The <code>tts:origin</code> style is illustrated by the following
-          example.</p><a id="style-attribute-origin-example-1" name=
-          "style-attribute-origin-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Origin
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style <span class="strong">tts:origin="40px 40px"</span>/&gt;
-  &lt;style tts:extent="308px 92px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="center"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  "To dine!" she shrieked in dragon-wrath.&lt;br/&gt;
-  "To swallow wines all foam and froth!&lt;br/&gt;
-   To simper at a table-cloth!"
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-origin-example-1-images" name=
-          "style-attribute-origin-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Origin
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/origin.png" alt=
-                "TTML origin style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-overflow" name=
-          "style-attribute-overflow"></a>8.2.15 tts:overflow</h4>
-
-          <p>The <code>tts:overflow</code> attribute is used to specify a style
-          property that defines whether a region area is clipped or not if the
-          descendant areas of the region overflow its extent.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-overflow" name=
-          "style-property-details-overflow"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>visible</code> | <code>hidden</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>hidden</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute is <code>visible</code>, then
-          content should not be clipped outside of the affected region, and
-          region composition and layout must be performed as if the region's
-          width and height were unconstrained, but with a well-defined origin.
-          If the value is <code>hidden</code>, then content should be clipped
-          outside of the affected region.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Unless a manual line break element <code>br</code> is used by
-            the content author, a paragraph of a given region will generate no
-            more than one line area in that region if the value of the
-            <code>tts:overflow</code> style that applies to the region is
-            <code>visible</code> and if the applicable
-            <code>tts:wrapOption</code> style is <code>noWrap</code>.</p>
-          </div>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>hidden</code> were specified.</p>
-
-          <p>The <code>tts:overflow</code> style is illustrated by the
-          following example.</p><a id="style-attribute-overflow-example-1"
-          name="style-attribute-overflow-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Overflow
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="232px 40px"/&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="red"/&gt;
-  &lt;style tts:displayAlign="before"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style tts:fontSize="18px"/&gt;
-  &lt;style tts:wrapOption="noWrap"/&gt;
-  &lt;style <span class="strong">tts:overflow="visible"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:extent="232px 40px"/&gt;
-  &lt;style tts:origin="0px 43px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="red"/&gt;
-  &lt;style tts:displayAlign="before"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style tts:fontSize="18px"/&gt;
-  &lt;style tts:wrapOption="noWrap"/&gt;
-  &lt;style <span class="strong">tts:overflow="hidden"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  "But wait a bit," the Oysters cried,&lt;br/&gt;
-  "Before we have our chat;
-&lt;/p&gt;
-&lt;p region="r2"&gt;
-  For some of us are out of breath,&lt;br/&gt;
-  And all of us are fat!"
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-overflow-example-1-images" name=
-          "style-attribute-overflow-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Overflow
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/overflow.png" alt=
-                "TTML overflow style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the <code>tts:noWrap</code> is set to
-            <code>noWrap</code> to prevent automatic line wrapping (breaking);
-            if this were not specified, then overflow would occur in the block
-            progression direction as opposed to the inline progression
-            direction.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.21.2.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-padding" name=
-          "style-attribute-padding"></a>8.2.16 tts:padding</h4>
-
-          <p>The <code>tts:padding</code> attribute is used to specify padding
-          (or inset) space on all sides of a region area.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-padding" name=
-          "style-property-details-padding"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><a href="#style-value-length">&lt;length&gt;</a> | <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> | <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> | <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>0px</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to width and height of region</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute consists of one <a href=
-          "#style-value-length">&lt;length&gt;</a> specification, then that
-          length applies to all edges of the affected areas. If the value
-          consists of two <a href="#style-value-length">&lt;length&gt;</a>
-          specifications, then the first applies to the before and after edges,
-          and the second applies to the start and end edges. If three <a href=
-          "#style-value-length">&lt;length&gt;</a> specifications are provided,
-          then the first applies to the before edge, the second applies to the
-          start and end edges, and the third applies to the after edge. If four
-          <a href="#style-value-length">&lt;length&gt;</a> specifications are
-          provided, then they apply to before, end, after, and start edges,
-          respectively.</p>
-
-          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used
-          to express padding must be non-negative.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>0px</code> were specified.</p>
-
-          <p>The <code>tts:padding</code> style is illustrated by the following
-          example.</p><a id="style-attribute-padding-example-1" name=
-          "style-attribute-padding-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Padding
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="446px 104px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-  &lt;style <span class="strong">tts:padding="10px 40px"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1" tts:backgroundColor="red"&gt;
-  Just the place for a Snark! I have said it twice:&lt;br/&gt;
-  That alone should encourage the crew.&lt;br/&gt;
-  Just the place for a Snark! I have said it thrice:&lt;br/&gt;
-  What I tell you three times is true.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>When rendering an area to which padding applies, the background
-          color that applies to the area is rendered into the padded portion of
-          the area.</p><a id="style-attribute-padding-example-1-images" name=
-          "style-attribute-padding-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Padding
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/padding.png" alt=
-                "TTML padding style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.31.15, except that individual shorthand values map to
-            writing mode relative padding values as defined by <a href=
-            "#xsl11">[XSL 1.1]</a>, § 7.8.31, 7.8.32, 7.8.33, and 7.8.34.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-showBackground" name=
-          "style-attribute-showBackground"></a>8.2.17 tts:showBackground</h4>
-
-          <p>The <code>tts:showBackground</code> attribute is used to specify
-          constraints on when the background color of a region is intended to
-          be presented.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-showBackground"
-          name="style-property-details-showBackground"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>always</code> | <code>whenActive</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>always</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If the value of this attribute is <code>always</code>, then the
-          background color of a region is always rendered when performing
-          presentation processing on a visual medium; if the value is
-          <code>whenActive</code>, then the background color of a region is
-          rendered only when some content is flowed into the region.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>always</code> were specified.</p>
-
-          <p>The <code>tts:showBackground</code> style is illustrated by the
-          following example.</p><a id=
-          "style-attribute-showBackground-example-1" name=
-          "style-attribute-showBackground-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Show Background
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:extent="265px 100px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style <span class="strong">tts:showBackground="always"</span>/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="before"/&gt;
-  &lt;style tts:textAlign="start"/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:origin="205px 60px"/&gt;
-  &lt;style tts:extent="290px 100px"/&gt;
-  &lt;style tts:backgroundColor="red"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="before"/&gt;
-  &lt;style tts:textAlign="end"/&gt;
-  &lt;style <span class="strong">tts:showBackground="whenActive"</span>/&gt;
-&lt;/region&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#smil21">[SMIL
-            2.1]</a>, § 5.3.3.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-textAlign" name=
-          "style-attribute-textAlign"></a>8.2.18 tts:textAlign</h4>
-
-          <p>The <code>tts:textAlign</code> attribute is used to specify a
-          style property that defines how inline areas are aligned within a
-          containing block area in the inline progression direction.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-textAlign"
-          name="style-property-details-textAlign"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>left</code> | <code>center</code> |
-                <code>right</code> | <code>start</code> | <code>end</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>start</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-p"><code>p</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>start</code> were specified.</p>
-
-          <p>The <code>tts:textAlign</code> style is illustrated by the
-          following example.</p><a id="style-attribute-textAlign-example-1"
-          name="style-attribute-textAlign-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Text Align
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="355px 43px"/&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:textAlign="start"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:extent="355px 43px"/&gt;
-  &lt;style tts:origin="0px 47px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:textAlign="end"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  Beware the Jabberwock, my son!&lt;br/&gt;
-  The jaws that bite, the claws that catch!
-&lt;/p&gt;
-&lt;p region="r2"&gt;
-  Beware the Jubjub bird, and shun&lt;br/&gt;
-  The frumious Bandersnatch!
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-textAlign-example-1-images" name=
-          "style-attribute-textAlign-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Text Align
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/textAlign.png" alt=
-                "TTML textAlign style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.16.9.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-textDecoration" name=
-          "style-attribute-textDecoration"></a>8.2.19 tts:textDecoration</h4>
-
-          <p>The <code>tts:textDecoration</code> attribute is used to specify a
-          style property that defines a text decoration effect to apply to
-          glyph areas or other inline areas that are generated by content
-          flowed into a region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-textDecoration"
-          name="style-property-details-textDecoration"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>none</code> | [ [ <code>underline</code> |
-                <code>noUnderline</code> ] || [ <code>lineThrough</code> |
-                <code>noLineThrough</code> ] || [ <code>overline</code> |
-                <code>noOverline</code> ] ]</td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>none</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>none</code> were specified.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The syntax used above in defining the value of this property is
-            based on the value component syntax defined in <a href=
-            "#css2">[CSS2]</a>, § 1.4.2.1. In essence, one or more of the
-            values separated by <code>||</code> may appear in the property
-            value in any order, such as <code>"noUnderline overline
-            lineThrough"</code>.</p>
-          </div>
-
-          <p>The <code>tts:textDecoration</code> style is illustrated by the
-          following example.</p><a id=
-          "style-attribute-textDecoration-example-1" name=
-          "style-attribute-textDecoration-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Text Decoration
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="385px 82px"/&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:padding="5px 2px"/&gt;
-  &lt;style <span class="strong">tts:textDecoration="underline"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  The sea was wet&lt;span <span class=
-"strong">tts:textDecoration="noUnderline"</span>&gt; as &lt;/span&gt;wet
-  &lt;span <span class="strong">tts:textDecoration="noUnderline"</span>&gt;
-    could be,&lt;br/&gt;
-    The sand was dry as dry.&lt;br/&gt;
-    &lt;span <span class=
-"strong">tts:textDecoration="lineThrough"</span>&gt;There weren't any&lt;/span&gt;
-    You &lt;span <span class=
-"strong">tts:textDecoration="lineThrough"</span>&gt;couldn't&lt;/span&gt;
-    could not see a cloud&lt;br/&gt;
-    Because no cloud was in the sky.
-  &lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-textDecoration-example-1-images" name=
-          "style-attribute-textDecoration-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Text Decoration
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/textDecoration.png" alt=
-                "TTML textDecoration style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.17.4.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-textOutline" name=
-          "style-attribute-textOutline"></a>8.2.20 tts:textOutline</h4>
-
-          <p>The <code>tts:textOutline</code> attribute is used to specify a
-          style property that defines a text outline effect to apply to glyphs
-          that are selected for glyph areas generated by content flowed into a
-          region.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-textOutline"
-          name="style-property-details-textOutline"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>none</code> | <a href=
-                "#style-value-color">&lt;color&gt;</a>? <a href=
-                "#style-value-length">&lt;length&gt;</a> <a href=
-                "#style-value-length">&lt;length&gt;</a>?</td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>none</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>relative to this element's font size</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>The value of this attribute consists of an optional <a href=
-          "#style-value-color">&lt;color&gt;</a> term followed by one or two
-          <a href="#style-value-length">&lt;length&gt;</a> terms. If a
-          <em>color</em> term is present, then it denotes the outline color; if
-          no <em>color</em> term is present, the computed value of the
-          <code>tts:color</code> applies. The first <em>length</em> term
-          denotes the outline thickness and the second length term, if present,
-          indicates the blur radius.</p>
-
-          <p>The <a href="#style-value-length">&lt;length&gt;</a> value(s) used
-          to express thickness and blur radius must be non-negative.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When a <a href="#style-value-length">&lt;length&gt;</a>
-            expressed in cells is used in a <code>tts:textOutline</code> value,
-            the cell's dimension in the block progression dimension applies.
-            For example, if text outline thickness is specified as 0.1c, the
-            cell resolution is 20 by 10, and the extent of the <em>Root
-            Container Region</em> is 640 by 480, then the outline thickness
-            will be a nominal 480 / 10 * 0.1 pixels, i.e., 4.8px, without
-            taking into account rasterization effects.</p>
-          </div>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>none</code> were specified.</p>
-
-          <p>The <code>tts:textOutline</code> style is illustrated by the
-          following example.</p><a id="style-attribute-textOutline-example-1"
-          name="style-attribute-textOutline-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Text Outline
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:backgroundColor="transparent"/&gt;
-  &lt;style tts:color="yellow"/&gt;
-  &lt;style <span class="strong">tts:textOutline="black 2px 0px"</span>/&gt;
-  &lt;style tts:fontFamily="proportionalSansSerif"/&gt;
-  &lt;style tts:fontSize="24px"/&gt;
-&lt;/region&gt;
-...
-&lt;p&gt;
-  How doth the little crocodile&lt;br/&gt;
-  Improve its shining tail,&lt;br/&gt;
-  And pour the waters of the Nile&lt;br/&gt;
-  On every golden scale!&lt;br/&gt;
-  How cheerfully he seems to grin,&lt;br/&gt;
-  How neatly spreads his claws,&lt;br/&gt;
-  And welcomes little fishes in,&lt;br/&gt;
-  With gently smiling jaws!
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-textOutline-example-1-images" name=
-          "style-attribute-textOutline-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Text Outline
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/textOutline.png" alt=
-                "backgroundColor style property"></td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-unicodeBidi" name=
-          "style-attribute-unicodeBidi"></a>8.2.21 tts:unicodeBidi</h4>
-
-          <p>The <code>tts:unicodeBidi</code> attribute is used to specify a
-          style property that defines a directional embedding or override
-          according to the Unicode bidirectional algorithm.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-unicodeBidi"
-          name="style-property-details-unicodeBidi"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>normal</code> | <code>embed</code> |
-                <code>bidiOverride</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>normal</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href="#content-vocabulary-p"><code>p</code></a>,
-                <a href="#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>normal</code> were specified.</p>
-
-          <p>The <code>tts:unicodeBidi</code> style is illustrated by the
-          following example.</p><a id="style-attribute-unicodeBidi-example-1"
-          name="style-attribute-unicodeBidi-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Unicode Bidirectionality
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="265px 84px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:textAlign="center"/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  Little birds are playing&lt;br/&gt;
-  Bagpipes on the shore,&lt;br/&gt;
-  &lt;span <span class=
-"strong">tts:unicodeBidi="bidiOverride"</span> tts:direction="rtl"&gt;where the tourists snore.&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-unicodeBidi-example-1-images" name=
-          "style-attribute-unicodeBidi-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Unicode Bidirectionality
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/unicodeBidi.png" alt=
-                "TTML unicodeBidi style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.29.6.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-visibility" name=
-          "style-attribute-visibility"></a>8.2.22 tts:visibility</h4>
-
-          <p>The <code>tts:visibility</code> attribute is used to specify a
-          style property that defines whether generated areas are visible or
-          not when rendered on a visual presentation medium.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-visibility"
-          name="style-property-details-visibility"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>visible</code> | <code>hidden</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>visible</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#document-structure-vocabulary-body"><code>body</code></a>,
-                <a href="#content-vocabulary-div"><code>div</code></a>,
-                <a href="#content-vocabulary-p"><code>p</code></a>, <a href=
-                "#layout-vocabulary-region"><code>region</code></a>, <a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>The <code>tts:visibility</code> style has no affect on content
-          layout or composition, but merely determines whether composed content
-          is visible or not.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>visible</code> were specified.</p>
-
-          <p>The <code>tts:visibility</code> style is illustrated by the
-          following example.</p><a id="style-attribute-visibility-example-1"
-          name="style-attribute-visibility-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Visibility
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="398px 121px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1" dur="4s"&gt;
-  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
-    &lt;set begin="1s" <span class=
-"strong">tts:visibility="visible"</span>/&gt;
-    Curiouser
-  &lt;/span&gt;
-  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
-    &lt;set begin="2s" <span class=
-"strong">tts:visibility="visible"</span>/&gt;
-    and
-  &lt;/span&gt;
-  &lt;span <span class="strong">tts:visibility="hidden"</span>&gt;
-    &lt;set begin="3s" <span class=
-"strong">tts:visibility="visible"</span>/&gt;
-    curiouser!
-  &lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-visibility-example-1-images" name=
-          "style-attribute-visibility-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Visibility
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/visibility_0.png" alt=
-                "TTML visibility style property - [0,1)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/visibility_1.png" alt=
-                "TTML visibility style property - [1,2)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/visibility_2.png" alt=
-                "TTML visibility style property - [2,3)"></td>
-              </tr>
-
-              <tr>
-                <td><img src="images/visibility_3.png" alt=
-                "TTML visibility style property - [3,4)"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.30.17.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-wrapOption" name=
-          "style-attribute-wrapOption"></a>8.2.23 tts:wrapOption</h4>
-
-          <p>The <code>tts:wrapOption</code> attribute is used to specify a
-          style property that defines whether or not automatic line wrapping
-          (breaking) applies within the context of the affected element.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-wrapOption"
-          name="style-property-details-wrapOption"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>wrap</code> | <code>noWrap</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>wrap</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#content-vocabulary-span"><code>span</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>yes</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>For the purpose of determining applicability of this style
-          property, each character child of a <code>p</code> element is
-          considered to be enclosed in an anonymous span.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>wrap</code> were specified.</p>
-
-          <p>The <code>tts:wrapOption</code> style is illustrated by the
-          following example.</p><a id="style-attribute-wrapOption-example-1"
-          name="style-attribute-wrapOption-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Wrap Option
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="192px 117px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:displayAlign="after"/&gt;
-  &lt;style tts:overflow="hidden"/&gt;
-  &lt;style <span class="strong">tts:wrapOption="noWrap"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p&gt;
-  I'll tell thee everything I can:&lt;br/&gt;
-  There's little to relate.&lt;br/&gt;
-  I saw an aged aged man,&lt;br/&gt;
-  A-sitting on a gate.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-wrapOption-example-1-images" name=
-          "style-attribute-wrapOption-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Wrap Option
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/wrapOption.png" alt=
-                "TTML wrapOption style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.16.13.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-writingMode" name=
-          "style-attribute-writingMode"></a>8.2.24 tts:writingMode</h4>
-
-          <p>The <code>tts:writingMode</code> attribute is used to specify a
-          style property that defines the block and inline progression
-          directions to be used for the purpose of stacking block and inline
-          areas within a region area.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-writingMode"
-          name="style-property-details-writingMode"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>lrtb</code> | <code>rltb</code> | <code>tbrl</code> |
-                <code>tblr</code> | <code>lr</code> | <code>rl</code> |
-                <code>tb</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>lrtb</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>lrtb</code> were specified.</p>
-
-          <p>The <code>tts:writingMode</code> style is illustrated by the
-          following example.</p><a id="style-attribute-writingMode-example-1"
-          name="style-attribute-writingMode-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Writing Mode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:extent="50px 570px"/&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:padding="10px 3px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:writingMode="tbrl"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:extent="310px 50px"/&gt;
-  &lt;style tts:origin="70px 120px"/&gt;
-  &lt;style tts:padding="10px 3px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:writingMode="rltb"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  I sometimes dig for buttered rolls,&lt;br/&gt;
-  Or set limed twigs for crabs:
-&lt;/p&gt;
-&lt;p region="r2" tts:direction="rtl" tts:unicodeBidi="bidiOverride"&gt;
-  I sometimes search the grassy knolls for the wheels of Hansom-cabs.
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-writingMode-example-1-images" name=
-          "style-attribute-writingMode-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Writing Mode
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/writingMode.png" alt=
-                "TTML writingMode style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the second paragraph in the above example that targets region
-            <code>r2</code>, the <code>tts:unicodeBidi</code> and
-            <code>tts:direction</code> properties are set to
-            <code>bidiOverride</code> and <code>rtl</code>, respectively, in
-            order to override the normally left-to-right directionality of
-            characters in the Latin script.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.29.7.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-attribute-zIndex" name=
-          "style-attribute-zIndex"></a>8.2.25 tts:zIndex</h4>
-
-          <p>The <code>tts:zIndex</code> attribute is used to specify a style
-          property that defines the front-to-back ordering of region areas in
-          the case that they overlap.</p>
-
-          <p>This attribute may be specified by any element type that permits
-          use of attributes in the TT Style Namespace; however, this attribute
-          applies as a style property only to those element types indicated in
-          the following table.</p><a id="style-property-details-zIndex" name=
-          "style-property-details-zIndex"></a>
-
-          <table class="common">
-            <col width="25%" span="1">
-            <col span="1">
-
-            <tbody>
-              <tr>
-                <td><em>Values:</em></td>
-
-                <td><code>auto</code> | <a href=
-                "#style-value-integer">&lt;integer&gt;</a></td>
-              </tr>
-
-              <tr>
-                <td><em>Initial:</em></td>
-
-                <td><code>auto</code></td>
-              </tr>
-
-              <tr>
-                <td><em>Applies to:</em></td>
-
-                <td><a href=
-                "#layout-vocabulary-region"><code>region</code></a></td>
-              </tr>
-
-              <tr>
-                <td><em>Inherited:</em></td>
-
-                <td>no</td>
-              </tr>
-
-              <tr>
-                <td><em>Percentages:</em></td>
-
-                <td>N/A</td>
-              </tr>
-
-              <tr>
-                <td><em>Animatable:</em></td>
-
-                <td>discrete</td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If two areas are associated with the same Z-index value, then, if
-          those areas overlap in space, the area(s) generated by lexically
-          subsequent elements must be rendered over area(s) generated by
-          lexically prior elements, where lexical order is defined as the
-          postorder traversal of a <em>Document Instance</em>.</p>
-
-          <p>The semantics of the value <code>auto</code> are those defined by
-          <a href="#xsl11">[XSL 1.1]</a>, § 7.30.18, where the <code>tt</code>
-          element is considered to establish the root stacking context.</p>
-
-          <p>If a specified value of this attribute is not supported, then a
-          presentation processor must interpret the attribute as if the value
-          <code>auto</code> were specified.</p>
-
-          <p>The <code>tts:zIndex</code> style is illustrated by the following
-          example.</p><a id="style-attribute-zIndex-example-1" name=
-          "style-attribute-zIndex-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Z Index
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region xml:id="r1"&gt;
-  &lt;style tts:origin="0px 0px"/&gt;
-  &lt;style tts:extent="400px 100px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:zIndex="0"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r2"&gt;
-  &lt;style tts:origin="100px 60px"/&gt;
-  &lt;style tts:extent="400px 100px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="red"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:textAlign="end"/&gt;
-  &lt;style <span class="strong">tts:zIndex="1"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r3"&gt;
-  &lt;style tts:origin="0px 120px"/&gt;
-  &lt;style tts:extent="400px 100px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="black"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style <span class="strong">tts:zIndex="2"</span>/&gt;
-&lt;/region&gt;
-&lt;region xml:id="r4"&gt;
-  &lt;style tts:origin="100px 180px"/&gt;
-  &lt;style tts:extent="400px 100px"/&gt;
-  &lt;style tts:padding="5px"/&gt;
-  &lt;style tts:backgroundColor="red"/&gt;
-  &lt;style tts:color="white"/&gt;
-  &lt;style tts:textAlign="end"/&gt;
-  &lt;style <span class="strong">tts:zIndex="3"</span>/&gt;
-&lt;/region&gt;
-...
-&lt;p region="r1"&gt;
-  I passed by his garden, and marked, with one eye,&lt;br/&gt;
-  How the Owl and the Panther were sharing a pie.
-&lt;/p&gt;
-&lt;p region="r2"&gt;
-  The Panther took pie-crust, and gravy, and meat,&lt;br/&gt;
-  While the Owl had the dish as its share of the treat.
-&lt;/p&gt;
-&lt;p region="r3"&gt;
-  When the pie was all finished, the Owl, as a boon,&lt;br/&gt;
-  Was kindly permitted to pocket the spoon:
-&lt;/p&gt;
-&lt;p region="r4"&gt;
-  While the Panther received knife and fork&lt;br/&gt;
-  with a growl,&lt;br/&gt;
-  And concluded the banquet by...
-&lt;/p&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table><a id="style-attribute-zIndex-example-1-images" name=
-          "style-attribute-zIndex-example-1-images"></a>
-
-          <table class="example-images">
-            <caption>
-              Example Rendition – Z Index
-            </caption>
-
-            <tbody>
-              <tr>
-                <td><img src="images/zIndex.png" alt=
-                "TTML zIndex style property"></td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the style property represented by this
-            attribute are based upon that defined by <a href="#xsl11">[XSL
-            1.1]</a>, § 7.30.18.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="styling-style-value-expressions" name=
-        "styling-style-value-expressions"></a>8.3 Style Value Expressions</h3>
-
-        <p>Style property values include the use of the following
-        expressions:</p>
-
-        <ul>
-          <li>
-            <p><a href="#style-value-alpha"><b>8.3.1 &lt;alpha&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-color"><b>8.3.2 &lt;color&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-digit"><b>8.3.3 &lt;digit&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-familyName"><b>8.3.5
-            &lt;familyName&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-genericFamilyName"><b>8.3.6
-            &lt;genericFamilyName&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-hexDigit"><b>8.3.7
-            &lt;hexDigit&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-integer"><b>8.3.8
-            &lt;integer&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-length"><b>8.3.9
-            &lt;length&gt;</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#style-value-namedColor"><b>8.3.10
-            &lt;namedColor&gt;</b></a></p>
-          </li>
-        </ul>
-
-        <p>In the syntax representations defined in this section, no linear
-        whitespace (LWSP) is implied or permitted between tokens unless
-        explicitly specified.</p>
-
-        <div class="div3">
-          <h4><a id="style-value-alpha" name="style-value-alpha"></a>8.3.1
-          &lt;alpha&gt;</h4>
-
-          <p>An &lt;alpha&gt; expression is used to express an opacity value,
-          where 0 means fully transparent and 1 means fully opaque.</p><a id=
-          "alpha-style-expression-syntax" name=
-          "alpha-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;alpha&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;alpha&gt;
-  : <em>float</em>
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>In the above syntax representation, the syntactic element
-          <em><code>float</code></em> must adhere to the lexical representation
-          defined by <a href="#xsd-2">[XML Schema Part 2]</a>&nbsp;§ 3.2.4.1.
-          If the value represented is less than 0.0, then it must be
-          interpreted as equal to 0.0; similarly, if the value represented is
-          greater than 1.0, then it must be interpreted as 1.0. The value NaN
-          must be interpreted as 0.0.</p>
-
-          <p>A specified value for &lt;alpha&gt; should not be
-          <code>NaN</code>, less than 0, or greater than 1.</p>
-
-          <p>If a presentation processor does not support a specific, valid
-          opacity value, then it must interpret it as being equal to the
-          closest supported value.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-color" name="style-value-color"></a>8.3.2
-          &lt;color&gt;</h4>
-
-          <p>A &lt;color&gt; expression is used to specify a named color, exact
-          RGB color triple, or exact RGBA color tuple, where the alpha
-          component, if expressed, is maximum (255) at 100% opacity and minimum
-          (0) at 0% opacity, and where the applicable color space is defined by
-          <a href="#srgb">[SRGB]</a>.</p><a id="color-style-expression-syntax"
-          name="color-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;color&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;color&gt;
-  : "#" rrggbb
-  | "#" rrggbbaa
-  | "rgb" "(" r-value "," g-value "," b-value ")"
-  | "rgba" "(" r-value "," g-value "," b-value "," a-value ")"
-  | <a href="#style-value-namedColor">&lt;namedColor&gt;</a>
-
-rrggbb
-  :  <a href="#style-value-hexDigit">&lt;hexDigit&gt;</a>{6}
-
-rrggbbaa
-  :  <a href="#style-value-hexDigit">&lt;hexDigit&gt;</a>{8}
-
-r-value | g-value | b-value | a-value
-  : component-value
-
-component-value
-  : non-negative-integer                    // valid range: [0,255]
-
-non-negative-integer
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>When expressing RGB component values, these values are considered
-          to <span class="strong">not</span> be premultiplied by alpha.</p>
-
-          <p>For the purpose of performing presentation processing such that
-          non-opaque or non-transparent alpha or opacity values apply, then the
-          semantics of compositing functions are defined with respect to the
-          use of the <a href="#srgb">[SRGB]</a> color space for both inputs and
-          outputs of the composition function.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The use of <a href="#srgb">[SRGB]</a> for the stated semantics
-            of composition is not meant to prevent an actual processor from
-            using some other color space either for internal or external
-            purposes. For example, a presentation processor may ultimately
-            convert the SRGB values used here to the YUV color space for
-            rendition on a television device.</p>
-          </div>
-
-          <p>If a presentation processor does not support a specific, valid
-          color or alpha value, then it must interpret it as being equal to the
-          closest supported value.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-digit" name="style-value-digit"></a>8.3.3
-          &lt;digit&gt;</h4>
-
-          <p>A &lt;digit&gt; is used to express integers and other types of
-          numbers or tokens.</p><a id="digit-style-expression-syntax" name=
-          "digit-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;digit&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;digit&gt;
-  : "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-duration" name=
-          "style-value-duration"></a>8.3.4 Deleted</h4>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The information from this section has been removed due to lack
-            of any normative use within this specification. This section is
-            retained in its empty form in order to prevent section
-            renumbering.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-familyName" name=
-          "style-value-familyName"></a>8.3.5 &lt;familyName&gt;</h4>
-
-          <p>A &lt;familyName&gt; expression specifies a font family
-          name.</p><a id="familyName-style-expression-syntax" name=
-          "familyName-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;familyName&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;familyName&gt;
-  : unquoted-string
-  | quoted-string
-
-unquoted-string
-  : identifier ( lwsp identifier )*
-
-lwsp
-  : ( ' ' | '\t' | '\n' | '\r' )+
-
-identifier
-  : [-]? identifier-start identifier-following*
-
-identifier-start
-  : [_a-zA-Z]
-  | non-ascii-or-c1
-  | escape
-
-identifier-following
-  : [_a-zA-Z0-9-]
-  | non-ascii-or-c1
-  | escape
-
-non-ascii-or-c1
-  : [^\0-\237]
-
-escape
-  : '\\' <em>char</em>
-
-quoted-string
-  : double-quoted-string
-  | single-quoted-string
-
-double-quoted-string
-  : '"' ( [^"\\] | escape )+ '"'
-
-single-quoted-string
-  : "'" ( [^'\\] | escape )+ "'"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>In addition to adhering to the syntax rules specified above, the
-          following semantic rules apply:</p>
-
-          <ul>
-            <li>
-              <p>the semantic value of a &lt;familyName&gt; expression is the
-              semantic value of its <code>unquoted-string</code> or
-              <code>quoted-string</code> non-terminal, according to whichever
-              applies;</p>
-            </li>
-
-            <li>
-              <p>the semantic value of an <code>unquoted-string</code>
-              non-terminal is a pair <code>&lt;</code><em>quoted</em>,
-              <em>content</em><code>&gt;</code>, where <em>quoted</em> is a
-              boolean <code>false</code>, and where <em>content</em> is the
-              result of appending the value of each <code>identifier</code>
-              non-terminal, in lexical order, where the value of each
-              identifier is preceded by a single SPACE (U+0020) character if it
-              is not the first identifier;</p>
-            </li>
-
-            <li>
-              <p>the semantic value of a <code>quoted-string</code>
-              non-terminal is a pair <code>&lt;</code><em>quoted</em>,
-              <em>content</em><code>&gt;</code>, where <em>quoted</em> is a
-              boolean <code>true</code>, and where <em>content</em> is the
-              unquoted content of the quoted string, i.e., the sequence of
-              characters between the delimiting quotes.</p>
-            </li>
-
-            <li>
-              <p>the semantic value of an <code>escape</code> non-terminal is
-              the value of the escaped <code>char</code>;</p>
-            </li>
-
-            <li>
-              <p>a &lt;familyName&gt; that takes the form of an
-              <code>unquoted-string</code> that contains an
-              <code>identifier</code> that starts with two <code>-</code>
-              HYPHEN-MINUS (U+002D) characters must be considered to be
-              invalid;</p>
-            </li>
-
-            <li>
-              <p>a &lt;familyName&gt; that takes the form of an
-              <code>unquoted-string</code> that contains a single
-              <code>identifier</code> that matches (by case sensitive
-              comparison) a &lt;genericFamilyName&gt; must be interpreted as
-              that &lt;genericFamilyName&gt;;</p>
-            </li>
-
-            <li>
-              <p>a &lt;familyName&gt; that takes the form of a
-              <code>quoted-string</code> whose content (unquoted value) matches
-              (by case sensitive comparison) a &lt;genericFamilyName&gt; must
-              not be interpreted as that &lt;genericFamilyName&gt;, but as the
-              actual name of a non-generic font family.</p>
-            </li>
-          </ul>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The syntactic element <em><code>char</code></em> is to be
-            interpreted according to the <code>Char</code> production defined
-            by <a href="#xml10">[XML 1.0]</a>&nbsp;§2.2.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The <code>{unicode}</code> escape mechanism defined by <a href=
-            "#css2">[CSS2]</a>&nbsp;§4.1.1 is not supported by this syntax;
-            rather, authors are expected to either (1) directly encode the
-            character using the document encoding or (2) use an XML character
-            reference according to <a href="#xml10">[XML 1.0]</a>&nbsp;§4.1.
-            When a syntactically significant character needs to be used without
-            its normal syntactic interpretation, it may be be escaped using the
-            backslash (reverse solidus) <code>escape</code> non-terminal
-            specified above.</p>
-
-            <p>When using the backslash (reverse solidus) <code>escape</code>
-            non-terminal, the above syntax does not place any restriction on
-            what character may be escaped, e.g., <code>\\[\n\r\f0-9a-f]</code>
-            are permitted. If one of these latter escapes appears in a
-            &lt;familyName&gt; expression, then it will need to be converted to
-            a <code>{unicode}</code> escape if it is to be used with a standard
-            XSL-FO or CSS parser. In particular, a backslash followed by a
-            newline is ignored by CSS, while it is not ignored by the above
-            syntax. Such an unignored escaped newline would need to be
-            represented using an equivalent <code>{unicode}</code> escape, such
-            as <code>\a</code>, to order to express in CSS.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-genericFamilyName" name=
-          "style-value-genericFamilyName"></a>8.3.6
-          &lt;genericFamilyName&gt;</h4>
-
-          <p>A &lt;genericFamilyName&gt; expression specifies a font family
-          using a general token that indicates a class of font families.</p>
-
-          <p>The resolution of a generic family name to a concrete font
-          instance is considered to be implementation dependent, both in the
-          case of content authoring and content interpretation.</p><a id=
-          "genericFamilyName-style-expression-syntax" name=
-          "genericFamilyName-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;genericFamilyName&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;genericFamilyName&gt;
-  : "default"
-  | "monospace"
-  | "sansSerif"
-  | "serif"
-  | "monospaceSansSerif"
-  | "monospaceSerif"
-  | "proportionalSansSerif"
-  | "proportionalSerif"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The mapping between a generic (font) family name and an actual
-          font is not determined by this specification; however, the
-          distinction of monospace versus proportional and serif versus
-          sans-serif should be maintained if possible when performing
-          presentation.</p>
-
-          <p>If a generic (font) family name of <code>monospace</code> is
-          specified, then it may be interpreted as equivalent to either
-          <code>monospaceSansSerif</code> or <code>monospaceSerif</code>. The
-          generic family names <code>sansSerif</code> and <code>serif</code>
-          are to be interpreted as equivalent to
-          <code>proportionalSansSerif</code> and
-          <code>proportionalSerif</code>, respectively.</p>
-
-          <p>If the generic family name <code>default</code> is specified (or
-          implied by an initial value), then its typographic characteristics
-          are considered to be implementation dependent; however, it is
-          recommended that this default font family be mapped to an monospaced,
-          sans-serif font.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-hexDigit" name=
-          "style-value-hexDigit"></a>8.3.7 &lt;hexDigit&gt;</h4>
-
-          <p>A &lt;hexDigit&gt; is used to express integers and other types of
-          numbers or tokens that employ base 16 arithmetic.</p>
-
-          <p>For the purpose of parsing, a distinction must not be made between
-          lower and upper case.</p><a id="hexDigit-style-expression-syntax"
-          name="hexDigit-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;hexDigit&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;hexDigit&gt;
-  : <a href="#style-value-digit">&lt;digit&gt;</a>
-  | "a" | "b" | "c" | "d" | "e" | "f"
-  | "A" | "B" | "C" | "D" | "E" | "F"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-integer" name="style-value-integer"></a>8.3.8
-          &lt;integer&gt;</h4>
-
-          <p>An &lt;integer&gt; expression is used to express an arbitrary,
-          signed integral value.</p><a id="integer-style-expression-syntax"
-          name="integer-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;integer&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;integer&gt;
-  : ( "+" | "-" )? <a href="#style-value-digit">&lt;digit&gt;</a>+
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-length" name="style-value-length"></a>8.3.9
-          &lt;length&gt;</h4>
-
-          <p>A &lt;length&gt; expression is used to express either a coordinate
-          component of point in a cartesian space or a distance between two
-          points in a cartesian space.</p><a id=
-          "length-style-expression-syntax" name=
-          "length-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;length&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;length&gt;
-  : scalar
-  | percentage
-
-scalar
-  : number units
-
-percentage
-  : number "%"
-
-sign
-  : "+" | "-"
-
-number
-  : sign? non-negative-number
-
-non-negative-number
-  : non-negative-integer
-  | non-negative-real
-
-non-negative-integer
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-non-negative-real
-  : <a href="#style-value-digit">&lt;digit&gt;</a>* "." <a href=
-"#style-value-digit">&lt;digit&gt;</a>+
-
-units
-  : "px"
-  | "em"
-  | "c"                                     // abbreviation of "cell"
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>It is an error to omit the units component of a scalar length
-          value.</p>
-
-          <p>The semantics of the unit of measure <code>px</code> (pixel) are
-          as defined by <a href="#xsl11">[XSL 1.1]</a>, § 5.9.13.</p>
-
-          <p>When specified relative to a font whose size is expressed as a
-          single length measure or as two length measures of equal length, the
-          unit of measure <code>em</code> is considered to be identical to that
-          defined by <a href="#xsl11">[XSL 1.1]</a>, § 5.9.13; however, when
-          specified relative to a font whose size is expressed as two length
-          measures of non-equal lengths, then one <code>em</code> is equal to
-          the inline progression dimension of the anamorphically scaled font
-          when used to specify lengths in the inline progression direction and
-          equal to the block progression dimension of the scaled font when used
-          to specify lengths in the block progression direction.</p>
-
-          <p>The semantics of the unit of measure <code>c</code> (cell) are
-          defined by the parameter <a href=
-          "#parameter-attribute-cellResolution"><b>6.2.1
-          ttp:cellResolution</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-namedColor" name=
-          "style-value-namedColor"></a>8.3.10 &lt;namedColor&gt;</h4>
-
-          <p>A &lt;namedColor&gt; is used to express an RGBA color with a
-          convenient name, and where the applicable color space is defined by
-          <a href="#srgb">[SRGB]</a>.</p>
-
-          <p>For the purpose of parsing, a distinction must not be made between
-          lower and upper case.</p><a id="namedColor-style-expression-syntax"
-          name="namedColor-style-expression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;namedColor&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;namedColor&gt;
-  : "transparent"                           // #00000000
-  | "black"                                 // #000000ff
-  | "silver"                                // #c0c0c0ff
-  | "gray"                                  // #808080ff
-  | "white"                                 // #ffffffff
-  | "maroon"                                // #800000ff
-  | "red"                                   // #ff0000ff
-  | "purple"                                // #800080ff
-  | "fuchsia"                               // #ff00ffff
-  | "magenta"                               // #ff00ffff (= fuchsia)
-  | "green"                                 // #008000ff
-  | "lime"                                  // #00ff00ff
-  | "olive"                                 // #808000ff
-  | "yellow"                                // #ffff00ff
-  | "navy"                                  // #000080ff
-  | "blue"                                  // #0000ffff
-  | "teal"                                  // #008080ff
-  | "aqua"                                  // #00ffffff
-  | "cyan"                                  // #00ffffff (= aqua)
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Except for <code>transparent</code>, the set of named colors
-            specified above constitutes a proper subset of the set of named
-            colors specified by <a href="#svg11">[SVG 1.1]</a>, § 4.2.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-quotedString" name=
-          "style-value-quotedString"></a>8.3.11 Deleted</h4>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The information from this section has been incorporated into
-            <a href="#style-value-familyName"><b>8.3.5
-            &lt;familyName&gt;</b></a>. This section is retained in its empty
-            form in order to prevent section renumbering.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="style-value-string" name="style-value-string"></a>8.3.12
-          Deleted</h4>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The information from this section has been incorporated into
-            <a href="#style-value-familyName"><b>8.3.5
-            &lt;familyName&gt;</b></a>. This section is retained in its empty
-            form in order to prevent section renumbering.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="semantics-style-resolution" name=
-        "semantics-style-resolution"></a>8.4 Style Resolution</h3>
-
-        <p>This section defines the semantics of style resolution in terms of a
-        standard processing model as follows:</p>
-
-        <ul>
-          <li>
-            <p><a href="#semantics-style-association"><b>8.4.1 Style
-            Association</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-style-inheritance"><b>8.4.2 Style
-            Inheritance</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-style-resolution-value-categories"><b>8.4.3
-            Style Resolution Value Categories</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-style-resolution-processing"><b>8.4.4 Style
-            Resolution Processing</b></a></p>
-          </li>
-        </ul>
-
-        <p>Any implementation of this model is permitted provided that the
-        externally observable results are consistent with the results produced
-        by this model.</p>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The semantics of style resolution employed here are based upon
-          <a href="#xsl11">[XSL 1.1]</a>, § 5.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-style-association" name=
-          "semantics-style-association"></a>8.4.1 Style Association</h4>
-
-          <p>Style association is a sub-process of <a href=
-          "#semantics-style-resolution-processing"><b>8.4.4 Style Resolution
-          Processing</b></a> used to determine the specified style set of each
-          content and layout element.</p>
-
-          <p>Style matter may be associated with content and layout matter in a
-          number of ways:</p>
-
-          <ul>
-            <li>
-              <p><a href="#semantics-style-association-inline">inline
-              styling</a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-association-referential">referential
-              styling</a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#semantics-style-association-chained-referential">chained
-              referential styling</a></p>
-            </li>
-          </ul>
-
-          <p>In addition to the above, style matter may be associated with
-          layout matter using:</p>
-
-          <ul>
-            <li>
-              <p><a href="#semantics-style-association-nested">nested
-              styling</a></p>
-            </li>
-          </ul>
-
-          <div class="div4">
-            <h5><a id="semantics-style-association-inline" name=
-            "semantics-style-association-inline"></a>8.4.1.1 Inline
-            Styling</h5>
-
-            <p>Style properties may be expressed in an inline manner by direct
-            specification of an attribute from the TT Style Namespace on the
-            affected element. When expressed in this manner, the association of
-            style information is referred to as <em>inline styling</em>.</p>
-
-            <p>Style properties associated by inline styling are afforded a
-            higher priority than all other forms of style
-            association.</p><a id="style-association-example-1" name=
-            "style-association-example-1"></a>
-
-            <table class="example">
-              <caption>
-                Example – Inline Styling
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;p <span class=
-"strong">tts:color="white"</span>&gt;White 1 &lt;span <span class=
-"strong">tts:color="yellow"</span>&gt;Yellow&lt;/span&gt; White 2&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In the above example, the two text fragments <code>"White 1
-              "</code> and <code>" White 2"</code>, which are interpreted as
-              anonymous spans, are not associated with a color style property;
-              rather, they inherit their color style from their parent
-              <code>p</code> element as described in <a href=
-              "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
-              Inheritance</b></a> below.</p>
-            </div>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-association-referential" name=
-            "semantics-style-association-referential"></a>8.4.1.2 Referential
-            Styling</h5>
-
-            <p>Style properties may be expressed in an out-of-line manner and
-            referenced by the affected element using the <code>style</code>
-            attribute. When expressed in this manner, the association of style
-            information is referred to as <em>referential styling</em>.</p>
-
-            <p>If a <code>style</code> attribute specifies multiple references,
-            then those references are evaluated in the specified order, and
-            that order applies to resolution of the value of a style property
-            in the case that it is specified along multiple reference
-            paths.</p>
-
-            <p>The use of referential styling is restricted to making reference
-            to <code>style</code> element descendants of a <code>styling</code>
-            element. It is considered an error to reference a
-            <code>style</code> element that is a descendant of a
-            <code>layout</code> element.</p>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>The use of referential styling encourages the reuse of style
-              specifications while sacrificing locality of reference.</p>
-            </div>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>A single content element may be associated with style
-              properties by a hybrid mixture of inline and referential styling,
-              in which case inline styling is given priority as described above
-              by <a href="#semantics-style-association-inline"><b>8.4.1.1
-              Inline Styling</b></a>.</p>
-            </div><a id="style-association-example-2" name=
-            "style-association-example-2"></a>
-
-            <table class="example">
-              <caption>
-                Example – Referential Styling
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;style <span class="strong">xml:id="s1"</span> tts:color="white"/&gt;
-&lt;style <span class="strong">xml:id="s2"</span> tts:color="yellow"/&gt;
-...
