[ttml1] tidy
authorGlenn Adams <glenn@skynav.com>
Thu, 19 Sep 2013 17:44:20 -0600
changeset 555 5453f4a441f1
parent 554 6991d7d867ef
child 556 37fa2ceeb41e
[ttml1] tidy
ttml1/spec/ttml1.html
--- a/ttml1/spec/ttml1.html	Thu Sep 19 17:00:50 2013 -0600
+++ b/ttml1/spec/ttml1.html	Thu Sep 19 17:44:20 2013 -0600
@@ -1,25 +1,28 @@
-<!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 1 (TTML1) (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;
+<!DOCTYPE html>
+<html lang="en-us">
+<head>
+  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+  <title>Timed Text Markup Language 1 (TTML1) (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;
+  div.exampleOuter {border: 4px double gray;
                   margin: 0em; padding: 0em}
-div.exampleInner { background-color: #d5dee3;
+  div.exampleInner { background-color: #d5dee3;
                    border-top-width: 4px;
                    border-top-style: double;
                    border-top-color: #d3d3d3;
@@ -27,465 +30,919 @@
                    border-bottom-style: double;
                    border-bottom-color: #d3d3d3;
                    padding: 4px; margin: 0em }
-div.exampleWrapper { margin: 4px }
-div.exampleHeader { font-weight: bold;
+  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 {
+  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 {
+  }
+  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 }
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-table.example-images-bordered { text-align: center; border: 0px solid black; width: 85%; border-collapse: collapse }
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-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-REC.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 1 (TTML1) (Second Edition)</h1>
-<h2><a id="w3c-doctype"></a>W3C Recommendation 24 September 2013</h2><dl><dt>This version:</dt><dd>
-<a href="http://www.w3.org/TR/2013/REC-ttml1-20130924/">http://www.w3.org/TR/2013/REC-ttml1-20130924/</a>
-</dd><dt>Latest version:</dt><dd><a href="http://www.w3.org/TR/ttml1/">http://www.w3.org/TR/ttml1/</a></dd><dt>Previous 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>Previous recommendation:</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="ttml1-errata.html"><strong>errata</strong></a> for this document, which may
-    include normative corrections.</p><p>See also <a href="http://www.w3.org/2003/03/Translations/byTechnology?technology=ttml1"><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 Timed Text Markup Language (TTML), Version 1, also known as TTML1,
-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"></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 has been reviewed by W3C Members, by software developers,
-and by other W3C groups and interested parties, and is endorsed by the Director
-as a W3C Recommendation. It is a stable document and may be used as reference
-material or cited from another document. W3C's role in making the Recommendation
-is to draw attention to the specification and to promote its widespread
-deployment. This enhances the functionality and interoperability of the Web.</p><p>This version reflects changes made as a result of applying errata and addressing
-comments received since the Recommendation was first published. With one minor
-exception noted below, these changes are editorial.</p><p>This document is a revision of Timed Text Markup Language (TTML) 1.0
-<a href="#ttml10">[TTML10]</a>, superseding that <a href="http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">previous
-Recommendation</a>. The only identified substantive difference between this version and
-its predecessor is a change of the default treatment of the <code>ttp:markerMode</code> parameter attribute
-from <code>continuous</code> to <code>discontinuous</code>. A cumulative summary of all changes applied
-to this version since the Recommendation was first published is available at
-<a href="ttml1-changes.html#change-history-rec-to-2e-per">Changes
-from Recommendation to Proposed Edited Recommendation (2nd Ed.)</a> and
-<a href="ttml1-changes.html#change-history-2e-per-to-rec-2e">Changes
-from Proposed Edited Recommendation (2nd Ed.) to Recommendation (2nd Ed.)</a>.</p><p>A <a href="http://www.w3.org/2008/10/dfxp-testsuite.zip">sample test suite</a> is available. This set of tests is not intended to
-be exhaustive. The <a href="http://www.w3.org/2009/05/dfxp-results.html">implementation report</a> used by the director to
-transition to Recommendation has been made available. There have been no formal objections
-to the publication of this document.</p><p>This document was 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>If you wish to report errors in or submit comments on this document, then please
-submit them to <a href="mailto:public-tt@w3.org">public-tt@w3.org</a>
-(<a href="mailto:public-tt-request@w3.org">subscribe</a>,
-<a href="http://lists.w3.org/Archives/Public/public-tt/">archive</a>). All comments are welcome.</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>
-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"></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="#d3e18942">Element Derivation</a><br>
-&nbsp;&nbsp;&nbsp;&nbsp;J.2 <a href="#d3e19424">Attribute Derivation</a><br>
-K <a href="#qa">QA Framework Compliance</a> (Non-Normative)<br>
-&nbsp;&nbsp;&nbsp;&nbsp;K.1 <a href="#d3e20309">Requirements</a><br>
-&nbsp;&nbsp;&nbsp;&nbsp;K.2 <a href="#d3e20473">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"></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) Version 1, also referred to as TTML1,
-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, 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 is 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 the first edition of this specification, the version number <code>1.0</code> was
-used to refer to this version of TTML. In this second edition, this version number is simplified
-to <code>1</code> as a result of a determination to call the next (future) version <code>2</code>
-instead of <code>1.1</code>.</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 older URLs to refer to this specification. Starting in
-this edition of the first version of TTML, the short name <code>ttml1</code> will be
-used, and subsequent versions of TTML are expected to use short names of
-<code>ttml2</code>, etc., with integer version numbers.</p></div><div class="div2">