-&lt;p <span class="strong">style="s1"</span>&gt;White 1 &lt;span <span class=
-"strong">style="s2"</span>&gt;Yellow&lt;/span&gt; White 2&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In the above example, the two text fragments <code>"White 1
-              "</code> and <code>" White 2"</code>, which are interpreted as
-              anonymous spans, are not associated with a color style property;
-              rather, they inherit their color style from their parent
-              <code>p</code> element as described in <a href=
-              "#semantics-style-inheritance-content"><b>8.4.2.1 Content Style
-              Inheritance</b></a> below.</p>
-            </div>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-association-chained-referential" name=
-            "semantics-style-association-chained-referential"></a>8.4.1.3
-            Chained Referential Styling</h5>
-
-            <p>Style properties may be expressed in an out-of-line manner and
-            may themselves reference other out-of-line style properties, thus
-            creating a chain of references starting at the affected element.
-            When expressed in this manner, the association of style information
-            is referred to as <em>chained referential styling</em>.</p>
-
-            <p>If the same style property is specified in more than one
-            referenced style set, then the last referenced style set applies,
-            where the order of application starts from the affected element and
-            proceeds to referenced style sets, and, in turn, to subsequent
-            referenced style sets.</p>
-
-            <p>A loop in a sequence of chained style references must be
-            considered an error.</p>
-
-            <p>The use of referential styling is restricted to making reference
-            to <code>style</code> element descendants of a <code>styling</code>
-            element. It is considered an error to reference a
-            <code>style</code> element that is a descendant of a
-            <code>layout</code> element.</p>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>The use of chained referential styling encourages the grouping
-              of style specifications into general and specific sets, which
-              further aids in style specification reuse.</p>
-            </div>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>A single content element may be associated with style
-              properties by a hybrid mixture of inline, referential styling,
-              and chained referential styling, in which case inline styling is
-              given priority as described above by <a href=
-              "#semantics-style-association-inline"><b>8.4.1.1 Inline
-              Styling</b></a>.</p>
-            </div><a id="style-association-example-3" name=
-            "style-association-example-3"></a>
-
-            <table class="example">
-              <caption>
-                Example – Chained Referential Styling
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;style <span class=
-"strong">xml:id="s1"</span> tts:color="white" tts:fontFamily="monospaceSerif"/&gt;
-&lt;style <span class="strong">xml:id="s2"</span> <span class=
-"strong">style="s1"</span> tts:color="yellow"/&gt;
-...
-&lt;p <span class="strong">style="s1"</span>&gt;White Monospace&lt;/p&gt;
-&lt;p <span class="strong">style="s2"</span>&gt;Yellow Monospace&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-association-nested" name=
-            "semantics-style-association-nested"></a>8.4.1.4 Nested
-            Styling</h5>
-
-            <p>Style properties may be expressed in a nested manner by direct
-            specification of one or more <code>style</code> element children of
-            the affected element. When expressed in this manner, the
-            association of style information is referred to as <em>nested
-            styling</em>.</p>
-
-            <p>Style properties associated by nested styling are afforded a
-            lower priority than inline styling but with higher priority than
-            referential styling.</p><a id="style-association-example-4" name=
-            "style-association-example-4"></a>
-
-            <table class="example">
-              <caption>
-                Example – Nested Styling
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;region xml:id="r1"&gt;
-  <span class="strong">&lt;style tts:extent="128px 66px"/&gt;</span>
-  <span class="strong">&lt;style tts:origin="0px 0px"/&gt;</span>
-  <span class="strong">&lt;style tts:displayAlign="center"/&gt;</span>
-&lt;/region&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In this version of this specification, nested styling applies
-              only to the <code>region</code> element.</p>
-            </div>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-style-inheritance" name=
-          "semantics-style-inheritance"></a>8.4.2 Style Inheritance</h4>
-
-          <p>Style inheritance is a sub-process of <a href=
-          "#semantics-style-resolution-processing"><b>8.4.4 Style Resolution
-          Processing</b></a> used to determine the specified style set of each
-          content and layout element.</p>
-
-          <p>Styles are further propagated to content matter using:</p>
-
-          <ul>
-            <li>
-              <p><a href="#semantics-style-inheritance-content">content style
-              inheritance</a></p>
-            </li>
-
-            <li>
-              <p><a href="#semantics-style-inheritance-content">region style
-              inheritance</a></p>
-            </li>
-          </ul>
-
-          <p>For the purpose of determining inherited styles, the element
-          hierarchy of an intermediate synchronic document form of a
-          <em>Document Instance</em> must be used, where such intermediate
-          forms are defined by <a href=
-          "#semantics-region-layout-step-1"><b>9.3.2 Intermediate Synchronic
-          Document Construction</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The intermediate synchronic document form is utilized rather
-            than the original form in order to facilitate region inheritance
-            processing.</p>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-inheritance-content" name=
-            "semantics-style-inheritance-content"></a>8.4.2.1 Content Style
-            Inheritance</h5>
-
-            <p>Style properties are inherited from ancestor content elements
-            within an intermediate synchronic document if a style property is
-            not associated with a content element (or an anonymous span) and
-            the style property is designated as inheritable.</p>
-
-            <p>If a style property is determined to require inheritance, then
-            the inherited value must be the value of the same named style
-            property in the computed style set of the element's immediate
-            ancestor element within the applicable intermediate synchronic
-            document.</p><a id="style-inheritance-example-2" name=
-            "style-inheritance-example-2"></a>
-
-            <table class="example">
-              <caption>
-                Example – Content Style Inheritance
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;p <span class="strong">tts:fontFamily="monospaceSansSerif"</span>&gt;
-  &lt;span tts:color="yellow"&gt;Yellow Monospace&lt;/span&gt;
-&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In the above example, the <code>span</code> element that
-              encloses the character items <code>Yellow Monospace</code> is not
-              associated with a <code>tts:fontFamily</code> style property and
-              this property is inheritable; therefore, the value of the
-              <code>tts:fontFamily</code> style is inherited from the computed
-              style set of the ancestor <code>p</code> element, and is added to
-              the specified style set of the <code>span</code> element.</p>
-            </div>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-inheritance-region" name=
-            "semantics-style-inheritance-region"></a>8.4.2.2 Region Style
-            Inheritance</h5>
-
-            <p>Style properties are inherited from a region element in the
-            following case:</p>
-
-            <ol class="enumar">
-              <li>
-                <p>if a style property <em>P</em> is not associated with a
-                content element or an anonymous span <em>E</em> and the style
-                property is designated as inheritable, and</p>
-              </li>
-
-              <li>
-                <p>if that style property <em>P</em> is in the computed style
-                set of region <em>R</em>, and</p>
-              </li>
-
-              <li>
-                <p>if that element <em>E</em> is flowed into (presented within)
-                region <em>R</em>.</p>
-              </li>
-            </ol><a id="style-inheritance-example-3" name=
-            "style-inheritance-example-3"></a>
-
-            <table class="example">
-              <caption>
-                Example – Region Style Inheritance
-              </caption>
-
-              <tbody>
-                <tr>
-                  <td>
-                    <div class="exampleInner">
-                      <pre>
-&lt;region <span class="strong">xml:id="r1"</span>&gt;
-  &lt;style tts:color="yellow"/&gt;
-  &lt;style tts:fontFamily="monospaceSerif"/&gt;
-&lt;/region&gt;
-...
-&lt;p <span class="strong">region="r1"</span>&gt;Yellow Monospace&lt;/p&gt;
-</pre>
-                    </div>
-                  </td>
-                </tr>
-              </tbody>
-            </table>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In the above example, the anonymous span that encloses the
-              character items <code>Yellow Monospace</code> effectively
-              inherits the <code>tts:color</code> and
-              <code>tts:fontFamily</code> styles specified on the
-              <code>region</code> element into which the <code>p</code> element
-              is flowed (presented).</p>
-            </div>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-style-resolution-value-categories" name=
-          "semantics-style-resolution-value-categories"></a>8.4.3 Style
-          Resolution Value Categories</h4>
-
-          <p>During style resolution, layout, and presentation processing,
-          three categories of style property values are distinguished as
-          follows:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#semantics-style-resolved-value-category-specified">specified
-              values</a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#semantics-style-resolved-value-category-computed">computed
-              values</a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#semantics-style-resolved-value-category-actual">actual
-              values</a></p>
-            </li>
-          </ul>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolved-value-category-specified" name=
-            "semantics-style-resolved-value-category-specified"></a>8.4.3.1
-            Specified Values</h5>
-
-            <p>Values of style properties that are associated with or inherited
-            by an element or anonymous span are referred to as <em>specified
-            values</em>. The set of all specified style properties of a given
-            element is referred to as the <em>specified style set</em> of that
-            element.</p>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolved-value-category-computed" name=
-            "semantics-style-resolved-value-category-computed"></a>8.4.3.2
-            Computed Values</h5>
-
-            <p>When style properties are specified using relative value
-            expressions, such as a named color, a relative unit (e.g., cell),
-            or a percentage, then they need to be further resolved into
-            absolute units, such as an RGB triple, pixels, etc.</p>
-
-            <p>During the style resolution process, all specified style values
-            are reinterpreted (or recalculated) in absolute terms, and then
-            recorded as <em>computed values</em>. The set of all computed style
-            properties of a given element is referred to as the <em>computed
-            style set</em> of that element.</p>
-
-            <p>When a style value is inherited, either explicitly or
-            implicitly, it is the computed value of the style that is inherited
-            from an ancestor element. This is required since the resolution of
-            certain relative units, such as percentage, require evaluating the
-            expression in the immediate (local) context of reference, and not
-            in a distant (remote) context of reference where the related
-            (resolving) expression is not available.</p>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolved-value-category-actual" name=
-            "semantics-style-resolved-value-category-actual"></a>8.4.3.3 Actual
-            Values</h5>
-
-            <p>During the actual presentation process, other transformations
-            occur that map some value expressions to concrete, physical values.
-            For example, the colors of computed style values are further
-            subjected to closest color approximation and gamma correction
-            during the display process. In addition, length value expressions
-            that use pixels in computed style values are considered to express
-            logical rather than physical (device) pixels. Consequently, these
-            logical pixels are subject to being further transformed or mapped
-            to physical (device) pixels during presentation.</p>
-
-            <p>The final values that result from the logical to device mapping
-            process are referred to as <em>actual values</em>. The set of all
-            actual style properties of a given element is referred to as the
-            <em>actual style set</em> of that element.</p>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>More than one set of actual values may be produced during the
-              process of presentation. For example, a TTML presentation
-              processor device may output an RGBA component video signal which
-              is then further transformed by an NTSC or PAL television to
-              produce a final image. In this case, both color and dimensions
-              may further be modified prior to presentation.</p>
-            </div>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>In general, a TTML presentation processor will not have access
-              to actual style set values; as a consequence, no further use or
-              reference to actual values is made below when formally describing
-              the style resolution process.</p>
-            </div>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-style-resolution-processing" name=
-          "semantics-style-resolution-processing"></a>8.4.4 Style Resolution
-          Processing</h4>
-
-          <p>The process of style resolution is defined herein as the procedure
-          (and results thereof) for resolving (determining) the computed values
-          of all style properties that apply to content and layout
-          elements:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#semantics-style-resolution-processing-definitions"><b>8.4.4.1
-              Conceptual Definitions</b></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#semantics-style-resolution-processing-sss"><b>8.4.4.2 Specified
-              Style Set Processing</b></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#semantics-style-resolution-processing-css"><b>8.4.4.3 Computed
-              Style Set Processing</b></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#semantics-style-resolution-process-overall"><b>8.4.4.4 Style
-              Resolution Process</b></a></p>
-            </li>
-          </ul>
-
-          <p>The process described here forms an integral sub-process of
-          <a href="#semantics-region-layout"><b>9.3 Region Layout and
-          Presentation</b></a>.</p>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolution-processing-definitions" name=
-            "semantics-style-resolution-processing-definitions"></a>8.4.4.1
-            Conceptual Definitions</h5>
-
-            <p>For the purpose of interpreting the style resolution processing
-            model specified below, the following conceptual definitions
-            apply:</p>
-
-            <dl>
-              <dt class="label">[style property]</dt>
-
-              <dd>
-                <p>a style property, <em>P</em>, is considered to consist of a
-                tuple <code>[name, value]</code>, where the name of the
-                property is a tuple <code>[namespace value, unqualified
-                name]</code> and the value of the property is a tuple
-                <code>[category, type, value expression]</code></p><a id=
-                "conceptual-definition-example-style-property" name=
-                "conceptual-definition-example-style-property"></a>
-
-                <table class="example">
-                  <caption>
-                    Example – conceptual style property
-                  </caption>
-
-                  <tbody>
-                    <tr>
-                      <td>
-                        <div class="exampleInner">
-                          <pre>
-[
-  ["http://www.w3.org/ns/ttml#styling", "color"],
-  ["specified", <em>color</em>, "red"]
-]
-</pre>
-                        </div>
-                      </td>
-                    </tr>
-                  </tbody>
-                </table>
-              </dd>
-
-              <dt class="label">[style (property) set]</dt>
-
-              <dd>
-                <p>a style (property) set consists of an unordered collection
-                of style properties, where no two style properties within the
-                set have an identical name, where by "identical name" is meant
-                equality of namespace value of name tuple and unqualified name
-                of name tuple;</p>
-
-                <p>in a specified style (property) set, the category of each
-                style property is "specified"; a specified style (property) set
-                of an element <em>E</em> is referred to as
-                <em>SSS(E)</em>;</p><a id=
-                "conceptual-definition-example-specified-style-set" name=
-                "conceptual-definition-example-specified-style-set"></a>
-
-                <table class="example">
-                  <caption>
-                    Example – conceptual (specified) style (property) set
-                  </caption>
-
-                  <tbody>
-                    <tr>
-                      <td>
-                        <div class="exampleInner">
-                          <pre>
-{
-  [
-    ["http://www.w3.org/ns/ttml#styling", "backgroundColor"],
-    ["specified", <em>color</em>, 0x00FF00 ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "color"],
-    ["specified", <em>color</em>, "red" ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "fontSize"],
-    ["specified", <em>length</em>, "1c" ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "lineHeight"],
-    ["specified", <em>length</em>, "117%" ]
-  ]
-}
-</pre>
-                        </div>
-                      </td>
-                    </tr>
-                  </tbody>
-                </table>
-
-                <p>in a computed style (property) set, the category of each
-                style property is either "specified" or "computed"; a computed
-                style (property) set of an element <em>E</em> is referred to as
-                <em>CSS(E)</em>;</p><a id=
-                "conceptual-definition-example-computed-style-set" name=
-                "conceptual-definition-example-computed-style-set"></a>
-
-                <table class="example">
-                  <caption>
-                    Example – conceptual (computed) style (property) set
-                  </caption>
-
-                  <tbody>
-                    <tr>
-                      <td>
-                        <div class="exampleInner">
-                          <pre>
-{
-  [
-    ["http://www.w3.org/ns/ttml#styling", "backgroundColor"],
-    ["specified", <em>color</em>, 0x00FF00 ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "color"],
-    ["computed", <em>color</em>, 0xFF0000 ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "fontSize"],
-    ["computed", <em>length</em>, "24px" ]
-  ],
-  [
-    ["http://www.w3.org/ns/ttml#styling", "lineHeight"],
-    ["computed", <em>length</em>, "28px" ]
-  ]
-}
-</pre>
-                        </div>
-                      </td>
-                    </tr>
-                  </tbody>
-                </table>
-              </dd>
-
-              <dt class="label">[style (property) merging]</dt>
-
-              <dd>
-                <p>a style property <em>P<sub>new</sub></em> is merged into a
-                style (property) set, <em>SS</em>, as follows: if a style
-                property <em>P<sub>old</sub></em> is already present in
-                <em>SS</em> where the name of <em>P<sub>new</sub></em> is
-                identical to the name of <em>P<sub>old</sub></em>, then replace
-                <em>P<sub>old</sub></em> in <em>SS</em> with
-                <em>P<sub>new</sub></em>; otherwise, add
-                <em>P<sub>new</sub></em> to <em>SS</em>;</p>
-              </dd>
-
-              <dt class="label">[style (property) set merging]</dt>
-
-              <dd>
-                <p>a style (property) set <em>SS<sub>new</sub></em> is merged
-                into an existing style (property) set <em>SS<sub>old</sub></em>
-                as follows: for each style property <em>P<sub>new</sub></em> in
-                <em>SS<sub>new</sub></em>, merge <em>P<sub>new</sub></em> into
-                <em>SS<sub>old</sub></em>;</p>
-              </dd>
-            </dl>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolution-processing-sss" name=
-            "semantics-style-resolution-processing-sss"></a>8.4.4.2 Specified
-            Style Set Processing</h5>
-
-            <p>The specified style set <em>SSS</em> of an element or anonymous
-            span <em>E</em>, <em>SSS(E)</em>, is determined according to the
-            following ordered rules:</p>
-
-            <ol class="enumar">
-              <li>
-                <p><span class="strong">[initialization]</span> initialize the
-                specified style set <em>SSS</em> of <em>E</em> to the empty
-                set;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[referential and chained referential
-                styling]</span> for each <code>style</code> element
-                <em>S<sub>REF</sub></em> referenced by a <code>style</code>
-                attribute specified on <em>E</em>, and in the order specified
-                in the <code>style</code> attribute, then, if
-                <em>S<sub>REF</sub></em> is a descendant of a
-                <code>styling</code> element, merge the specified style set of
-                <em>S<sub>REF</sub></em>, <em>SSS(S<sub>REF</sub>)</em>, into
-                the specified style set of <em>E</em>, <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[nested styling]</span> for each nested
-                <code>style</code> element child <em>S<sub>NEST</sub></em> of
-                <em>E</em>, and in the specified order of child elements, merge
-                the specified style set of <em>S<sub>NEST</sub></em>,
-                <em>SSS(S<sub>NEST</sub>)</em>, into the specified style set of
-                <em>E</em>, <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[inline styling]</span> for each style
-                property <em>P</em> expressed as a specified styling attribute
-                of <em>E</em>, merge <em>P</em> into the specified style set of
-                <em>E</em>, <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[animation styling]</span> for each
-                style property <em>P</em> expressed as a specified styling
-                attribute of an immediate animation (<code>set</code>) element
-                child of element <em>E</em>, merge <em>P</em> into the
-                specified style set of <em>E</em>, <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[implicit inheritance]</span> if the
-                element type of <em>E</em> is not the styling element type
-                <code>style</code>, then for each inheritable style property
-                <em>P<sub>INH</sub></em> in the set of style properties defined
-                above in <a href="#styling-attribute-vocabulary"><b>8.2 Styling
-                Attribute Vocabulary</b></a>, perform the following ordered
-                sub-steps:</p>
-
-                <ol class="enumla">
-                  <li>
-                    <p>if <em>P<sub>INH</sub></em> is present in the specified
-                    style set of <em>E</em>, <em>SSS(E)</em>, then continue to
-                    the next inheritable style property;</p>
-                  </li>
-
-                  <li>
-                    <p>if the element type of <em>E</em> is the layout element
-                    type <code>region</code>, then set <em>P′</em> to the
-                    initial value of property <em>P</em>, where the initial
-                    value of a property is determined according to the specific
-                    property definition found above in <a href=
-                    "#styling-attribute-vocabulary"><b>8.2 Styling Attribute
-                    Vocabulary</b></a>;</p>
-                  </li>
-
-                  <li>
-                    <p>if the element type of <em>E</em> is a content element
-                    type or anonymous span, then set <em>P′</em> to the result
-                    of looking up the value of <em>P</em> in the computed style
-                    set of the immediate ancestor element of <em>E</em>, i.e.,
-                    <em>CSS(PARENT(E))</em>;</p>
-                  </li>
-
-                  <li>
-                    <p>if the value of <em>P′</em> is not undefined, then merge
-                    <em>P′</em> into the specified style set of <em>E</em>,
-                    <em>SSS(E)</em>.</p>
-                  </li>
-                </ol>
-              </li>
-            </ol>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolution-processing-css" name=
-            "semantics-style-resolution-processing-css"></a>8.4.4.3 Computed
-            Style Set Processing</h5>
-
-            <p>The computed style set <em>CSS</em> of an element or anonymous
-            span <em>E</em>, <em>CSS(E)</em>, is determined according to the
-            following ordered rules:</p>
-
-            <ol class="enumar">
-              <li>
-                <p><span class="strong">[resolve specified styles]</span>
-                determine (obtain) the specified style set <em>SSS</em> of
-                <em>E</em>, namely, <em>SSS(E)</em>, in accordance with
-                <a href="#semantics-style-resolution-processing-sss"><b>8.4.4.2
-                Specified Style Set Processing</b></a>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[initialization]</span> initialize
-                <em>CSS(E)</em> to a (deep) copy of <em>SSS(E)</em>;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[filter]</span> if <em>E</em> is a
-                <code>style</code> element, then return <em>CSS(E)</em> as the
-                resulting computed style set without further resolution;
-                otherwise, continue with the next rule;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[relative value resolution]</span> for
-                each style property <em>P</em> in <em>CSS(E)</em>, where the
-                value type of <em>P</em> is relative, perform the following
-                ordered sub-steps:</p>
-
-                <ol class="enumla">
-                  <li>
-                    <p>replace the relative value of <em>P</em> with an
-                    equivalent, non-relative (computed) value;</p>
-                  </li>
-
-                  <li>
-                    <p>set the category of <em>P</em> to "computed";</p>
-                  </li>
-                </ol>
-              </li>
-            </ol>
-
-            <div class="note">
-              <p class="prefix"><b>Note:</b></p>
-
-              <p>As a result of the filtering rule above, the computed style
-              set of a <code>style</code> element includes only specified
-              values, in which case relative value expressions remain relative;
-              consequently, the resolution of relative value expressions (that
-              may be assigned by means of referential style association) always
-              takes place in the context of a layout or content element which
-              has a presentation context, and not in the non-presentation,
-              declaration context of a referentiable <code>style</code>
-              element.</p>
-            </div>
-          </div>
-
-          <div class="div4">
-            <h5><a id="semantics-style-resolution-process-overall" name=
-            "semantics-style-resolution-process-overall"></a>8.4.4.4 Style
-            Resolution Process</h5>
-
-            <p>The top-level style resolution process is defined as follows:
-            using a preorder traversal of each element and anonymous span,
-            <em>E</em>, of an intermediate synchronic document,
-            <em>DOC<sub>inter</sub></em>, perform the following ordered
-            sub-steps:</p>
-
-            <ol class="enumar">
-              <li>
-                <p><span class="strong">[filter]</span> if the element type of
-                <em>E</em> is not the styling element type <code>style</code>,
-                is not the layout element type <code>region</code>, and is not
-                one of the content element types <code>body</code>,
-                <code>div</code>, <code>p</code>, <code>span</code>,
-                <code>br</code>, or anonymous span, then continue to the next
-                element in the preorder traversal;</p>
-              </li>
-
-              <li>
-                <p><span class="strong">[resolve computed styles]</span>
-                determine (obtain) the computed style set <em>CSS</em> of
-                <em>E</em>, namely, <em>CSS(E)</em>, in accordance with
-                <a href="#semantics-style-resolution-processing-css"><b>8.4.4.3
-                Computed Style Set Processing</b></a>.</p>
-              </li>
-            </ol>
-          </div>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="layout" name="layout"></a>9 Layout</h2>
-
-      <p>This section specifies the <em>layout</em> matter of the core
-      vocabulary catalog, where layout is to be understood as a separable layer
-      of information that applies to content and that denotes authorial
-      intentions about the presentation of that content.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>The two layers of layout and style matter are considered to be
-        independently separable. Layout matter specifies one or more spaces or
-        areas into which content is intended to be presented, while style
-        matter specifies the manner in which presentation occurs within the
-        layout.</p>
-
-        <p>In certain cases, a content author may choose to embed (inline)
-        style matter directly into layout or content matter. In such cases, an
-        alternative exists – use of referential styling – in which the style
-        matter is not embedded (inlined).</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="layout-element-vocabulary" name=
-        "layout-element-vocabulary"></a>9.1 Layout Element Vocabulary</h3>
-
-        <p>The following elements specify the structure and principal layout
-        aspects of a <em>Document Instance</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#layout-vocabulary-layout"><b>9.1.1 layout</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#layout-vocabulary-region"><b>9.1.2 region</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="layout-vocabulary-layout" name=
-          "layout-vocabulary-layout"></a>9.1.1 layout</h4>
-
-          <p>The <code>layout</code> element is a container element used to
-          group layout matter, including metadata that applies to layout
-          matter.</p>
-
-          <p>The <code>layout</code> element accepts as its children zero or
-          more elements in the <code>Metadata.class</code> element group,
-          followed by zero or more <code>region</code> elements.</p><a id=
-          "elt-syntax-layout" name="elt-syntax-layout"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: layout
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;layout
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#layout-vocabulary-region">region</a>*
-&lt;/layout&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>To the extent that time semantics apply to the content of the
-          <code>layout</code> element, the implied time interval of this
-          element is defined to be coterminous with the <em>Root Temporal
-          Extent</em>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="layout-vocabulary-region" name=
-          "layout-vocabulary-region"></a>9.1.2 region</h4>
-
-          <p>The <code>region</code> element is used to define a rectangular
-          space or area into which content is to be flowed for the purpose of
-          presentation.</p>
-
-          <p>In addition, and in accordance with <a href=
-          "#semantics-style-inheritance-region"><b>8.4.2.2 Region Style
-          Inheritance</b></a>, the <code>region</code> element may be used to
-          specify inheritable style properties to be inherited by content that
-          is flowed into it.</p>
-
-          <p>The <code>region</code> element accepts as its children zero or
-          more elements in the <code>Metadata.class</code> element group,
-          followed by zero or more elements in the <code>Animation.class</code>
-          element group, followed by zero or more <code>style</code>
-          elements.</p>
-
-          <p>Any metadata specified by children in the
-          <code>Metadata.class</code> element group applies semantically to the
-          <code>region</code> element and its descendants as a whole. Any
-          animation elements specified by children in the
-          <code>Animation.class</code> element group apply semantically to the
-          <code>region</code> element. Any <code>style</code> child element
-          must be considered a local style definition that applies only to the
-          containing <code>region</code> element, i.e., does not apply for
-          resolving referential styling (but does apply for region style
-          inheritance).</p><a id="elt-syntax-region" name=
-          "elt-syntax-region"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: region
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;region
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#style-attribute-style">style</a> = IDREFS
-  <a href=
-"#timing-attribute-timeContainer">timeContainer</a> = (<em>par</em>|<em>seq</em>)
-  <a href="#metadata-attribute-role">ttm:role</a> = string
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href=
-"#element-vocab-group-table">Metadata.class</a>*, <a href=
-"#element-vocab-group-table">Animation.class</a>*, <a href=
-"#styling-vocabulary-style">style</a>*
-&lt;/region&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If <code>begin</code> and (or) <code>end</code> attributes are
-          specified on a <code>region</code> element, then they specify the
-          beginning and (or) ending points of a time interval during which the
-          region is eligible for activation and with respect to which animation
-          child elements of the region are timed. If specified, these begin and
-          end points are relative to the time interval of the nearest ancestor
-          element associated with a time interval, irregardless of whether that
-          interval is explicit or implied.</p>
-
-          <p>The nearest ancestor element of a <code>region</code> element that
-          is associated with a time interval is the <code>layout</code>
-          element.</p>
-
-          <p>If a <code>dur</code> attribute is specified on the
-          <code>region</code> element, then it specifies the simple duration of
-          the region.</p>
-
-          <p>For the purpose of determining the semantics of presentation
-          processing, a region that is temporally inactive must not produce any
-          visible marks when presented on a visual medium.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>A <code>region</code> element may be associated with a time
-            interval for two purposes: (1) in order to temporally bound the
-            presentation of the region and its content, and (2) to provide a
-            temporal context in which animations of region styles may be
-            effected.</p>
-
-            <p>For example, an author may wish to specify a region that is
-            otherwise empty, but may have a visible background color to be
-            presented starting at some time and continuing over the region's
-            duration. The simple duration of the region serves additionally to
-            scope the presentation effects of content that is targeted to the
-            region. An author may also wish to move a region within the
-            <em>Root Container Region</em> or change a region's background
-            color by means of animation effects. In both of these cases, it is
-            necessary to posit an active time interval for a region.</p>
-          </div>
-
-          <p>If no <code>timeContainer</code> attribute is specified on a
-          <code>region</code> element, then it must be interpreted as having
-          <em>parallel</em> time containment semantics.</p>
-
-          <p>If a <a href="#metadata-attribute-role"><code>ttm:role</code></a>
-          attribute is specified on a <code>region</code> element, then it must
-          adhere to the value syntax defined by <a href=
-          "#metadata-attribute-role-syntax"><b>Syntax Representation –
-          ttm:role</b></a>, and where the roles identified by this attribute
-          express the semantic roles of the region independently from the
-          semantic roles of any content targeted to (associated with) the
-          region.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="layout-attribute-vocabulary" name=
-        "layout-attribute-vocabulary"></a>9.2 Layout Attribute Vocabulary</h3>
-
-        <p>This section defines the <a href="#layout-attribute-region"><b>9.2.1
-        region</b></a> attribute used with content elements.</p>
-
-        <div class="div3">
-          <h4><a id="layout-attribute-region" name=
-          "layout-attribute-region"></a>9.2.1 region</h4>
-
-          <p>The <code>region</code> attribute is used to reference a
-          <code>region</code> element which defines a space or area into which
-          a content element is intended to be flowed.</p>
-
-          <p>If specified, the value of a <code>region</code> attribute must
-          adhere to the <code>IDREF</code> data type defined by <a href=
-          "#xsd-2">[XML Schema Part 2]</a>, § 3.3.9, and, furthermore, this
-          IDREF must reference a <code>region</code> element which has a
-          <code>layout</code> element as an ancestor.</p>
-
-          <p>The <code>region</code> attribute may be specified by an instance
-          of the following element types:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#document-structure-vocabulary-body"><code>body</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
-            </li>
-          </ul>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#semantics-region-layout"><b>9.3 Region Layout and
-            Presentation</b></a> below for further information on content flow
-            in a region.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="semantics-region-layout" name=
-        "semantics-region-layout"></a>9.3 Region Layout and Presentation</h3>
-
-        <p>This section defines the semantics of region layout and presentation
-        in terms of a standard processing model as follows:</p>
-
-        <ul>
-          <li>
-            <p><a href="#semantics-default-region"><b>9.3.1 Default
-            Region</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-region-layout-step-1"><b>9.3.2 Intermediate
-            Synchronic Document Construction</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-region-layout-step-2"><b>9.3.3 Synchronic
-            Flow Processing</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#semantics-region-layout-example"><b>9.3.4 Elaborated
-            Example (Informative)</b></a></p>
-          </li>
-        </ul>
-
-        <p>Any implementation is permitted provided that the externally
-        observable results are consistent with the results produced by this
-        model.</p>
-
-        <div class="div3">
-          <h4><a id="semantics-default-region" name=
-          "semantics-default-region"></a>9.3.1 Default Region</h4>
-
-          <p>If a <em>Document Instance</em> does not specify a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element, then a
-          <em>default region</em> is implied with the following
-          characteristics:</p>
-
-          <ul>
-            <li>
-              <p>the identity of the default region is considered to be
-              anonymous;</p>
-            </li>
-
-            <li>
-              <p>the extent of the default region is the same as the extent of
-              the <em>Root Container Region</em>;</p>
-            </li>
-
-            <li>
-              <p>the temporal interval of the default region is the same as the
-              interval defined by the <em>Root Temporal Extent</em>;</p>
-            </li>
-          </ul>
-
-          <p>Furthermore, if no <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element is
-          specified, then the <a href=
-          "#layout-attribute-region"><code>region</code></a> attribute must not
-          be specified on any content element in the <em>Document
-          Instance</em>.</p>
-
-          <p>If a default region is implied for a given <em>Document
-          Instance</em>, then the <a href=
-          "#document-structure-vocabulary-body"><code>body</code></a> element
-          is implicitly targeted to (associated with) the default region.</p>
-
-          <p>When implying a default region, the <em>Document Instance</em> is
-          to be treated as if a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element and its
-          parent <a href="#layout-vocabulary-layout"><code>layout</code></a>
-          element were specified in a <a href=
-          "#document-structure-vocabulary-head"><code>head</code></a> element,
-          and a matching <a href=
-          "#layout-attribute-region"><code>region</code></a> attribute were
-          specified on the <a href=
-          "#document-structure-vocabulary-body"><code>body</code></a> element
-          as shown in the following example:</p><a id=
-          "semantics-default-region-example" name=
-          "semantics-default-region-example"></a>
-
-          <table class="example">
-            <caption>
-              Example – Implied Default Region
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"&gt;
-  &lt;head&gt;
-    <span class="strong">&lt;layout&gt;
-      &lt;region xml:id="anonymous"/&gt;
-    &lt;/layout&gt;</span>
-  &lt;/head&gt;
-  &lt;body <span class="strong">region="anonymous"</span>/&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, a default <code>region</code> element and
-            <code>region</code> attribute are implied. In addition, a
-            <code>layout</code> container element is implied for the implied
-            <code>region</code> element.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-region-layout-step-1" name=
-          "semantics-region-layout-step-1"></a>9.3.2 Intermediate Synchronic
-          Document Construction</h4>
-
-          <p>For the purposes of performing presentation processing, the active
-          time duration of a <em>Document Instance</em> is divided into a
-          sequence of time coordinates where at each time coordinate, some
-          element becomes temporally active or inactive, then, at each such
-          time coordinate, a <em>Document Instance</em> is mapped from its
-          original, source form, <em>DOC<sub>source</sub></em> , to an
-          intermediate synchronic document form, <em>DOC<sub>inter</sub></em> ,
-          according to the <span class="strong">[construct intermediate
-          document]</span> procedure:</p>
-
-          <dl>
-            <dt class="label">[construct intermediate document]</dt>
-
-            <dd>
-              <ol class="enumar">
-                <li>
-                  <p>for each temporally active region <em>R</em>, replicate
-                  the sub-tree of <em>DOC<sub>source</sub></em> headed by the
-                  <code>body</code> element;</p>
-                </li>
-
-                <li>
-                  <p>evaluating this sub-tree in a postorder traversal, prune
-                  elements if they are not a content element, if they are
-                  temporally inactive, if they are empty, or if they aren't
-                  associated with region <em>R</em> according to the
-                  <span class="strong">[associate region]</span> procedure;</p>
-                </li>
-
-                <li>
-                  <p>if the pruned sub-tree is non-empty, then reparent it to
-                  the <em>R</em> element;</p>
-                </li>
-
-                <li>
-                  <p>finally, after completing the above steps, prune the
-                  original <code>body</code> element from the intermediate
-                  document, then prune all <code>region</code>,
-                  <code>begin</code>, <code>end</code>, and <code>dur</code>
-                  attributes, which are no longer semantically relevant;</p>
-                </li>
-              </ol>
-
-              <div class="note">
-                <p class="prefix"><b>Note:</b></p>
-
-                <p>In this section, the term <em>prune</em>, when used in
-                reference to an element, means that the element is to be
-                removed from its parent's children, which, in turn, implies
-                that the descendants of the pruned element will no longer be
-                descendants of the element's parent. When <em>prune</em> is
-                used in reference to an attribute, it means that attribute is
-                to be removed from its associated (owning) element node.</p>
-              </div>
-            </dd>
-
-            <dt class="label">[associate region]</dt>
-
-            <dd>
-              <p>A content element is associated with a region according to the
-              following ordered rules, where the first rule satisfied is used
-              and remaining rules are skipped:</p>
-
-              <ol class="enumar">
-                <li>
-                  <p>if the element specifies a <a href=
-                  "#layout-attribute-region"><code>region</code></a> attribute,
-                  then the element is associated with the region referenced by
-                  that attribute;</p>
-                </li>
-
-                <li>
-                  <p>if some ancestor of that element specifies a <a href=
-                  "#layout-attribute-region"><code>region</code></a> attribute,
-                  then the element is associated with the region referenced by
-                  the most immediate ancestor that specifies this
-                  attribute;</p>
-                </li>
-
-                <li>
-                  <p>if the element contains a descendant element that
-                  specifies a <a href=
-                  "#layout-attribute-region"><code>region</code></a> attribute,
-                  then the element is associated with the region referenced by
-                  that attribute;</p>
-                </li>
-
-                <li>
-                  <p>if a default region was implied (due to the absence of any
-                  <a href="#layout-vocabulary-region"><code>region</code></a>
-                  element), then the element is associated with the default
-                  region;</p>
-                </li>
-
-                <li>
-                  <p>the element is not associated with any region.</p>
-                </li>
-              </ol>
-            </dd>
-          </dl>
-
-          <p>The result of performing the processing described above will be a
-          sequence of <em>N</em> intermediate synchronic <em>Document
-          Instances</em>, <em>DOC<sub><span>inter<sub>0</sub></span></sub></em>
-          … <em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>.</p>
-
-          <div class="note" id="semantics-smooth-scrolling-recommendation">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Where an implementation is able to detect significant similarity
-            between two adjacent synchronic <em>Document Instances</em>,
-            <em>DOC<sub><span>inter<sub>N</sub></span></sub></em>
-            <em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>, then it is
-            preferred that the implementation make the transition between
-            presenting the two instances as smooth as possible, e.g., as
-            described by <a href="#cea608c">[CEA-608-C]</a>, § C.3.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-region-layout-step-2" name=
-          "semantics-region-layout-step-2"></a>9.3.3 Synchronic Flow
-          Processing</h4>
-
-          <p>Subsequent to performing a temporal (synchronic) slice and
-          subsequent remapping of regionally selected content hierarchy, the
-          resulting intermediate synchronic document is subjected to a flow
-          transformation step that produces a rooted flow object tree
-          represented as an XSL FO document instance as defined by <a href=
-          "#xsl11">[XSL 1.1]</a>, and semantically extended by TTML specific
-          style properties that have no XSL FO counterpart.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In this section, the use of XSL FO is intended to be conceptual
-            only, employed solely for the purpose of defining the normative
-            presentation semantics of TTML. An actual implementation of this
-            algorithm is not required to create or process XSL-FO
-            representations. In particular, it is possible to implement these
-            semantics using alternative presentation models, such as Cascading
-            Style Sheets (CSS).</p>
-          </div>
-
-          <p>Each intermediate synchronic document produced by <a href=
-          "#semantics-region-layout-step-1"><b>9.3.2 Intermediate Synchronic
-          Document Construction</b></a> is mapped to an XSL FO document
-          instance, <em>F</em>, as follows:</p>
-
-          <ol class="enumar">
-            <li>
-              <p>perform the following ordered sub-steps to create anonymous
-              spans:</p>
-
-              <ol class="enumla">
-                <li>
-                  <p>for each significant text node in a content element,
-                  synthesize an anonymous span to enclose the text node,
-                  substituting the new anonymous span for the original text
-                  node child in its sibling and parent hierarchy;</p>
-                </li>
-
-                <li>
-                  <p>for each contiguous sequence of anonymous spans, replace
-                  the sequence with a single anonymous span which contains a
-                  sequence of text nodes representing the individual text node
-                  children of the original sequence of anonymous spans;</p>
-                </li>
-
-                <li>
-                  <p>for each span element whose child is a single anonymous
-                  span, replace the anonymous span with its sequence of child
-                  text nodes;</p>
-                </li>
-              </ol>
-            </li>
-
-            <li>
-              <p>resolve styles according to <a href=
-              "#semantics-style-resolution-process-overall"><b>8.4.4.4 Style
-              Resolution Process</b></a>;</p>
-            </li>
-
-            <li>
-              <p>map the <code>tt</code> element to an <code>fo:root</code>
-              element, populated initially with an
-              <code>fo:layout-master-set</code> element that contains a valid
-              <code>fo:simple-page-master</code> that, in turn, contains an
-              <code>fo:region-body</code> child, where the extent of the
-              <em>Root Container Region</em> expressed on the <code>tt</code>
-              element is mapped to <code>page-width</code> and
-              <code>page-height</code> attributes on the
-              <code>fo:simple-page-master</code> element;</p>
-            </li>
-
-            <li>
-              <p>map the <code>layout</code> element to an
-              <code>fo:page-sequence</code> element and a child
-              <code>fo:flow</code> element that reference the page master and
-              page region defined by the simple page master produced above;</p>
-            </li>
-
-            <li>
-              <p>map each non-empty <code>region</code> element to an
-              <code>fo:block-container</code> element with an
-              <code>absolute-position</code> attribute with value
-              <code>absolute</code>, with <code>top</code>, <code>left</code>,
-              <code>bottom</code>, and <code>right</code> attributes that
-              express a rectangle equivalent to the region's origin and extent,
-              and with a <code>line-stacking-strategy</code> attribute with
-              value <code>line-height</code>;</p>
-            </li>
-
-            <li>
-              <p>for each <code>body</code>, <code>div</code>, and
-              <code>p</code> element that is not associated with a
-              <code>tts:display</code> style property with the value
-              <code>none</code>, map the element to a distinct
-              <code>fo:block</code> element, populating the style properties of
-              <code>fo:block</code> by using the computed style set associated
-              with each original TTML Content element;</p>
-            </li>
-
-            <li>
-              <p>for the resulting <code>fo:block</code> formatting object
-              produced in the previous step that corresponds to the
-              <code>body</code> element, perform the following ordered
-              sub-steps:</p>
-
-              <ol class="enumla">
-                <li>
-                  <p>if the <code>display-align</code> style property of this
-                  <code>fo:block</code> has the value <code>center</code> or
-                  <code>after</code>, then synthesize and insert as the first
-                  child of this <code>fo:block</code> an empty
-                  <code>fo:block</code> with the following attributes:
-                  <code>space-after.optimum</code>,
-                  <code>space-after.maximum</code>, and
-                  <code>space-after.conditionality</code>, where the value of
-                  the former two attributes is the height or width of the
-                  containing <code>fo:block-container</code> element, whichever
-                  of these is designated as the block progression dimension,
-                  and where the value of the last is <code>retain</code>;</p>
-                </li>
-
-                <li>
-                  <p>if the <code>display-align</code> style property of this
-                  <code>fo:block</code> has the value <code>center</code> or
-                  <code>before</code>, then synthesize and insert as the last
-                  child of this <code>fo:block</code> an empty
-                  <code>fo:block</code> with the following attributes:
-                  <code>space-after.optimum</code>,
-                  <code>space-after.maximum</code>, and
-                  <code>space-after.conditionality</code>, where the value of
-                  the former two attributes is the height or width of the
-                  containing <code>fo:block-container</code> element, whichever
-                  of these is designated as the block progression dimension,
-                  and where the value of the last is <code>retain</code>;</p>
-                </li>
-              </ol>
-            </li>
-
-            <li>
-              <p>for each <code>span</code> element that is not associated with
-              a <code>tts:display</code> style property with the value
-              <code>none</code> and for each anonymous span that is a child of
-              a <code>p</code> or <code>span</code> element, map the element or
-              sequence of character items to a distinct <code>fo:inline</code>
-              element, populating the style properties of
-              <code>fo:inline</code> by using the computed style set associated
-              with each original TTML Content element or anonymous span;</p>
-            </li>
-
-            <li>
-              <p>for each <code>br</code> element that is not associated with a
-              <code>tts:display</code> style property with the value
-              <code>none</code>, map the element to a distinct
-              <code>fo:character</code> element having the following
-              properties:</p>
-
-              <ul>
-                <li>
-                  <p><code>character="&amp;#x000A;"</code></p>
-                </li>
-
-                <li>
-                  <p><code>suppress-at-line-break="retain"</code></p>
-                </li>
-              </ul>
-            </li>
-
-            <li>
-              <p>for each TTML style property attribute in some computed style
-              set that has no counterpart in <a href="#xsl11">[XSL 1.1]</a>,
-              map that attribute directly through to the relevant formatting
-              object produced by the input TTML Content element to which the
-              style property applies;</p>
-            </li>
-
-            <li>
-              <p>optionally, synthesize a unique <code>id</code> attribute on
-              each resulting formatting object element that relates that
-              element to the input element that resulted in that formatting
-              object element;</p>
-            </li>
-          </ol>
-
-          <p>For each resulting document instance F, if processing requires
-          presentation on a visual medium, then apply formatting and rendering
-          semantics consistent with that prescribed by <a href="#xsl11">[XSL
-          1.1]</a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In an XSL FO area tree produced by formatting <em>F</em> using
-            an <a href="#xsl11">[XSL 1.1]</a> formatting processor, the
-            <code>page-viewport-area</code>, which is generated by
-            <code>fo:page-sequence</code> element by reference to the sole
-            generated <code>fo:simple-page-master</code> element, would
-            correspond to the <em>Root Container Region</em> defined above in
-            <a href="#definitions"><b>2 Definitions</b></a>.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Due to the possible presence of TTML style properties or style
-            property values in a given <em>Document Instance</em> for which
-            there is no <a href="#xsl11">[XSL 1.1]</a> counterpart,
-            Implementors should recognize that it is the layout model of
-            <a href="#xsl11">[XSL 1.1]</a> that is being referenced by this
-            specification, not the requirement to use a compliant <a href=
-            "#xsl11">[XSL 1.1]</a> formatting processor, since such would not
-            necessarily be sufficient to satisfy the full presentation
-            semantics defined by this specification, and would contain a large
-            number of features not needed to implement the presentation
-            semantics of TTML.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The purpose of inserting additional, collapsible space in the
-            block progression dimension of the <code>fo:block</code> that
-            corresponds with the <code>body</code> element is to ensure that
-            the before and after edges of this <code>fo:block</code> are
-            coincident with the before and after edges of the
-            <code>fo:block-container</code> that corresponds to the containing
-            <code>region</code>, while simultaneously taking into account the
-            needs to satisfy alignment in the block progression dimension. For
-            example, this assures that the background color associated with the
-            <code>body</code> element, if not <code>transparent</code>, will
-            fill the containing region wholly.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="semantics-region-layout-example" name=
-          "semantics-region-layout-example"></a>9.3.4 Elaborated Example
-          (Informative)</h4>
-
-          <p>An example of the processing steps described above is elaborated
-          below, starting with <a href="#region-mapping-example-1-s"><b>Example
-          – Sample Source Document</b></a>.</p><a id=
-          "region-mapping-example-1-s" name="region-mapping-example-1-s"></a>
-
-          <table class="example">
-            <caption>
-              Example – Sample Source Document
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt tts:extent="640px 480px" xml:lang="en"
-  xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1"&gt;
-        &lt;style tts:origin="10px 100px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="red"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-      &lt;/region&gt;
-      &lt;region xml:id="r2"&gt;
-        &lt;style tts:origin="10px 300px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="yellow"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-      &lt;/region&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-  &lt;body xml:id="b1"&gt;
-    &lt;div xml:id="d1" begin="0s" dur="2s"&gt;
-      &lt;p xml:id="p1" region="r1"&gt;Text 1&lt;/p&gt;
-      &lt;p xml:id="p2" region="r2"&gt;Text 2&lt;/p&gt;
-    &lt;/div&gt;
-    &lt;div xml:id="d2" begin="1s" dur="2s"&gt;
-      &lt;p xml:id="p3" region="r2"&gt;Text 3&lt;/p&gt;
-      &lt;p xml:id="p4" region="r1"&gt;Text 4&lt;/p&gt;
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>In the above document, the content hierarchy consists of two
-          divisions, each containing two paragraphs. This content is targeted
-          (associated with) one of two non-overlapping regions that are styled
-          identically except for their position and their foreground colors,
-          the latter of which is inherited by and applies to the (and, in this
-          case, anonymous) spans reparented into the regions.</p>
-
-          <p>The following, first intermediate document shows the synchronic
-          state for time interval [0,1), during which time only division
-          <code>d1</code> is temporally active, and where paragraphs
-          <code>p1</code> and <code>p2</code> (and their ancestors) are
-          associated with regions <code>r1</code> and <code>r2</code>,
-          respectively.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The intermediate documents shown below are not valid
-            <em>Document Instances</em>, but rather, are representations of
-            possible internal processing states used for didactic purposes.</p>
-          </div><a id="region-mapping-example-1-i0" name=
-          "region-mapping-example-1-i0"></a>
-
-          <table class="example">
-            <caption>
-              Example – Intermediate Document – [0s,1s)
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt tts:extent="640px 480px" xml:lang="en"
-  xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1"&gt;
-        &lt;style tts:origin="10px 100px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="red"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-1"&gt;
-          &lt;div xml:id="d1-1"&gt;
-            &lt;p xml:id="p1"&gt;Text 1&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-      &lt;region xml:id="r2"&gt;
-        &lt;style tts:origin="10px 300px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="yellow"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-2"&gt;
-          &lt;div xml:id="d1-2"&gt;
-            &lt;p xml:id="p2"&gt;Text 2&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>An XSL FO document instance that would yield rendering consistent
-          with TTML, and which may be produced by performing flow processing
-          upon the first intermediate document is illustrated below.</p><a id=
-          "region-mapping-example-1-f0" name="region-mapping-example-1-f0"></a>
-
-          <table class="example">
-            <caption>
-              Example – XSL FO Document – [0s,1s)
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format"&gt;
-  &lt;fo:layout-master-set&gt;
-    &lt;fo:simple-page-master master-name="m1"
-      page-width="640px" page-height="480px"&gt;
-      &lt;fo:region-body/&gt;
-    &lt;/fo:simple-page-master&gt;
-  &lt;/fo:layout-master-set&gt;
-  &lt;fo:page-sequence master-reference="m1"&gt;
-    &lt;fo:flow flow-name="xsl-region-body"&gt;
-      &lt;!-- region (r1) --&gt;
-      &lt;fo:block-container id="r1" absolute-position="absolute"
-        left="10px" top="100px" width="620px" height="96px"
-        background-color="black" display-align="center"&gt;
-        &lt;!-- body (b1) --&gt;
-        &lt;fo:block id="b1-1"&gt;
-          &lt;!-- body's space (before) filler --&gt;
-          &lt;fo:block
-            space-after.optimum="96px"
-            space-after.maximum="96px"
-            space-after.conditionality="retain"/&gt;
-          &lt;!-- div (d1) --&gt;
-          &lt;fo:block id="d1-1"&gt;
-            &lt;!-- p (p1) --&gt;
-            &lt;fo:block id="p1" text-align="center"&gt;
-              &lt;fo:inline font-size="40px" font-weight="bold"
-              color="red"&gt;Text 1&lt;/fo:inline&gt;
-            &lt;/fo:block&gt;
-          &lt;/fo:block&gt;
-          &lt;!-- body's space (after) filler --&gt;
-          &lt;fo:block
-            space-after.optimum="96px"
-            space-after.maximum="96px"
-            space-after.conditionality="retain"/&gt;
-        &lt;/fo:block&gt;
-      &lt;/fo:block-container&gt;
-      &lt;!-- region (r2) --&gt;
-      &lt;fo:block-container id="r2" absolute-position="absolute"
-        left="10px" top="300px" width="620px" height="96px"
-        background-color="black" display-align="center"&gt;
-        &lt;!-- body (b1) --&gt;
-        &lt;fo:block id="b1-2"&gt;
-          &lt;!-- body's space (before) filler --&gt;
-          &lt;fo:block
-            space-after.optimum="96px"
-            space-after.maximum="96px"
-            space-after.conditionality="retain"/&gt;
-          &lt;!-- div (d1) --&gt;
-          &lt;fo:block id="d1-2"&gt;
-            &lt;!-- p (p2) --&gt;
-            &lt;fo:block id="p2" text-align="center"&gt;
-              &lt;fo:inline font-size="40px" font-weight="bold"
-              color="yellow"&gt;Text 2&lt;/fo:inline&gt;
-            &lt;/fo:block&gt;
-          &lt;/fo:block&gt;
-          &lt;!-- body's space (after) filler --&gt;
-          &lt;fo:block
-            space-after.optimum="96px"
-            space-after.maximum="96px"
-            space-after.conditionality="retain"/&gt;
-        &lt;/fo:block&gt;
-      &lt;/fo:block-container&gt;
-    &lt;/fo:flow&gt;
-  &lt;/fo:page-sequence&gt;
-&lt;/fo:root&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The following, second intermediate document shows the synchronic
-          state for time interval [1,2), during which time both divisions
-          <code>d1</code> and <code>d2</code> are temporally active, and where
-          paragraphs <code>p1</code> and <code>p4</code> (and their ancestors)
-          are associated with region <code>r1</code> and paragraphs
-          <code>p2</code> and <code>p3</code> (and their ancestors) are
-          associated with region <code>r2</code>.</p><a id=
-          "region-mapping-example-1-i1" name="region-mapping-example-1-i1"></a>
-
-          <table class="example">
-            <caption>
-              Example – Intermediate Document – [1s,2s)
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt tts:extent="640px 480px" xml:lang="en"
-  xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1"&gt;
-        &lt;style tts:origin="10px 100px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="red"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-1"&gt;
-          &lt;div xml:id="d1-1"&gt;
-            &lt;p xml:id="p1"&gt;Text 1&lt;/p&gt;
-          &lt;/div&gt;
-          &lt;div xml:id="d2-1"&gt;
-            &lt;p xml:id="p4"&gt;Text 4&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-      &lt;region xml:id="r2"&gt;
-        &lt;style tts:origin="10px 300px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="yellow"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-2"&gt;
-          &lt;div xml:id="d1-2"&gt;
-            &lt;p xml:id="p2"&gt;Text 2&lt;/p&gt;
-          &lt;/div&gt;
-          &lt;div xml:id="d2-2"&gt;
-            &lt;p xml:id="p3"&gt;Text 3&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The following, third intermediate document shows the synchronic
-          state for time interval [2,3), during which time only division
-          <code>d2</code> is temporally active, and where paragraphs
-          <code>p4</code> and <code>p3</code> (and their ancestors) are
-          associated with regions <code>r1</code> and <code>r2</code>,
-          respectively.</p><a id="region-mapping-example-1-i2" name=
-          "region-mapping-example-1-i2"></a>
-
-          <table class="example">
-            <caption>
-              Example – Intermediate Document – [2s,3s)
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt tts:extent="640px 480px" xml:lang="en"
-  xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1"&gt;
-        &lt;style tts:origin="10px 100px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="red"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-1"&gt;
-          &lt;div xml:id="d2-1"&gt;
-            &lt;p xml:id="p4"&gt;Text 4&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-      &lt;region xml:id="r2"&gt;
-        &lt;style tts:origin="10px 300px"/&gt;
-        &lt;style tts:extent="620px 96px"/&gt;
-        &lt;style tts:fontSize="40px"/&gt;
-        &lt;style tts:fontWeight="bold"/&gt;
-        &lt;style tts:backgroundColor="black"/&gt;
-        &lt;style tts:color="yellow"/&gt;
-        &lt;style tts:textAlign="center"/&gt;
-        &lt;style tts:displayAlign="center"/&gt;
-        &lt;body xml:id="b1-2"&gt;
-          &lt;div xml:id="d2-2"&gt;
-            &lt;p xml:id="p3"&gt;Text 3&lt;/p&gt;
-          &lt;/div&gt;
-        &lt;/body&gt;
-      &lt;/region&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="semantics-line-layout" name="semantics-line-layout"></a>9.4
-        Line Layout</h3>
-
-        <p>If a profile that applies to a <em>Document Instance</em> requires
-        use of the <a href="#feature-lineBreak-uax14">#lineBreak-uax14</a>
-        feature (i.e., the value attribute for the feature is specified as
-        <code>use</code>), then the recommendations defined by <a href=
-        "http://www.unicode.org/reports/tr14/#Algorithm">Line Breaking
-        Algorithm</a> <a href="#uax14">[UAX14]</a> apply when performing line
-        layout on the content of the <em>Document Instance</em>.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="timing" name="timing"></a>10 Timing</h2>
-
-      <p>This section specifies the <em>timing</em> matter of the core
-      vocabulary catalog, where timing is to be understood as a separable layer
-      of information that applies to content and that denotes authorial
-      intentions about the temporal presentation of that content.</p>
-
-      <div class="div2">
-        <h3><a id="timing-element-vocabulary" name=
-        "timing-element-vocabulary"></a>10.1 Timing Element Vocabulary</h3>
-
-        <p>No timing related element vocabulary is defined for use in the core
-        vocabulary catalog.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="timing-attribute-vocabulary" name=
-        "timing-attribute-vocabulary"></a>10.2 Timing Attribute Vocabulary</h3>
-
-        <p>This section defines the following basic timing attributes for use
-        with timed elements:</p>
-
-        <ul>
-          <li>
-            <p><a href="#timing-attribute-begin"><b>10.2.1 begin</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#timing-attribute-end"><b>10.2.2 end</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#timing-attribute-dur"><b>10.2.3 dur</b></a></p>
-          </li>
-        </ul>
-
-        <p>In addition, this section defines the <a href=
-        "#timing-attribute-timeContainer"><b>10.2.4 timeContainer</b></a>
-        attribute for use with timed elements that serve simultaneously as
-        timing containers.</p>
-
-        <div class="div3">
-          <h4><a id="timing-attribute-begin" name=
-          "timing-attribute-begin"></a>10.2.1 begin</h4>
-
-          <p>The <code>begin</code> attribute is used to specify the begin
-          point of a temporal interval associated with a timed element. If
-          specified, the value of a <code>begin</code> attribute must adhere to
-          a &lt;timeExpression&gt; specification as defined by <a href=
-          "#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>The begin point of a temporal interval is included in the
-          interval; i.e., the interval is left-wise closed.</p>
-
-          <p>The semantics of the <code>begin</code> attribute are those
-          defined by <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking
-          into account any overriding semantics defined by this
-          specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="timing-attribute-end" name=
-          "timing-attribute-end"></a>10.2.2 end</h4>
-
-          <p>The <code>end</code> attribute is used to specify the ending point
-          of a temporal interval associated with a timed element. If specified,
-          the value of an <code>end</code> attribute must adhere to a
-          &lt;timeExpression&gt; specification as defined by <a href=
-          "#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <p>The ending point of a temporal interval is not included in the
-          interval; i.e., the interval is right-wise open.</p>
-
-          <p>The presentation effects of a non-empty active temporal interval
-          include the frame immediately prior to the frame (or tick) equal to
-          or immediately following the time specified by the ending point, but
-          do not extend into this latter frame (or tick).</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>For example, if an active interval is [10s,10.33333s), and the
-            frame rate is 30 frames per second, then the presentation effects
-            of the interval are limited to frames 300 through 309 only
-            (assuming that 0s corresponds with frame 0). The same holds if the
-            active interval is specified as [300f,310f).</p>
-          </div>
-
-          <p>The semantics of the <code>end</code> attribute are those defined
-          by <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking into
-          account any overriding semantics defined by this specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="timing-attribute-dur" name=
-          "timing-attribute-dur"></a>10.2.3 dur</h4>
-
-          <p>The <code>dur</code> attribute is used to specify the duration of
-          a temporal interval associated with a timed element. If specified,
-          the value of a <code>dur</code> attribute must adhere to a
-          &lt;timeExpression&gt; specification as defined by <a href=
-          "#timing-value-timeExpression"><b>10.3.1
-          &lt;timeExpression&gt;</b></a>.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>When the <code>clock-time</code> form of a
-            &lt;timeExpression&gt; specification is used with a
-            <code>dur</code> attribute, it is intended to be interpreted as a
-            difference between two implied clock time expressions.</p>
-          </div>
-
-          <p>When a <em>Document Instance</em> specifies the use of the
-          <code>smpte</code> time base and <code>discontinuous</code> marker
-          mode, a (well-formed) <code>dur</code> attribute must not be
-          specified on any element.</p>
-
-          <p>The semantics of the <code>dur</code> attribute are those defined
-          by <a href="#smil21">[SMIL 2.1]</a>, § 10.4.1, while taking into
-          account any overriding semantics defined by this specification.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the context of the subset of <a href="#smil21">[SMIL 2.1]</a>
-            semantics supported by this specification, the active duration of
-            an element that specifies both <code>end</code> and
-            <code>dur</code> attributes is equal to the lesser of the value of
-            the <code>dur</code> attribute and the difference between the value
-            of the <code>end</code> attribute and the element's begin time.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="timing-attribute-timeContainer" name=
-          "timing-attribute-timeContainer"></a>10.2.4 timeContainer</h4>
-
-          <p>The <code>timeContainer</code> attribute is used to specify a
-          local temporal context by means of which timed child elements are
-          temporally situated.</p>
-
-          <p>If specified, the value of a <code>timeContainer</code> attribute
-          must be one of the following:</p>
-
-          <ul>
-            <li>
-              <p><code>par</code></p>
-            </li>
-
-            <li>
-              <p><code>seq</code></p>
-            </li>
-          </ul>
-
-          <p>If the time container semantics of an element instance is
-          <code>par</code>, then the temporal intervals of child elements are
-          considered to apply in parallel, i.e., simultaneously in time.
-          Furthermore, the specification of the time interval of each child
-          element is considered to be relative to the temporal interval of the
-          container element instance. For the purpose of determining the
-          <a href="#smil21">[SMIL 2.1]</a> <code>endsync</code> semantics of a
-          <code>par</code> time container, a default value of <code>all</code>
-          applies.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The use of a default value of <code>all</code> for the
-            <code>endsync</code> behavior is distinct from <a href=
-            "#smil21">[SMIL 2.1]</a> which uses a default value of
-            <code>last</code>.</p>
-          </div>
-
-          <p>If the time container semantics of an element instance is
-          <code>seq</code>, then the temporal intervals of child elements are
-          considered to apply in sequence, i.e., sequentially in time.
-          Furthermore, the specification of the time interval of each child
-          element is considered to be relative to the temporal interval of its
-          sibling elements, unless it is the first child element, in which case
-          it is considered to be relative to the temporal interval of the
-          container element instance.</p>
-
-          <p>Each time container is considered to constitute an independent
-          time base, i.e., time coordinate system.</p>
-
-          <p>If a <code>timeContainer</code> attribute is not specified on an
-          element that has time container semantics, then <code>par</code> time
-          container semantics must apply.</p>
-
-          <p>Time container semantics applies only to the following element
-          types:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#document-structure-vocabulary-body"><code>body</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#layout-vocabulary-region"><code>region</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
-            </li>
-          </ul>
-
-          <p>The semantics of parallel and sequential time containment are
-          those defined by <a href="#smil21">[SMIL 2.1]</a>, § 10.4.2, while
-          taking into account any overriding semantics defined by this
-          specification.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="timing-time-value-expressions" name=
-        "timing-time-value-expressions"></a>10.3 Time Value Expressions</h3>
-
-        <p>Timing attribute values include the use of the following
-        expressions:</p>
-
-        <ul>
-          <li>
-            <p><a href="#timing-value-timeExpression"><b>10.3.1
-            &lt;timeExpression&gt;</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="timing-value-timeExpression" name=
-          "timing-value-timeExpression"></a>10.3.1 &lt;timeExpression&gt;</h4>
-
-          <p>A &lt;timeExpression&gt; is used to specify a coordinate within
-          some time base, where the applicable time base is determined by the
-          <code>ttp:timeBase</code> parameter, and where the semantics defined
-          by <a href="#time-expression-semantics"><b>N Time Expression
-          Semantics</b></a> apply.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>See <a href="#parameter-attribute-frameRate"><b>6.2.4
-            ttp:frameRate</b></a>, <a href=
-            "#parameter-attribute-subFrameRate"><b>6.2.9
-            ttp:subFrameRate</b></a>, <a href=
-            "#parameter-attribute-tickRate"><b>6.2.10 ttp:tickRate</b></a>, and
-            <a href="#parameter-attribute-timeBase"><b>6.2.11
-            ttp:timeBase</b></a> for further information on explicit
-            specification of frame rate, sub-frame rate, tick rate, and time
-            base.</p>
-          </div><a id="timeExpression-syntax" name="timeExpression-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – &lt;timeExpression&gt;
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;timeExpression&gt;
-  : clock-time
-  | offset-time
-
-clock-time
-  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?
-
-offset-time
-  : time-count fraction? metric
-
-hours
-  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a>
-  | <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a>+
-
-minutes | seconds
-  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a>
-
-frames
-  : <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a>
-  | <a href="#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a> <a href=
-"#style-value-digit">&lt;digit&gt;</a>+
-
-sub-frames
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-fraction
-  : "." <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-time-count
-  : <a href="#style-value-digit">&lt;digit&gt;</a>+
-
-metric
-  : "h"                 // hours
-  | "m"                 // minutes
-  | "s"                 // seconds
-  | "ms"                // milliseconds
-  | "f"                 // frames
-  | "t"                 // ticks
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>If a &lt;timeExpression&gt; is expressed in terms of a
-          <em>clock-time</em>, then leading zeroes are used when expressing
-          hours, minutes, seconds, and frames less than 10. Minutes are
-          constrained to [0…59], while seconds (including any fractional part)
-          are constrained to the closed interval [0,60], where the value 60
-          applies only to leap seconds.</p>
-
-          <p>If a &lt;timeExpression&gt; is expressed in terms of a
-          <em>clock-time</em> and a <em>frames</em> term is specified, then the
-          value of this term must be constrained to the interval
-          [0…<em>F-1</em>], where <em>F</em> is the frame rate determined by
-          the <code>ttp:frameRate</code> parameter as defined by <a href=
-          "#parameter-attribute-frameRate"><b>6.2.4 ttp:frameRate</b></a>. It
-          is considered an error if a <em>frames</em> term or <code>f</code>
-          (frames) metric is specified when the <code>clock</code> time base
-          applies.</p>
-
-          <p>If a &lt;timeExpression&gt; is expressed in terms of a
-          <em>clock-time</em> and a <em>sub-frames</em> term is specified, then
-          the value of this term must be constrained to the interval
-          [0…<em>S-1</em>], where <em>S</em> is the sub-frame rate determined
-          by the <code>ttp:subFrameRate</code> parameter as defined by <a href=
-          "#parameter-attribute-subFrameRate"><b>6.2.9
-          ttp:subFrameRate</b></a>. It is considered an error if a
-          <em>sub-frames</em> term is specified when the <code>clock</code>
-          time base applies.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="timing-time-intervals" name="timing-time-intervals"></a>10.4
-        Time Intervals</h3>
-
-        <p>The semantics of time containment, durations, and intervals defined
-        by <a href="#smil21">[SMIL 2.1]</a> apply to the interpretation of
-        like-named timed elements and timing vocabulary defined by this
-        specification, given the following constraints:</p>
-
-        <ul>
-          <li>
-            <p>The implicit duration of an anonymous span is defined as
-            follows: if the anonymous span's parent time container is a
-            parallel time container, then the implicit duration is equivalent
-            to the <code>indefinite</code> duration value as defined by
-            <a href="#smil21">[SMIL 2.1]</a>; if the anonymous span's parent
-            time container is a sequential time container, then the implicit
-            duration is equivalent to zero.</p>
-          </li>
-
-          <li>
-            <p>The implicit duration of a <code>body</code>, <code>div</code>,
-            <code>p</code>, or <code>span</code> element is determined in
-            accordance to (1) whether the element is a parallel or sequential
-            time container, (2) the default <code>endsync</code> semantics
-            defined above by <a href=
-            "#timing-attribute-timeContainer"><b>10.2.4 timeContainer</b></a>,
-            and (3) the semantics of <a href="#smil21">[SMIL 2.1]</a> as
-            applied to these time containers.</p>
-          </li>
-
-          <li>
-            <p>The implicit duration of the <code>region</code> element is
-            defined to be equivalent to the <code>indefinite</code> duration
-            value as defined by <a href="#smil21">[SMIL 2.1]</a>.</p>
-          </li>
-
-          <li>
-            <p>If the governing time base is <code>clock</code>, then time
-            expressions are considered to be equivalent to wall-clock based
-            timing in <a href="#smil21">[SMIL 2.1]</a>, where the specific
-            semantics of <a href="#time-expression-semantics-clock"><b>N.1
-            Clock Time Base</b></a> apply.</p>
-          </li>
-
-          <li>
-            <p>If the governing time base is <code>media</code>, then time
-            expressions are considered to be equivalent to offset based timing
-            in <a href="#smil21">[SMIL 2.1]</a>, where the specific semantics
-            of <a href="#time-expression-semantics-media"><b>N.2 Media Time
-            Base</b></a> apply.</p>
-          </li>
-
-          <li>
-            <p>If the governing time base is <code>smpte</code>, then time
-            expressions are considered to be equivalent to either offset based
-            timing or event based timing in <a href="#smil21">[SMIL 2.1]</a>,
-            where the specific semantics of <a href=
-            "#time-expression-semantics-smpte"><b>N.3 SMPTE Time Base</b></a>
-            apply.</p>
-          </li>
-        </ul>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="animation" name="animation"></a>11 Animation</h2>
-
-      <p>This section specifies the <em>animation</em> matter of the core
-      vocabulary catalog, where animation is to be understood as a separable
-      layer of information that combines timing and styling in order to denote
-      authorial intention about (temporally) dynamic styling of content.</p>
-
-      <div class="div2">
-        <h3><a id="animation-element-vocabulary" name=
-        "animation-element-vocabulary"></a>11.1 Animation Element
-        Vocabulary</h3>
-
-        <p>The following elements specify the structure and principal animation
-        aspects of a <em>Document Instance</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#animation-vocabulary-set"><b>11.1.1 set</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="animation-vocabulary-set" name=
-          "animation-vocabulary-set"></a>11.1.1 set</h4>
-
-          <p>The <code>set</code> element is used as a child element of a
-          content element or a <code>region</code> element in order to express
-          a discrete change of some style parameter value that applies over
-          some time interval.</p>
-
-          <p>The <code>set</code> element accepts as its children zero or more
-          elements in the <code>Metadata.class</code> element group.</p><a id=
-          "elt-syntax-set" name="elt-syntax-set"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: set
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;set
-  <a href="#timing-attribute-begin">begin</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-dur">dur</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#timing-attribute-end">end</a> = <a href=
-"#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>a single attribute in TT Style namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#element-vocab-group-table">Metadata.class</a>*
-&lt;/set&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The use of multiple <code>set</code> element children may be
-            used to effect fade and position transitions.</p>
-          </div>
-
-          <p>An example of using the <code>set</code> element to animate
-          content styling is illustrated below:</p><a id=
-          "animation-vocabulary-set-example-1" name=
-          "animation-vocabulary-set-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Content Style Animation
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;p dur="5s" tts:color="yellow"&gt;
-<span class="strong">&lt;set begin="1s" dur="1s" tts:color="red"/&gt;</span>
-<span class="strong">&lt;set begin="2s" dur="1s" tts:color="green"/&gt;</span>
-<span class="strong">&lt;set begin="3s" dur="1s" tts:color="red"/&gt;</span>
-Text with Flashing Colors!
-&lt;/p&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the foreground color of the content "Text
-            with Flashing Colors" is animated from yellow, to red, to green, to
-            red, then back to yellow over a 5 second period.</p>
-          </div>
-
-          <p>An example of using the <code>set</code> element to animate region
-          styling is illustrated below:</p><a id=
-          "animation-vocabulary-set-example-2" name=
-          "animation-vocabulary-set-example-2"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Region Style Animation
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"
-    xmlns:ttp="http://www.w3.org/ns/ttml#parameter"
-    xmlns:tts="http://www.w3.org/ns/ttml#styling"
-    ttp:cellResolution="40 16"&gt;
-    &lt;head&gt;
-      &lt;layout&gt;
-        &lt;region xml:id="r1" timeContainer="seq"&gt;
-          <span class=
-"strong">&lt;set dur="10s" tts:origin=" 8c 14c"/&gt;</span>
-          <span class=
-"strong">&lt;set dur="2s"  tts:origin=" 2c  2c"/&gt;</span>
-          <span class=
-"strong">&lt;set dur="3s"  tts:origin=" 8c 14c"/&gt;</span>
-          <span class=
-"strong">&lt;set dur="2s"  tts:origin="14c  4c"/&gt;</span>
-          <span class=
-"strong">&lt;set dur="10s" tts:origin=" 8c 14c"/&gt;</span>
-          &lt;style tts:extent="24c 2c"/&gt;
-        &lt;/region&gt;
-      &lt;/layout&gt;
-    &lt;/head&gt;
-    &lt;body region="r1"&gt;...&lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, the <em>Root Container Region</em> is
-            divided into a cell grid of 40 columns and 16 rows. A region,
-            <code>r1</code>, with dimensions of 24 columns and 2 rows is then
-            positioned within the <em>Root Container Region</em>, with its
-            position varying over time in order to create an effect of moving
-            the region, which may be desirable so as to avoid obscuring
-            characters in an underlying video with captions.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The semantics of the <code>set</code> element are based upon
-            that defined by <a href="#smil21">[SMIL 2.1]</a>, § 3.6.2.</p>
-          </div>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="animation-attribute-vocabulary" name=
-        "animation-attribute-vocabulary"></a>11.2 Animation Attribute
-        Vocabulary</h3>
-
-        <p>No animation related attribute vocabulary is defined for use in the
-        core vocabulary catalog.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="metadata" name="metadata"></a>12 Metadata</h2>
-
-      <p>This section specifies the <em>metadata</em> matter of the core
-      vocabulary catalog, where metadata is to be understood as a separable
-      layer of information that applies to parameters, content, style, layout,
-      timing, and even metadata itself, where the information represented by
-      metadata takes one of two forms: (1) metadata defined by this
-      specification for standardized use in a <em>Document Instance</em>, and
-      (2) arbitrary metadata defined outside of the scope of this
-      specification, whose use and semantics depend entirely upon an
-      application's use of TTML Content.</p>
-
-      <div class="div2">
-        <h3><a id="metadata-element-vocabulary" name=
-        "metadata-element-vocabulary"></a>12.1 Metadata Element Vocabulary</h3>
-
-        <p>The <a href="#metadata-vocabulary-metadata"><b>12.1.1
-        metadata</b></a> element serves as a generic container element for
-        grouping metadata information.</p>
-
-        <p>In addition, the following elements, all defined in the TT Metadata
-        Namespace, provide standard representations for metadata that is
-        expected to be commonly used in a <em>Document Instances</em>:</p>
-
-        <ul>
-          <li>
-            <p><a href="#metadata-vocabulary-title"><b>12.1.2
-            ttm:title</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-desc"><b>12.1.3
-            ttm:desc</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-copyright"><b>12.1.4
-            ttm:copyright</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-agent"><b>12.1.5
-            ttm:agent</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-name"><b>12.1.6
-            ttm:name</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-vocabulary-actor"><b>12.1.7
-            ttm:actor</b></a></p>
-          </li>
-        </ul>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-metadata" name=
-          "metadata-vocabulary-metadata"></a>12.1.1 metadata</h4>
-
-          <p>The <code>metadata</code> element functions as a generic container
-          for metadata information.</p>
-
-          <p>Metadata information may be expressed with a <code>metadata</code>
-          element by specifying (1) one or more metadata attributes on the
-          <code>metadata</code> element, (2) one or more metadata child
-          elements in the <code>metadata</code> element, or (3) a combination
-          of metadata attributes and metadata child elements. Both types of
-          metadata information are referred to in this document as <em>metadata
-          items</em>.</p><a id="elt-syntax-metadata" name=
-          "elt-syntax-metadata"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;metadata
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute in TT Metadata namespace</em>}
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> ({<em>any element in TT Metadata namespace</em>}|{<em>any element not in any TT namespace</em>})*
-&lt;/metadata&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>The meaning of a specific metadata item must be evaluated in the
-            context where it appears. The core vocabulary catalog permits an
-            arbitrary number of <code>metadata</code> element children on any
-            content element type except for the <code>tt</code> element. See
-            specific element vocabulary definitions for any constraints that
-            apply to such usage.</p>
-          </div>
-
-          <p>The use of document metadata is illustrated by the following
-          example.</p><a id="metadata-vocabulary-metadata-example-1" name=
-          "metadata-vocabulary-metadata-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Document Metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;head&gt;
-  &lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
-    &lt;ttm:title&gt;Document Metadata Example&lt;/ttm:title&gt;
-    &lt;ttm:desc&gt;This document employs document metadata.&lt;/ttm:desc&gt;
-  &lt;/metadata&gt;
-&lt;/head&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The use of element metadata is illustrated by the following
-          example.</p><a id="metadata-vocabulary-metadata-example-2" name=
-          "metadata-vocabulary-metadata-example-2"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Element Metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;div&gt;
-  &lt;metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
-    &lt;ttm:title&gt;Chapter 6 – Sherlock Holmes Gives a Demonstration&lt;/ttm:title&gt;
-    &lt;ttm:desc&gt;Holmes shows Watson how the murderer entered the window.&lt;/ttm:desc&gt;
-  &lt;/metadata&gt;
-&lt;/div&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The use of metadata attribute items is illustrated by the
-          following example.</p><a id="metadata-vocabulary-metadata-example-3"
-          name="metadata-vocabulary-metadata-example-3"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Foreign Metadata Attribute Items
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;div xmlns:ext="http://example.org/ttml#metadata"&gt;
-  &lt;metadata ext:ednote="remove this division prior to publishing"/&gt;
-&lt;/div&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, a global attribute from a foreign
-            (external) namespace is used to express a metadata attribute that
-            applies semantically to the containing <code>div</code> element.
-            Note that the attribute may also be expressed directly on the
-            <code>div</code> element; however, in this case the author wishes
-            to segregate certain metadata attributes by expressing them
-            indirectly on <code>metadata</code> elements.</p>
-          </div>
-
-          <p>The use of foreign element metadata is illustrated by the
-          following example.</p><a id="metadata-vocabulary-metadata-example-4"
-          name="metadata-vocabulary-metadata-example-4"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Foreign Element Metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-...
-&lt;metadata
-  xmlns:dc="http://purl.org/dc/elements/1.1/"
-  xmlns:dcterms="http://purl.org/dc/terms/"
-  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"&gt;
-  &lt;dc:title&gt;Foreign Element Metadata Example&lt;/dc:title&gt;
-  &lt;dc:description&gt;Express metadata using elements in foreign namespace.&lt;/dc:description&gt;
-  &lt;dc:format xsi:type="dcterms:IMT"&gt;application/ttml+xml&lt;/dc:format&gt;
-&lt;/metadata&gt;
-...
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, a number of elements defined by the Dublin
-            Core metadata vocabulary are used to express document level
-            metadata.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-title" name=
-          "metadata-vocabulary-title"></a>12.1.2 ttm:title</h4>
-
-          <p>The <code>ttm:title</code> element is used to express a
-          human-readable title of a specific element instance.</p><a id=
-          "elt-syntax-metadata-title" name="elt-syntax-metadata-title"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:title
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:title
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttm:title&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>No specific use of the <code>ttm:title</code> element is defined
-            by this specification.</p>
-          </div>
-
-          <p>Examples of the <code>ttm:title</code> element are shown above in
-          <a href="#metadata-vocabulary-metadata-example-1"><b>Example Fragment
-          – Document Metadata</b></a> and <a href=
-          "#metadata-vocabulary-metadata-example-2"><b>Example Fragment –
-          Element Metadata</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-desc" name=
-          "metadata-vocabulary-desc"></a>12.1.3 ttm:desc</h4>
-
-          <p>The <code>ttm:desc</code> element is used to express a
-          human-readable description of a specific element instance.</p><a id=
-          "elt-syntax-metadata-desc" name="elt-syntax-metadata-desc"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:desc
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:desc
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttm:desc&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>No specific use of the <code>ttm:desc</code> element is defined
-            by this specification.</p>
-          </div>
-
-          <p>Examples of the <code>ttm:desc</code> element are shown above in
-          <a href="#metadata-vocabulary-metadata-example-1"><b>Example Fragment
-          – Document Metadata</b></a> and <a href=
-          "#metadata-vocabulary-metadata-example-2"><b>Example Fragment –
-          Element Metadata</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-copyright" name=
-          "metadata-vocabulary-copyright"></a>12.1.4 ttm:copyright</h4>
-
-          <p>The <code>ttm:copyright</code> element is used to express a
-          human-readable copyright that applies to some scoping level.</p>
-
-          <p>A copyright statement that applies to a document as a whole should
-          appear as a child of the <code>head</code> element.</p><a id=
-          "elt-syntax-metadata-copyright" name=
-          "elt-syntax-metadata-copyright"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:copyright
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:copyright
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttm:copyright&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>No specific use of the <code>ttm:copyright</code> element is
-            defined by this specification.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-agent" name=
-          "metadata-vocabulary-agent"></a>12.1.5 ttm:agent</h4>
-
-          <p>The <code>ttm:agent</code> element is used to define an agent for
-          the purpose of associating content information with an agent who is
-          involved in the production or expression of that content.</p>
-
-          <p>The <code>ttm:agent</code> element accepts as its children zero or
-          more <code>ttm:name</code> elements followed by zero or one
-          <code>ttm:actor</code> element.</p>
-
-          <p>At least one <code>ttm:name</code> element child should be
-          specified that expresses a name for the agent, whether it be the name
-          of a person, character, group, or organization.</p><a id=
-          "elt-syntax-metadata-agent" name="elt-syntax-metadata-agent"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:agent
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:agent
-  <span class=
-"reqattr">type</span> = (<em>person</em>|<em>character</em>|<em>group</em>|<em>organization</em>|<em>other</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> <a href="#metadata-vocabulary-name">ttm:name</a>*, <a href=
-"#metadata-vocabulary-actor">ttm:actor</a>?