-<h3><a id="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"></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"></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"></a><table class="example"><caption>Example Fragment – TTML Document Structure</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+  }
+  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-REC.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 1 (TTML1) (Second
+    Edition)</h1>
+
+    <h2><a id="w3c-doctype" name="w3c-doctype"></a>W3C Recommendation 24 September
+    2013</h2>
+
+    <dl>
+      <dt>This version:</dt>
+
+      <dd><a href=
+      "http://www.w3.org/TR/2013/REC-ttml1-20130924/">http://www.w3.org/TR/2013/REC-ttml1-20130924/</a></dd>
+
+      <dt>Latest version:</dt>
+
+      <dd><a href="http://www.w3.org/TR/ttml1/">http://www.w3.org/TR/ttml1/</a></dd>
+
+      <dt>Previous 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>Previous recommendation:</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="ttml1-errata.html"><strong>errata</strong></a> for
+    this document, which may include normative corrections.</p>
+
+    <p>See also <a href=
+    "http://www.w3.org/2003/03/Translations/byTechnology?technology=ttml1"><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 Timed Text Markup Language (TTML), Version 1, also known
+    as TTML1, 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 has been reviewed by W3C Members, by software developers, and by
+    other W3C groups and interested parties, and is endorsed by the Director as a W3C
+    Recommendation. It is a stable document and may be used as reference material or
+    cited from another document. W3C's role in making the Recommendation is to draw
+    attention to the specification and to promote its widespread deployment. This
+    enhances the functionality and interoperability of the Web.</p>
+
+    <p>This version reflects changes made as a result of applying errata and addressing
+    comments received since the Recommendation was first published. With one minor
+    exception noted below, these changes are editorial.</p>
+
+    <p>This document is a revision of Timed Text Markup Language (TTML) 1.0 <a href=
+    "#ttml10">[TTML10]</a>, superseding that <a href=
+    "http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">previous Recommendation</a>. The
+    only identified substantive difference between this version and its predecessor is a
+    change of the default treatment of the <code>ttp:markerMode</code> parameter
+    attribute from <code>continuous</code> to <code>discontinuous</code>. A cumulative
+    summary of all changes applied to this version since the Recommendation was first
+    published is available at <a href=
+    "ttml1-changes.html#change-history-rec-to-2e-per">Changes from Recommendation to
+    Proposed Edited Recommendation (2nd Ed.)</a> and <a href=
+    "ttml1-changes.html#change-history-2e-per-to-rec-2e">Changes from Proposed Edited
+    Recommendation (2nd Ed.) to Recommendation (2nd Ed.)</a>.</p>
+
+    <p>A <a href="http://www.w3.org/2008/10/dfxp-testsuite.zip">sample test suite</a> is
+    available. This set of tests is not intended to be exhaustive. The <a href=
+    "http://www.w3.org/2009/05/dfxp-results.html">implementation report</a> used by the
+    director to transition to Recommendation has been made available. There have been no
+    formal objections to the publication of this document.</p>
+
+    <p>This document was 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>If you wish to report errors in or submit comments on this document, then please
+    submit them to <a href="mailto:public-tt@w3.org">public-tt@w3.org</a> (<a href=
+    "mailto:public-tt-request@w3.org">subscribe</a>, <a href=
+    "http://lists.w3.org/Archives/Public/public-tt/">archive</a>). All comments are
+    welcome.</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="#d3e18942">Element Derivation</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;J.2 <a href="#d3e19424">Attribute Derivation</a><br>
+    K <a href="#qa">QA Framework Compliance</a> (Non-Normative)<br>
+    &nbsp;&nbsp;&nbsp;&nbsp;K.1 <a href="#d3e20309">Requirements</a><br>
+    &nbsp;&nbsp;&nbsp;&nbsp;K.2 <a href="#d3e20473">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) Version 1, also referred to as TTML1,
+      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, 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 is 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 the first edition of this specification, the version number
+        <code>1.0</code> was used to refer to this version of TTML. In this second
+        edition, this version number is simplified to <code>1</code> as a result of a
+        determination to call the next (future) version <code>2</code> instead of
+        <code>1.1</code>.</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 older URLs to refer to this
+        specification. Starting in this edition of the first version of TTML, the short
+        name <code>ttml1</code> will be used, and subsequent versions of TTML are
+        expected to use short names of <code>ttml2</code>, etc., with integer version
+        numbers.</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;
@@ -494,21 +951,58 @@
   &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"></a><table class="example"><caption>Example Fragment – TTML Metadata</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></a><table class="example"><caption>Example Fragment – TTML Styling</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"
@@ -524,18 +1018,34 @@
   &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"></a><table class="example"><caption>Example Fragment – TTML Layout</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"
@@ -545,18 +1055,35 @@
     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"></a><table class="example"><caption>Example Fragment – TTML Body</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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;
@@ -599,157 +1126,631 @@
     &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><div class="note"><p class="prefix"><b>Note:</b></p><p>In this example, the <code>p</code> element is used as a presentational
-element rather than as a semantic element, i.e., as a linguistic paragraph.