-&lt;/ttm:agent&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>A <code>type</code> attribute must be specified on each
-          <code>ttm:agent</code> element, and, if specified, must have one of
-          the following values:</p>
-
-          <ul>
-            <li>
-              <p><code>person</code></p>
-            </li>
-
-            <li>
-              <p><code>character</code></p>
-            </li>
-
-            <li>
-              <p><code>group</code></p>
-            </li>
-
-            <li>
-              <p><code>organization</code></p>
-            </li>
-
-            <li>
-              <p><code>other</code></p>
-            </li>
-          </ul>
-
-          <p>If the value of the <code>type</code> attribute is
-          <code>character</code>, then the <code>ttm:agent</code> element
-          instance should specify a <code>ttm:actor</code> child that specifies
-          the agent that plays the role of the actor.</p>
-
-          <p>A <code>ttm:agent</code> metadata item is considered to be
-          significant only when specified as a child of the <code>head</code>
-          element or as a child of a <code>metadata</code> element child of the
-          <code>head</code> element.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>A <code>ttm:agent</code> element instance is typically
-            referenced using a <code>ttm:agent</code> attribute on a content
-            element.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>If a character agent is played by multiple actors, then multiple
-            character agents may be specified (and referenced) wherein
-            different definitions of the character specify different
-            actors.</p>
-          </div>
-
-          <p>The use of agent metadata is illustrated by the following
-          example.</p><a id="metadata-vocabulary-agent-example-1" name=
-          "metadata-vocabulary-agent-example-1"></a>
-
-          <table class="example">
-            <caption>
-              Example Fragment – Agent Metadata
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-
-&lt;tt xml:lang="en" xmlns="http://www.w3.org/ns/ttml" xmlns:ttm="http://www.w3.org/ns/ttml#metadata"&gt;
-  &lt;head&gt;
-    <span class=
-"strong">&lt;ttm:agent xml:id="connery" type="person"&gt;</span>
-      &lt;ttm:name type="family"&gt;Connery&lt;/ttm:name&gt;
-      &lt;ttm:name type="given"&gt;Thomas Sean&lt;/ttm:name&gt;
-      &lt;ttm:name type="alias"&gt;Sean&lt;/ttm:name&gt;
-      &lt;ttm:name type="full"&gt;Sir Thomas Sean Connery&lt;/ttm:name&gt;
-    <span class="strong">&lt;/ttm:agent&gt;</span>
-    <span class=
-"strong">&lt;ttm:agent xml:id="bond" type="character"&gt;</span>
-      &lt;ttm:name type="family"&gt;Bond&lt;/ttm:name&gt;
-      &lt;ttm:name type="given"&gt;James&lt;/ttm:name&gt;
-      &lt;ttm:name type="alias"&gt;007&lt;/ttm:name&gt;
-      &lt;ttm:actor agent="connery"/&gt;
-    <span class="strong">&lt;/ttm:agent&gt;</span>
-  &lt;/head&gt;
-  &lt;body&gt;
-    &lt;div&gt;
-      ...  
-      &lt;p <span class=
-"strong">ttm:agent="bond"</span>&gt;I travel, a sort of licensed troubleshooter.&lt;/p&gt;
-      ...  
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>In the above example, two agents, a real (person) agent, Sean
-            Connery, and a fictitious (character) agent, James Bond, are
-            defined, where the latter is linked to the former by means of the a
-            <code>ttm:actor</code> element. A reference is then made from
-            content (the <code>p</code> element) to the character agent
-            associated with (responsible for producing) that content. Note that
-            in this example the <code>ttm:agent</code> metadata items are
-            specified as immediate children of the document's <code>head</code>
-            element rather than being placed in a container
-            <code>metadata</code> element.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-name" name=
-          "metadata-vocabulary-name"></a>12.1.6 ttm:name</h4>
-
-          <p>The <code>ttm:name</code> element is used to specify a name of a
-          person, character, group, or organization.</p><a id=
-          "elt-syntax-metadata-name" name="elt-syntax-metadata-name"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:name
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:name
-  <span class=
-"reqattr">type</span> = (<em>full</em>|<em>family</em>|<em>given</em>|<em>alias</em>|<em>other</em>)
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> #PCDATA
-&lt;/ttm:name&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>A <code>type</code> attribute must be specified on each
-          <code>ttm:name</code> element, and, if specified, must have one of
-          the following values:</p>
-
-          <ul>
-            <li>
-              <p><code>full</code></p>
-            </li>
-
-            <li>
-              <p><code>family</code></p>
-            </li>
-
-            <li>
-              <p><code>given</code></p>
-            </li>
-
-            <li>
-              <p><code>alias</code></p>
-            </li>
-
-            <li>
-              <p><code>other</code></p>
-            </li>
-          </ul>
-
-          <p>The relationship between the type of a name and the syntactic
-          expression of the name is not defined by this specification.</p>
-
-          <p>Two examples of the <code>ttm:name</code> element are shown above
-          in <a href="#metadata-vocabulary-agent-example-1"><b>Example Fragment
-          – Agent Metadata</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-vocabulary-actor" name=
-          "metadata-vocabulary-actor"></a>12.1.7 ttm:actor</h4>
-
-          <p>The <code>ttm:actor</code> element is used to link the definition
-          of a (role-based) character agent with another agent that portrays
-          the character.</p><a id="elt-syntax-metadata-actor" name=
-          "elt-syntax-metadata-actor"></a>
-
-          <table class="syntax">
-            <caption>
-              XML Representation – Element Information Item: ttm:actor
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-&lt;ttm:actor
-  <span class="reqattr">agent</span> = IDREF
-  <a href="#content-attribute-id">xml:id</a> = ID
-  <a href="#content-attribute-lang">xml:lang</a> = string
-  <a href=
-"#content-attribute-space">xml:space</a> = (<em>default</em>|<em>preserve</em>)
-  {<em>any attribute not in default or any TT namespace</em>}&gt;
-  <em>Content:</em> EMPTY
-&lt;/ttm:actor&gt;
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The <code>agent</code> attribute of a <code>ttm:actor</code>
-          element must reference a <code>ttm:agent</code> element that denotes
-          the person, group, or organization acting the part of a
-          character.</p>
-
-          <p>An example of the <code>ttm:actor</code> element is shown above in
-          <a href="#metadata-vocabulary-agent-example-1"><b>Example Fragment –
-          Agent Metadata</b></a>.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="metadata-attribute-vocabulary" name=
-        "metadata-attribute-vocabulary"></a>12.2 Metadata Attribute
-        Vocabulary</h3>
-
-        <p>This section specifies the following attributes in the TT Metadata
-        Namespace for use with the <code>metadata</code> element and with
-        certain content elements:</p>
-
-        <ul>
-          <li>
-            <p><a href="#metadata-attribute-agent"><b>12.2.1
-            ttm:agent</b></a></p>
-          </li>
-
-          <li>
-            <p><a href="#metadata-attribute-role"><b>12.2.2
-            ttm:role</b></a></p>
-          </li>
-        </ul>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>Only certain metadata item attributes may be used with content
-          elements. See the definitions of content elements to determine
-          permissible usage.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-attribute-agent" name=
-          "metadata-attribute-agent"></a>12.2.1 ttm:agent</h4>
-
-          <p>The <code>ttm:agent</code> attribute takes an <code>IDREFS</code>
-          value, and is used with certain content elements to designate the
-          agents that perform or are involved in the performance of the
-          content.</p>
-
-          <p>If specified, a <code>ttm:agent</code> attribute must reference
-          <code>ttm:agent</code> element instances that appear as a descendent
-          of the same <em>Document Instance</em> as that of the referring
-          element.</p>
-
-          <p>The same IDREF, <em>ID</em>, should not appear more than once in
-          the value of a <code>ttm:agent</code> attribute.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>This constraint is intended to discourage the use of redundant
-            agent references.</p>
-          </div>
-
-          <p>An example of the <code>ttm:agent</code> attribute is shown above
-          in <a href="#metadata-vocabulary-agent-example-1"><b>Example Fragment
-          – Agent Metadata</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="metadata-attribute-role" name=
-          "metadata-attribute-role"></a>12.2.2 ttm:role</h4>
-
-          <p>The <code>ttm:role</code> attribute may be used by a content
-          author to express the roles, functions, or characteristics of some
-          content element that is so labeled.</p>
-
-          <p>If specified, the value of this attribute must adhere to the
-          following syntax, where the syntactic element <em>S</em> must adhere
-          to production [3] <code>S</code> as defined by <a href="#xml10">[XML
-          1.0]</a>&nbsp;§ 2.3:</p><a id="metadata-attribute-role-syntax" name=
-          "metadata-attribute-role-syntax"></a>
-
-          <table class="syntax">
-            <caption>
-              Syntax Representation – ttm:role
-            </caption>
-
-            <tbody>
-              <tr>
-                <td>
-                  <div class="exampleInner">
-                    <pre>
-ttm:role
-  role ( <em>S</em> role )*
-
-role
-  : "action"
-  | "caption"
-  | "description"
-  | "dialog"
-  | "expletive"
-  | "kinesic"
-  | "lyrics"
-  | "music"
-  | "narration"
-  | "quality"
-  | "sound"
-  | "source"
-  | "suppressed"
-  | "reproduction"
-  | "thought"
-  | "title"
-  | "transcription"
-  | extension-role
-
-extension-role
-  : "x-" token-char+
-
-token-char
-  : { XML NameChar }    // XML 1.1 Production [4a]
-</pre>
-                  </div>
-                </td>
-              </tr>
-            </tbody>
-          </table>
-
-          <p>The same <code>role</code> token, <em>R</em>, should not appear
-          more than once in the value of a <code>ttm:role</code> attribute.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>This constraint is intended to discourage the use of redundant
-            role tokens.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>All values of <code>ttm:role</code> that do not start with the
-            prefix <code>x-</code> are reserved for future standardization.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>If using a custom <code>x-</code> prefixed form of
-            <code>ttm:role</code>, it is recommended that an organization
-            unique infix be used as well in order to prevent collisions. For
-            example, <code>x-example-org-custom-role</code>. Furthermore, a
-            registry for role values is available at <a href=
-            "http://www.w3.org/wiki/TTML/RoleRegistry">http://www.w3.org/wiki/TTML/RoleRegistry</a>
-            in order to promote interoperability and collision avoidance.</p>
-          </div>
-        </div>
-      </div>
-    </div>
-  </div>
-
-  <div class="back">
-    <div class="div1">
-      <h2><a id="reduced-infoset" name="reduced-infoset"></a>A Reduced XML
-      Infoset</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>For the purposes of this specification, a <em>Reduced XML Infoset</em>
-      is an XML Information Set <a href="#infoset">[XML InfoSet]</a> that
-      consists of only the following information items and information item
-      properties:</p>
-
-      <div class="div2">
-        <h3><a id="reduced-infoset-document" name=
-        "reduced-infoset-document"></a>A.1 Document Information Item</h3>
-
-        <ul>
-          <li>
-            <p><code>[document element]</code></p>
-          </li>
-        </ul>
-      </div>
-
-      <div class="div2">
-        <h3><a id="reduced-infoset-element" name=
-        "reduced-infoset-element"></a>A.2 Element Information Item</h3>
-
-        <ul>
-          <li>
-            <p><code>[namespace URI]</code></p>
-          </li>
-
-          <li>
-            <p><code>[local name]</code></p>
-          </li>
-
-          <li>
-            <p><code>[children]</code></p>
-          </li>
-
-          <li>
-            <p><code>[attributes]</code></p>
-          </li>
-        </ul>
-
-        <p>Child information items <code>[children]</code> are reduced to only
-        element and character information items.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="reduced-infoset-attribute" name=
-        "reduced-infoset-attribute"></a>A.3 Attribute Information Item</h3>
-
-        <ul>
-          <li>
-            <p><code>[namespace URI]</code></p>
-          </li>
-
-          <li>
-            <p><code>[local name]</code></p>
-          </li>
-
-          <li>
-            <p><code>[normalized value]</code></p>
-          </li>
-        </ul>
-      </div>
-
-      <div class="div2">
-        <h3><a id="reduced-infoset-character" name=
-        "reduced-infoset-character"></a>A.4 Character Information Item</h3>
-
-        <ul>
-          <li>
-            <p><code>[character code]</code></p>
-          </li>
-        </ul>
-
-        <p>Contiguous character information items are not required to be
-        represented distinctly, but may be aggregated (chunked) into a sequence
-        of character codes (i.e., a character string).</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="schemas" name="schemas"></a>B Schemas</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix specifies the following schemas for use with
-      <em>Document Instances</em>:</p>
-
-      <ul>
-        <li>
-          <p>Relax NG, Compact Syntax (RNC) Schema</p>
-        </li>
-
-        <li>
-          <p>XML Schema Definition (XSD) Schema</p>
-        </li>
-      </ul>
-
-      <p>In any case where a schema specified by this appendix differs from the
-      normative definitions of document type, element type, or attribute type
-      as defined by the body of this specification, then the body of this
-      specification takes precedence.</p>
-
-      <div class="div2">
-        <h3><a id="ttml-schema-rnc" name="ttml-schema-rnc"></a>B.1 Relax NG
-        Compact (RNC) Schema</h3>
-
-        <p>A Relax NG Compact Syntax (RNC) <a href="#rng">[RELAX NG]</a> based
-        schema for TTML Content is available at <a href="rnc/schema.zip">ZIP
-        Archive</a>. This schema does not normatively define the validity of
-        Timed Text Markup Language content as defined by this specification. In
-        particular, the formal validity of TTML Content is defined by <a href=
-        "#conformance-content"><b>3.1 Content Conformance</b></a>.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="ttml-schema-xsd" name="ttml-schema-xsd"></a>B.2 XML Schema
-        Definition (XSD) Schema</h3>
-
-        <p>A W3C XML Schema Definition (XSD) <a href="#xsd-1">[XML Schema Part
-        1]</a> based schema for TTML Content is available at <a href=
-        "xsd/schema.zip">ZIP Archive</a>. This schema does not normatively
-        define the validity of Timed Text Markup Language content as defined by
-        this specification. In particular, the formal validity of TTML Content
-        is defined by <a href="#conformance-content"><b>3.1 Content
-        Conformance</b></a>.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="media-types-registration" name=
-      "media-types-registration"></a>C Media Type Registration</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix registers a new media type, "application/ttml+xml" in
-      conformance with <a href="http://www.ietf.org/rfc/rfc4288.txt">BCP 13</a>
-      and <a href=
-      "http://www.w3.org/2002/06/registering-mediatype.html">W3CRegMedia</a>.
-      The information in this appendix is being submitted to the Internet
-      Engineering Steering Group (IESG) for review, approval, and registration
-      with the Internet Assigned Numbers Authority (IANA).</p>
-
-      <dl>
-        <dt class="label">Type name:</dt>
-
-        <dd>
-          <p>application</p>
-        </dd>
-
-        <dt class="label">Subtype name:</dt>
-
-        <dd>
-          <p>ttml+xml</p>
-        </dd>
-
-        <dt class="label">Required parameters:</dt>
-
-        <dd>
-          <p>None.</p>
-        </dd>
-
-        <dt class="label">Optional parameters:</dt>
-
-        <dd>
-          <dl>
-            <dt class="label">charset</dt>
-
-            <dd>
-              <p>If specified, the <code>charset</code> parameter must match
-              the XML encoding declaration, or if absent, the actual
-              encoding.</p>
-            </dd>
-
-            <dt class="label">profile</dt>
-
-            <dd>
-              <p>The document profile of a TTMLDocument Instance may be
-              specified using an optional <code>profile</code> parameter,
-              which, if specified, the value of which must adhere to the syntax
-              and semantics of <code>ttp:profile</code> parameter defined by
-              Section <a href="#parameter-attribute-profile"><b>6.2.8
-              ttp:profile</b></a> of the published specification.</p>
-            </dd>
-          </dl>
-        </dd>
-
-        <dt class="label">Encoding considerations:</dt>
-
-        <dd>
-          <p>Same for application/xml, except constrained to either UTF-8 or
-          UTF-16. See <a href="#xml-media">[XML Media Types]</a>, Section
-          3.2.</p>
-        </dd>
-
-        <dt class="label">Security considerations:</dt>
-
-        <dd>
-          <p>As with other XML types and as noted in <a href="#xml-media">[XML
-          Media Types]</a> Section 10, repeated expansion of maliciously
-          constructed XML entities can be used to consume large amounts of
-          memory, which may cause XML processors in constrained environments to
-          fail.</p>
-
-          <p>In addition, because of the extensibility features for TTML and of
-          XML in general, it is possible that "application/ttml+xml" may
-          describe content that has security implications beyond those
-          described here. However, TTML does not provide for any sort of active
-          or executable content, and if the processor follows only the
-          normative semantics of the published specification, this content will
-          be outside TTML namespaces and may be ignored. Only in the case where
-          the processor recognizes and processes the additional content, or
-          where further processing of that content is dispatched to other
-          processors, would security issues potentially arise. And in that
-          case, they would fall outside the domain of this registration
-          document.</p>
-
-          <p>Although not prohibited, there are no expectations that XML
-          signatures or encryption would normally be employed.</p>
-        </dd>
-
-        <dt class="label">Interoperability considerations:</dt>
-
-        <dd>
-          <p>The published specification describes processing semantics that
-          dictate behavior that must be followed when dealing with, among other
-          things, unrecognized elements and attributes, both in TTML namespaces
-          and in other namespaces.</p>
-
-          <p>Because TTML is extensible, conformant "application/ttml+xml"
-          processors may expect (and enforce) that content received is
-          well-formed XML, but it cannot be guaranteed that the content is
-          valid to a particular DTD or Schema or that the processor will
-          recognize all of the elements and attributes in the document.</p>
-        </dd>
-
-        <dt class="label">Published specification:</dt>
-
-        <dd>
-          <p>This media type registration is extracted from Appendix C Media
-          Type Registration of the Timed Text Markup Language (TTML) 1.0
-          specification: <a href="http://www.w3.org/TR/ttaf1-dfxp/">Timed Text
-          Markup Language (TTML) 1.0</a>.</p>
-        </dd>
-
-        <dt class="label">Applications that use this media type:</dt>
-
-        <dd>
-          <p>TTML is used in the television industry for the purpose of
-          authoring, transcoding and exchanging timed text information and for
-          delivering captions, subtitles, and other metadata for television
-          material repurposed for the Web or, more generally, the Internet.</p>
-
-          <p>There is partial and full support of TTML in components used by
-          several Web browsers plugins, and in a number of caption authoring
-          tools. A TTML verification (including validation) utility is
-          available in open source form at <a href=
-          "http://github.com/skynav/ttv">http://github.com/skynav/ttv</a>.</p>
-        </dd>
-
-        <dt class="label">Additional information:</dt>
-
-        <dd>
-          <dl>
-            <dt class="label">Magic number(s):</dt>
-
-            <dt class="label">File extension(s):</dt>
-
-            <dd>
-              <p>.ttml</p>
-            </dd>
-
-            <dt class="label">Macintosh file type code(s):</dt>
-
-            <dd>
-              <p>"TTML"</p>
-            </dd>
-
-            <dt class="label">Fragment identifiers:</dt>
-
-            <dd>
-              <p>For documents labeled as application/ttml+xml, the fragment
-              identifier notation is intended to be used with xml:id
-              attributes, as described in section 7.2.1 of the <a href=
-              "http://www.w3.org/TR/ttaf1-dfxp/">Timed Text Markup Language
-              (TTML) 1.0</a> specification.</p>
-            </dd>
-          </dl>
-        </dd>
-
-        <dt class="label">Person &amp; email address to contact for further
-        information:</dt>
-
-        <dd>
-          <p>Timed Text Working Group (public-tt@w3.org)</p>
-        </dd>
-
-        <dt class="label">Intended usage:</dt>
-
-        <dd>
-          <p>COMMON</p>
-        </dd>
-
-        <dt class="label">Restrictions on usage:</dt>
-
-        <dd>
-          <p>None</p>
-        </dd>
-
-        <dt class="label">Author:</dt>
-
-        <dd>
-          <p>The published specification is a work product of the World Wide
-          Web Consortium's Timed Text (TT) Working Group.</p>
-        </dd>
-
-        <dt class="label">Change controller:</dt>
-
-        <dd>
-          <p>The W3C has change control over this specification.</p>
-        </dd>
-      </dl>
-    </div>
-
-    <div class="div1">
-      <h2><a id="features" name="features"></a>D Features</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix specifies (1) a set of feature designations, each of
-      which labels one or more syntactic and/or semantic features defined by
-      this specification, and (2) for each designated feature, whether the
-      feature is mandatory or optional for a transformation or presentation
-      processor.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>A TTML processor is said to <em>implement the transformation
-        semantics</em> or <em>implement the presentation semantics</em> of
-        feature designation <em>F</em> if it satisfies the requirements of this
-        appendix with respect to the definition of feature designation
-        <em>F</em> as pertains to transformation or presentation processing,
-        respectively.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="feature-designations" name="feature-designations"></a>D.1
-        Feature Designations</h3>
-
-        <p>A feature designation is expressed as a string that adheres to the
-        following form:</p>
-
-        <div class="exampleInner">
-          <pre>
-feature-designation
-  : feature-namespace designation
-
-feature-namespace
-  : <em>TT Feature Namespace</em>                    // http://www.w3.org/ns/ttml/feature/
-
-designation
-  : "#" token-char+
-
-token-char
-  : { XML NameChar }                        // XML 1.1 Production [4a]
-</pre>
-        </div>
-
-        <p>All values of <code>feature-designation</code> not defined by this
-        specification are reserved for future standardization.</p>
-
-        <p>The following sub-sections define all feature designations,
-        expressed as relative URIs (fragment identifiers) with respect to the
-        TT Feature Namespace base URI.</p>
-
-        <div class="div3">
-          <h4><a id="feature-animation" name="feature-animation"></a>D.1.1
-          #animation</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#animation</code> feature if it recognizes and is capable of
-          transforming the following vocabulary defined by <a href=
-          "#animation"><b>11 Animation</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#animation-vocabulary-set"><code>set</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#animation</code>
-          feature if it implements presentation semantic support for the same
-          vocabulary enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-backgroundColor" name=
-          "feature-backgroundColor"></a>D.1.2 #backgroundColor</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#backgroundColor</code> feature if it recognizes and is capable
-          of transforming the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#backgroundColor</code> feature if it (1) implements
-          presentation semantic support for the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute and (2) is capable of displaying or generating an output
-          display signal that distinguishes between at least sixteen (16)
-          values of color, including all primary and secondary colors of the
-          SRGB color space.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-backgroundColor-block" name=
-          "feature-backgroundColor-block"></a>D.1.3 #backgroundColor-block</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#backgroundColor-block</code> feature if it recognizes and is
-          capable of transforming all defined values of the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a content element that would generate a
-          block area during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#backgroundColor-block</code> feature if it (1) implements
-          presentation semantic support for the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a content element that generates a block
-          area and (2) is capable of displaying or generating an output display
-          signal that distinguishes between at least sixteen (16) values of
-          color, including all primary and secondary colors of the SRGB color
-          space.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-backgroundColor-inline" name=
-          "feature-backgroundColor-inline"></a>D.1.4
-          #backgroundColor-inline</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#backgroundColor-inline</code> feature if it recognizes and is
-          capable of transforming all defined values of the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a content element that would generate an
-          inline area during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#backgroundColor-inline</code> feature if it (1) implements
-          presentation semantic support for the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a content element that generates an inline
-          area and (2) is capable of displaying or generating an output display
-          signal that distinguishes between at least sixteen (16) values of
-          color, including all primary and secondary colors of the SRGB color
-          space.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-backgroundColor-region" name=
-          "feature-backgroundColor-region"></a>D.1.5
-          #backgroundColor-region</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#backgroundColor-region</code> feature if it recognizes and is
-          capable of transforming all defined values of the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#backgroundColor-region</code> feature if it (1) implements
-          presentation semantic support for the <a href=
-          "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element and (2)
-          is capable of displaying or generating an output display signal that
-          distinguishes between at least sixteen (16) values of color,
-          including all primary and secondary colors of the SRGB color space
-          .</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-bidi" name="feature-bidi"></a>D.1.6 #bidi</h4>
-
-          <p>A TTML processor supports the <code>#bidi</code> feature if it
-          supports the following features:</p>
-
-          <ul>
-            <li>
-              <p><a href="#feature-direction"><code>#direction</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#feature-unicodeBidi"><code>#unicodeBidi</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#feature-writingMode-horizontal"><code>#writingMode-horizontal</code></a></p>
-            </li>
-          </ul>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-cellResolution" name=
-          "feature-cellResolution"></a>D.1.7 #cellResolution</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#cellResolution</code> feature if it recognizes and is capable
-          of transforming the <a href=
-          "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#cellResolution</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-clockMode" name="feature-clockMode"></a>D.1.8
-          #clockMode</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#clockMode</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#clockMode</code>
-          feature if it implements presentation semantic support for the
-          <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-clockMode-gps" name=
-          "feature-clockMode-gps"></a>D.1.9 #clockMode-gps</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#clockMode-gps</code> feature if it recognizes and is capable
-          of transforming the <code>gps</code> value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#clockMode-gps</code> feature if it implements presentation
-          semantic support for the <code>gps</code> value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-clockMode-local" name=
-          "feature-clockMode-local"></a>D.1.10 #clockMode-local</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#clockMode-local</code> feature if it recognizes and is capable
-          of transforming the <code>local</code> value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#clockMode-local</code> feature if it implements presentation
-          semantic support for the <code>local</code> value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-clockMode-utc" name=
-          "feature-clockMode-utc"></a>D.1.11 #clockMode-utc</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#clockMode-utc</code> feature if it recognizes and is capable
-          of transforming the <code>utc</code> value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#clockMode-utc</code> feature if it implements presentation
-          semantic support for the <code>utc</code> value of the <a href=
-          "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-color" name="feature-color"></a>D.1.12 #color</h4>
-
-          <p>A TTML transformation processor supports the <code>#color</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-color"><code>tts:color</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#color</code>
-          feature if it (1) implements presentation semantic support for the
-          <a href="#style-attribute-color"><code>tts:color</code></a> attribute
-          and (2) is capable of displaying or generating an output display
-          signal that distinguishes between at least sixteen (16) values of
-          color, including all primary and secondary colors of the SRGB color
-          space.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-content" name="feature-content"></a>D.1.13
-          #content</h4>
-
-          <p>A TTML transformation processor supports the <code>#content</code>
-          feature if it recognizes and is capable of transforming the following
-          vocabulary defined by <a href="#content"><b>7 Content</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#document-structure-vocabulary-body"><code>body</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-div"><code>div</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-p"><code>p</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-span"><code>span</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-vocabulary-br"><code>br</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#content</code>
-          feature if it implements presentation semantic support for the same
-          vocabulary enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-core" name="feature-core"></a>D.1.14 #core</h4>
-
-          <p>A TTML transformation processor supports the <code>#core</code>
-          feature if it recognizes and is capable of transforming the following
-          core attributes vocabulary defined by <a href="#content"><b>7
-          Content</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#content-attribute-id">@<code>xml:id</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#content-attribute-id">@<code>xml:lang</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#content-attribute-id">@<code>xml:space</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#core</code>
-          feature if it implements presentation semantic support for the same
-          vocabulary enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-direction" name="feature-direction"></a>D.1.15
-          #direction</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#direction</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-direction"><code>tts:direction</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#direction</code>
-          feature if it implements presentation semantic support for all
-          defined values of the <a href=
-          "#style-attribute-direction"><code>tts:direction</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-display" name="feature-display"></a>D.1.16
-          #display</h4>
-
-          <p>A TTML transformation processor supports the <code>#display</code>
-          feature if it recognizes and is capable of transforming all defined
-          values of the <a href=
-          "#style-attribute-display"><code>tts:display</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#display</code>
-          feature if it implements presentation semantic support for all
-          defined values of the <a href=
-          "#style-attribute-display"><code>tts:display</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-display-block" name=
-          "feature-display-block"></a>D.1.17 #display-block</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#display-block</code> feature if it recognizes and is capable
-          of transforming all defined values of the <a href=
-          "#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a content element that would generate a block area
-          during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#display-block</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a content element that generates a block area.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-display-inline" name=
-          "feature-display-inline"></a>D.1.18 #display-inline</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#display-inline</code> feature if it recognizes and is capable
-          of transforming all defined values of the <a href=
-          "#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a content element that would generate an inline area
-          during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#display-inline</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a content element that generates an inline area.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-display-region" name=
-          "feature-display-region"></a>D.1.19 #display-region</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#display-region</code> feature if it recognizes and is capable
-          of transforming all defined values of the <a href=
-          "#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#display-region</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-display"><code>tts:display</code></a> attribute
-          when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-displayAlign" name=
-          "feature-displayAlign"></a>D.1.20 #displayAlign</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#displayAlign</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-displayAlign"><code>tts:displayAlign</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#displayAlign</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-displayAlign"><code>tts:displayAlign</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-dropMode" name="feature-dropMode"></a>D.1.21
-          #dropMode</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#dropMode</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#dropMode</code>
-          feature if it implements presentation semantic support for the
-          <a href="#parameter-attribute-dropMode"><code>ttp:dropMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-dropMode-dropNTSC" name=
-          "feature-dropMode-dropNTSC"></a>D.1.22 #dropMode-dropNTSC</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#dropMode-dropNTSC</code> feature if it recognizes and is
-          capable of transforming the <code>dropNTSC</code> value of the
-          <a href="#parameter-attribute-dropMode"><code>ttp:dropMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#dropMode-dropNTSC</code> feature if it implements presentation
-          semantic support for the <code>dropNTSC</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-dropMode-dropPAL" name=
-          "feature-dropMode-dropPAL"></a>D.1.23 #dropMode-dropPAL</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#dropMode-dropPAL</code> feature if it recognizes and is
-          capable of transforming the <code>dropPAL</code> value of the
-          <a href="#parameter-attribute-dropMode"><code>ttp:dropMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#dropMode-dropPAL</code> feature if it implements presentation
-          semantic support for the <code>dropPAL</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-dropMode-nonDrop" name=
-          "feature-dropMode-nonDrop"></a>D.1.24 #dropMode-nonDrop</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#dropMode-nonDrop</code> feature if it recognizes and is
-          capable of transforming the <code>nonDrop</code> value of the
-          <a href="#parameter-attribute-dropMode"><code>ttp:dropMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#dropMode-nonDrop</code> feature if it implements presentation
-          semantic support for the <code>nonDrop</code> value of the <a href=
-          "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-extent" name="feature-extent"></a>D.1.25
-          #extent</h4>
-
-          <p>A TTML transformation processor supports the <code>#extent</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#extent</code>
-          feature if it implements presentation semantic support for the
-          <a href="#style-attribute-extent"><code>tts:extent</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-extent-region" name=
-          "feature-extent-region"></a>D.1.26 #extent-region</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#extent-region</code> feature if it recognizes and is capable
-          of transforming the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute when
-          applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#extent-region</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute when
-          applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-extent-root" name="feature-extent-root"></a>D.1.27
-          #extent-root</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#extent-root</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute when
-          applied to the <a href=
-          "#document-structure-vocabulary-tt"><code>tt</code></a> element.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#extent-root</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#style-attribute-extent"><code>tts:extent</code></a> attribute when
-          applied to a <a href=
-          "#document-structure-vocabulary-tt"><code>tt</code></a> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontFamily" name="feature-fontFamily"></a>D.1.28
-          #fontFamily</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontFamily</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontFamily</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontFamily-generic" name=
-          "feature-fontFamily-generic"></a>D.1.29 #fontFamily-generic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontFamily-generic</code> feature if it recognizes and is
-          capable of transforming <a href=
-          "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a> values
-          when used with the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontFamily-generic</code> feature if it implements
-          presentation semantic support for <a href=
-          "#style-value-genericFamilyName">&lt;genericFamilyName&gt;</a> values
-          when used with the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontFamily-non-generic" name=
-          "feature-fontFamily-non-generic"></a>D.1.30
-          #fontFamily-non-generic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontFamily-non-generic</code> feature if it recognizes and is
-          capable of transforming <a href=
-          "#style-value-familyName">&lt;familyName&gt;</a> values when used
-          with the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontFamily-non-generic</code> feature if it implements
-          presentation semantic support for <a href=
-          "#style-value-familyName">&lt;familyName&gt;</a> values when used
-          with the <a href=
-          "#style-attribute-fontFamily"><code>tts:fontFamily</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontSize" name="feature-fontSize"></a>D.1.31
-          #fontSize</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontSize</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontSize</code>
-          feature if it implements presentation semantic support for the
-          <a href="#style-attribute-fontSize"><code>tts:fontSize</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontSize-anamorphic" name=
-          "feature-fontSize-anamorphic"></a>D.1.32 #fontSize-anamorphic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontSize-anamorphic</code> feature if it recognizes and is
-          capable of transforming values of the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute
-          that consist of two <a href="#style-value-length">&lt;length&gt;</a>
-          specifications.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontSize-anamorphic</code> feature if it implements
-          presentation semantic support for defined values of the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute
-          that consist of two <a href="#style-value-length">&lt;length&gt;</a>
-          specifications.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontSize-isomorphic" name=
-          "feature-fontSize-isomorphic"></a>D.1.33 #fontSize-isomorphic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontSize-isomorphic</code> feature if it recognizes and is
-          capable of transforming values of the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute
-          that consist of a single <a href=
-          "#style-value-length">&lt;length&gt;</a> specification.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontSize-isomorphic</code> feature if it implements
-          presentation semantic support for defined values of the <a href=
-          "#style-attribute-fontSize"><code>tts:fontSize</code></a> attribute
-          that consist of a single <a href=
-          "#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontStyle" name="feature-fontStyle"></a>D.1.34
-          #fontStyle</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontStyle</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#fontStyle</code>
-          feature if it implements presentation semantic support for all
-          defined values of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontStyle-italic" name=
-          "feature-fontStyle-italic"></a>D.1.35 #fontStyle-italic</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontStyle-italic</code> feature if it recognizes and is
-          capable of transforming the <code>italic</code> value of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontStyle-italic</code> feature if it implements presentation
-          semantic support for the <code>italic</code> of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontStyle-oblique" name=
-          "feature-fontStyle-oblique"></a>D.1.36 #fontStyle-oblique</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontStyle-oblique</code> feature if it recognizes and is
-          capable of transforming the <code>oblique</code> value of the
-          <a href="#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontStyle-oblique</code> feature if it implements presentation
-          semantic support for the <code>oblique</code> of the <a href=
-          "#style-attribute-fontStyle"><code>tts:fontStyle</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontWeight" name="feature-fontWeight"></a>D.1.37
-          #fontWeight</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontWeight</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontWeight</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-fontWeight-bold" name=
-          "feature-fontWeight-bold"></a>D.1.38 #fontWeight-bold</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#fontWeight-bold</code> feature if it recognizes and is capable
-          of transforming <code>bold</code> value of the <a href=
-          "#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#fontWeight-bold</code> feature if it implements presentation
-          semantic support for the <code>bold</code> of the <a href=
-          "#style-attribute-fontWeight"><code>tts:fontWeight</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-frameRate" name="feature-frameRate"></a>D.1.39
-          #frameRate</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#frameRate</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#frameRate</code>
-          feature if it implements presentation semantic support for the
-          <a href=
-          "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-frameRateMultiplier" name=
-          "feature-frameRateMultiplier"></a>D.1.40 #frameRateMultiplier</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#frameRateMultiplier</code> feature if it recognizes and is
-          capable of transforming the <a href=
-          "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#frameRateMultiplier</code> feature if it implements
-          presentation semantic support for the <a href=
-          "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-layout" name="feature-layout"></a>D.1.41
-          #layout</h4>
-
-          <p>A TTML transformation processor supports the <code>#layout</code>
-          feature if it (1) recognizes and is capable of transforming the
-          following vocabulary defined by <a href="#layout"><b>9
-          Layout</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#layout-vocabulary-layout"><code>layout</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#layout-vocabulary-region"><code>region</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#layout-attribute-region">@<code>region</code></a></p>
-            </li>
-          </ul>
-
-          <p>and (2) supports the following attributes when applied to the
-          <a href="#layout-vocabulary-region"><code>region</code></a>
-          element:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#style-attribute-extent"><code>tts:extent</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#style-attribute-origin"><code>tts:origin</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#layout</code>
-          feature if it implements presentation semantic support for the same
-          vocabulary and features enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length" name="feature-length"></a>D.1.42
-          #length</h4>
-
-          <p>A TTML transformation processor supports the <code>#length</code>
-          feature if it recognizes and is capable of transforming all defined
-          values of the <a href="#style-value-length">&lt;length&gt;</a> style
-          value expression.</p>
-
-          <p>A TTML presentation processor supports the <code>#length</code>
-          feature if it implements presentation semantic support for all
-          defined values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length</code> is intended to imply support
-            for the following features: <code>#length-integer</code>,
-            <code>#length-real</code>, <code>#length-positive</code>,
-            <code>#length-negative</code>, <code>#length-cell</code>,
-            <code>#length-em</code>, <code>#length-percentage</code>, and
-            <code>#length-pixel</code>.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-cell" name="feature-length-cell"></a>D.1.43
-          #length-cell</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#length-cell</code> feature if it recognizes and is capable of
-          transforming scalar values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>c</code> (cell) units.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#length-cell</code> feature if it implements presentation
-          semantic support for scalar values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>c</code> (cell) units.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-cell</code> does not, by itself, imply
-            support for <code>#length-integer</code>,
-            <code>#length-real</code>, <code>#length-positive</code>, or
-            <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-em" name="feature-length-em"></a>D.1.44
-          #length-em</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#length-em</code> feature if it recognizes and is capable of
-          transforming scalar values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>em</code> (EM) units.</p>
-
-          <p>A TTML presentation processor supports the <code>#length-em</code>
-          feature if it implements presentation semantic support for scalar
-          values of the <a href="#style-value-length">&lt;length&gt;</a> style
-          value expression that use <code>em</code> (EM) units.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-em</code> does not, by itself, imply
-            support for <code>#length-integer</code>,
-            <code>#length-real</code>, <code>#length-positive</code>, or
-            <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-integer" name=
-          "feature-length-integer"></a>D.1.45 #length-integer</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#length-integer</code> feature if it recognizes and is capable
-          of transforming integer values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#length-integer</code> feature if it implements presentation
-          semantic support for integer values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-integer</code> does not, by itself,
-            imply support for <code>#length-positive</code> or
-            <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-negative" name=
-          "feature-length-negative"></a>D.1.46 #length-negative</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#length-negative</code> feature if it recognizes and is capable
-          of transforming negative values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#length-negative</code> feature if it implements presentation
-          semantic support for negative values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-negative</code> does not, by itself,
-            imply support for <code>#length-integer</code> or
-            <code>#length-real</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-percentage" name=
-          "feature-length-percentage"></a>D.1.47 #length-percentage</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#length-percentage</code> feature if it recognizes and is
-          capable of transforming percentage values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#length-percentage</code> feature if it implements presentation
-          semantic support for percentage values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-percentage</code> does not, by itself,
-            imply support for <code>#length-integer</code>,
-            <code>#length-real</code>, <code>#length-positive</code>, or
-            <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-pixel" name=
-          "feature-length-pixel"></a>D.1.48 #length-pixel</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#length-pixel</code> feature if it recognizes and is capable of
-          transforming scalar values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>px</code> (pixel) units.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#length-pixel</code> feature if it implements presentation
-          semantic support for scalar values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression that
-          use <code>px</code> (pixel) units.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-pixel</code> does not, by itself,
-            imply support for <code>#length-integer</code>,
-            <code>#length-real</code>, <code>#length-positive</code>, or
-            <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-positive" name=
-          "feature-length-positive"></a>D.1.49 #length-positive</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#length-positive</code> feature if it recognizes and is capable
-          of transforming positive values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#length-positive</code> feature if it implements presentation
-          semantic support for positive values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-positive</code> is intended to imply
-            support for zero valued <a href=
-            "#style-value-length">&lt;length&gt;</a> style value
-            expressions.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-positive</code> does not, by itself,
-            imply support for <code>#length-integer</code> or
-            <code>#length-real</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-length-real" name="feature-length-real"></a>D.1.50
-          #length-real</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#length-real</code> feature if it recognizes and is capable of
-          transforming real values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#length-real</code> feature if it implements presentation
-          semantic support for real values of the <a href=
-          "#style-value-length">&lt;length&gt;</a> style value expression.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-real</code> is intended to imply
-            support for integer valued <a href=
-            "#style-value-length">&lt;length&gt;</a> style value expressions as
-            well as real valued expressions.</p>
-          </div>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>Support for <code>#length-real</code> does not, by itself, imply
-            support for <code>#length-positive</code> or
-            <code>#length-negative</code> features.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-lineBreak-uax14" name=
-          "feature-lineBreak-uax14"></a>D.1.51 #lineBreak-uax14</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#lineBreak-uax14</code> feature if it recognizes and is capable
-          of transforming requirements expressed by <a href=
-          "#uax14">[UAX14]</a> into its target document space.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#lineBreak-uax14</code> feature if it implements presentation
-          semantic support for <a href="#uax14">[UAX14]</a> as applies to line
-          breaking.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-lineHeight" name="feature-lineHeight"></a>D.1.52
-          #lineHeight</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#lineHeight</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#style-attribute-lineHeight"><code>tts:lineHeight</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#lineHeight</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#style-attribute-lineHeight"><code>tts:lineHeight</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-markerMode" name="feature-markerMode"></a>D.1.53
-          #markerMode</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#markerMode</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#markerMode</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-markerMode-continuous" name=
-          "feature-markerMode-continuous"></a>D.1.54
-          #markerMode-continuous</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#markerMode-continuous</code> feature if it recognizes and is
-          capable of transforming the <code>continuous</code> value of the
-          <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#markerMode-continuous</code> feature if it implements
-          presentation semantic support for the <code>continuous</code> value
-          of the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-markerMode-discontinuous" name=
-          "feature-markerMode-discontinuous"></a>D.1.55
-          #markerMode-discontinuous</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#markerMode-discontinuous</code> feature if it recognizes and
-          is capable of transforming the <code>discontinuous</code> value of
-          the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#markerMode-discontinuous</code> feature if it implements
-          presentation semantic support for the <code>discontinuous</code>
-          value of the <a href=
-          "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-metadata" name="feature-metadata"></a>D.1.56
-          #metadata</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#metadata</code> feature if it recognizes and is capable of
-          transforming the following vocabulary defined by <a href=
-          "#metadata"><b>12 Metadata</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#metadata-vocabulary-metadata"><code>metadata</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#metadata-vocabulary-title"><code>ttm:title</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#metadata-vocabulary-title"><code>ttm:desc</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#metadata-vocabulary-title"><code>ttm:copyright</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#metadata-vocabulary-title"><code>ttm:agent</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#metadata-vocabulary-title"><code>ttm:name</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#metadata-vocabulary-title"><code>ttm:actor</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#metadata-attribute-agent">@<code>ttm:agent</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#metadata-attribute-role">@<code>ttm:role</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#metadata</code>
-          feature if it recognizes and is capable of presenting the information
-          expressed by the same vocabulary enumerated above.</p>
-
-          <div class="note">
-            <p class="prefix"><b>Note:</b></p>
-
-            <p>This specification does not define a standardized form for the
-            presentation of metadata information. The presentation or ability
-            to present metadata information is considered to be implementation
-            dependent.</p>
-          </div>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-nested-div" name="feature-nested-div"></a>D.1.57
-          #nested-div</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#nested-div</code> feature if it recognizes and is capable of
-          transforming nested <a href=
-          "#content-vocabulary-div"><code>div</code></a> elements.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#nested-div</code> feature if it implements presentation
-          semantic support for nested <a href=
-          "#content-vocabulary-div"><code>div</code></a> elements.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-nested-span" name="feature-nested-span"></a>D.1.58
-          #nested-span</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#nested-span</code> feature if it recognizes and is capable of
-          transforming nested <a href=
-          "#content-vocabulary-span"><code>span</code></a> elements.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#nested-span</code> feature if it implements presentation
-          semantic support for nested <a href=
-          "#content-vocabulary-span"><code>span</code></a> elements.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-opacity" name="feature-opacity"></a>D.1.59
-          #opacity</h4>
-
-          <p>A TTML transformation processor supports the <code>#opacity</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-opacity"><code>tts:opacity</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#opacity</code>
-          feature if it (1) implements presentation semantic support for the
-          <a href="#style-attribute-opacity"><code>tts:opacity</code></a>
-          attribute and (2) is capable of displaying or generating an output
-          display signal that distinguishes between at least eight (8) values
-          of opacity.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-origin" name="feature-origin"></a>D.1.60
-          #origin</h4>
-
-          <p>A TTML transformation processor supports the <code>#origin</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-origin"><code>tts:origin</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#origin</code>
-          feature if it implements presentation semantic support for the
-          <a href="#style-attribute-origin"><code>tts:origin</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-overflow" name="feature-overflow"></a>D.1.61
-          #overflow</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#overflow</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-overflow"><code>tts:overflow</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#overflow</code>
-          feature if it implements presentation semantic support for all
-          defined values of the <a href=
-          "#style-attribute-overflow"><code>tts:overflow</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-overflow-visible" name=
-          "feature-overflow-visible"></a>D.1.62 #overflow-visible</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#overflow-visible</code> feature if it recognizes and is
-          capable of transforming the <code>visible</code> value of the
-          <a href="#style-attribute-overflow"><code>tts:overflow</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#overflow-visible</code> feature if it implements presentation
-          semantic support for the <code>visible</code> value of the <a href=
-          "#style-attribute-overflow"><code>tts:overflow</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding" name="feature-padding"></a>D.1.63
-          #padding</h4>
-
-          <p>A TTML transformation processor supports the <code>#padding</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding</code>
-          feature if it implements presentation semantic support for the
-          <a href="#style-attribute-padding"><code>tts:padding</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding-1" name="feature-padding-1"></a>D.1.64
-          #padding-1</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#padding-1</code> feature if it recognizes and is capable of
-          transforming values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute
-          that consist of one <a href="#style-value-length">&lt;length&gt;</a>
-          specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding-1</code>
-          feature if it implements presentation semantic support for values of
-          the <a href="#style-attribute-padding"><code>tts:padding</code></a>
-          attribute that consist of one <a href=
-          "#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding-2" name="feature-padding-2"></a>D.1.65
-          #padding-2</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#padding-2</code> feature if it recognizes and is capable of
-          transforming values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute
-          that consist of two <a href="#style-value-length">&lt;length&gt;</a>
-          specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding-2</code>
-          feature if it implements presentation semantic support for values of
-          the <a href="#style-attribute-padding"><code>tts:padding</code></a>
-          attribute that consist of two <a href=
-          "#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding-3" name="feature-padding-3"></a>D.1.66
-          #padding-3</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#padding-3</code> feature if it recognizes and is capable of
-          transforming values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute
-          that consist of three <a href=
-          "#style-value-length">&lt;length&gt;</a> specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding-3</code>
-          feature if it implements presentation semantic support for values of
-          the <a href="#style-attribute-padding"><code>tts:padding</code></a>
-          attribute that consist of three <a href=
-          "#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-padding-4" name="feature-padding-4"></a>D.1.67
-          #padding-4</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#padding-4</code> feature if it recognizes and is capable of
-          transforming values of the <a href=
-          "#style-attribute-padding"><code>tts:padding</code></a> attribute
-          that consist of four <a href="#style-value-length">&lt;length&gt;</a>
-          specification.</p>
-
-          <p>A TTML presentation processor supports the <code>#padding-4</code>
-          feature if it implements presentation semantic support for values of
-          the <a href="#style-attribute-padding"><code>tts:padding</code></a>
-          attribute that consist of four <a href=
-          "#style-value-length">&lt;length&gt;</a> specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-pixelAspectRatio" name=
-          "feature-pixelAspectRatio"></a>D.1.68 #pixelAspectRatio</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#pixelAspectRatio</code> feature if it recognizes and is
-          capable of transforming the <a href=
-          "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#pixelAspectRatio</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-presentation" name=
-          "feature-presentation"></a>D.1.69 #presentation</h4>
-
-          <p>A TTML processor supports the <code>#presentation</code> feature
-          if it (1) satisfies the generic processor criteria defined by
-          <a href="#conformance-generic-processor"><b>3.2.1 Generic Processor
-          Conformance</b></a>, (2) implements support for the region and line
-          layout semantics defined by <a href="#semantics-region-layout"><b>9.3
-          Region Layout and Presentation</b></a> and <a href=
-          "#semantics-line-layout"><b>9.4 Line Layout</b></a>, respectively,
-          and (3) implements presentation semantics for the following
-          features:</p>
-
-          <ul>
-            <li>
-              <p><a href="#content"><code>#content</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-core"><code>#core</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-profile"><code>#profile</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-structure"><code>#structure</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#feature-time-offset"><code>#time-offset</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing"><code>#timing</code></a></p>
-            </li>
-          </ul>
-
-          <p>In addition, a TTML processor that supports the
-          <code>#presentation</code> feature should satisfy the user agent
-          accessibility guidelines specified by <a href="#uaag">[UAAG]</a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-profile" name="feature-profile"></a>D.1.70
-          #profile</h4>
-
-          <p>A TTML transformation processor supports the <code>#profile</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#parameter-attribute-profile"><code>ttp:profile</code></a> attribute
-          on the <a href=
-          "#document-structure-vocabulary-tt"><code>tt</code></a> element and
-          transforming the following vocabulary defined by <a href=
-          "#parameter-element-vocabulary"><b>6.1 Parameter Element
-          Vocabulary</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#parameter-vocabulary-profile"><code>ttp:profile</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#parameter-vocabulary-features"><code>ttp:features</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#parameter-vocabulary-feature"><code>ttp:feature</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#parameter-vocabulary-extensions"><code>ttp:extensions</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#parameter-vocabulary-extension"><code>ttp:extension</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#profile</code>
-          feature if it implements presentation semantic support for the same
-          vocabulary specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-showBackground" name=
-          "feature-showBackground"></a>D.1.71 #showBackground</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#showBackground</code> feature if it recognizes and is capable
-          of transforming all defined values of the <a href=
-          "#style-attribute-showBackground"><code>tts:showBackground</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#showBackground</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-showBackground"><code>tts:showBackground</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-structure" name="feature-structure"></a>D.1.72
-          #structure</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#structure</code> feature if it recognizes and is capable of
-          transforming the following vocabulary defined by <a href=
-          "#content"><b>7 Content</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#document-structure-vocabulary-tt"><code>tt</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#document-structure-vocabulary-head"><code>head</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#structure</code>
-          feature if it implements presentation semantic support for the same
-          vocabulary enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling" name="feature-styling"></a>D.1.73
-          #styling</h4>
-
-          <p>A TTML transformation processor supports the <code>#styling</code>
-          feature if it recognizes and is capable of transforming the following
-          vocabulary defined by <a href="#styling"><b>8 Styling</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href=
-              "#styling-vocabulary-styling"><code>styling</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#styling-vocabulary-style"><code>style</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#style-attribute-style">@<code>style</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#styling</code>
-          feature if it implements presentation semantic support for the same
-          vocabulary enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-chained" name=
-          "feature-styling-chained"></a>D.1.74 #styling-chained</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-chained</code> feature if it recognizes and is capable
-          of transforming chained style association as defined by <a href=
-          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
-          Referential Styling</b></a>.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#styling-chained</code> feature if it implements presentation
-          semantic support for chained style association as defined by <a href=
-          "#semantics-style-association-chained-referential"><b>8.4.1.3 Chained
-          Referential Styling</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-inheritance-content" name=
-          "feature-styling-inheritance-content"></a>D.1.75
-          #styling-inheritance-content</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-inheritance</code> feature if it recognizes and is
-          capable of transforming content style inheritance as defined by
-          <a href="#semantics-style-inheritance-content"><b>8.4.2.1 Content
-          Style Inheritance</b></a>.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#styling-inheritance-content</code> feature if it implements
-          presentation semantic support for content style inheritance as
-          defined by <a href="#semantics-style-inheritance-content"><b>8.4.2.1
-          Content Style Inheritance</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-inheritance-region" name=
-          "feature-styling-inheritance-region"></a>D.1.76
-          #styling-inheritance-region</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-inheritance</code> feature if it recognizes and is
-          capable of transforming region style inheritance as defined by
-          <a href="#semantics-style-inheritance-region"><b>8.4.2.2 Region Style
-          Inheritance</b></a>.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#styling-inheritance-region</code> feature if it implements
-          presentation semantic support for region style inheritance as defined
-          by <a href="#semantics-style-inheritance-region"><b>8.4.2.2 Region
-          Style Inheritance</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-inline" name=
-          "feature-styling-inline"></a>D.1.77 #styling-inline</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-inline</code> feature if it recognizes and is capable
-          of transforming inline style association as defined by <a href=
-          "#semantics-style-association-inline"><b>8.4.1.1 Inline
-          Styling</b></a>.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#styling-inline</code> feature if it implements presentation
-          semantic support for inline style association as defined by <a href=
-          "#semantics-style-association-inline"><b>8.4.1.1 Inline
-          Styling</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-nested" name=
-          "feature-styling-nested"></a>D.1.78 #styling-nested</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-nested</code> feature if it recognizes and is capable
-          of transforming nested style association as defined by <a href=
-          "#semantics-style-association-nested"><b>8.4.1.4 Nested
-          Styling</b></a>.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#styling-nested</code> feature if it implements presentation
-          semantic support for nested style association as defined by <a href=
-          "#semantics-style-association-nested"><b>8.4.1.4 Nested
-          Styling</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-styling-referential" name=
-          "feature-styling-referential"></a>D.1.79 #styling-referential</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#styling-referential</code> feature if it recognizes and is
-          capable of transforming referential style association as defined by
-          <a href="#semantics-style-association-referential"><b>8.4.1.2
-          Referential Styling</b></a>.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#styling-referential</code> feature if it implements
-          presentation semantic support for referential style association as
-          defined by <a href=
-          "#semantics-style-association-referential"><b>8.4.1.2 Referential
-          Styling</b></a>.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-subFrameRate" name=
-          "feature-subFrameRate"></a>D.1.80 #subFrameRate</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#subFrameRate</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#subFrameRate</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textAlign" name="feature-textAlign"></a>D.1.81
-          #textAlign</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textAlign</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#textAlign</code>
-          feature if it implements presentation semantic support for all
-          defined values of the <a href=
-          "#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textAlign-absolute" name=
-          "feature-textAlign-absolute"></a>D.1.82 #textAlign-absolute</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textAlign-absolute</code> feature if it recognizes and is
-          capable of transforming the <code>left</code>, <code>center</code>,
-          and <code>right</code> values of the <a href=
-          "#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textAlign-absolute</code> feature if it implements
-          presentation semantic support for the <code>left</code>,
-          <code>center</code>, and <code>right</code> values of the <a href=
-          "#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textAlign-relative" name=
-          "feature-textAlign-relative"></a>D.1.83 #textAlign-relative</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textAlign-relative</code> feature if it recognizes and is
-          capable of transforming the <code>start</code>, <code>center</code>,
-          and <code>end</code> values of the <a href=
-          "#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textAlign-relative</code> feature if it implements
-          presentation semantic support for the <code>start</code>,
-          <code>center</code>, and <code>end</code> values of the <a href=
-          "#style-attribute-textAlign"><code>tts:textAlign</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textDecoration" name=
-          "feature-textDecoration"></a>D.1.84 #textDecoration</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textDecoration</code> feature if it recognizes and is capable
-          of transforming all defined values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textDecoration</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textDecoration-over" name=
-          "feature-textDecoration-over"></a>D.1.85 #textDecoration-over</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textDecoration-over</code> feature if it recognizes and is
-          capable of transforming the <code>overline</code> and
-          <code>noOverline</code> values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textDecoration-over</code> feature if it implements
-          presentation semantic support for the <code>overline</code> and
-          <code>noOverline</code> values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textDecoration-through" name=
-          "feature-textDecoration-through"></a>D.1.86
-          #textDecoration-through</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textDecoration-through</code> feature if it recognizes and is
-          capable of transforming the <code>lineThrough</code> and
-          <code>noLineThrough</code> values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textDecoration-through</code> feature if it implements
-          presentation semantic support for the <code>lineThrough</code> and
-          <code>noLineThrough</code> values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textDecoration-under" name=
-          "feature-textDecoration-under"></a>D.1.87 #textDecoration-under</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textDecoration-under</code> feature if it recognizes and is
-          capable of transforming the <code>underline</code> and
-          <code>noUnderline</code> values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textDecoration-under</code> feature if it implements
-          presentation semantic support for the <code>underline</code> and
-          <code>noUnderline</code> values of the <a href=
-          "#style-attribute-textDecoration"><code>tts:textDecoration</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textOutline" name="feature-textOutline"></a>D.1.88
-          #textOutline</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textOutline</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textOutline</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textOutline-blurred" name=
-          "feature-textOutline-blurred"></a>D.1.89 #textOutline-blurred</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textOutline-blurred</code> feature if it recognizes and is
-          capable of transforming values of the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a>
-          attribute that includes a blur radius specification.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textOutline-blurred</code> feature if it implements
-          presentation semantic support for values of the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a>
-          attribute that includes a blur radius specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-textOutline-unblurred" name=
-          "feature-textOutline-unblurred"></a>D.1.90
-          #textOutline-unblurred</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#textOutline-unblurred</code> feature if it recognizes and is
-          capable of transforming values of the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a>
-          attribute that does not include a blur radius specification.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#textOutline-unblurred</code> feature if it implements
-          presentation semantic support for values of the <a href=
-          "#style-attribute-textOutline"><code>tts:textOutline</code></a>
-          attribute that does not include a blur radius specification.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-tickRate" name="feature-tickRate"></a>D.1.91
-          #tickRate</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#tickRate</code> feature if it recognizes and is capable of
-          transforming the <a href=
-          "#parameter-attribute-tickRate"><code>ttp:tickRate</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#tickRate</code>
-          feature if it implements presentation semantic support for the
-          <a href="#parameter-attribute-tickRate"><code>ttp:tickRate</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timeBase-clock" name=
-          "feature-timeBase-clock"></a>D.1.92 #timeBase-clock</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#timeBase-clock</code> feature if it recognizes and is capable
-          of transforming the <code>clock</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a>
-          attribute and if it supports the <a href=
-          "#feature-clockMode"><code>#clockMode</code></a> feature.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#timeBase-clock</code> feature if it implements presentation
-          semantic support for the <code>clock</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a>
-          attribute and if it supports the <a href=
-          "#feature-clockMode"><code>#clockMode</code></a> feature.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timeBase-media" name=
-          "feature-timeBase-media"></a>D.1.93 #timeBase-media</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#timeBase-media</code> feature if it recognizes and is capable
-          of transforming the <code>media</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#timeBase-media</code> feature if it implements presentation
-          semantic support for the <code>media</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timeBase-smpte" name=
-          "feature-timeBase-smpte"></a>D.1.94 #timeBase-smpte</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#timeBase-smpte</code> feature if it recognizes and is capable
-          of transforming the <code>smpte</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a>
-          attribute and if it supports the <a href=
-          "#feature-dropMode"><code>#dropMode</code></a> feature.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#timeBase-smpte</code> feature if it implements presentation
-          semantic support for the <code>smpte</code> value of the <a href=
-          "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a>
-          attribute and if it supports the <a href=
-          "#feature-dropMode"><code>#dropMode</code></a> feature.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timeContainer" name=
-          "feature-timeContainer"></a>D.1.95 #timeContainer</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#timeContainer</code> feature if it recognizes and is capable
-          of transforming the <a href=
-          "#timing-attribute-timeContainer"><code>timeContainer</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#timeContainer</code> feature if it implements presentation
-          semantic support for the <a href=
-          "#timing-attribute-timeContainer"><code>timeContainer</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-clock" name="feature-time-clock"></a>D.1.96
-          #time-clock</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#time-clock</code> feature if it recognizes and is capable of
-          transforming all values of the <a href=
-          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that
-          satisfy the following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : hours ":" minutes ":" seconds ( fraction )?
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the
-          <code>#time-clock</code> feature if it implements presentation
-          semantic support for the same syntax specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-clock-with-frames" name=
-          "feature-time-clock-with-frames"></a>D.1.97
-          #time-clock-with-frames</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#time-clock-with-frames</code> feature if it supports the
-          <a href="#feature-frameRate"><code>#frameRate</code></a>, <a href=
-          "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a>,
-          and <a href="#feature-subFrameRate"><code>#subFrameRate</code></a>
-          features and if it recognizes and is capable of transforming all
-          values of the <a href=
-          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that
-          satisfy the following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the
-          <code>#time-clock-with-frames</code> feature if it implements
-          presentation semantic support for the same features and syntax
-          specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-offset" name="feature-time-offset"></a>D.1.98
-          #time-offset</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#time-offset</code> feature if it recognizes and is capable of
-          transforming all values of the <a href=
-          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that
-          satisfy the following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : time-count fraction? ( "h" | "m" | "s" | "ms" )
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the
-          <code>#time-offset</code> feature if it implements presentation
-          semantic support for the same syntax specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-offset-with-frames" name=
-          "feature-time-offset-with-frames"></a>D.1.99
-          #time-offset-with-frames</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#time-offset-with-frames</code> feature if it supports the
-          <a href="#feature-frameRate"><code>#frameRate</code></a>, <a href=
-          "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a>,
-          and <a href="#feature-subFrameRate"><code>#subFrameRate</code></a>
-          features and if it recognizes and is capable of transforming all
-          values of the <a href=
-          "#timing-value-timeExpression">&lt;timeExpression&gt;</a> that
-          satisfy the following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : time-count fraction? "f"
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the
-          <code>#time-offset-with-frames</code> feature if it implements
-          presentation semantic support for the same features and syntax
-          specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-time-offset-with-ticks" name=
-          "feature-time-offset-with-ticks"></a>D.1.100
-          #time-offset-with-ticks</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#time-offset-with-ticks</code> feature if it supports the
-          <a href="#feature-tickRate"><code>#tickRate</code></a> feature and if
-          it recognizes and is capable of transforming all values of the
-          <a href="#timing-value-timeExpression">&lt;timeExpression&gt;</a>
-          that satisfy the following subset of time expression syntax:</p>
-
-          <div class="exampleInner">
-            <pre>
-&lt;timeExpression&gt;
-  : time-count fraction? "t"
-</pre>
-          </div>
-
-          <p>A TTML presentation processor supports the
-          <code>#time-offset-with-ticks</code> feature if it implements
-          presentation semantic support for the same features and syntax
-          specified above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-timing" name="feature-timing"></a>D.1.101
-          #timing</h4>
-
-          <p>A TTML transformation processor supports the <code>#timing</code>
-          feature if it recognizes and is capable of transforming the following
-          vocabulary defined by <a href="#timing"><b>10 Timing</b></a>:</p>
-
-          <ul>
-            <li>
-              <p><a href="#timing-attribute-begin">@<code>begin</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing-attribute-dur">@<code>dur</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing-attribute-end">@<code>end</code></a></p>
-            </li>
-          </ul>
-
-          <p>A TTML presentation processor supports the <code>#timing</code>
-          feature if it implements presentation semantic support for the same
-          vocabulary enumerated above.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-transformation" name=
-          "feature-transformation"></a>D.1.102 #transformation</h4>
-
-          <p>A TTML processor supports the <code>#transformation</code> feature
-          if it (1) satisfies the generic processor criteria defined by
-          <a href="#conformance-generic-processor"><b>3.2.1 Generic Processor
-          Conformance</b></a> and (2) implements the transformation semantics
-          of the following features:</p>
-
-          <ul>
-            <li>
-              <p><a href="#content"><code>#content</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-core"><code>#core</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-profile"><code>#profile</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#feature-structure"><code>#structure</code></a></p>
-            </li>
-
-            <li>
-              <p><a href=
-              "#feature-time-offset"><code>#time-offset</code></a></p>
-            </li>
-
-            <li>
-              <p><a href="#timing"><code>#timing</code></a></p>
-            </li>
-          </ul>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-unicodeBidi" name=
-          "feature-unicodeBidi"></a>D.1.103 #unicodeBidi</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#unicodeBidi</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#unicodeBidi</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-visibility" name="feature-visibility"></a>D.1.104
-          #visibility</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#visibility</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#visibility</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-visibility-block" name=
-          "feature-visibility-block"></a>D.1.105 #visibility-block</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#visibility-block</code> feature if it recognizes and is
-          capable of transforming all defined values of the <a href=
-          "#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a content element that would generate a
-          block area during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#visibility-block</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a content element that generates a block
-          area.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-visibility-inline" name=
-          "feature-visibility-inline"></a>D.1.106 #visibility-inline</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#visibility-inline</code> feature if it recognizes and is
-          capable of transforming all defined values of the <a href=
-          "#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a content element that would generate an
-          inline area during presentation processing.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#visibility-inline</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a content element that generates an inline
-          area.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-visibility-region" name=
-          "feature-visibility-region"></a>D.1.107 #visibility-region</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#visibility-region</code> feature if it recognizes and is
-          capable of transforming all defined values of the <a href=
-          "#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#visibility-region</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-visibility"><code>tts:visibility</code></a>
-          attribute when applied to a <a href=
-          "#layout-vocabulary-region"><code>region</code></a> element.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-wrapOption" name="feature-wrapOption"></a>D.1.108
-          #wrapOption</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#wrapOption</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-wrapOption"><code>tts:wrapOption</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#wrapOption</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-wrapOption"><code>tts:wrapOption</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode" name=
-          "feature-writingMode"></a>D.1.109 #writingMode</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode</code> feature if it recognizes and is capable of
-          transforming all defined values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode</code> feature if it implements presentation
-          semantic support for all defined values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode-vertical" name=
-          "feature-writingMode-vertical"></a>D.1.110 #writingMode-vertical</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode-vertical</code> feature if it recognizes and is
-          capable of transforming the <code>tbrl</code>, <code>tblr</code>, and
-          <code>tb</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode-vertical</code> feature if it implements
-          presentation semantic support for the <code>tbrl</code>,
-          <code>tblr</code>, and <code>tb</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode-horizontal" name=
-          "feature-writingMode-horizontal"></a>D.1.111
-          #writingMode-horizontal</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode-horizontal</code> feature if it recognizes and is
-          capable of transforming the <code>lrtb</code>, <code>rltb</code>,
-          <code>lr</code> and <code>rl</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode-horizontal</code> feature if it implements
-          presentation semantic support for the <code>lrtb</code>,
-          <code>rltb</code>, <code>lr</code> and <code>rl</code> values of the
-          <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode-horizontal-lr" name=
-          "feature-writingMode-horizontal-lr"></a>D.1.112
-          #writingMode-horizontal-lr</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode-horizontal</code> feature if it recognizes and is
-          capable of transforming the <code>lrtb</code> and <code>lr</code>
-          values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode-horizontal-lr</code> feature if it implements
-          presentation semantic support for the <code>lrtb</code> and
-          <code>lr</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-writingMode-horizontal-rl" name=
-          "feature-writingMode-horizontal-rl"></a>D.1.113
-          #writingMode-horizontal-rl</h4>
-
-          <p>A TTML transformation processor supports the
-          <code>#writingMode-horizontal</code> feature if it recognizes and is
-          capable of transforming the <code>rltb</code> and <code>rl</code>
-          values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-
-          <p>A TTML presentation processor supports the
-          <code>#writingMode-horizontal-rl</code> feature if it implements
-          presentation semantic support for the <code>rltb</code> and
-          <code>rl</code> values of the <a href=
-          "#style-attribute-writingMode"><code>tts:writingMode</code></a>
-          attribute.</p>
-        </div>
-
-        <div class="div3">
-          <h4><a id="feature-zIndex" name="feature-zIndex"></a>D.1.114
-          #zIndex</h4>
-
-          <p>A TTML transformation processor supports the <code>#zIndex</code>
-          feature if it recognizes and is capable of transforming the <a href=
-          "#style-attribute-zIndex"><code>tts:zIndex</code></a> attribute.</p>
-
-          <p>A TTML presentation processor supports the <code>#zIndex</code>
-          feature if it implements presentation semantic support for the
-          <a href="#style-attribute-zIndex"><code>tts:zIndex</code></a>
-          attribute.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="feature-support" name="feature-support"></a>D.2 Feature
-        Support</h3>
-
-        <p>The following table, <a href="#feature-support-table"><b>Table D-1 –
-        Feature Support</b></a>, enumerates every defined feature designation
-        (expressed without the TT Feature Namespace), and, for each designated
-        feature, specifies whether the feature must be implemented, i.e., is
-        mandatory (M), or may be implemented, i.e., is optional (O), for
-        transformation and presentation processors.</p><a id=
-        "feature-support-table" name="feature-support-table"></a>
-
-        <table class="common">
-          <caption>
-            Table D-1 – Feature Support
-          </caption>
-          <col width="60%" span="1">
-          <col width="20%" span="1">
-          <col width="20%" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Feature</span></td>
-
-              <td><span class="strong">Transformation</span></td>
-
-              <td><span class="strong">Presentation</span></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-animation"><code>#animation</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-backgroundColor"><code>#backgroundColor</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-backgroundColor-block"><code>#backgroundColor-block</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-backgroundColor-inline"><code>#backgroundColor-inline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-backgroundColor-region"><code>#backgroundColor-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-bidi"><code>#bidi</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-cellResolution"><code>#cellResolution</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-clockMode"><code>#clockMode</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-clockMode-gps"><code>#clockMode-gps</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-clockMode-local"><code>#clockMode-local</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-clockMode-utc"><code>#clockMode-utc</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-color"><code>#color</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-content"><code>#content</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-core"><code>#core</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-direction"><code>#direction</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-display"><code>#display</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-display-block"><code>#display-block</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-display-inline"><code>#display-inline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-display-region"><code>#display-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-displayAlign"><code>#displayAlign</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-dropMode"><code>#dropMode</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-dropMode-dropNTSC"><code>#dropMode-dropNTSC</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-dropMode-dropPAL"><code>#dropMode-dropPAL</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-dropMode-nonDrop"><code>#dropMode-nonDrop</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-extent"><code>#extent</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-extent-region"><code>#extent-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-extent-root"><code>#extent-root</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontFamily"><code>#fontFamily</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontFamily-generic"><code>#fontFamily-generic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontFamily-non-generic"><code>#fontFamily-non-generic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-fontSize"><code>#fontSize</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontSize-anamorphic"><code>#fontSize-anamorphic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontSize-isomorphic"><code>#fontSize-isomorphic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-fontStyle"><code>#fontStyle</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontStyle-italic"><code>#fontStyle-italic</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontStyle-oblique"><code>#fontStyle-oblique</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontWeight"><code>#fontWeight</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-fontWeight-bold"><code>#fontWeight-bold</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-frameRate"><code>#frameRate</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-frameRateMultiplier"><code>#frameRateMultiplier</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-layout"><code>#layout</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-length"><code>#length</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-cell"><code>#length-cell</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-length-em"><code>#length-em</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-integer"><code>#length-integer</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-negative"><code>#length-negative</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-percentage"><code>#length-percentage</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-pixel"><code>#length-pixel</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-positive"><code>#length-positive</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-length-real"><code>#length-real</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-lineBreak-uax14"><code>#lineBreak-uax14</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-lineHeight"><code>#lineHeight</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-markerMode"><code>#markerMode</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-markerMode-continuous"><code>#markerMode-continuous</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-markerMode-discontinuous"><code>#markerMode-discontinuous</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-metadata"><code>#metadata</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-nested-div"><code>#nested-div</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-nested-span"><code>#nested-span</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-opacity"><code>#opacity</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-origin"><code>#origin</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-overflow"><code>#overflow</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-overflow-visible"><code>#overflow-visible</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding"><code>#padding</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding-1"><code>#padding-1</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding-2"><code>#padding-2</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding-3"><code>#padding-3</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-padding-4"><code>#padding-4</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-pixelAspectRatio"><code>#pixelAspectRatio</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-presentation"><code>#presentation</code></a></td>
-
-              <td>O</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-profile"><code>#profile</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-showBackground"><code>#showBackground</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-structure"><code>#structure</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-styling"><code>#styling</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-chained"><code>#styling-chained</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-inheritance-content"><code>#styling-inheritance-content</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-inheritance-region"><code>#styling-inheritance-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-inline"><code>#styling-inline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-nested"><code>#styling-nested</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-styling-referential"><code>#styling-referential</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-subFrameRate"><code>#subFrameRate</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-textAlign"><code>#textAlign</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textAlign-absolute"><code>#textAlign-absolute</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textAlign-relative"><code>#textAlign-relative</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textDecoration"><code>#textDecoration</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textDecoration-over"><code>#textDecoration-over</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textDecoration-through"><code>#textDecoration-through</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textDecoration-under"><code>#textDecoration-under</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textOutline"><code>#textOutline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textOutline-blurred"><code>#textOutline-blurred</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-textOutline-unblurred"><code>#textOutline-unblurred</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-tickRate"><code>#tickRate</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-timeBase-clock"><code>#timeBase-clock</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-timeBase-media"><code>#timeBase-media</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-timeBase-smpte"><code>#timeBase-smpte</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-timeContainer"><code>#timeContainer</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-clock"><code>#time-clock</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-clock-with-frames"><code>#time-clock-with-frames</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-offset"><code>#time-offset</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-offset-with-frames"><code>#time-offset-with-frames</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-offset-with-ticks"><code>#time-offset-with-ticks</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timing"><code>#timing</code></a></td>
-
-              <td>M</td>
-
-              <td>M</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-transformation"><code>#transformation</code></a></td>
-
-              <td>M</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-unicodeBidi"><code>#unicodeBidi</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-visibility"><code>#visibility</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-visibility-block"><code>#visibility-block</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-visibility-inline"><code>#visibility-inline</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-visibility-region"><code>#visibility-region</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-wrapOption"><code>#wrapOption</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode"><code>#writingMode</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode-vertical"><code>#writingMode-vertical</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode-horizontal"><code>#writingMode-horizontal</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode-horizontal-lr"><code>#writingMode-horizontal-lr</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-writingMode-horizontal-rl"><code>#writingMode-horizontal-rl</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-zIndex"><code>#zIndex</code></a></td>
-
-              <td>O</td>
-
-              <td>O</td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>For the sake of convenience, the following table, <a href=
-        "#feature-transformation-mandatory-table"><b>Table D-2 – Mandatory
-        Features - Transformation</b></a>, enumerates all mandatory features
-        for a TTML Transformation Processor, providing additional comments to
-        summarize the context of usage or the nature of the feature. The
-        <em>Profile Definition Document</em> that defines the corresponding
-        DFXP Transformation Profile is specified in <a href=
-        "#profile-dfxp-transformation"><b>F.1 DFXP Transformation
-        Profile</b></a>.</p><a id="feature-transformation-mandatory-table"
-        name="feature-transformation-mandatory-table"></a>
-
-        <table class="common">
-          <caption>