-It is up to an author to determine which TTML elements are used to convey
-the intended meaning. For instance, this example could be written to use
-timing on <code>span</code> elements in order to preserve the integrity of
-semantic paragraphs.</p></div><a id="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"></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"></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"></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"></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"></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"></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"></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"></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"></a>2 Definitions</h2><div class="div2">
-<h3><a id="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"></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 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 profile.</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 profile of content 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">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 of this media object,
-expressed in the coordinate system that applies to the <em>Document Instance</em> that is associated with the
-related 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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: example</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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>
+
+        <div class="note">
+          <p class="prefix"><b>Note:</b></p>
+
+          <p>In this example, the <code>p</code> element is used as a presentational
+          element rather than as a semantic element, i.e., as a linguistic paragraph. It
+          is up to an author to determine which TTML elements are used to convey the
+          intended meaning. For instance, this example could be written to use timing on
+          <code>span</code> elements in order to preserve the integrity of semantic
+          paragraphs.</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 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 profile.</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 profile of content 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">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 of this
+            media object, expressed in the coordinate system that applies to the
+            <em>Document Instance</em> that is associated with the related 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"></a><table class="example"><caption>Example Fragment – Sample</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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;
@@ -758,240 +1759,660 @@
   &lt;/head&gt;
   &lt;body/&gt;
 &lt;/tt&gt;
-</pre></div>
-</td></tr></tbody></table></div></div><div class="div1">
-<h2><a id="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"></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"></a>3.2 Processor Conformance</h3><div class="div3">
-<h4><a id="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 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"></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"></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"></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"></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>, 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"></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"></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"></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"></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"></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"></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 <code>used</code> (mandatory and enabled) and by
-another profile to be <code>required</code> (mandatory) or <code>optional</code> (voluntary),
-then that feature or extension must be considered to be <code>used</code>
-(mandatory and enabled); if some feature or some extension is
-specified by one profile to be merely <code>required</code> (mandatory) and by
-another profile to be <code>optional</code> (voluntary), then that feature or
-extension must be considered to be <code>required</code> (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 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 profile 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 profile 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 <code>required</code> (mandatory) that was either not specified in the underlying, baseline
-profile or was specified as <code>optional</code> (voluntary) in the baseline profile.
-A predefined profile is subsetted by specifying some feature or extension to
-be <code>optional</code> (voluntary) that was specified as <code>required</code> (mandatory)
-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 <em>required feature</em> or <em>used feature</em>
-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 <em>required extension</em> or <em>used
-extension</em> 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"></a><table class="example"><caption>Example Fragment – DFXP Additive Profile</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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
+              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>, 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
+        <code>used</code> (mandatory and enabled) and by another profile to be
+        <code>required</code> (mandatory) or <code>optional</code> (voluntary), then that
+        feature or extension must be considered to be <code>used</code> (mandatory and
+        enabled); if some feature or some extension is specified by one profile to be
+        merely <code>required</code> (mandatory) and by another profile to be
+        <code>optional</code> (voluntary), then that feature or extension must be
+        considered to be <code>required</code> (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 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
+          profile 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 profile 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 <code>required</code> (mandatory) that was either not specified in the
+          underlying, baseline profile or was specified as <code>optional</code>
+          (voluntary) in the baseline profile. A predefined profile is subsetted by
+          specifying some feature or extension to be <code>optional</code> (voluntary)
+          that was specified as <code>required</code> (mandatory) 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 <em>required feature</em> or <em>used feature</em> 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 <em>required extension</em> or <em>used
+          extension</em> 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;
@@ -1002,1075 +2423,2482 @@
  &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"></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"></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"></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 id="element-vocab-type-animation"><td>
-Animation
-</td><td>
-<a href="#animation-vocabulary-set">set</a>
-</td></tr><tr id="element-vocab-type-content"><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 id="element-vocab-type-document"><td>
-Document
-</td><td>
-<a href="#document-structure-vocabulary-tt">tt</a>
-</td></tr><tr id="element-vocab-type-head"><td>
-Head
-</td><td>
-<a href="#document-structure-vocabulary-head">head</a>
-</td></tr><tr id="element-vocab-type-layout"><td>
-Layout
-</td><td>
-<a href="#layout-vocabulary-layout">layout</a>,
-<a href="#layout-vocabulary-region">region</a>
-</td></tr><tr id="element-vocab-type-metadata"><td>
-Metadata
-</td><td>
-<a href="#metadata-vocabulary-metadata">metadata</a>
-</td></tr><tr id="element-vocab-type-metadata-items"><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 id="element-vocab-type-parameter-items"><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 id="element-vocab-type-styling"><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"></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"></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"></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"></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"></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"></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>ttp: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>ttp: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 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"></a><table class="syntax"><caption>XML Representation – Element Information Item: ttp:profile</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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 id="element-vocab-type-animation">