-            Table D-2 – Mandatory Features - Transformation
-          </caption>
-          <col width="60%" span="1">
-          <col width="40%" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Feature</span></td>
-
-              <td><span class="strong">Comments</span></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-content"><code>#content</code></a></td>
-
-              <td><a href=
-              "#document-structure-vocabulary-body"><code>body</code></a>,
-              <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
-              "#content-vocabulary-p"><code>p</code></a>, <a href=
-              "#content-vocabulary-span"><code>span</code></a>, <a href=
-              "#content-vocabulary-br"><code>br</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-core"><code>#core</code></a></td>
-
-              <td><a href="#content-attribute-id">@<code>xml:id</code></a>,
-              <a href="#content-attribute-id">@<code>xml:lang</code></a>,
-              <a href="#content-attribute-id">@<code>xml:space</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-profile"><code>#profile</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-structure"><code>#structure</code></a></td>
-
-              <td><a href=
-              "#document-structure-vocabulary-tt"><code>tt</code></a>, <a href=
-              "#document-structure-vocabulary-head"><code>head</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-offset"><code>#time-offset</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timing"><code>#timing</code></a></td>
-
-              <td><a href="#timing-attribute-begin">@<code>begin</code></a>,
-              <a href="#timing-attribute-dur">@<code>dur</code></a>, <a href=
-              "#timing-attribute-end">@<code>end</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-transformation"><code>#transformation</code></a></td>
-
-              <td></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>For the sake of convenience, the following table, <a href=
-        "#feature-presentation-mandatory-table"><b>Table D-3 – Mandatory
-        Features - Presentation</b></a>, enumerates all mandatory features for
-        a TTML Presentation Processor, providing additional comments to
-        summarize the context of usage or the nature of the feature. The
-        <em>Profile Definition Document</em> that defines the corresponding
-        DFXP Presentation Profile is specified in <a href=
-        "#profile-dfxp-presentation"><b>F.2 DFXP Presentation
-        Profile</b></a>.</p><a id="feature-presentation-mandatory-table" name=
-        "feature-presentation-mandatory-table"></a>
-
-        <table class="common">
-          <caption>
-            Table D-3 – Mandatory Features - Presentation
-          </caption>
-          <col width="60%" span="1">
-          <col width="40%" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Feature</span></td>
-
-              <td><span class="strong">Comments</span></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-content"><code>#content</code></a></td>
-
-              <td><a href=
-              "#document-structure-vocabulary-body"><code>body</code></a>,
-              <a href="#content-vocabulary-div"><code>div</code></a>, <a href=
-              "#content-vocabulary-p"><code>p</code></a>, <a href=
-              "#content-vocabulary-span"><code>span</code></a>, <a href=
-              "#content-vocabulary-br"><code>br</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-core"><code>#core</code></a></td>
-
-              <td><a href="#content-attribute-id">@<code>xml:id</code></a>,
-              <a href="#content-attribute-id">@<code>xml:lang</code></a>,
-              <a href="#content-attribute-id">@<code>xml:space</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-profile"><code>#profile</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-presentation"><code>#presentation</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-structure"><code>#structure</code></a></td>
-
-              <td><a href=
-              "#document-structure-vocabulary-tt"><code>tt</code></a>, <a href=
-              "#document-structure-vocabulary-head"><code>head</code></a></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#feature-time-offset"><code>#time-offset</code></a></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#feature-timing"><code>#timing</code></a></td>
-
-              <td><a href="#timing-attribute-begin">@<code>begin</code></a>,
-              <a href="#timing-attribute-dur">@<code>dur</code></a>, <a href=
-              "#timing-attribute-end">@<code>end</code></a></td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="extensions" name="extensions"></a>E Extensions</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix specifies the syntactic form of extension designations,
-      which are used to express authorial intent regarding the support for
-      extension mechanisms in a TTML processor.</p>
-
-      <div class="div2">
-        <h3><a id="extension-designations" name=
-        "extension-designations"></a>E.1 Extension Designations</h3>
-
-        <p>An extension designation is expressed as a string that adheres to
-        the following form:</p>
-
-        <div class="exampleInner">
-          <pre>
-extension-designation
-  : extension-namespace designation
-
-extension-namespace
-  : <em>TT Extension Namespace</em>                  // http://www.w3.org/ns/ttml/extension/
-  | <em>Other Extension Namespace</em>               // expressed as an absolute URI
-
-designation
-  : "#" token-char+
-
-token-char
-  : { XML NameChar }                        // XML 1.1 Production [4a]
-</pre>
-        </div>
-
-        <p>If the extension namespace of an extension designation is the TT
-        Extension Namespace, then all values of the following
-        <code>designation</code> token are reserved for future
-        standardization.</p>
-
-        <p>If the extension namespace of an extension designation is not the TT
-        Extension Namespace, i.e., is an <em>Other Extension Namespace</em>,
-        then the extension namespace must be expressed as an absolute URI
-        capable of serving as a base URI used in combination with a
-        <code>designation</code> token that takes the form of a fragment
-        identifier.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="profiles" name="profiles"></a>F Profiles</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <p>This appendix specifies the following standard TTML profiles:</p>
-
-      <ul>
-        <li>
-          <p><a href="#profile-dfxp-transformation"><b>F.1 DFXP Transformation
-          Profile</b></a></p>
-        </li>
-
-        <li>
-          <p><a href="#profile-dfxp-presentation"><b>F.2 DFXP Presentation
-          Profile</b></a></p>
-        </li>
-
-        <li>
-          <p><a href="#profile-dfxp-full"><b>F.3 DFXP Full Profile</b></a></p>
-        </li>
-      </ul>
-
-      <p>The SDP US profile is defined in <a href=
-      "http://www.w3.org/TR/ttml10-sdp-us/">TTML Simple Delivery Profile for
-      Closed Captions (US)</a>.</p>
-
-      <p>Each TTML profile is defined in terms of a <em>Profile Definition
-      Document</em>, which is expressed as an XML document wherein the root
-      element adheres to <a href="#parameter-vocabulary-profile"><b>6.1.1
-      ttp:profile</b></a>.</p>
-
-      <div class="div2">
-        <h3><a id="profile-dfxp-transformation" name=
-        "profile-dfxp-transformation"></a>F.1 DFXP Transformation Profile</h3>
-
-        <p>The DFXP Transformation Profile is intended to be used to express
-        minimum compliance for transformation processing.</p>
-
-        <div class="exampleInner">
-          <pre>
-&lt;?xml version="1.0" encoding="utf-8"?&gt;
-&lt;!-- this file defines the "dfxp-transformation" profile of ttml --&gt;
-&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
-  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    &lt;!-- required (mandatory) feature support --&gt;
-    &lt;feature value="required"&gt;#content&lt;/feature&gt;
-    &lt;feature value="required"&gt;#core&lt;/feature&gt;
-    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
-    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
-    &lt;feature value="required"&gt;#transformation&lt;/feature&gt;
-    &lt;!-- optional (voluntary) feature support --&gt;
-    &lt;feature value="optional"&gt;#animation&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#bidi&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#cellResolution&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-gps&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-local&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-utc&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#color&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#direction&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#displayAlign&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-dropNTSC&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-dropPAL&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-nonDrop&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent-root&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily-generic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily-non-generic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize-anamorphic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize-isomorphic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle-italic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle-oblique&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontWeight-bold&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontWeight&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#frameRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#frameRateMultiplier&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#layout&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-cell&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-em&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-integer&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-negative&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-percentage&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-pixel&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-positive&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-real&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#lineBreak-uax14&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#lineHeight&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode-continuous&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode-discontinuous&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#metadata&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#nested-div&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#nested-span&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#opacity&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#origin&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#overflow-visible&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#overflow&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-1&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-2&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-3&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-4&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#pixelAspectRatio&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#presentation&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#showBackground&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-chained&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inheritance-content&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inheritance-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-nested&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-referential&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#subFrameRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign-absolute&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign-relative&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-over&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-through&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-under&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline-blurred&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline-unblurred&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#tickRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-clock-with-frames&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-clock&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-offset-with-frames&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-offset-with-ticks&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-clock&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-media&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-smpte&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeContainer&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#unicodeBidi&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#wrapOption&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-vertical&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#zIndex&lt;/feature&gt;
-  &lt;/features&gt;
-  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
-    &lt;!-- required (mandatory) extension support --&gt;
-    &lt;!-- optional (voluntary) extension support --&gt;
-  &lt;/extensions&gt;
-&lt;/profile&gt;
-
-</pre>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="profile-dfxp-presentation" name=
-        "profile-dfxp-presentation"></a>F.2 DFXP Presentation Profile</h3>
-
-        <p>The DFXP Presentation Profile is intended to be used to express
-        minimum compliance for presentation processing.</p>
-
-        <div class="exampleInner">
-          <pre>
-&lt;?xml version="1.0" encoding="utf-8"?&gt;
-&lt;!-- this file defines the "dfxp-presentation" profile of ttml --&gt;
-&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
-  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    &lt;!-- required (mandatory) feature support --&gt;
-    &lt;feature value="required"&gt;#content&lt;/feature&gt;
-    &lt;feature value="required"&gt;#core&lt;/feature&gt;
-    &lt;feature value="required"&gt;#presentation&lt;/feature&gt;
-    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
-    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
-    &lt;!-- optional (voluntary) feature support --&gt;
-    &lt;feature value="optional"&gt;#animation&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#backgroundColor&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#bidi&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#cellResolution&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-gps&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-local&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode-utc&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#clockMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#color&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#direction&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#display&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#displayAlign&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-dropNTSC&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-dropPAL&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode-nonDrop&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#dropMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent-root&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#extent&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily-generic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily-non-generic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontFamily&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize-anamorphic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize-isomorphic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontSize&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle-italic&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle-oblique&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontStyle&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontWeight-bold&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#fontWeight&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#frameRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#frameRateMultiplier&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#layout&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-cell&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-em&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-integer&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-negative&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-percentage&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-pixel&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-positive&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length-real&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#length&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#lineBreak-uax14&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#lineHeight&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode-continuous&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode-discontinuous&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#markerMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#metadata&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#nested-div&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#nested-span&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#opacity&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#origin&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#overflow-visible&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#overflow&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-1&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-2&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-3&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding-4&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#padding&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#pixelAspectRatio&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#showBackground&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-chained&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inheritance-content&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inheritance-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-nested&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling-referential&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#styling&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#subFrameRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign-absolute&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign-relative&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textAlign&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-over&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-through&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration-under&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textDecoration&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline-blurred&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline-unblurred&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#textOutline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#tickRate&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-clock-with-frames&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-clock&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-offset-with-frames&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#time-offset-with-ticks&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-clock&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-media&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeBase-smpte&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#timeContainer&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#transformation&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#unicodeBidi&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-block&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-inline&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility-region&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#visibility&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#wrapOption&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-horizontal&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode-vertical&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#writingMode&lt;/feature&gt;
-    &lt;feature value="optional"&gt;#zIndex&lt;/feature&gt;
-  &lt;/features&gt;
-  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
-    &lt;!-- required (mandatory) extension support --&gt;
-    &lt;!-- optional (voluntary) extension support --&gt;
-  &lt;/extensions&gt;
-&lt;/profile&gt;
-
-</pre>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="profile-dfxp-full" name="profile-dfxp-full"></a>F.3 DFXP
-        Full Profile</h3>
-
-        <p>The DFXP Full Profile is intended to be used to express maximum
-        compliance for both transformation and presentation processing.</p>
-
-        <div class="exampleInner">
-          <pre>
-&lt;?xml version="1.0" encoding="utf-8"?&gt;
-&lt;!-- this file defines the "dfxp-full" profile of ttml --&gt;
-&lt;profile xmlns="http://www.w3.org/ns/ttml#parameter"&gt;
-  &lt;features xml:base="http://www.w3.org/ns/ttml/feature/"&gt;
-    &lt;!-- required (mandatory) feature support --&gt;
-    &lt;feature value="required"&gt;#animation&lt;/feature&gt;
-    &lt;feature value="required"&gt;#backgroundColor-block&lt;/feature&gt;
-    &lt;feature value="required"&gt;#backgroundColor-inline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#backgroundColor-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#backgroundColor&lt;/feature&gt;
-    &lt;feature value="required"&gt;#bidi&lt;/feature&gt;
-    &lt;feature value="required"&gt;#cellResolution&lt;/feature&gt;
-    &lt;feature value="required"&gt;#clockMode-gps&lt;/feature&gt;
-    &lt;feature value="required"&gt;#clockMode-local&lt;/feature&gt;
-    &lt;feature value="required"&gt;#clockMode-utc&lt;/feature&gt;
-    &lt;feature value="required"&gt;#clockMode&lt;/feature&gt;
-    &lt;feature value="required"&gt;#color&lt;/feature&gt;
-    &lt;feature value="required"&gt;#content&lt;/feature&gt;
-    &lt;feature value="required"&gt;#core&lt;/feature&gt;
-    &lt;feature value="required"&gt;#direction&lt;/feature&gt;
-    &lt;feature value="required"&gt;#display-block&lt;/feature&gt;
-    &lt;feature value="required"&gt;#display-inline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#display-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#display&lt;/feature&gt;
-    &lt;feature value="required"&gt;#displayAlign&lt;/feature&gt;
-    &lt;feature value="required"&gt;#dropMode-dropNTSC&lt;/feature&gt;
-    &lt;feature value="required"&gt;#dropMode-dropPAL&lt;/feature&gt;
-    &lt;feature value="required"&gt;#dropMode-nonDrop&lt;/feature&gt;
-    &lt;feature value="required"&gt;#dropMode&lt;/feature&gt;
-    &lt;feature value="required"&gt;#extent-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#extent-root&lt;/feature&gt;
-    &lt;feature value="required"&gt;#extent&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontFamily-generic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontFamily-non-generic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontFamily&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontSize-anamorphic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontSize-isomorphic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontSize&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontStyle-italic&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontStyle-oblique&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontStyle&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontWeight-bold&lt;/feature&gt;
-    &lt;feature value="required"&gt;#fontWeight&lt;/feature&gt;
-    &lt;feature value="required"&gt;#frameRate&lt;/feature&gt;
-    &lt;feature value="required"&gt;#frameRateMultiplier&lt;/feature&gt;
-    &lt;feature value="required"&gt;#layout&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-cell&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-em&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-integer&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-negative&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-percentage&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-pixel&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-positive&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length-real&lt;/feature&gt;
-    &lt;feature value="required"&gt;#length&lt;/feature&gt;
-    &lt;feature value="required"&gt;#lineBreak-uax14&lt;/feature&gt;
-    &lt;feature value="required"&gt;#lineHeight&lt;/feature&gt;
-    &lt;feature value="required"&gt;#markerMode-continuous&lt;/feature&gt;
-    &lt;feature value="required"&gt;#markerMode-discontinuous&lt;/feature&gt;
-    &lt;feature value="required"&gt;#markerMode&lt;/feature&gt;
-    &lt;feature value="required"&gt;#metadata&lt;/feature&gt;
-    &lt;feature value="required"&gt;#nested-div&lt;/feature&gt;
-    &lt;feature value="required"&gt;#nested-span&lt;/feature&gt;
-    &lt;feature value="required"&gt;#opacity&lt;/feature&gt;
-    &lt;feature value="required"&gt;#origin&lt;/feature&gt;
-    &lt;feature value="required"&gt;#overflow-visible&lt;/feature&gt;
-    &lt;feature value="required"&gt;#overflow&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding-1&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding-2&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding-3&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding-4&lt;/feature&gt;
-    &lt;feature value="required"&gt;#padding&lt;/feature&gt;
-    &lt;feature value="required"&gt;#pixelAspectRatio&lt;/feature&gt;
-    &lt;feature value="required"&gt;#presentation&lt;/feature&gt;
-    &lt;feature value="required"&gt;#profile&lt;/feature&gt;
-    &lt;feature value="required"&gt;#showBackground&lt;/feature&gt;
-    &lt;feature value="required"&gt;#structure&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-chained&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-inheritance-content&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-inheritance-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-inline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-nested&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling-referential&lt;/feature&gt;
-    &lt;feature value="required"&gt;#styling&lt;/feature&gt;
-    &lt;feature value="required"&gt;#subFrameRate&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textAlign-absolute&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textAlign-relative&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textAlign&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textDecoration-over&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textDecoration-through&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textDecoration-under&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textDecoration&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textOutline-blurred&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textOutline-unblurred&lt;/feature&gt;
-    &lt;feature value="required"&gt;#textOutline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#tickRate&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-clock-with-frames&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-clock&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset-with-frames&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset-with-ticks&lt;/feature&gt;
-    &lt;feature value="required"&gt;#time-offset&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timeBase-clock&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timeBase-media&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timeBase-smpte&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timeContainer&lt;/feature&gt;
-    &lt;feature value="required"&gt;#timing&lt;/feature&gt;
-    &lt;feature value="required"&gt;#transformation&lt;/feature&gt;
-    &lt;feature value="required"&gt;#unicodeBidi&lt;/feature&gt;
-    &lt;feature value="required"&gt;#visibility-block&lt;/feature&gt;
-    &lt;feature value="required"&gt;#visibility-inline&lt;/feature&gt;
-    &lt;feature value="required"&gt;#visibility-region&lt;/feature&gt;
-    &lt;feature value="required"&gt;#visibility&lt;/feature&gt;
-    &lt;feature value="required"&gt;#wrapOption&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode-horizontal-lr&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode-horizontal-rl&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode-horizontal&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode-vertical&lt;/feature&gt;
-    &lt;feature value="required"&gt;#writingMode&lt;/feature&gt;
-    &lt;feature value="required"&gt;#zIndex&lt;/feature&gt;
-    &lt;!-- optional (voluntary) feature support --&gt;
-  &lt;/features&gt;
-  &lt;extensions xml:base="http://www.w3.org/ns/ttml/extension/"&gt;
-    &lt;!-- required (mandatory) extension support --&gt;
-    &lt;!-- optional (voluntary) extension support --&gt;
-  &lt;/extensions&gt;
-&lt;/profile&gt;
-
-</pre>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="references" name="references"></a>G References</h2>
-
-      <p><em>This appendix is normative.</em></p>
-
-      <dl>
-        <dt class="label"><a id="css2" name="css2"></a>CSS2</dt>
-
-        <dd>Bert Bos et al., <a href=
-        "http://www.w3.org/TR/2011/REC-CSS2-20110607/"><cite>Cascading Style
-        Sheets, Level 2 Revision 1</cite></a>, W3C Recommendation, 07 June
-        2011. (See <a href=
-        "http://www.w3.org/TR/2011/REC-CSS2-20110607/">http://www.w3.org/TR/2011/REC-CSS2-20110607/</a>.)</dd>
-
-        <dt class="label"><a id="css3-color" name="css3-color"></a>CSS3
-        Color</dt>
-
-        <dd>Tantek Çelik and Chris Lilley, <a href=
-        "http://www.w3.org/TR/2011/REC-css3-color-20110607/"><cite>CSS Color
-        Module Level 3</cite></a>, W3C Recommendation, 07 June 2011. (See
-        <a href=
-        "http://www.w3.org/TR/2011/REC-css3-color-20110607/">http://www.w3.org/TR/2011/REC-css3-color-20110607/</a>.)</dd>
-
-        <dt class="label"><a id="gps" name="gps"></a>GPS</dt>
-
-        <dd><a href="http://tycho.usno.navy.mil/gpsinfo.html"><cite>Global
-        Positioning System</cite></a>, US Naval Observatory. (See <a href=
-        "http://tycho.usno.navy.mil/gpsinfo.html">http://tycho.usno.navy.mil/gpsinfo.html</a>.)</dd>
-
-        <dt class="label"><a id="media-types" name="media-types"></a>Media
-        Types</dt>
-
-        <dd>Ned Freed and Nathaniel Borenstein, <a href=
-        "http://www.rfc-editor.org/rfc/rfc2046.txt"><cite>Multipurpose Internet
-        Mail Extensions (MIME) Part Two: Media Types</cite></a>, RFC 2046,
-        November 1996, IETF.(See <a href=
-        "http://www.rfc-editor.org/rfc/rfc2046.txt">http://www.rfc-editor.org/rfc/rfc2046.txt</a>.)</dd>
-
-        <dt class="label"><a id="rng" name="rng"></a>RELAX NG</dt>
-
-        <dd>ISO/IEC 19757-2, <a href="http://www.iso.org/"><cite>Information
-        technology – Document Schema Definition Language (DSDL) – Part 2:
-        Regular-grammar-based validation – RELAX NG</cite></a>, International
-        Organization for Standardization (ISO).</dd>
-
-        <dt class="label"><a id="smil21" name="smil21"></a>SMIL 2.1</dt>
-
-        <dd>Dick Bultermann, et al., <a href=
-        "http://www.w3.org/TR/2005/REC-SMIL2-20051213/"><cite>Synchronized
-        Multimedia Integration Language (SMIL 2.1)</cite></a>, W3C
-        Recommendation, 13 December 2005. (See <a href=
-        "http://www.w3.org/TR/2005/REC-SMIL2-20051213/">http://www.w3.org/TR/2005/REC-SMIL2-20051213/</a>.)</dd>
-
-        <dt class="label"><a id="smpte12m" name="smpte12m"></a>SMPTE 12M</dt>
-
-        <dd>ANSI/SMPTE 12M, <a href="https://www.smpte.org/"><cite>Television,
-        Audio and Film – Time and Control Code</cite></a>, SMPTE Standard.</dd>
-
-        <dt class="label"><a id="srgb" name="srgb"></a>SRGB</dt>
-
-        <dd>IEC 61966-2-1, <a href="http://www.iec.ch/"><cite>Multimedia
-        systems and equipment – Colour measurement and management – Part 2-1:
-        Colour management – Default RGB colour space – sRGB</cite></a>,
-        International Electrotechnical Commission (IEC).</dd>
-
-        <dt class="label"><a id="uaag" name="uaag"></a>UAAG</dt>
-
-        <dd>Ian Jacobs, Jon Gunderson, and Eric Hansen, Eds., <a href=
-        "http://www.w3.org/TR/2002/REC-UAAG10-20021217/"><cite>User Agent
-        Accessibility Guidelines 1.0</cite></a>, W3C Recommendation, 17
-        December 2002. (See <a href=
-        "http://www.w3.org/TR/2002/REC-UAAG10-20021217/">http://www.w3.org/TR/2002/REC-UAAG10-20021217/</a>.)</dd>
-
-        <dt class="label"><a id="uax14" name="uax14"></a>UAX14</dt>
-
-        <dd>Asmus Freytag, <a href=
-        "http://www.unicode.org/reports/tr14/tr14-17.html"><cite>Line Breaking
-        Properties</cite></a>, Unicode Consortium, 29 August 2005. (See
-        <a href="http://www.unicode.org/reports/tr14/tr14-17.html">http://www.unicode.org/reports/tr14/tr14-17.html</a>.)</dd>
-
-        <dt class="label"><a id="utc" name="utc"></a>UTC</dt>
-
-        <dd>Recommendation TF.460, <a href=
-        "http://www.itu.int/"><cite>Standard-Frequency and Time-Signal
-        Emissions</cite></a>, International Telecommunciations Union, Radio
-        Sector (ITU-R).</dd>
-
-        <dt class="label"><a id="wcag" name="wcag"></a>WCAG</dt>
-
-        <dd>Ben Caldwell, et al., Eds., <a href=
-        "http://www.w3.org/TR/2008/REC-WCAG20-20081211/"><cite>Web Content
-        Accessibility Guidelines (WCAG) 2.0</cite></a>, W3C Recommendation, 11
-        December 2008. (See <a href=
-        "http://www.w3.org/TR/2008/REC-WCAG20-20081211/">http://www.w3.org/TR/2008/REC-WCAG20-20081211/</a>.)</dd>
-
-        <dt class="label"><a id="xml10" name="xml10"></a>XML 1.0</dt>
-
-        <dd>Tim Bray, et al. <a href=
-        "http://www.w3.org/TR/2008/REC-xml-20081126/"><cite>Extensible Markup
-        Language (XML) 1.0 (Fifth Edition)</cite></a>, W3C Recommendation, 26
-        November 2008. (See <a href=
-        "http://www.w3.org/TR/2008/REC-xml-20081126/">http://www.w3.org/TR/2008/REC-xml-20081126/</a>.)</dd>
-
-        <dt class="label"><a id="xml11" name="xml11"></a>XML 1.1</dt>
-
-        <dd>Tim Bray, et al. <a href=
-        "http://www.w3.org/TR/2006/REC-xml11-20060816/"><cite>Extensible Markup
-        Language (XML) 1.1 (Second Edition)</cite></a>, W3C Recommendation, 16
-        August 2006, edited in place 29 September 2006. (See <a href=
-        "http://www.w3.org/TR/2006/REC-xml11-20060816/">http://www.w3.org/TR/2006/REC-xml11-20060816/</a>.)</dd>
-
-        <dt class="label"><a id="xmlbase" name="xmlbase"></a>XML Base</dt>
-
-        <dd>Jonathan Marsh and Richard Tobin, Eds., <a href=
-        "http://www.w3.org/TR/2009/REC-xmlbase-20090128/"><cite>XML Base
-        (Second Edition)</cite></a>, W3C Recommendation, 28 January 2009. (See
-        <a href=
-        "http://www.w3.org/TR/2009/REC-xmlbase-20090128/">http://www.w3.org/TR/2009/REC-xmlbase-20090128/</a>.)</dd>
-
-        <dt class="label"><a id="xmlid" name="xmlid"></a>XML ID</dt>
-
-        <dd>Jonathan Marsh, Daniel Veillard, Norman Walsh, Eds., <a href=
-        "http://www.w3.org/TR/2005/REC-xml-id-20050909/"><cite>xml:id Version
-        1.0</cite></a>, W3C Recommendation, 09 September 2005. (See <a href=
-        "http://www.w3.org/TR/2005/REC-xml-id-20050909/">http://www.w3.org/TR/2005/REC-xml-id-20050909/</a>.)</dd>
-
-        <dt class="label"><a id="infoset" name="infoset"></a>XML InfoSet</dt>
-
-        <dd>John Cowan and Richard Tobin, Eds., <a href=
-        "http://www.w3.org/TR/2004/REC-xml-infoset-20040204/"><cite>XML
-        Information Set (Second Edition)</cite></a>, W3C Recommendation, 04
-        February 2004. (See <a href=
-        "http://www.w3.org/TR/2004/REC-xml-infoset-20040204/">http://www.w3.org/TR/2004/REC-xml-infoset-20040204/</a>.)</dd>
-
-        <dt class="label"><a id="xml-media" name="xml-media"></a>XML Media
-        Types</dt>
-
-        <dd>Makato Murata, Simon St. Laurent, Kan Khon, Eds., <a href=
-        "http://www.rfc-editor.org/rfc/rfc3023.txt"><cite>XML Media
-        Types</cite></a>, RFC 3023, January 2001, IETF.(See <a href=
-        "http://www.rfc-editor.org/rfc/rfc3023.txt">http://www.rfc-editor.org/rfc/rfc3023.txt</a>.)</dd>
-
-        <dt class="label"><a id="xmlns10" name="xmlns10"></a>XML Namespaces
-        1.0</dt>
-
-        <dd>Tim Bray, et al. <a href=
-        "http://www.w3.org/TR/2009/REC-xml-names-20091208/"><cite>Namespaces in
-        XML 1.0 (Third Edition)</cite></a>, W3C Recommendation, 8 December
-        2009. (See <a href=
-        "http://www.w3.org/TR/2009/REC-xml-names-20091208/">http://www.w3.org/TR/2009/REC-xml-names-20091208/</a>.)</dd>
-
-        <dt class="label"><a id="xsd-1" name="xsd-1"></a>XML Schema Part 1</dt>
-
-        <dd>Henry S. Thompson, David Beech, Murray Maloney, Noah Mendelsohn,
-        Eds., <a href="http://www.w3.org/TR/xmlschema-1/"><cite>XML Schema Part
-        1: Structures</cite></a>, W3C Recommendation, 28 October 2004. (See
-        <a href=
-        "http://www.w3.org/TR/xmlschema-1/">http://www.w3.org/TR/xmlschema-1/</a>.)</dd>
-
-        <dt class="label"><a id="xsd-2" name="xsd-2"></a>XML Schema Part 2</dt>
-
-        <dd>Paul Biron and Ashok Malhotra, <a href=
-        "http://www.w3.org/TR/xmlschema-2/"><cite>XML Schema Part 2:
-        Datatypes</cite></a>, W3C Recommendation, 28 October 2004. (See
-        <a href="http://www.w3.org/TR/xmlschema-2/">http://www.w3.org/TR/xmlschema-2/</a>.)</dd>
-
-        <dt class="label"><a id="xsl11" name="xsl11"></a>XSL 1.1</dt>
-
-        <dd>Anders Berglund, <a href=
-        "http://www.w3.org/TR/2006/REC-xsl11-20061205/"><cite>Extensible
-        Stylesheet Language (XSL) Version 1.1</cite></a>, W3C Recommendation,
-        05 December 2006. (See <a href=
-        "http://www.w3.org/TR/2006/REC-xsl11-20061205/">http://www.w3.org/TR/2006/REC-xsl11-20061205/</a>.)</dd>
-      </dl>
-    </div>
-
-    <div class="div1">
-      <h2><a id="other-references" name="other-references"></a>H Other
-      References (Non-Normative)</h2>
-
-      <dl>
-        <dt class="label"><a id="ccreq" name="ccreq"></a>CC-DECODER-REQ</dt>
-
-        <dd><a href=
-        "http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml">
-        <cite>Closed Caption Decoder Requirements for Analog
-        Television</cite></a>, United States Code of Federal Regulations, Title
-        47, Volume 1, Part 15, § 15.119. (See <a href=
-        "http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml">
-        http://www.gpo.gov/fdsys/pkg/CFR-2005-title47-vol1/xml/CFR-2005-title47-vol1-sec15-119.xml</a>.)</dd>
-
-        <dt class="label"><a id="cea608c" name="cea608c"></a>CEA-608-C</dt>
-
-        <dd>EIA/CEA-608-C, <a href="http://www.ce.org/"><cite>Line 21 Data
-        Services</cite></a>, EIA/CEA Standard, Consumer Electronics Association
-        (CEA).</dd>
-
-        <dt class="label"><a id="cea708d" name="cea708d"></a>CEA-708-D</dt>
-
-        <dd>CEA-708-D, <a href="http://www.ce.org/"><cite>Digital Television
-        (DTV) Closed Captioning</cite></a>, CEA Standard, Consumer Electronics
-        Association (CEA).</dd>
-
-        <dt class="label"><a id="dcmes" name="dcmes"></a>DCMES 1.1</dt>
-
-        <dd>Dublin Core Metadata Initiative, <a href=
-        "http://dublincore.org/documents/dces/"><cite>Dublin Core Metadata
-        Element Set, Version 1.1: Reference Description</cite></a>. (See
-        <a href=
-        "http://dublincore.org/documents/dces/">http://dublincore.org/documents/dces/</a>.)</dd>
-
-        <dt class="label"><a id="mpeg7-5" name="mpeg7-5"></a>MPEG7-5</dt>
-
-        <dd>ISO/IEC 15938-5, <a href="http://www.iso.org/"><cite>Information
-        technology – Multimedia content description interface – Part 5:
-        Multimedia description schemes</cite></a>, International Organization
-        for Standardization (ISO).</dd>
-
-        <dt class="label"><a id="nsstate" name="nsstate"></a>NSState</dt>
-
-        <dd>Norman Walsh, Ed., <a href=
-        "http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09.html"><cite>The
-        Disposition of Names in an XML Namespace</cite></a>, TAG Finding, 9
-        January 2006. (See <a href=
-        "http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09.html">http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09</a>.)</dd>
-
-        <dt class="label"><a id="qaf-sg" name="qaf-sg"></a>QAF SG</dt>
-
-        <dd>Karl Dubost, et al., <a href=
-        "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/"><cite>QA
-        Framework: Specifications Guidelines</cite></a>, W3C Recommendation, 17
-        August 2005. (See <a href=
-        "http://www.w3.org/TR/qaframe-spec/">http://www.w3.org/TR/qaframe-spec/</a>.)</dd>
-
-        <dt class="label"><a id="smpte170m" name="smpte170m"></a>SMPTE
-        170M</dt>
-
-        <dd>ANSI/SMPTE 170M, <a href="http://www.smpte.org/"><cite>Television –
-        Composite Analog Video Signal – NTSC for Studio
-        Applications</cite></a>, SMPTE Standard.</dd>
-
-        <dt class="label"><a id="smpte2052" name="smpte2052"></a>SMPTE
-        2052-11</dt>
-
-        <dd>SMPTE 2052-11, <a href="http://www.smpte.org/"><cite>Conversion
-        from CEA-708 Caption Data to SMPTE-TT</cite></a>, SMPTE Recommended
-        Practice.</dd>
-
-        <dt class="label"><a id="svg11" name="svg11"></a>SVG 1.1</dt>
-
-        <dd>Jon Ferraiolo, Jun Fujisawa, Dean Jackson, Eds., <a href=
-        "http://www.w3.org/TR/2003/REC-SVG11-20030114/"><cite>Scalable Vector
-        Graphics (SVG) 1.1 Specification</cite></a>, W3C Recommendation, 14
-        January 2003. (See <a href=
-        "http://www.w3.org/TR/2003/REC-SVG11-20030114/">http://www.w3.org/TR/2003/REC-SVG11-20030114/</a>.)</dd>
-
-        <dt class="label"><a id="ttaf1-req" name="ttaf1-req"></a>TTAF1-REQ</dt>
-
-        <dd>Glenn Adams, Ed., <a href=
-        "http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/"><cite>Timed Text
-        (TT) Authoring Format 1.0 Use Cases and Requirements</cite></a>, W3C
-        Working Group Note, 27 April 2006. (See <a href=
-        "http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/">http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/</a>.)</dd>
-
-        <dt class="label"><a id="xhtml10" name="xhtml10"></a>XHTML 1.0</dt>
-
-        <dd>Steven Pemberton, et al., <a href=
-        "http://www.w3.org/TR/2002/REC-xhtml1-20020801/"><cite>XHTML™ 1.0, The
-        Extensible Hypertext Markup Language (Second Edition)</cite></a>, W3C
-        Recommendation, 01 August 2002. (See <a href=
-        "http://www.w3.org/TR/2002/REC-xhtml1-20020801/">http://www.w3.org/TR/2002/REC-xhtml1-20020801/</a>.)</dd>
-      </dl>
-    </div>
-
-    <div class="div1">
-      <h2><a id="requirements" name="requirements"></a>I Requirements
-      (Non-Normative)</h2>
-
-      <p>The Timed Text Markup Language (TTML), also known as the Distribution
-      Format Exchange Profile (DFXP) of the Timed Text Authoring Format (TTAF),
-      satisfies a subset of the requirements established by <a href=
-      "#ttaf1-req">[TTAF1-REQ]</a>. The following table enumerates these
-      requirements and indicates the extent to which they are satisfied by this
-      specification, where <em>S</em> denotes a requirement is satisfied,
-      <em>P</em> denotes a requirement is partially satisfied, and <em>N</em>
-      denotes a requirement is not satisfied.</p><a id="requirements-table"
-      name="requirements-table"></a>
-
-      <table class="common">
-        <caption>
-          Table I-1 – Requirement Satisfaction
-        </caption>
-        <col width="10%" span="1">
-        <col width="40%" span="1">
-        <col width="10%" span="1">
-        <col span="1">
-
-        <tbody>
-          <tr>
-            <th>ID</th>
-
-            <th>Name</th>
-
-            <th>Status</th>
-
-            <th>Comments</th>
-          </tr>
-
-          <tr>
-            <td>R100</td>
-
-            <td>Specification Format</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R101</td>
-
-            <td>Specification Modularity</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R102</td>
-
-            <td>Specification Organization</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R103</td>
-
-            <td>Core and Periphery</td>
-
-            <td>S</td>
-
-            <td>TT extension namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R104</td>
-
-            <td>Evolution of Core</td>
-
-            <td>S</td>
-
-            <td>TT extension namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R105</td>
-
-            <td>Ownership of Core</td>
-
-            <td>S</td>
-
-            <td>TT namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R106</td>
-
-            <td>Surjection of Core</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R107</td>
-
-            <td>Evolution of Periphery</td>
-
-            <td>S</td>
-
-            <td>TT extension namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R108</td>
-
-            <td>Ownership of Periphery</td>
-
-            <td>S</td>
-
-            <td>Non-TT namespaces</td>
-          </tr>
-
-          <tr>
-            <td>R109</td>
-
-            <td>Transformation</td>
-
-            <td>S</td>
-
-            <td>Supports 3GPP, QText, RealText, SAMI</td>
-          </tr>
-
-          <tr>
-            <td>R110</td>
-
-            <td>Streamable Transformation</td>
-
-            <td>S</td>
-
-            <td>Progressive decoding</td>
-          </tr>
-
-          <tr>
-            <td>R111</td>
-
-            <td>Accessibility – Content</td>
-
-            <td>S</td>
-
-            <td>Alternative document instances</td>
-          </tr>
-
-          <tr>
-            <td>R112</td>
-
-            <td>Accessibility – Authoring System</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R200</td>
-
-            <td>Authorability</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R201</td>
-
-            <td>Multiple Natural Languages</td>
-
-            <td>S</td>
-
-            <td>Alternative document instances</td>
-          </tr>
-
-          <tr>
-            <td>R202</td>
-
-            <td>Natural Language Coverage</td>
-
-            <td>S</td>
-
-            <td>Unicode 4.0</td>
-          </tr>
-
-          <tr>
-            <td>R203</td>
-
-            <td>Natural Language Association Granularity</td>
-
-            <td>S</td>
-
-            <td>See <code>xml:lang</code></td>
-          </tr>
-
-          <tr>
-            <td>R204</td>
-
-            <td>Minimum Character Representability</td>
-
-            <td>S</td>
-
-            <td>Unicode 4.0</td>
-          </tr>
-
-          <tr>
-            <td>R205</td>
-
-            <td>Intrinsic and Extrinsic Text Content</td>
-
-            <td>P</td>
-
-            <td>Intrinsic only</td>
-          </tr>
-
-          <tr>
-            <td>R206</td>
-
-            <td>Markup Association</td>
-
-            <td>P</td>
-
-            <td>Intrinsic only</td>
-          </tr>
-
-          <tr>
-            <td>R207</td>
-
-            <td>Conditional Content</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R208</td>
-
-            <td>Flowed Text</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R209</td>
-
-            <td>Logical Flowed Text Vocabulary</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R210</td>
-
-            <td>Presentational Flowed Text Vocabulary</td>
-
-            <td>S</td>
-
-            <td>Implied mapping from logical flowed text.</td>
-          </tr>
-
-          <tr>
-            <td>R211</td>
-
-            <td>Flowed Text Vocabulary Relationship</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R212</td>
-
-            <td>Flowed Text Vocabulary Separation</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R213</td>
-
-            <td>Non-Flowed Text</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R214</td>
-
-            <td>Non-Flowed Text Vocabulary</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R215</td>
-
-            <td>Hybrid Flowed and Non-Flowed Text</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R216</td>
-
-            <td>Hyperlinking</td>
-
-            <td>N</td>
-
-            <td>Can support via XLink</td>
-          </tr>
-
-          <tr>
-            <td>R217</td>
-
-            <td>Embedded Graphics</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R218</td>
-
-            <td>Non-Embedded Graphics</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R219</td>
-
-            <td>Embedded Fonts</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R220</td>
-
-            <td>Non-Embedded Fonts</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R221</td>
-
-            <td>Descriptive Vocabulary</td>
-
-            <td>S</td>
-
-            <td>See <code>ttm:agent</code>, <code>ttm:role</code></td>
-          </tr>
-
-          <tr>
-            <td>R222</td>
-
-            <td>Embedded Audio</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R223</td>
-
-            <td>Non-Embedded Audio</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R290</td>
-
-            <td>Markup Format</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R291</td>
-
-            <td>Markup Format and Unicode Interaction</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R292</td>
-
-            <td>Extrinsic Resource References</td>
-
-            <td>N</td>
-
-            <td>No extrinsic references</td>
-          </tr>
-
-          <tr>
-            <td>R293</td>
-
-            <td>Schema Validity Specification</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R300</td>
-
-            <td>Inline Styling</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R301</td>
-
-            <td>Inline Styling Form</td>
-
-            <td>P</td>
-
-            <td>Inline and referential styling</td>
-          </tr>
-
-          <tr>
-            <td>R301</td>
-
-            <td>Out-of-Line Styling</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R301</td>
-
-            <td>Out-of-Line Styling Form</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R304</td>
-
-            <td>Styling Prioritization</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R305</td>
-
-            <td>Style Parameters – Aural</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R306</td>
-
-            <td>Style Parameters – Visual</td>
-
-            <td>P</td>
-
-            <td>Supports absolute position, background color, color, display
-            none, display alignment, font family, font size, font style, font
-            weight, height, line height, origin, opacity, overflow, padding
-            (before, after, start, end), text alignment, text shadow (as
-            outline), visibility, width, writing mode, z-index</td>
-          </tr>
-
-          <tr>
-            <td>R390</td>
-
-            <td>Style Parameter Symmetry</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R391</td>
-
-            <td>Style Parameter Definitions</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R392</td>
-
-            <td>Style Parameter Shorthands</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R401</td>
-
-            <td>Inline Timing</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R402</td>
-
-            <td>Out-of-Line Timing</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R403</td>
-
-            <td>Synchronization Parameters</td>
-
-            <td>P</td>
-
-            <td>Supports begin, end, dur</td>
-          </tr>
-
-          <tr>
-            <td>R404</td>
-
-            <td>Synchronization Parameter Value Spaces</td>
-
-            <td>P</td>
-
-            <td>Supports offset values, media marker values (SMPTE 12M),
-            wall-clock values</td>
-          </tr>
-
-          <tr>
-            <td>R405</td>
-
-            <td>Time Containment Semantics</td>
-
-            <td>P</td>
-
-            <td>Supports sequential, parallel</td>
-          </tr>
-
-          <tr>
-            <td>R500</td>
-
-            <td>Animation Modes</td>
-
-            <td>P</td>
-
-            <td>Supports discrete</td>
-          </tr>
-
-          <tr>
-            <td>R502</td>
-
-            <td>Highlight Animation</td>
-
-            <td>S</td>
-
-            <td><code>&lt;set tts:backgroundColor="..."/&gt;</code></td>
-          </tr>
-
-          <tr>
-            <td>R503</td>
-
-            <td>Fade Transition Animation</td>
-
-            <td>S</td>
-
-            <td><code>&lt;set tts:opacity="..."/&gt;</code></td>
-          </tr>
-
-          <tr>
-            <td>R504</td>
-
-            <td>Animated Style Parameters – Aural</td>
-
-            <td>N</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R505</td>
-
-            <td>Animated Style Parameters – Visual</td>
-
-            <td>P</td>
-
-            <td>Supports animating background color, color, display, opacity,
-            origin, visibility</td>
-          </tr>
-
-          <tr>
-            <td>N506</td>
-
-            <td>Animated Content</td>
-
-            <td>S</td>
-
-            <td></td>
-          </tr>
-
-          <tr>
-            <td>R600</td>
-
-            <td>Metadata Item Association</td>
-
-            <td>S</td>
-
-            <td>See <code>metadata</code>, <code>Metadata.class</code></td>
-          </tr>
-
-          <tr>
-            <td>R601</td>
-
-            <td>Metadata Item Constituents</td>
-
-            <td>P</td>
-
-            <td>Supports name, value</td>
-          </tr>
-
-          <tr>
-            <td>R602</td>
-
-            <td>Metadata Item Value Representation</td>
-
-            <td>P</td>
-
-            <td>See <code>metadata</code></td>
-          </tr>
-
-          <tr>
-            <td>R603</td>
-
-            <td>Metadata Item Extensibility</td>
-
-            <td>S</td>
-
-            <td>See <code>metadata</code></td>
-          </tr>
-
-          <tr>
-            <td>R604</td>
-
-            <td>Metadata Item Validation</td>
-
-            <td>S</td>
-
-            <td>See <code>metadata</code></td>
-          </tr>
-
-          <tr>
-            <td>R690</td>
-
-            <td>Dublin Core Preference</td>
-
-            <td>N</td>
-
-            <td>Uses <code>ttm:copyright</code>, <code>ttm:desc</code>,
-            <code>ttm:title</code></td>
-          </tr>
-        </tbody>
-      </table>
-    </div>
-
-    <div class="div1">
-      <h2><a id="derivation" name="derivation"></a>J Vocabulary Derivation
-      (Non-Normative)</h2>
-
-      <p>This appendix provides information about the derivation of TTML
-      vocabulary, separately describing derivation of elements and
-      attributes.</p>
-
-      <div class="div2">
-        <h3><a id="d3e18638" name="d3e18638"></a>J.1 Element Derivation</h3>
-
-        <p>The first column of <a href=
-        "#element-vocab-derivation-table"><b>Table J-1 – Elements</b></a>
-        specifies a TTML element vocabulary item; the second column specifies
-        the syntactic and/or semantic model on which the vocabulary item is
-        based; the third column specifies the reference that defines the model
-        (if a model is indicated); the fourth column specifies details about
-        the derivation; the last column refers to additional notes describing
-        the nature of the derivation.</p>
-
-        <p>In the fourth column, which describes details of derivation, a
-        notation is use to indicate the addition or removal of an attribute.
-        For example, in the derivation of the <code>tt:div</code> element, the
-        details column includes "-@class", which denotes that the
-        <code>class</code> attribute that is specified for use with the
-        <code>xhtml:div</code> model element is not specified for use with the
-        corresponding TTML element; in contrast, the details column includes
-        "+@begin", which denotes that a <code>begin</code> attribute is added
-        that is not specified for use with the <code>xhtml:div</code> model
-        element.</p><a id="element-vocab-derivation-table" name=
-        "element-vocab-derivation-table"></a>
-
-        <table class="common">
-          <caption>
-            Table J-1 – Elements
-          </caption>
-          <col width="20%" span="1">
-          <col width="17%" span="1">
-          <col width="13%" align="center" span="1">
-          <col width="40%" span="1">
-          <col width="10%" align="center" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Element</span></td>
-
-              <td><span class="strong">Model</span></td>
-
-              <td><span class="strong">Reference</span></td>
-
-              <td><span class="strong">Details</span></td>
-
-              <td><span class="strong">Notes</span></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#document-structure-vocabulary-body"><code>tt:body</code></a></td>
-
-              <td><code>xhtml:body</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur,
-              +@end, +@region, +@timeContainer, +@ttm:*, +@tts:*; content model
-              subsetted to zero or more division (div) children, and
-              supersetted by optional metadata and animation children</td>
-
-              <td>1,2</td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-vocabulary-br"><code>tt:br</code></a></td>
-
-              <td><code>xhtml:br</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@title; +@ttm:*, +@tts:*, +@xml:lang, +@xml:space;
-              content model supersetted by optional metadata and animation
-              children for congruity with other content vocabulary</td>
-
-              <td>1,2</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#content-vocabulary-div"><code>tt:div</code></a></td>
-
-              <td><code>xhtml:div</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur,
-              +@end, +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space;
-              content model subsetted to zero or more paragraph (p) children,
-              and supersetted by optional metadata and animation children</td>
-
-              <td>1,2,3</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#document-structure-vocabulary-head"><code>tt:head</code></a></td>
-
-              <td><code>xhtml:head</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@dir, -@lang, -@profile; +@id, +@xml:space; content model
-              changed to optional metadata children, followed by optional
-              styling child, followed by optional layout child</td>
-
-              <td>1,3</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#layout-vocabulary-layout"><code>tt:layout</code></a></td>
-
-              <td><code>fo:simple-page-master</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-metadata"><code>tt:metadata</code></a></td>
-
-              <td><code>svg:metadata</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>-@xml:base; +@ttm:*, +@xml:lang, +@xml:space; content model
-              subsetted to foreign namespace element content only (no
-              #PCDATA)</td>
-
-              <td>3,5</td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-vocabulary-p"><code>tt:p</code></a></td>
-
-              <td><code>xhtml:p</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur,
-              +@end, +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space;
-              content model subsetted to zero or more span children, and
-              supersetted by optional metadata and animation children</td>
-
-              <td>1,2,3</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#layout-vocabulary-region"><code>tt:region</code></a></td>
-
-              <td><code>fo:region-*</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#animation-vocabulary-set"><code>tt:set</code></a></td>
-
-              <td><code>svg:set</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>-@* except begin, dur, end; +@tts:*, +@xml:lang,
-              +@xml:space</td>
-
-              <td>3,6</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#content-vocabulary-span"><code>tt:span</code></a></td>
-
-              <td><code>xhtml:span</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur,
-              +@end, +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space;
-              content model subsetted to zero or more #PCDATA or break (br)
-              children, and supersetted by optional metadata and animation
-              children</td>
-
-              <td>1,2,3</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#styling-vocabulary-style"><code>tt:style</code></a></td>
-
-              <td><em>style specification</em></td>
-
-              <td><a href="#css2">[CSS2]</a></td>
-
-              <td>XML representation of identified set of pairs of style
-              property name and value, with optional inclusion of other styles
-              by reference to other style elements</td>
-
-              <td>7</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#styling-vocabulary-styling"><code>tt:styling</code></a></td>
-
-              <td><code>xhtml:style</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>XML representation of a set of style specifications sets,
-              each represented by a style child element</td>
-
-              <td>1,7</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#document-structure-vocabulary-tt"><code>tt:tt</code></a></td>
-
-              <td><code>xhtml:html</code></td>
-
-              <td><a href="#xhtml10">[XHTML 1.0]</a></td>
-
-              <td>-@dir, -@lang; +@id, +@ttp:*, +@xml:space; content model
-              subsetted by permitting body and/or head to be optional</td>
-
-              <td>1,8</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-actor"><code>ttm:actor</code></a></td>
-
-              <td><code>mpeg7:Creator</code></td>
-
-              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-agent"><code>ttm:agent</code></a></td>
-
-              <td><code>mpeg7:Agent</code></td>
-
-              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-copyright"><code>ttm:copyright</code></a></td>
-
-              <td><code>mpeg7:CopyrightString</code></td>
-
-              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-desc"><code>ttm:desc</code></a></td>
-
-              <td><code>svg:desc</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>-@class, -@style, -@xml:base</td>
-
-              <td>2,5,9</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-name"><code>ttm:name</code></a></td>
-
-              <td><code>mpeg7:Name</code></td>
-
-              <td><a href="#mpeg7-5">[MPEG7-5]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-vocabulary-title"><code>ttm:title</code></a></td>
-
-              <td><code>svg:title</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>-@class, -@style, -@xml:base</td>
-
-              <td>2,5,9</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-extension"><code>ttp:extension</code></a></td>
-
-              <td><code>@requiredExtensions</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>10</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-extensions"><code>ttp:extensions</code></a></td>
-
-              <td><code>@requiredExtensions</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>10</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-feature"><code>ttp:feature</code></a></td>
-
-              <td><code>@requiredFeatures</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>10</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-features"><code>ttp:features</code></a></td>
-
-              <td><code>@requiredFeatures</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>10</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-vocabulary-profile"><code>ttp:profile</code></a></td>
-
-              <td><code>@baseProfile</code></td>
-
-              <td><a href="#svg11">[SVG 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td>11</td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <ol class="enumar">
-            <li>
-              <p>Derivation is indicated with respect to the strict DTD defined
-              by <a href="#xhtml10">[XHTML 1.0]</a>, §A.1.</p>
-            </li>
-
-            <li>
-              <p>The <code>class</code> attribute is effectively replaced by
-              the <code>style</code> attribute, which, instead of specifying an
-              inline style, refers indirectly to one or more <a href=
-              "#styling-vocabulary-style"><code>style</code></a> elements that
-              define a set of style specification sets.</p>
-            </li>
-
-            <li>
-              <p>The <code>xml:lang</code> and <code>xml:space</code>
-              attributes are defined for all element types in order to support
-              their inheritance semantics to operate in the context of foreign
-              namespace elements.</p>
-            </li>
-
-            <li>
-              <p>Derivation is conceptual (notional) only.</p>
-            </li>
-
-            <li>
-              <p>The <code>xml:base</code> attribute is not used since there
-              are no external references from core vocabulary.</p>
-            </li>
-
-            <li>
-              <p>The <code>attributeName</code> and <code>to</code> attributes
-              of <code>svg:set</code> are replaced by the direct expression of
-              the target attribute name and value by use of a
-              <code>tts:*</code> attribute.</p>
-            </li>
-
-            <li>
-              <p>CSS style specification syntax is mapped to XML by use of
-              attributes defined in the TT Style Namespace.</p>
-            </li>
-
-            <li>
-              <p>The <code>xml:id</code> attribute is defined for use on all
-              element types.</p>
-            </li>
-
-            <li>
-              <p>The <code>style</code> attribute is supported only on content
-              elements.</p>
-            </li>
-
-            <li>
-              <p>Derived from the use of <code>@requiredExtensions</code> and
-              <code>@requiredFeatures</code> on the <code>svg:svg</code>
-              element, but extended to support distinct specification of
-              optionality.</p>
-            </li>
-
-            <li>
-              <p>Derived from the use of <code>@baseProfile</code> and
-              <code>@version</code> on the <code>svg:svg</code> element.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="d3e19117" name="d3e19117"></a>J.2 Attribute Derivation</h3>
-
-        <p>The first column of <a href=
-        "#attribute-vocab-derivation-table"><b>Table J-2 – Attributes</b></a>
-        specifies a TTML attribute vocabulary item; the second column specifies
-        the syntactic and/or semantic model on which the vocabulary item is
-        based; the third column specifies the reference that defines the model
-        (if a model is indicated); the fourth column specifies details about
-        the derivation; the last column refers to additional notes describing
-        the nature of the derivation.</p>
-
-        <p>In the fourth column, which describes details of derivation, a
-        notation is use to indicate the addition or removal of an attribute
-        value. For example, in the derivation of the <code>timeContainer</code>
-        attribute, the details column includes "-excl", which denotes that the
-        <code>excl</code> value that is specified for use with the
-        <code>timeContainer</code> model attribute is not specified for use
-        with the corresponding TTML attribute; similarly, an "+<em>value</em>"
-        in the details column indicates that the attribute's values have been
-        extended to include <em>value</em>.</p>
-
-        <p>Only those attributes that are specified for use on more than one
-        TTML element type are listed below. Those per-element namespace
-        attributes that are uniquely defined for a specific TTML element type
-        are not listed below, but are considered to be part of the specific
-        element type's derivation described in <a href=
-        "#element-vocab-derivation-table"><b>Table J-1 – Elements</b></a>
-        above.</p><a id="attribute-vocab-derivation-table" name=
-        "attribute-vocab-derivation-table"></a>
-
-        <table class="common">
-          <caption>
-            Table J-2 – Attributes
-          </caption>
-          <col width="20%" span="1">
-          <col width="17%" span="1">
-          <col width="13%" align="center" span="1">
-          <col width="40%" span="1">
-          <col width="10%" align="center" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Attribute</span></td>
-
-              <td><span class="strong">Model</span></td>
-
-              <td><span class="strong">Reference</span></td>
-
-              <td><span class="strong">Details</span></td>
-
-              <td><span class="strong">Notes</span></td>
-            </tr>
-
-            <tr>
-              <td><a href="#timing-attribute-begin"><code>begin</code></a></td>
-
-              <td><code>begin</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td>see notes</td>
-
-              <td>2,3,4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#timing-attribute-dur"><code>dur</code></a></td>
-
-              <td><code>dur</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td>see notes</td>
-
-              <td>2,3,4</td>
-            </tr>
-
-            <tr>
-              <td><a href="#timing-attribute-end"><code>end</code></a></td>
-
-              <td><code>end</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td>see notes</td>
-
-              <td>2,3,4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#layout-attribute-region"><code>region</code></a></td>
-
-              <td><code>master-reference</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>conceptual derivation</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href="#style-attribute-style"><code>style</code></a></td>
-
-              <td><code>class</code></td>
-
-              <td><a href="#css2">[CSS2]</a></td>
-
-              <td>dereferences style specification(s) directly</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#timing-attribute-timeContainer"><code>timeContainer</code></a></td>
-
-              <td><code>timeContainer</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td>-excl, -none; no default attribute value</td>
-
-              <td>5</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-attribute-agent"><code>ttm:agent</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to attribute agent of content</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#metadata-attribute-role"><code>ttm:role</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to attribute role of content</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-cellResolution"><code>ttp:cellResolution</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses uniform grid resolution for cell based
-              coordinates</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-clockMode"><code>ttp:clockMode</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>determines how to interpret time expressions</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-frameRate"><code>ttp:frameRate</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses integral frame rate</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-frameRateMultiplier"><code>ttp:frameRateMultiplier</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to express non-integral, rational frame rates</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-markerMode"><code>ttp:markerMode</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses marker continuity semantics</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-pixelAspectRatio"><code>ttp:pixelAspectRatio</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses pixel aspect ratio of related media</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-profile"><code>ttp:profile</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses profile of TTML used by a <em>Document
-              Instance</em></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-dropMode"><code>ttp:dropMode</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses frame counting (drop) modes</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-subFrameRate"><code>ttp:subFrameRate</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>expresses sub-frame rate</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-tickRate"><code>ttp:tickRate</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to interpret tick based time expressions</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#parameter-attribute-timeBase"><code>ttp:timeBase</code></a></td>
-
-              <td><em>none</em></td>
-
-              <td></td>
-
-              <td>used to interpret semantics of time expressions</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-backgroundColor"><code>tts:backgroundColor</code></a></td>
-
-              <td><code>background-color</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1,6</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-color"><code>tts:color</code></a></td>
-
-              <td><code>color</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>6</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-direction"><code>tts:direction</code></a></td>
-
-              <td><code>direction</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-display"><code>tts:display</code></a></td>
-
-              <td><code>display</code></td>
-
-              <td><a href="#css2">[CSS2]</a></td>
-
-              <td>only <code>auto</code>, <code>none</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-displayAlign"><code>tts:displayAlign</code></a></td>
-
-              <td><code>display-align</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-extent"><code>tts:extent</code></a></td>
-
-              <td><code>width</code>, <code>height</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>shorthand property</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-fontFamily"><code>tts:fontFamily</code></a></td>
-
-              <td><code>font-family</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, extends generic family names</td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-fontSize"><code>tts:fontSize</code></a></td>
-
-              <td><code>font-size</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1,7</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-fontStyle"><code>tts:fontStyle</code></a></td>
-
-              <td><code>font-style</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-backslant</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-fontWeight"><code>tts:fontWeight</code></a></td>
-
-              <td><code>font-weight</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-bolder</code>,
-              <code>-lighter</code>, <code>-&lt;number&gt;</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-lineHeight"><code>tts:lineHeight</code></a></td>
-
-              <td><code>line-height</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-&lt;number&gt;</code>,
-              <code>-&lt;space&gt;</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-opacity"><code>tts:opacity</code></a></td>
-
-              <td><code>opacity</code></td>
-
-              <td><a href="#css3-color">[CSS3 Color]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-origin"><code>tts:origin</code></a></td>
-
-              <td><code>top</code>, <code>left</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td>shorthand property</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-overflow"><code>tts:overflow</code></a></td>
-
-              <td><code>overflow</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-auto</code>,
-              <code>-error-if-overflow</code></td>
-
-              <td>8</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-padding"><code>tts:padding</code></a></td>
-
-              <td><code>padding</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>9</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-showBackground"><code>tts:showBackground</code></a></td>
-
-              <td><code>showBackground</code></td>
-
-              <td><a href="#smil21">[SMIL 2.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-textAlign"><code>tts:textAlign</code></a></td>
-
-              <td><code>text-align</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-textDecoration"><code>tts:textDecoration</code></a></td>
-
-              <td><code>text-decoration</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1,10,13</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-textOutline"><code>tts:textOutline</code></a></td>
-
-              <td><code>text-shadow</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>11,13</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-unicodeBidi"><code>tts:unicodeBidi</code></a></td>
-
-              <td><code>unicode-bidi</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-visibility"><code>tts:visibility</code></a></td>
-
-              <td><code>visibility</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>-collapse</code></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-wrapOption"><code>tts:wrapOption</code></a></td>
-
-              <td><code>wrap-option</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-writingMode"><code>tts:writingMode</code></a></td>
-
-              <td><code>writing-mode</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code>, <code>+tblr</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#style-attribute-zIndex"><code>tts:zIndex</code></a></td>
-
-              <td><code>z-index</code></td>
-
-              <td><a href="#xsl11">[XSL 1.1]</a></td>
-
-              <td><code>-inherit</code></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href="#content-attribute-id"><code>xml:id</code></a></td>
-
-              <td><code>xml:id</code></td>
-
-              <td><a href="#xmlid">[XML ID]</a></td>
-
-              <td>complies with model</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#content-attribute-lang"><code>xml:lang</code></a></td>
-
-              <td><code>xml:lang</code></td>
-
-              <td><a href="#xml10">[XML 1.0]</a></td>
-
-              <td>complies with model</td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "#content-attribute-space"><code>xml:space</code></a></td>
-
-              <td><code>xml:space</code></td>
-
-              <td><a href="#xml10">[XML 1.0]</a></td>
-
-              <td>see notes</td>
-
-              <td>12</td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <ol class="enumar">
-            <li>
-              <p>Attribute name and/or value(s) are normalized to use
-              <em>lowerCamelCase</em> naming convention.</p>
-            </li>
-
-            <li>
-              <p>Restricted to expressing a clock value that denotes one of the
-              following in accordance to whether the parameter expressed by the
-              <code>ttp:timeBase</code> attribute is <code>media</code>,
-              <code>smpte</code>, or <code>clock</code>, respectively: (1) an
-              offset from an implicit syncbase that is linked to a media time
-              line, (2) an event time that represents the occurrence of an
-              implicit media marker, or (3) a wall-clock time.</p>
-            </li>
-
-            <li>
-              <p>Syntactically subsets and supersets the <a href=
-              "#smil21">[SMIL 2.1]</a>&nbsp;<code>Clock-value</code> syntax as
-              follows: (1) requires non-negative <code>Full-clock-value</code>
-              or <code>Timecount-value</code>; (2) if
-              <code>Full-clock-value</code> then <em>hours</em> must be two or
-              more digits; (3) if <code>Timecount-value</code>, then
-              <em>metric</em> must be specified; (4) uses <code>m</code> as
-              alias for <code>min</code> metric to denote minutes; (5) adds
-              <code>f</code> and <code>t</code> metrics denoting frames and
-              ticks, respectively; (6) adds alternative expression of optional
-              <code>Fraction</code> in <code>Full-clock-value</code> by
-              specifying frame count or frame count with subframe count.</p>
-            </li>
-
-            <li>
-              <p>Interpretation of time expression is further constrained by
-              parameters expressed by <code>ttp:clockMode</code>,
-              <code>ttp:dropMode</code>, <code>ttp:frameRate</code>,
-              <code>ttp:frameRateMultiplier</code>,
-              <code>ttp:markerMode</code>, <code>ttp:subFrameRate</code>,
-              <code>ttp:tickRate</code>, and <code>ttp:timeBase</code>
-              attributes.</p>
-            </li>
-
-            <li>
-              <p>Uses subset of named colors from model to which two aliases
-              are added as follows: <code>magenta</code> as
-              <code>fuchsia</code>, and <code>cyan</code> as
-              <code>aqua</code>.</p>
-            </li>
-
-            <li>
-              <p>If not specified, then parallel (par) container semantics
-              apply to the element types specified by <a href=
-              "#timing-attribute-timeContainer"><b>10.2.4
-              timeContainer</b></a>.</p>
-            </li>
-
-            <li>
-              <p>Restricts size to length specification which can be a
-              percentage; adds optional second length (or percentage) for
-              specifying separate horizontal and vertical scaling of glyph's EM
-              square.</p>
-            </li>
-
-            <li>
-              <p>Expressed in terms of writing mode relative padding properties
-              rather than absolute padding properties.</p>
-            </li>
-
-            <li>
-              <p>Excludes <code>blink</code> and <code>no-blink</code>
-              values.</p>
-            </li>
-
-            <li>
-              <p>Uses only one length specification instead of two, where one
-              length defines distance of outline effect from nominal edge of
-              glyph contour outline perpendicular to point of glyph contour.
-              Percentage lengths are also added to express outline effect in
-              relative to font size. Outline effects are intended to be drawn
-              both outside of outer closed contours and inside of inner closed
-              contours.</p>
-            </li>
-
-            <li>
-              <p>On root element, default attribute value specified as
-              <code>default</code>, which is defined in terms of whitespace
-              normalization. Semantics of preservation and default
-              normalization are defined in terms of presentation semantics by
-              <a href="#content-attribute-space"><b>7.2.3
-              xml:space</b></a>.</p>
-            </li>
-
-            <li>
-              <p>Defined to be inheritable.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="qa" name="qa"></a>K QA Framework Compliance
-      (Non-Normative)</h2>
-
-      <p>This appendix specifies the compliance of this specification with the
-      requirements and guidelines defined by <a href=
-      "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/">QA Framework
-      Specifications Guidelines</a>&nbsp;<a href="#qaf-sg">[QAF SG]</a>.</p>
-
-      <div class="div2">
-        <h3><a id="d3e20003" name="d3e20003"></a>K.1 Requirements</h3><a id=
-        "qa-framework-requirements-table" name=
-        "qa-framework-requirements-table"></a>
-
-        <table class="common">
-          <caption>
-            Table K-1 – QA Framework Requirements Checklist
-          </caption>
-          <col width="76%" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Requirement</span></td>
-
-              <td><span class="strong">YES</span></td>
-
-              <td><span class="strong">NO</span></td>
-
-              <td><span class="strong">N/A</span></td>
-
-              <td><span class="strong">Notes</span></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#include-conformance-clause-principle">
-              Requirement 01: Include a conformance clause</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-scope-principle">
-              Requirement 02: Define the scope.</a></td>
-
-              <td><a href="#intro">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#implement-principle">
-              Requirement 03: Identify who or what will implement the
-              specification.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-norm-principle">
-              Requirement 04: Make a list of normative references.</a></td>
-
-              <td><a href="#references">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-principle">
-              Requirement 05: Define the terms used in the normative parts of
-              the specification.</a></td>
-
-              <td><a href="#definitions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conf-label-principle">
-              Requirement 06: Create conformance labels for each part of the
-              conformance model.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#consistent-style-principle">
-              Requirement 07: Use a consistent style for conformance
-              requirements and explain how to distinguish them.</a></td>
-
-              <td><a href="#conventions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#req-opt-conf-principle">
-              Requirement 08: Indicate which conformance requirements are
-              mandatory, which are recommended, and which are
-              optional.</a></td>
-
-              <td><a href="#conventions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-mandatory-principle">
-              Requirement 09: If the technology is subdivided, then indicate
-              which subdivisions are mandatory for conformance.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdiv-constraints-principle">
-              Requirement 10: If the technology is subdivided, then address
-              subdivision constraints.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#likehood-extension-principle">
-              Requirement 11: Address Extensibility.</a></td>
-
-              <td><a href="#doctypes">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#deprecated-feature-principle">
-              Requirement 12: Identify deprecated features.</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>N/A</td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#degree-support-principle">
-              Requirement 13: Define how each class of product handles each
-              deprecated feature.</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>N/A</td>
-
-              <td>1</td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <ol class="enumar">
-            <li>
-              <p>No feature is deprecated by this version of this
-              specification.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="d3e20167" name="d3e20167"></a>K.2 Guidelines</h3><a id=
-        "qa-framework-guidelines-table" name=
-        "qa-framework-guidelines-table"></a>
-
-        <table class="common">
-          <caption>
-            Table K-2 – QA Framework Guidelines Checklist
-          </caption>
-          <col width="76%" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-          <col width="6%" align="center" span="1">
-
-          <tbody>
-            <tr>
-              <td><span class="strong">Guideline</span></td>
-
-              <td><span class="strong">YES</span></td>
-
-              <td><span class="strong">NO</span></td>
-
-              <td><span class="strong">N/A</span></td>
-
-              <td><span class="strong">Notes</span></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-model-gp">
-              Good Practice 01: Define the specification's conformance model in
-              the conformance clause.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#norm-informative-gp">
-              Good Practice 02: Specify in the conformance clause how to
-              distinguish normative from informative content.</a></td>
-
-              <td><a href="#conventions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-claim-gp">
-              Good Practice 03: Provide the wording for conformance
-              claims.</a></td>
-
-              <td><a href="#claims">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-gp">Good
-              Practice 04: Provide an Implementation Conformance Statement Pro
-              Forma.</a></td>
-
-              <td></td>
-
-              <td>NO</td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-claim-gp">
-              Good Practice 05: Require an Implementation Conformance Statement
-              as part of valid conformance claims.</a></td>
-
-              <td><a href="#claims">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#use-example-gp">
-              Good Practice 06: Provide examples, use cases, and
-              graphics.</a></td>
-
-              <td><a href="#example">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-sample-gp">
-              Good Practice 07: Write sample code or tests.</a></td>
-
-              <td>YES</td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-define-practice">
-              Good Practice 08: When imposing requirements by normative
-              references, address conformance dependencies.</a></td>
-
-              <td><a href="#references">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>1</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-inline-gp">
-              Good Practice 09: Define unfamiliar terms in-line and consolidate
-              the definitions in a glossary section.</a></td>
-
-              <td><a href="#definitions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#reuse-terms-gp">
-              Good Practice 10: Use terms already defined without changing
-              their definition.</a></td>
-
-              <td><a href="#definitions">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>2</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#formal-language-gp">
-              Good Practice 11: Use formal languages when possible.</a></td>
-
-              <td><a href="#schemas">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-assertion-gp">
-              Good Practice 12: Write Test Assertions.</a></td>
-
-              <td></td>
-
-              <td>NO</td>
-
-              <td></td>
-
-              <td>3</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-foster-gp">
-              Good Practice 13: Create subdivisions of the technology when
-              warranted.</a></td>
-
-              <td><a href="#conformance">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#rules-profiles-gp">
-              Good Practice 14: If the technology is profiled, define rules for
-              creating new profiles.</a></td>
-
-              <td><a href="#vocabulary-profiles">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#need-option-gp">
-              Good Practice 15:Use optional features as warranted.</a></td>
-
-              <td>YES</td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#label-options-gp">
-              Good Practice 16: Clearly identify optional features.</a></td>
-
-              <td>YES</td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#constraints-gp">
-              Good Practice 17: Indicate any limitations or constraints on
-              optional features.</a></td>
-
-              <td>YES</td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#extensions-prohibited-gp">
-              Good Practice 18: If extensibility is allowed, define an
-              extension mechanism.</a></td>
-
-              <td><a href="#extension-vocabulary-overview">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#breaking-conformance-gp">
-              Good Practice 19: Warn extension creators to create extensions
-              that do not interfere with conformance.</a></td>
-
-              <td><a href="#extension-vocabulary-overview">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-error-gp">
-              Good Practice 20: Define error-handling for unknown
-              extensions.</a></td>
-
-              <td><a href="#conformance-processor">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>4</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#workaround-gp">
-              Good Practice 21: Explain how to avoid using a deprecated
-              feature.</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>N/A</td>
-
-              <td>5</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#obsolete-gp">
-              Good Practice 22: Identify obsolete features.</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td>N/A</td>
-
-              <td>5</td>
-            </tr>
-
-            <tr>
-              <td><a href=
-              "http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#error-handling-gp">
-              Good Practice 23: Define an error handling mechanism.</a></td>
-
-              <td><a href="#reduced-infoset">YES</a></td>
-
-              <td></td>
-
-              <td></td>
-
-              <td></td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <ol class="enumar">
-            <li>
-              <p>When making normative references to external specifications,
-              specific clauses or sections are cited.</p>
-            </li>
-
-            <li>
-              <p>See also <a href="#derivation"><b>J Vocabulary
-              Derivation</b></a>.</p>
-            </li>
-
-            <li>
-              <p>Test assertions and test suites will be provided prior to
-              entering Proposed Recommendation (PR) phase.</p>
-            </li>
-
-            <li>
-              <p>See criterion #3 in <a href="#conformance-processor"><b>3.2
-              Processor Conformance</b></a> and definition of TTML <a href=
-              "#doctypes">Abstract Document Instance</a>.</p>
-            </li>
-
-            <li>
-              <p>No feature is deprecated or obsoleted by this version of this
-              specification.</p>
-            </li>
-          </ol>
-        </div>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="streaming" name="streaming"></a>L Streaming TTML Content
-      (Non-Normative)</h2>
-
-      <p>TTML Content is designed to support streamability by implementing the
-      following properties:</p>
-
-      <ul>
-        <li>
-          <p>can be progressively encoded (i.e., does not require computing
-          subsequent data prior to sending current data);</p>
-        </li>
-
-        <li>
-          <p>can be progressively decoded (i.e., does not require forward
-          references, but uses only reverse references when necessary);</p>
-        </li>
-
-        <li>
-          <p>does not require dereferencing (and subsequent loading) of any
-          resources other than TTML Content (i.e., no embedded URIs);</p>
-        </li>
-
-        <li>
-          <p>does not support alternative content forms (e.g., different
-          language, graphics formats, time bases) in a single document;</p>
-        </li>
-
-        <li>
-          <p>has timing structure compiled into inline format that makes
-          possible a temporal ordering of content that follows temporal
-          presentation order;</p>
-        </li>
-
-        <li>
-          <p>constrains content models to prevent arbitrary nested content
-          structures;</p>
-        </li>
-      </ul>
-
-      <p>One possible means by which TTML Content may be streamed is to
-      partition a <em>Document Instance</em>'s information set into
-      non-overlapping fragments, where one particular fragment, call it the
-      <em>root fragment</em>, represents the front matter (head) of the
-      <em>Document Instance</em> as well as its top level structural elements,
-      and other fragments represent content whose time intervals are expected
-      to be active in parallel.</p>
-
-      <p>In applications that require arbitrary (random) entry into a stream,
-      i.e., the property of being able to start reading data at an arbitrary
-      data access unit, the root fragment will be repetitively transmitted
-      (inserted) into the stream in order to permit a decoder to resynchronize
-      and acquire sufficient structural information in the information set in
-      order to interpret subsequent content fragments.</p>
-
-      <p>An example of such a fragmentation of a <em>Document Instance</em> is
-      shown in <a href="#fragment-streaming-graphic"><b>Figure 3 – Fragment
-      Streaming</b></a>.</p><a id="fragment-streaming-graphic" name=
-      "fragment-streaming-graphic"></a>
-
-      <table class="example-images">
-        <caption>
-          Figure 3 – Fragment Streaming
-        </caption>
-        <col span="1">
-
-        <tbody>
-          <tr>
-            <td><img src="images/streaming.png" alt="Fragment Streaming"></td>
-          </tr>
-        </tbody>
-      </table>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>This specification does not define a transport buffer model or a
-        decoder capabilities model.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="concrete-encoding" name="concrete-encoding"></a>M Concrete
-      Encoding (Non-Normative)</h2>
-
-      <p>In the absence of other requirements, it is recommended that a
-      <em>Document Instance</em> be concretely encoded as a well-formed XML 1.0
-      <a href="#xml10">[XML 1.0]</a> document using the UTF-8 character
-      encoding.</p>
-    </div>
-
-    <div class="div1">
-      <h2><a id="time-expression-semantics" name=
-      "time-expression-semantics"></a>N Time Expression Semantics
-      (Non-Normative)</h2>
-
-      <p>This appendix describes the intended semantics for interpreting time
-      expressions in <em>Document Instances</em>.</p>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>It is expected that the information in this appendix will be
-        elevated to normative status in a future revision of this
-        specification.</p>
-      </div>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>The phrase <em>local real time</em> as used below is intended to
-        model a virtual real time clock in the document processing context,
-        where <em>local</em> means in the immediate proximity of the
-        implementation of this processing context. The intent of defining
-        relationships with this virtual clock is to establish a locally valid
-        physical realization of time for didactic purposes.</p>
-      </div>
-
-      <div class="note">
-        <p class="prefix"><b>Note:</b></p>
-
-        <p>The phrase <em>play rate</em> as used below is intended to model a
-        (possibly variable) parameter in the document processing context
-        wherein the rate of playback (or interpretation) of time may
-        artificially dilated or narrowed, for example, when slowing down or
-        speeding up the rate of playback of a <em>Related Media Object</em>.
-        Without loss of generality, the following discussion assumes a fixed
-        play(back) rate. In the case of variable play rates, appropriate
-        adjustments may need to be made to the resulting computations.</p>
-      </div>
-
-      <div class="div2">
-        <h3><a id="time-expression-semantics-clock" name=
-        "time-expression-semantics-clock"></a>N.1 Clock Time Base</h3>
-
-        <p>When operating with the <code>clock</code> time base, the following
-        semantics should be applied for interpreting time expressions, as
-        defined by <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their
-        relationship to media time and local real time.</p>
-
-        <p>The clock time base <span class="strong"><code>C</code></span> is
-        related to local real time <span class="strong"><code>R</code></span>
-        expressed in an arbitrary (implementation defined) epoch <span class=
-        "strong"><code>E</code></span> as follows:</p><a id=
-        "clock-time-and-real-time" name="clock-time-and-real-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Clock Time and Real Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><br>
-                  <code>R = C + epochOffset + discontinuityOffset</code><br>
-                  <br>
-                  where <code>C ∈ ℜ</code>, <code>0 ≤ C &lt; ∞</code>,
-                  <code>C</code> in seconds since the most immediately prior
-                  midnight of the reference clock base;<br>
-                  <br>
-                  <code>epochOffset ∈ ℜ</code>, <code>0 ≤ epochOffset &lt;
-                  ∞</code>, <code>epochOffset</code> in seconds, with 0 being
-                  the beginning of epoch <code>E</code>, and where the value of
-                  <code>epochOffset</code> is determined from the computed
-                  value of the <code>ttp:clockMode</code> parameter as
-                  follows:<br>
-                  <br>
-                  (1) if <code>local</code>, then the difference between the
-                  local real time at the most immediately prior local midnight
-                  and the local real time at the beginning of epoch
-                  <code>E</code>, expressed in seconds;<br>
-                  <br>
-                  (2) if <code>gps</code>, then the difference between the GPS
-                  time at the most immediately prior GPS midnight and the GPS
-                  time at the beginning of epoch <code>E</code>, expressed in
-                  seconds;<br>
-                  <br>
-                  (3) if <code>utc</code>, then the difference between the UTC
-                  time at the most immediately prior UTC midnight and the UTC
-                  time at the beginning of epoch <code>E</code>, expressed in
-                  seconds;<br>
-                  <br>
-                  <code>discontinuityOffset ∈ ℜ</code>, <code>−∞ &lt;
-                  discontinuityOffset &lt; ∞</code>,
-                  <code>discontinuityOffset</code> in seconds, and where the
-                  value of <code>discontinuityOffset</code> is equal to the sum
-                  of leap seconds (and fractions thereof) that have been added
-                  (or subtracted) since the most immediately prior midnight in
-                  the reference clock base;<br>
-                  <br>
-                  and <code>epochOffset</code> and
-                  <code>discontinuityOffset</code> are determined once and only
-                  once prior to the beginning of the <em>Root Temporal
-                  Extent</em> such that during the period between value
-                  determination and the beginning of the <em>Root Temporal
-                  Extent</em> there occurs no local midnight or reference clock
-                  base discontinuity.<br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Time value expressions, as denoted by a <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, are related
-        to clock time <span class="strong"><code>C</code></span> as
-        follows:</p><a id="time-expressions-and-clock-time" name=
-        "time-expressions-and-clock-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Time Expressions and Clock Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><br>
-                  If a time expression uses the <em>clock-time</em> form or an
-                  <em>offset-time</em> form that doesn't use the ticks
-                  (<code>t</code>) metric, then:<br>
-                  <br>
-                  <code>C = 3600 * hours + 60 * minutes + seconds</code><br>
-                  <br>
-                  where <code>hours</code>, <code>minutes</code>,
-                  <code>seconds</code> components are extracted from time
-                  expression if present, or zero if not present.<br>
-                  <br>
-                  Otherwise, if a time expression uses an <em>offset-time</em>
-                  form that uses the ticks (<code>t</code>) metric, then:<br>
-                  <br>
-                  <code>C = ticks / tickRate</code><br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The <em>frames</em> and <em>sub-frames</em> terms and the frames
-          (<code>f</code>) metric of time expressions do not apply when using
-          the <code>clock</code> time base.</p>
-        </div>
-
-        <p>The clock time base <span class="strong"><code>C</code></span> is
-        independent of media time <span class=
-        "strong"><code>M</code></span>:</p><a id="clock-time-and-media-time"
-        name="clock-time-and-media-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Clock Time and Media Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><br>
-                  <code>M ¬∝ C</code><br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>That is to say, timing is disconnected from (not necessarily
-          proportional to) media time when the <code>clock</code> time base is
-          used. For example, if the media play rate is zero (0), media playback
-          is suspended; however, timing coordinates will continue to advance
-          according to the natural progression of clock time in direct
-          proportion to the reference clock base. Furthermore, if the media
-          play rate changes during playback, presentation timing is not
-          affected.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="time-expression-semantics-media" name=
-        "time-expression-semantics-media"></a>N.2 Media Time Base</h3>
-
-        <p>When operating with the <code>media</code> time base, the following
-        semantics should be applied for interpreting time expressions, as
-        defined by <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their
-        relationship to media time and local real time.</p>
-
-        <p>The media time base <span class="strong"><code>M</code></span> is
-        related to local real time <span class="strong"><code>R</code></span>
-        expressed in an arbitrary (implementation defined) epoch <span class=
-        "strong"><code>E</code></span> as follows:</p><a id=
-        "media-time-and-real-time" name="media-time-and-real-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Media Time and Real Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><br>
-                  <code>R = playRate * M + epochOffset</code><br>
-                  <br>
-                  where <code>M ∈ ℜ</code>, <code>0 ≤ M &lt; ∞</code>,
-                  <code>M</code> in seconds, with 0 corresponding to the
-                  beginning of the <em>Root Temporal Extent</em>;<br>
-                  <br>
-                  <code>playRate ∈ ℜ</code>, <code>−∞ &lt; playRate &lt;
-                  ∞</code>, <code>playRate</code> is unit-less, and where the
-                  value of <code>playRate</code> is determined by the document
-                  processing context;<br>
-                  <br>
-                  and <code>epochOffset ∈ ℜ</code>, <code>0 ≤ epochOffset &lt;
-                  ∞</code>, <code>epochOffset</code> in seconds, with 0
-                  corresponding to the beginning of an epoch <code>E</code>,
-                  and where the value of <code>epochOffset</code> is the
-                  difference between the local real time at the beginning of
-                  the <em>Root Temporal Extent</em> and the local real time at
-                  the the beginning of epoch <code>E</code>, expressed in
-                  seconds.</p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Time value expressions, as denoted by a <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, are related
-        to media time <span class="strong"><code>M</code></span> in accordance
-        to the <code>ttp:frameRate</code>, <code>ttp:subFrameRate</code>, and
-        <code>ttp:frameRateMultipler</code> parameters as follows:</p><a id=
-        "time-expressions-and-media-time" name=
-        "time-expressions-and-media-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Time Expressions and Media Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><br>
-                  If a time expression uses a <em>clock-time</em> form or an
-                  <em>offset-time</em> form that doesn't use the ticks
-                  (<code>t</code>) metric, then:<br>
-                  <br>
-                  <code>M = referenceBegin + 3600 * hours + 60 * minutes +
-                  seconds + ((frames + (subFrames / subFrameRate)) /
-                  effectiveFrameRate)</code><br>
-                  <br>
-                  where <code>referenceBegin</code> is determined according to
-                  whether the nearest ancestor time container employs parallel
-                  (<code>par</code>) or sequential (<code>seq</code>)
-                  semantics: if parallel or if sequential and no prior sibling
-                  timed element exists, then <code>referenceBegin</code> is the
-                  media time that corresponds to the beginning of the nearest
-                  ancestor time container or zero (0) if this time container is
-                  the <em>Root Temporal Extent</em>; otherwise, if sequential
-                  and a prior sibling timed element exists, then
-                  <code>referenceBegin</code> is the media time that
-                  corresponds to the active end of the immediate prior sibling
-                  timed element;<br>
-                  <br>
-                  the <code>hours</code>, <code>minutes</code>,
-                  <code>seconds</code>, <code>frames</code>,
-                  <code>subFrames</code> components are extracted from time
-                  expression if present, or zero if not present;<br>
-                  <br>
-                  <code>subFrameRate</code> is the computed value of the
-                  <code>ttp:subFrameRate</code> parameter;<br>
-                  <br>
-                  and <code>effectiveFrameRate</code> (in frames per second) is
-                  <code>frameRate * frameRateMultipler</code> where
-                  <code>frameRate</code> is the computed value of the
-                  <code>ttp:frameRate</code> parameter and
-                  <code>frameRateMultipler</code> is the computed value of the
-                  <code>ttp:frameRateMultiplier</code> parameter.<br>
-                  <br>
-                  Otherwise, if a time expression uses an <em>offset-time</em>
-                  form that uses the ticks (<code>t</code>) metric, then:<br>
-                  <br>
-                  <code>M = referenceBegin + ticks / tickRate</code><br>
-                  <br>
-                  where <code>referenceBegin</code> is as described above;<br>
-                  <br>
-                  the <code>ticks</code> component is extracted from time
-                  expression;<br>
-                  <br>
-                  and <code>tickRate</code> is the computed value of the
-                  <code>ttp:tickRate</code> parameter;<br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>If the computed <code>frameRateMultipler</code> ratio is not
-          integral, then <code>effectiveFrameRate</code> will be a non-integral
-          rational.</p>
-        </div>
-
-        <div class="note">
-          <p class="prefix"><b>Note:</b></p>
-
-          <p>The above formalisms assumes that the <em>Root Temporal
-          Extent</em> corresponds with the beginning of a related media object.
-          If this assumption doesn't hold, then an additional offset that
-          accounts for the difference may be introduced when computing media
-          time <code>M</code>.</p>
-        </div>
-      </div>
-
-      <div class="div2">
-        <h3><a id="time-expression-semantics-smpte" name=
-        "time-expression-semantics-smpte"></a>N.3 SMPTE Time Base</h3>
-
-        <p>When operating with the <code>smpte</code> time base, the following
-        semantics should be applied for interpreting time expressions, as
-        defined by <a href=
-        "#timing-value-timeExpression">&lt;timeExpression&gt;</a>, and their
-        relationship to media time and local real time.</p>
-
-        <p>If the computed value of the <code>ttp:markerMode</code> parameter
-        is <code>discontinuous</code>, then there is no direct relationship
-        between time expressions and media time <span class=
-        "strong"><code>M</code></span> or local real time <span class=
-        "strong"><code>R</code></span>. In this case, time expressions refer to
-        synchronization events (markers) emitted by the <em>Document Processing
-        Context</em> when <em>SMPTE Time Codes</em> are encountered in the
-        <em>Related Media Object</em>.</p>
-
-        <p>Otherwise, if the computed value of the <code>ttp:markerMode</code>
-        parameter is <code>continuous</code>, then the relationships between
-        time expressions and local real time and media time are as described
-        below in terms of a <em>Synthetic SMPTE Document Syncbase</em>, here
-        referred to as the SMPTE time base <span class=
-        "strong"><code>S</code></span>.</p><a id=
-        "time-expressions-and-smpte-time" name=
-        "time-expressions-and-smpte-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – Time Expressions and SMPTE Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><br>
-                  <code>S = (countedFrames - droppedFrames + (subFrames /
-                  subFrameRate)) / effectiveFrameRate</code><br>
-                  <br>
-                  where<br>
-                  <br>
-                  <code>countedFrames = (3600 * hours + 60 * minutes + seconds)
-                  * frameRate + frames</code><br>
-                  <br>
-                  <code>hours</code>, <code>minutes</code>,
-                  <code>seconds</code>, <code>frames</code>,
-                  <code>subFrames</code> components are extracted from time
-                  expression if present, or zero if not present;<br>
-                  <br>
-                  <code>droppedFrames</code> is computed as follows:<br>
-                  <br>
-                  1. let <em>dropMode</em> be the computed value of the
-                  <code>ttp:dropMode</code> parameter;<br>
-                  <br>
-                  2. if <em>dropMode</em> is <code>dropNTSC</code>, let
-                  <code>droppedFrames = (hours * 54 + floor(minutes -
-                  minutes/10)) * 2</code>;<br>
-                  <br>
-                  3. otherwise, if <em>dropMode</em> is <code>dropPAL</code>,
-                  let <code>droppedFrames = (hours * 27 + floor(minutes/2 -
-                  minutes/20)) * 4</code>;<br>
-                  <br>
-                  4. otherwise, let <code>droppedFrames = 0</code>;<br>
-                  <br>
-                  <code>frameRate</code> is the computed value of the
-                  <code>ttp:frameRate</code> parameter;<br>
-                  <br>
-                  <code>subFrameRate</code> is the computed value of the
-                  <code>ttp:subFrameRate</code> parameter;<br>
-                  <br>
-                  and <code>effectiveFrameRate</code> (in frames per second) is
-                  <code>frameRate * frameRateMultipler</code> where
-                  <code>frameRate</code> is the computed value of the
-                  <code>ttp:frameRate</code> parameter and
-                  <code>frameRateMultipler</code> is the computed value of the
-                  <code>ttp:frameRateMultiplier</code> parameter.<br>
-                  <br>
-                  Notwithstanding the above, if a time expression contains a
-                  frame code that is designated as dropped according to
-                  <a href="#parameter-attribute-dropMode"><b>6.2.3
-                  ttp:dropMode</b></a>, then that time expression should be
-                  considered to be invalid for purposes of validation
-                  assessment.<br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>The SMPTE time base <span class="strong"><code>S</code></span> is
-        related to the media time base <span class=
-        "strong"><code>M</code></span> as follows:</p><a id=
-        "smpte-time-and-media-time" name="smpte-time-and-media-time"></a>
-
-        <table class="semantics">
-          <caption>
-            TTML Semantics – SMPTE Time and Media Time Relationship
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <blockquote>
-                  <p><br>
-                  <code>M = referenceBegin + S</code><br>
-                  <br>
-                  where <code>referenceBegin</code> is determined according to
-                  whether the nearest ancestor time container employs parallel
-                  (<code>par</code>) or sequential (<code>seq</code>)
-                  semantics: if parallel or if sequential and no prior sibling
-                  timed element exists, then <code>referenceBegin</code> is the
-                  SMPTE time that corresponds to the beginning of the nearest
-                  ancestor time container or zero (0) if this time container is
-                  the <em>Root Temporal Extent</em>; otherwise, if sequential
-                  and a prior sibling timed element exists, then
-                  <code>referenceBegin</code> is the SMPTE time that
-                  corresponds to the active end of the immediate prior sibling
-                  timed element;<br></p>
-                </blockquote>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-
-        <p>Given the derived media time base as described above, then media
-        time base <span class="strong"><code>M</code></span> is related to the
-        local real time <span class="strong"><code>R</code></span> as described
-        in <a href="#time-expression-semantics-media"><b>N.2 Media Time
-        Base</b></a> above.</p>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="common-styling" name="common-styling"></a>O Common Caption
-      Style Examples (Non-Normative)</h2>
-
-      <p>This section provides examples of the following common caption styles
-      using TTML Content to obtain the desired behavior:</p>
-
-      <ul>
-        <li>
-          <p>Pop-On Captions</p>
-        </li>
-
-        <li>
-          <p>Roll-Up Captions</p>
-        </li>
-
-        <li>
-          <p>Paint-On Captions</p>
-        </li>
-      </ul>
-
-      <div class="div2">
-        <h3><a id="pop-on-example" name="pop-on-example"></a>O.1 Pop-On Caption
-        Example</h3>
-
-        <p>An example of paint-on captions. In this example, two regions are
-        targeted with alternating, paint-on content, where content is timed
-        using explicit sequential time containment rules. Each paragraph is
-        non-overlapping in time and appears in the same single row of its
-        targeted region.</p><a id="pop-on-example-1-s" name=
-        "pop-on-example-1-s"></a>
-
-        <table class="example">
-          <caption>
-            Example – Pop-On Captions
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 1c"/&gt;
-      &lt;region xml:id="r2" tts:color="yellow" tts:origin="10c 8c" tts:extent="40c 1c"/&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-  &lt;body&gt;
-    &lt;div timeContainer="seq"&gt;
-      &lt;p region="r1" dur="4s"&gt;Lorem ipsum dolor sit&lt;/p
-      &lt;p region="r2" dur="4s"&gt;Amet consectetur adipiscing elit&lt;/p&gt;
-      &lt;p region="r1" dur="6s"&gt;Sed do eiusmod tempor incididunt labore&lt;/p&gt;
-      &lt;p region="r2" dur="4s"&gt;et dolore magna aliqua&lt;/p&gt;
-      &lt;p region="r1" dur="7s"&gt;Ut enim ad minim veniam quis, nostrud&lt;/p&gt;
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-
-      <div class="div2">
-        <h3><a id="roll-up-example" name="roll-up-example"></a>O.2 Roll-Up
-        Caption Example</h3>
-
-        <p>An example of roll-up captions. Roll-up effects are achieved by
-        using overlapped time intervals, where zero, one, or two paragraphs
-        appear in the region at a given time. Each paragraph consumes a single
-        row (line) of the region since no wrapping occurs. Depending on whether
-        a presentation processor supports <a href=
-        "#semantics-smooth-scrolling-recommendation">smooth scrolling between
-        adjacent synchronic intermediate document instances</a>, the
-        transitions, i.e., moving an old paragraph (line) out and a new
-        paragraph (line) in, will be either smooth or discrete.</p><a id=
-        "roll-up-example-1-s" name="roll-up-example-1-s"></a>
-
-        <table class="example">
-          <caption>
-            Example – Roll-Up Captions
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 2c"/&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-  &lt;body&gt;
-    &lt;div region="r1"&gt;
-      &lt;p begin="0s" end="8s"&gt;Lorem ipsum dolor sit&lt;/p
-      &lt;p begin="4s" end="12s"&gt;Amet consectetur adipiscing elit&lt;/p&gt;
-      &lt;p begin="8s" end="18s"&gt;Sed do eiusmod tempor incididunt labore&lt;/p&gt;
-      &lt;p begin="14s" end="25s"&gt;et dolore magna aliqua&lt;/p&gt;
-      &lt;p begin="18s" end="29s"&gt;Ut enim ad minim veniam quis, nostrud&lt;/p&gt;
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-
-      <div class="div2">
-        <h3><a id="paint-on-example" name="paint-on-example"></a>O.3 Paint-On
-        Caption Example</h3>
-
-        <p>An example of paint-on captions. Paint-on effects are achieved by
-        using timed <code>span</code> elements in order to expose (paint)
-        inline text units, e.g., words, over some time interval. Here, five
-        paragraphs have their individual words sequentially timed in order to
-        paint one new word every second. The end of the active duration of each
-        inline element coincides with the end of the <code>div</code> element's
-        parallel time container, so that once a word is painted, it remains in
-        the region (on its rendered line) until the <code>div</code> element's
-        active time interval lapses.</p><a id="paint-on-example-1-s" name=
-        "paint-on-example-1-s"></a>
-
-        <table class="example">
-          <caption>
-            Example – Paint-On Captions
-          </caption>
-
-          <tbody>
-            <tr>
-              <td>
-                <div class="exampleInner">
-                  <pre>
-&lt;tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
-  xmlns:tts="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling"&gt;
-  &lt;head&gt;
-    &lt;layout&gt;
-      &lt;region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 5c"/&gt;
-    &lt;/layout&gt;
-  &lt;/head&gt;
-  &lt;body&gt;
-    &lt;div begin="0s" end="25s"&gt;
-      &lt;p&gt;
-        &lt;span begin="0s"&gt;Lorem&lt;/span&gt;
-        &lt;span begin="1s"&gt;ipsum&lt;/span&gt;
-        &lt;span begin="2s"&gt;dolor&lt;/span&gt;
-        &lt;span begin="3s"&gt;sit&lt;/span&gt;
-      &lt;/p&gt;
-      &lt;p&gt;
-        &lt;span begin="4s"&gt;Amet&lt;/span&gt;                
-        &lt;span begin="5s"&gt;consectetur&lt;/span&gt;
-        &lt;span begin="6s"&gt;adipiscing&lt;/span&gt;
-        &lt;span begin="7s"&gt;elit&lt;/span&gt;
-      &lt;/p&gt;
-      &lt;p&gt;
-        &lt;span begin="8s"&gt;Sed&lt;/span&gt;
-        &lt;span begin="9s"&gt;do&lt;/span&gt;
-        &lt;span begin="10s"&gt;eiusmod&lt;/span&gt;
-        &lt;span begin="11s"&gt;tempor&lt;/span&gt;
-        &lt;span begin="12s"&gt;incididunt &lt;/span&gt;
-        &lt;span begin="13s"&gt;labore&lt;/span&gt;
-     &lt;/p&gt;
-     &lt;p&gt;
-        &lt;span begin="14s"&gt;et&lt;/span&gt;
-        &lt;span begin="15s"&gt;dolore&lt;/span&gt;
-        &lt;span begin="16s"&gt;magna&lt;/span&gt;
-        &lt;span begin="17s"&gt;aliqua&lt;/span&gt;
-      &lt;/p&gt;
-      &lt;p&gt;
-        &lt;span begin="18s"&gt;Ut&lt;/span&gt;
-        &lt;span begin="19s"&gt;enim&lt;/span&gt;
-        &lt;span begin="20s"&gt;ad&lt;/span&gt;
-        &lt;span begin="21s"&gt;minim&lt;/span&gt;
-        &lt;span begin="22s"&gt;veniam&lt;/span&gt;
-        &lt;span begin="23s"&gt;quis,&lt;/span&gt;
-        &lt;span begin="24s"&gt;nostrud&lt;/span&gt;
-      &lt;/p&gt;
-    &lt;/div&gt;
-  &lt;/body&gt;
-&lt;/tt&gt;
-</pre>
-                </div>
-              </td>
-            </tr>
-          </tbody>
-        </table>
-      </div>
-    </div>
-
-    <div class="div1">
-      <h2><a id="acknowledgments" name="acknowledgments"></a>P Acknowledgments
-      (Non-Normative)</h2>
-
-      <p>The editor acknowledges the current and former members of the Timed
-      Text Working Group, the members of other W3C Working Groups, and industry
-      experts in other forums who have contributed directly or indirectly to
-      the process or content of this document as follows:</p>
-
-      <p>Glenn Adams, Thomas Bause-Mason, John Birch, Kees Blom, Bert Bos, Brad
-      Botkin, Dick Bulterman, Frans de Jong, Mike Dolan, Martin Dürst, Donald
-      Evans, Geoff Freed, Al Gilman, Giles Godart-Brown, Markus Gylling, Markku
-      Hakkinen, Sean Hayes, Erik Hodge, Philipp Hoschka, Suzi Hyun, Michael
-      Jordan, Masahiko Kaneko, Courtney Kennedy, George Kerscher, David Kirby,
-      Andrew Kirkpatrick, Philippe Le Hégaret, Chris Lilley, Pierre-Anthony
-      Lemieux, Jason Livingston, Monica Martin, Thierry Michel, Matthew May,
-      Frank Olivier, Soohong Daniel Park, Silvia Pfeiffer, Brian Raymor, David
-      Ronca, Patrick Schmitz, David Singer, Craig Smithpeters, Andreas Tai, and
-      Mohamed Zergaoui.</p>
-
-      <p>The editor wishes to especially acknowledge the following
-      contributions by members: Micheal Dolan (SMPTE time codes, streaming;
-      SMPTE liaison), David Kirby (introductory example document; SMPTE time
-      codes, descriptive metadata; EBU/AAF liaison), Geoff Freed (styling and
-      example images of style properties), Sean Hayes (advanced profile
-      concepts, including applicative timing), Eric Hodge (timing), Thierry
-      Michel (metadata), and Dave Singer (animation, scrolling).</p>
-
-      <p>The Working Group dedicates this specification to our colleague David
-      Kirby.</p>
-    </div>
-  </div>
-</body>
-</html>
Binary file ttml10/spec/PER-ttaf1-dfxp-201307DD.zip has changed
--- a/ttml10/spec/build.xml	Thu Jun 27 10:35:37 2013 -0600
+++ b/ttml10/spec/build.xml	Fri Jun 28 00:19:59 2013 -0600
@@ -286,7 +286,7 @@
       <echo>WARNING: changelog.xml and acknowledgments.xml MAY be out of date. Use "main" target if necessary.</echo>
     </target>
 
-    <property name="per.name" value="PER-ttaf1-dfxp-201307DD"/>
+    <property name="per.name" value="PER-ttaf1-dfxp-20130709"/>
     <property name="per.target" value="${basedir}/${per.name}"/>
     <target name="per-archive" description="Create PER Archive">
         <fail>
--- a/ttml10/spec/entities.dtd	Thu Jun 27 10:35:37 2013 -0600
+++ b/ttml10/spec/entities.dtd	Fri Jun 28 00:19:59 2013 -0600
@@ -1,9 +1,9 @@
 
 <!-- comment / uncomment the appropriate entity -->
-<!ENTITY % sub.entities SYSTEM "entitiesedcopy.dtd" >
+<!-- <!ENTITY % sub.entities SYSTEM "entitiesedcopy.dtd" > -->
 <!-- <!ENTITY % sub.entities SYSTEM "entitieswd.dtd" > -->
 <!-- <!ENTITY % sub.entities SYSTEM "entitiescr.dtd" > -->
-<!-- <!ENTITY % sub.entities SYSTEM "entitiesper.dtd" > -->
+<!ENTITY % sub.entities SYSTEM "entitiesper.dtd" >
 %sub.entities;
 
 <!-- Titles -->
--- a/ttml10/spec/entitiesper.dtd	Thu Jun 27 10:35:37 2013 -0600
+++ b/ttml10/spec/entitiesper.dtd	Fri Jun 28 00:19:59 2013 -0600
@@ -6,10 +6,11 @@
 <!ENTITY draft.year "2013">
 <!ENTITY draft.month "July">
 <!ENTITY draft.mm "07">
-<!ENTITY draft.day "DD">
-<!ENTITY draft.dd "DD">
+<!ENTITY draft.day "09">
+<!ENTITY draft.dd "09">
 
 <!ENTITY draft.date "&draft.year;&draft.mm;&draft.dd;">
+<!ENTITY review.end.date "06 August 2013">
 
 <!ENTITY prefix "ttaf1-dfxp">
 
--- a/ttml10/spec/statusper.xml	Thu Jun 27 10:35:37 2013 -0600
+++ b/ttml10/spec/statusper.xml	Fri Jun 28 00:19:59 2013 -0600
@@ -18,7 +18,10 @@
 part of the W3C <loc href="http://www.w3.org/2008/WebVideo/">Video
 in the Web Activity</loc>, following the procedures set out for the W3C <loc
 href="http://www.w3.org/Consortium/Process/">Process</loc>.  The authors of this
-document are listed in the header of this document.</p>
+document are listed in the header of this document, including input and review
+by liaisons from the <loc href="http://www3.ebu.ch/cms/en/home">European
+Broadcasting Union (EBU)</loc>, and the <loc href="https://www.smpte.org">Society
+of Motion Picture &amp; Television Engineers (SMPTE)</loc>.</p>
 
 <p>Publication as a Proposed Edited Recommendation does not imply endorsement by
 the W3C Membership. This is a draft document and may be updated,
@@ -26,7 +29,7 @@
 inappropriate to cite this document as other than work in progress.</p>
 
 <p>W3C Advisory Committee Members are invited to send formal review comments
-on this Proposed Edited Recommendation to the W3C Team until DD August 2013.
+on this Proposed Edited Recommendation to the W3C Team until &review.end.date;.
 Members of the W3C Advisory Committee will find the appropriate review form
 for this document by consulting their
 <loc href="http://www.w3.org/2002/09/wbs/myQuestionnaires">list
@@ -54,7 +57,7 @@
 
 <p>The Timed Text Working Group plans to submit this specification for
 consideration as a W3C Recommendation (Second Edition) as soon as the Working
-Group has responded formally to all issues raised during the PER period
+Group has responded formally to all issues raised during the PER review period
 against this document.</p>
 
 <p>This document was produced by a group operating under the <loc
--- a/ttml10/spec/ttaf1-dfxp.html	Thu Jun 27 10:35:37 2013 -0600
+++ b/ttml10/spec/ttaf1-dfxp.html	Fri Jun 28 00:19:59 2013 -0600
@@ -1,6 +1,6 @@
 <!DOCTYPE html
   PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
-<html lang="en-us"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>Timed Text Markup Language (TTML) 1.0 (Second Edition) -- (Editor's copy)</title><style type="text/css">
+<html lang="en-us"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>Timed Text Markup Language (TTML) 1.0 (Second Edition)</title><style type="text/css">
 code           { font-family: monospace; }
 
 div.constraint,
@@ -80,14 +80,14 @@
 .strong { font-weight: bold }
 .reqattr { font-weight: bold }
 .optattr { font-style: italic }
-</style><link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-ED.css"></head><body>Last Modified: $Date: 2013/06/27 16:25:13 $<div id="revisions"></div><div class="head">
+</style><link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-PER.css"></head><body><div class="head"><p><a href="http://www.w3.org/"><img src="http://www.w3.org/Icons/w3c_home" alt="W3C" height="48" width="72"></a></p>
 <h1><a id="title"></a>Timed Text Markup Language (TTML) 1.0 (Second Edition)</h1>
-<h2><a id="w3c-doctype"></a>Editors' copy $Date: 2013/06/27 16:25:13 $ @@ @@@@ @@@@</h2><dl><dt>This version:</dt><dd>
-<a href="ttaf1-dfxp.html">ttaf1-dfxp.html</a>
-</dd><dt>Latest version:</dt><dd><a href="http://dvcs.w3.org/hg/ttml/raw-file/tip/ttml10/spec/ttaf1-dfxp.html?content-type=text/html;charset=utf-8">http://dvcs.w3.org/hg/ttml/raw-file/tip/ttml10/spec/ttaf1-dfxp.html?content-type=text/html;charset=utf-8</a></dd><dt>Previous version:</dt><dd>
+<h2><a id="w3c-doctype"></a>W3C Proposed Edited Recommendation 09 July 2013</h2><dl><dt>This version:</dt><dd>
+<a href="http://www.w3.org/TR/2013/PER-ttaf1-dfxp-20130709/">http://www.w3.org/TR/2013/PER-ttaf1-dfxp-20130709/</a>
+</dd><dt>Latest version:</dt><dd><a href="http://www.w3.org/TR/ttaf1-dfxp/">http://www.w3.org/TR/ttaf1-dfxp/</a></dd><dt>Previous version:</dt><dd>
 <a href="http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/</a>
 </dd><dt>Editor:</dt><dd>Glenn Adams, Cox Communications, Inc.</dd><dt>Contributing Authors:</dt><dd>Mike Dolan, Invited Expert</dd><dd>Geoff Freed, WGBH National Center for Accessible Media</dd><dd>Sean Hayes, Microsoft</dd><dd>Erik Hodge, RealNetworks</dd><dd>David Kirby, British Broadcasting Corporation (BBC)</dd><dd>Thierry Michel, W3C</dd><dd>Dave Singer, Apple Computer</dd></dl><p>Please refer to the <a href="https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttml-issues.html">errata</a> for this document, which may
-      include normative corrections.</p><p>See also <a href="http://www.w3.org/2003/03/Translations/byTechnology?technology=ttaf1-dfxp"><strong>translations</strong></a>.</p><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>&nbsp;©&nbsp;@@@@&nbsp;<a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p></div><hr><div>
+      include normative corrections.</p><p>See also <a href="http://www.w3.org/2003/03/Translations/byTechnology?technology=ttaf1-dfxp"><strong>translations</strong></a>.</p><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>&nbsp;©&nbsp;2013&nbsp;<a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p></div><hr><div>
 <h2><a id="abstract"></a>Abstract</h2><p>This document specifies the Timed Text Markup Language (TTML) in terms of a
 vocabulary and semantics thereof.</p><p>The Timed Text Markup Language is a content type that represents
 timed text media for the purpose of interchange among authoring
@@ -100,8 +100,53 @@
 for example, providing a standard content format to reference from a <code>&lt;track&gt;</code>
 element in an HTML5 document, or a <code>&lt;text&gt;</code> or 
 <code>&lt;textstream&gt;</code> media element in a <a href="#smil21">[SMIL 2.1]</a> document.</p></div><div>
-<h2><a id="status"></a>Status of this Document</h2><p><strong>This document is an editor's copy that has
-        no official standing.</strong></p><p></p></div><div class="toc">
+<h2><a id="status"></a>Status of this Document</h2><p><em>This section describes the status of this document at the
+time of its publication. Other documents may supersede this document.
+A list of current W3C publications and the latest revision of this
+technical report can be found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at
+http://www.w3.org/TR/.</em></p><p>This document, published on 09 July 2013, 
+is a <a href="http://www.w3.org/2005/10/Process-20051014/tr.html#ProposedEditedRec">Proposed Edited Recommendation</a>
+of the W3C. This second edition is not a new version of this specification;
+its purpose is to clarify a number of issues that have become apparent since the
+first edition was published.</p><p>This document has been produced by the <a href="http://www.w3.org/AudioVideo/TT/">Timed Text (TT) Working Group</a> as
+part of the W3C <a href="http://www.w3.org/2008/WebVideo/">Video
+in the Web Activity</a>, following the procedures set out for the W3C <a href="http://www.w3.org/Consortium/Process/">Process</a>.  The authors of this
+document are listed in the header of this document, including input and review
+by liaisons from the <a href="http://www3.ebu.ch/cms/en/home">European
+Broadcasting Union (EBU)</a>, and the <a href="https://www.smpte.org">Society
+of Motion Picture &amp; Television Engineers (SMPTE)</a>.</p><p>Publication as a Proposed Edited Recommendation does not imply endorsement by
+the W3C Membership. This is a draft document and may be updated,
+replaced or obsoleted by other documents at any time. It is
+inappropriate to cite this document as other than work in progress.</p><p>W3C Advisory Committee Members are invited to send formal review comments
+on this Proposed Edited Recommendation to the W3C Team until 06 August 2013.
+Members of the W3C Advisory Committee will find the appropriate review form
+for this document by consulting their
+<a href="http://www.w3.org/2002/09/wbs/myQuestionnaires">list
+of WBS questionnaires</a>.</p><p>This document incorporates changes made against the
+<a href="http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">Recommendation</a>
+of 18 November 2010 that resolve all errata known at the date of publication.
+A list of the errata that have been applied is provided in
+<a href="https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttml-changes.html#change-history-rec-to-2e-per">Changes
+from Recommendation to Proposed Edited Recommendation (2nd Ed.)</a>.</p><p>Please report errors in and submit comments on this document to the
+W3C Timed Text public comments mailing list,
+<a href="mailto:public-tt-comments@w3.org">public-tt-comments@w3.org</a>.
+Please include the string <code>[ttml10se]</code> at the beginning of the
+subject line of your report. Each email message should contain only one
+error report. Archives of the comments and responses are available at
+<a href="http://lists.w3.org/Archives/Public/public-tt-comments/">http://lists.w3.org/Archives/Public/public-tt-comments/</a>.</p><p>An updated <a href="http://www.w3.org/2009/05/dfxp-results.html">implementation
+report</a>  will be made available, but the decision of the Director to transition
+this document to Proposed Edited Recommendation did not depend on the existence of that
+report.</p><p>The Timed Text Working Group plans to submit this specification for
+consideration as a W3C Recommendation (Second Edition) as soon as the Working
+Group has responded formally to all issues raised during the PER review period
+against this document.</p><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
+2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/34314/status#disclosures" rel="disclosure">public list of any patent
+disclosures</a> made in connection with the deliverables of the group;
+that page also includes instructions for disclosing a patent. An
+individual who has actual knowledge of a patent which the individual
+believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
+Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
+6 of the W3C Patent Policy</a>.</p></div><div class="toc">
 <h2><a id="contents"></a>Table of Contents</h2><p class="toc">1 <a href="#intro">Introduction</a><br>
 &nbsp;&nbsp;&nbsp;&nbsp;1.1 <a href="#model">System Model</a><br>
 &nbsp;&nbsp;&nbsp;&nbsp;1.2 <a href="#example">Document Example</a><br>
@@ -392,11 +437,11 @@
 H <a href="#other-references">Other References</a> (Non-Normative)<br>
 I <a href="#requirements">Requirements</a> (Non-Normative)<br>
 J <a href="#derivation">Vocabulary Derivation</a> (Non-Normative)<br>
-&nbsp;&nbsp;&nbsp;&nbsp;J.1 <a href="#d3e18570">Element Derivation</a><br>
-&nbsp;&nbsp;&nbsp;&nbsp;J.2 <a href="#d3e19049">Attribute Derivation</a><br>
+&nbsp;&nbsp;&nbsp;&nbsp;J.1 <a href="#d3e18678">Element Derivation</a><br>
+&nbsp;&nbsp;&nbsp;&nbsp;J.2 <a href="#d3e19157">Attribute Derivation</a><br>
 K <a href="#qa">QA Framework Compliance</a> (Non-Normative)<br>
-&nbsp;&nbsp;&nbsp;&nbsp;K.1 <a href="#d3e19935">Requirements</a><br>
-&nbsp;&nbsp;&nbsp;&nbsp;K.2 <a href="#d3e20099">Guidelines</a><br>
+&nbsp;&nbsp;&nbsp;&nbsp;K.1 <a href="#d3e20043">Requirements</a><br>
+&nbsp;&nbsp;&nbsp;&nbsp;K.2 <a href="#d3e20207">Guidelines</a><br>
 L <a href="#streaming">Streaming TTML Content</a> (Non-Normative)<br>
 M <a href="#concrete-encoding">Concrete Encoding</a> (Non-Normative)<br>
 N <a href="#time-expression-semantics">Time Expression Semantics</a> (Non-Normative)<br>
@@ -6479,7 +6524,7 @@
 <h2><a id="derivation"></a>J Vocabulary Derivation (Non-Normative)</h2><p>This appendix provides information about the derivation of TTML
 vocabulary, separately describing derivation of elements and
 attributes.</p><div class="div2">
-<h3><a id="d3e18570"></a>J.1 Element Derivation</h3><p>The first column of <a href="#element-vocab-derivation-table"><b>Table J-1 – Elements</b></a>
+<h3><a id="d3e18678"></a>J.1 Element Derivation</h3><p>The first column of <a href="#element-vocab-derivation-table"><b>Table J-1 – Elements</b></a>
 specifies a TTML element vocabulary item; the second column specifies the
 syntactic and/or semantic model on which the vocabulary item is based;
 the third column specifies the reference that defines
@@ -6534,7 +6579,7 @@
 and <code>@requiredFeatures</code> on the <code>svg:svg</code> element,
 but extended to support distinct specification of optionality.</p></li><li><p>Derived from the use of <code>@baseProfile</code>
 and <code>@version</code> on the <code>svg:svg</code> element.</p></li></ol></div></div><div class="div2">
-<h3><a id="d3e19049"></a>J.2 Attribute Derivation</h3><p>The first column of <a href="#attribute-vocab-derivation-table"><b>Table J-2 – Attributes</b></a>
+<h3><a id="d3e19157"></a>J.2 Attribute Derivation</h3><p>The first column of <a href="#attribute-vocab-derivation-table"><b>Table J-2 – Attributes</b></a>
 specifies a TTML attribute vocabulary item; the second column specifies the
 syntactic and/or semantic model on which the vocabulary item is based;
 the third column specifies the reference that defines
@@ -6606,9 +6651,9 @@
 <h2><a id="qa"></a>K QA Framework Compliance (Non-Normative)</h2><p>This appendix specifies the compliance of this specification with the
 requirements and guidelines defined by <a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/">QA
 Framework Specifications Guidelines</a>&nbsp;<a href="#qaf-sg">[QAF SG]</a>.</p><div class="div2">
-<h3><a id="d3e19935"></a>K.1 Requirements</h3><a id="qa-framework-requirements-table"></a><table class="common"><caption>Table K-1 – QA Framework Requirements Checklist</caption><col width="76%" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><tbody><tr><td><span class="strong">Requirement</span></td><td><span class="strong">YES</span></td><td><span class="strong">NO</span></td><td><span class="strong">N/A</span></td><td><span class="strong">Notes</span></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#include-conformance-clause-principle">Requirement 01: Include a conformance
+<h3><a id="d3e20043"></a>K.1 Requirements</h3><a id="qa-framework-requirements-table"></a><table class="common"><caption>Table K-1 – QA Framework Requirements Checklist</caption><col width="76%" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><tbody><tr><td><span class="strong">Requirement</span></td><td><span class="strong">YES</span></td><td><span class="strong">NO</span></td><td><span class="strong">N/A</span></td><td><span class="strong">Notes</span></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#include-conformance-clause-principle">Requirement 01: Include a conformance
 clause</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-scope-principle">Requirement 02: Define the scope.</a></td><td><a href="#intro">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#implement-principle">Requirement 03: Identify who or what will implement the specification.</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-norm-principle">Requirement 04: Make a list of normative references.</a></td><td><a href="#references">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-principle">Requirement 05: Define the terms used in the normative parts of the specification.</a></td><td><a href="#definitions">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conf-label-principle">Requirement 06: Create conformance labels for each part of the conformance model.</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#consistent-style-principle">Requirement 07: Use a consistent style for conformance requirements and explain how to distinguish them.</a></td><td><a href="#conventions">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#req-opt-conf-principle">Requirement 08: Indicate which conformance requirements are mandatory, which are recommended, and which are optional.</a></td><td><a href="#conventions">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-mandatory-principle">Requirement 09: If the technology is subdivided, then indicate which subdivisions are mandatory for conformance.</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdiv-constraints-principle">Requirement 10: If the technology is subdivided, then address subdivision constraints.</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#likehood-extension-principle">Requirement 11: Address Extensibility.</a></td><td><a href="#doctypes">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#deprecated-feature-principle">Requirement 12: Identify deprecated features.</a></td><td></td><td></td><td>N/A</td><td>1</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#degree-support-principle">Requirement 13: Define how each class of product handles each deprecated feature.</a></td><td></td><td></td><td>N/A</td><td>1</td></tr></tbody></table><div class="note"><p class="prefix"><b>Note:</b></p><ol class="enumar"><li><p>No feature is deprecated by this version of this specification.</p></li></ol></div></div><div class="div2">
-<h3><a id="d3e20099"></a>K.2 Guidelines</h3><a id="qa-framework-guidelines-table"></a><table class="common"><caption>Table K-2 – QA Framework Guidelines Checklist</caption><col width="76%" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><tbody><tr><td><span class="strong">Guideline</span></td><td><span class="strong">YES</span></td><td><span class="strong">NO</span></td><td><span class="strong">N/A</span></td><td><span class="strong">Notes</span></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-model-gp">Good Practice 01: Define the specification's conformance model in the conformance clause.</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#norm-informative-gp">Good Practice 02: Specify in the conformance clause how to distinguish normative from informative content.</a></td><td><a href="#conventions">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-claim-gp">Good Practice 03: Provide the wording for conformance claims.</a></td><td><a href="#claims">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-gp">Good Practice 04: Provide an Implementation Conformance Statement Pro Forma.</a></td><td></td><td>NO</td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-claim-gp">Good Practice 05: Require an Implementation Conformance Statement as part of valid conformance claims.</a></td><td><a href="#claims">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#use-example-gp">Good Practice 06: Provide examples, use cases, and graphics.</a></td><td><a href="#example">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-sample-gp">Good Practice 07: Write sample code or tests.</a></td><td>YES</td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-define-practice">Good Practice 08: When imposing requirements by normative references, address conformance dependencies.</a></td><td><a href="#references">YES</a></td><td></td><td></td><td>1</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-inline-gp">Good Practice 09: Define unfamiliar terms in-line and consolidate the definitions in a glossary section.</a></td><td><a href="#definitions">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#reuse-terms-gp">Good Practice 10: Use terms already defined without changing their definition.</a></td><td><a href="#definitions">YES</a></td><td></td><td></td><td>2</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#formal-language-gp">Good Practice 11: Use formal languages when possible.</a></td><td><a href="#schemas">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-assertion-gp">Good Practice 12: Write Test Assertions.</a></td><td></td><td>NO</td><td></td><td>3</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-foster-gp">Good Practice 13: Create subdivisions of the technology when warranted.</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#rules-profiles-gp">Good Practice 14: If the technology is profiled, define rules for creating new profiles.</a></td><td><a href="#vocabulary-profiles">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#need-option-gp">Good Practice 15:Use optional features as warranted.</a></td><td>YES</td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#label-options-gp">Good Practice 16: Clearly identify optional features.</a></td><td>YES</td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#constraints-gp">Good Practice 17: Indicate any limitations or constraints on optional features.</a></td><td>YES</td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#extensions-prohibited-gp">Good Practice 18: If extensibility is allowed, define an extension mechanism.</a></td><td><a href="#extension-vocabulary-overview">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#breaking-conformance-gp">Good Practice 19: Warn extension creators to create extensions that do not interfere with conformance.</a></td><td><a href="#extension-vocabulary-overview">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-error-gp">Good Practice 20: Define error-handling for unknown extensions.</a></td><td><a href="#conformance-processor">YES</a></td><td></td><td></td><td>4</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#workaround-gp">Good Practice 21: Explain how to avoid using a deprecated feature.</a></td><td></td><td></td><td>N/A</td><td>5</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#obsolete-gp">Good Practice 22: Identify obsolete features.</a></td><td></td><td></td><td>N/A</td><td>5</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#error-handling-gp">Good Practice 23: Define an error handling mechanism.</a></td><td><a href="#reduced-infoset">YES</a></td><td></td><td></td><td></td></tr></tbody></table><div class="note"><p class="prefix"><b>Note:</b></p><ol class="enumar"><li><p>When making normative references to external specifications,
+<h3><a id="d3e20207"></a>K.2 Guidelines</h3><a id="qa-framework-guidelines-table"></a><table class="common"><caption>Table K-2 – QA Framework Guidelines Checklist</caption><col width="76%" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><col width="6%" align="center" span="1"><tbody><tr><td><span class="strong">Guideline</span></td><td><span class="strong">YES</span></td><td><span class="strong">NO</span></td><td><span class="strong">N/A</span></td><td><span class="strong">Notes</span></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-model-gp">Good Practice 01: Define the specification's conformance model in the conformance clause.</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#norm-informative-gp">Good Practice 02: Specify in the conformance clause how to distinguish normative from informative content.</a></td><td><a href="#conventions">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-claim-gp">Good Practice 03: Provide the wording for conformance claims.</a></td><td><a href="#claims">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-gp">Good Practice 04: Provide an Implementation Conformance Statement Pro Forma.</a></td><td></td><td>NO</td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-claim-gp">Good Practice 05: Require an Implementation Conformance Statement as part of valid conformance claims.</a></td><td><a href="#claims">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#use-example-gp">Good Practice 06: Provide examples, use cases, and graphics.</a></td><td><a href="#example">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-sample-gp">Good Practice 07: Write sample code or tests.</a></td><td>YES</td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-define-practice">Good Practice 08: When imposing requirements by normative references, address conformance dependencies.</a></td><td><a href="#references">YES</a></td><td></td><td></td><td>1</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-inline-gp">Good Practice 09: Define unfamiliar terms in-line and consolidate the definitions in a glossary section.</a></td><td><a href="#definitions">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#reuse-terms-gp">Good Practice 10: Use terms already defined without changing their definition.</a></td><td><a href="#definitions">YES</a></td><td></td><td></td><td>2</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#formal-language-gp">Good Practice 11: Use formal languages when possible.</a></td><td><a href="#schemas">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-assertion-gp">Good Practice 12: Write Test Assertions.</a></td><td></td><td>NO</td><td></td><td>3</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-foster-gp">Good Practice 13: Create subdivisions of the technology when warranted.</a></td><td><a href="#conformance">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#rules-profiles-gp">Good Practice 14: If the technology is profiled, define rules for creating new profiles.</a></td><td><a href="#vocabulary-profiles">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#need-option-gp">Good Practice 15:Use optional features as warranted.</a></td><td>YES</td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#label-options-gp">Good Practice 16: Clearly identify optional features.</a></td><td>YES</td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#constraints-gp">Good Practice 17: Indicate any limitations or constraints on optional features.</a></td><td>YES</td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#extensions-prohibited-gp">Good Practice 18: If extensibility is allowed, define an extension mechanism.</a></td><td><a href="#extension-vocabulary-overview">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#breaking-conformance-gp">Good Practice 19: Warn extension creators to create extensions that do not interfere with conformance.</a></td><td><a href="#extension-vocabulary-overview">YES</a></td><td></td><td></td><td></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-error-gp">Good Practice 20: Define error-handling for unknown extensions.</a></td><td><a href="#conformance-processor">YES</a></td><td></td><td></td><td>4</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#workaround-gp">Good Practice 21: Explain how to avoid using a deprecated feature.</a></td><td></td><td></td><td>N/A</td><td>5</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#obsolete-gp">Good Practice 22: Identify obsolete features.</a></td><td></td><td></td><td>N/A</td><td>5</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#error-handling-gp">Good Practice 23: Define an error handling mechanism.</a></td><td><a href="#reduced-infoset">YES</a></td><td></td><td></td><td></td></tr></tbody></table><div class="note"><p class="prefix"><b>Note:</b></p><ol class="enumar"><li><p>When making normative references to external specifications,
 specific clauses or sections are cited.</p></li><li><p>See also <a href="#derivation"><b>J Vocabulary Derivation</b></a>.</p></li><li><p>Test assertions and test suites will be provided prior to entering
 Proposed Recommendation (PR) phase.</p></li><li><p>See criterion #3 in <a href="#conformance-processor"><b>3.2 Processor Conformance</b></a> and definition of
 TTML <a href="#doctypes">Abstract Document Instance</a>.</p></li><li><p>No feature is deprecated or obsoleted by this version of this specification.</p></li></ol></div></div></div><div class="div1">
@@ -6960,4 +7005,4 @@
 Kirby (introductory example document; SMPTE time codes, descriptive metadata; EBU/AAF liaison), Geoff Freed (styling
 and example images of style properties), Sean Hayes (advanced profile
 concepts, including applicative timing), Eric Hodge (timing),
-Thierry Michel (metadata), and Dave Singer (animation, scrolling).</p><p>The Working Group dedicates this specification to our colleague David Kirby.</p></div></div></body></html>
\ No newline at end of file
+Thierry Michel (metadata), and Dave Singer (animation, scrolling).</p><p>The Working Group dedicates this specification to our colleague David Kirby.</p></div></div></body></html>
--- a/ttml10/spec/ttaf1-dfxp.xml	Thu Jun 27 10:35:37 2013 -0600
+++ b/ttml10/spec/ttaf1-dfxp.xml	Fri Jun 28 00:19:59 2013 -0600
@@ -1241,7 +1241,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <p>A profile designator must adhere to the
 <code>xsd:anyURI</code> data type defined by <bibref ref="xsd-2"/>,
 &sect;3.2.17. If the profile designator is expressed as a relative URI,
@@ -1511,7 +1511,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <p>Element vocabulary groups that are used in defining content models
 for TTML element types are enumerated in <specref ref="element-vocab-group-table"/>.</p>
 <table id="element-vocab-group-table" role="common">
@@ -1569,7 +1569,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <p>The attribute vocabulary specified for use with the core vocabulary
 catalog is enumerated in
 <specref ref="attribute-vocab-table"/>.</p>
@@ -3566,7 +3566,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-backgroundColor-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Background Color</caption>
 <tbody>
@@ -3653,7 +3653,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-color-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Color</caption>
 <tbody>
@@ -3746,7 +3746,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-direction-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Direction</caption>
 <tbody>
@@ -3859,7 +3859,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-display-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Display</caption>
 <tbody>
@@ -3987,7 +3987,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-displayAlign-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Display Align</caption>
 <tbody>
@@ -4089,7 +4089,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-extent-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Extent</caption>
 <tbody>
@@ -4192,7 +4192,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-fontFamily-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Font Family</caption>
 <tbody>
@@ -4312,7 +4312,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-fontSize-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Font Size</caption>
 <tbody>
@@ -4412,7 +4412,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-fontStyle-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Font Style</caption>
 <tbody>
@@ -4421,7 +4421,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <note role="derivation">
 <p>The semantics of the style property
 represented by this attribute are based upon that defined by <bibref ref="xsl11"/>,
@@ -4510,7 +4510,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-fontWeight-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Font Weight</caption>
 <tbody>
@@ -4609,7 +4609,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-lineHeight-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Line Height</caption>
 <tbody>
@@ -4618,7 +4618,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <note role="derivation">
 <p>The semantics of the style property
 represented by this attribute are based upon that defined by <bibref ref="xsl11"/>,
@@ -4704,7 +4704,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-opacity-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Opacity</caption>
 <tbody>
@@ -4819,7 +4819,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-origin-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Origin</caption>
 <tbody>
@@ -4935,7 +4935,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-overflow-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Overflow</caption>
 <tbody>
@@ -5234,7 +5234,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-textAlign-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Text Align</caption>
 <tbody>
@@ -5347,7 +5347,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-textDecoration-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Text Decoration</caption>
 <tbody>
@@ -5461,7 +5461,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-textOutline-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Text Outline</caption>
 <tbody>
@@ -5551,7 +5551,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-unicodeBidi-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Unicode Bidirectionality</caption>
 <tbody>
@@ -5659,7 +5659,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-visibility-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Visibility</caption>
 <tbody>
@@ -5768,7 +5768,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-wrapOption-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Wrap Option</caption>
 <tbody>
@@ -5871,7 +5871,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <table id="style-attribute-writingMode-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Writing Mode</caption>
 <tbody>
@@ -6011,8 +6011,8 @@
 </tr>
 </tbody>
 </table>
-<p/>
-<p/>
+<p></p>
+<p></p>
 <table id="style-attribute-zIndex-example-1-images" role="example-images">
 <caption>Example Rendition &ndash; Z Index</caption>
 <tbody>
@@ -6833,7 +6833,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 </def>
 </gitem>
 <gitem>
@@ -6907,7 +6907,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 </def>
 </gitem>
 <gitem>
@@ -8148,7 +8148,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 <p>The use of element metadata is illustrated by the following example.</p>
 <table id="metadata-vocabulary-metadata-example-2" role="example">
 <caption>Example Fragment &ndash; Element Metadata</caption>
@@ -8169,7 +8169,7 @@
 </tr>
 </tbody>
 </table>
-<p/>
+<p></p>
 
 <p>The use of metadata attribute items is illustrated by the following example.</p>
 <table id="metadata-vocabulary-metadata-example-3" role="example">
@@ -8197,7 +8197,7 @@
 attributes by expressing them indirectly on <el>metadata</el>
 elements.</p>
 </note>
-<p/>
+<p></p>
 <p>The use of foreign element metadata is illustrated by the following example.</p>
 <table id="metadata-vocabulary-metadata-example-4" role="example">
 <caption>Example Fragment &ndash; Foreign Element Metadata</caption>
@@ -8224,7 +8224,7 @@
 <p>In the above example, a number of elements defined by the Dublin
 Core metadata vocabulary are used to express document level metadata.</p>
 </note>
-<p/>
+<p></p>
 </div3>
 <div3 id="metadata-vocabulary-title">
 <head>ttm:title</head>