+                <td>Animation</td>
+
+                <td><a href="#animation-vocabulary-set">set</a></td>
+              </tr>
+
+              <tr id="element-vocab-type-content">
+                <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 id="element-vocab-type-document">
+                <td>Document</td>
+
+                <td><a href="#document-structure-vocabulary-tt">tt</a></td>
+              </tr>
+
+              <tr id="element-vocab-type-head">
+                <td>Head</td>
+
+                <td><a href="#document-structure-vocabulary-head">head</a></td>
+              </tr>
+
+              <tr id="element-vocab-type-layout">
+                <td>Layout</td>
+
+                <td><a href="#layout-vocabulary-layout">layout</a>, <a href=
+                "#layout-vocabulary-region">region</a></td>
+              </tr>
+
+              <tr id="element-vocab-type-metadata">
+                <td>Metadata</td>
+
+                <td><a href="#metadata-vocabulary-metadata">metadata</a></td>
+              </tr>
+
+              <tr id="element-vocab-type-metadata-items">
+                <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 id="element-vocab-type-parameter-items">
+                <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 id="element-vocab-type-styling">
+                <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>ttp: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>ttp: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 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>*
+  <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"></a><table class="example"><caption>Example Fragment – ttp:profile</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: ttp:features</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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>*
+  <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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: ttp:feature</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></a><table class="example"><caption>Example Fragment – ttp:feature</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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>
+    <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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: ttp:extensions</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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>*
+  <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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: ttp:extension</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></a><table class="example"><caption>Example Fragment – ttp:extension</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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>
+    <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"></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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:cellResolution</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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="#cea608e">[CEA-608-E]</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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:clockMode</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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="#cea608e">[CEA-608-E]</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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:dropMode</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:frameRate</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:frameRateMultiplier</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+  : <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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:markerMode</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:pixelAspectRatio</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:subFrameRate</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:tickRate</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+  : <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"></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"></a><table class="syntax"><caption>Syntax Representation – ttp:timeBase</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+  : <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"></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"></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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: tt</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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
+  <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>?
+  <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="#cea708e">[CEA-708-E]</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"></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
-<a href="#element-vocab-type-content">Content</a> elements.</p><p>A <code>layout</code> child element is used to specify layout constructs that
-are referenced by <a href="#element-vocab-type-content">Content</a> elements.</p><a id="elt-syntax-head"></a><table class="syntax"><caption>XML Representation – Element Information Item: head</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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=
+            "#cea708e">[CEA-708-E]</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
+          <a href="#element-vocab-type-content">Content</a> elements.</p>
+
+          <p>A <code>layout</code> child element is used to specify layout constructs
+          that are referenced by <a href="#element-vocab-type-content">Content</a>
+          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>?
+  <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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: body</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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="#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=
+"#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>*
+  <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 <a href="#element-vocab-type-content">Content</a> 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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: div</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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
+            <a href="#element-vocab-type-content">Content</a> 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="#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=
+"#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>*
+  <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 <a href="#element-vocab-type-content">Content</a> 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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: p</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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
+            <a href="#element-vocab-type-content">Content</a> 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="#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=
+"#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>*
+  <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 <a href="#element-vocab-type-content">Content</a> 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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: span</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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
+            <a href="#element-vocab-type-content">Content</a> 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="#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=
+"#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>*
+  <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 <a href="#element-vocab-type-content">Content</a> 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"></a>7.1.7 br</h4><p>The <code>br</code> element denotes an explicit line break.</p><p>Any metadata specified by children in the <code>Metadata.class</code>
-element group applies semantically to the <code>br</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>br</code> element.</p><a id="elt-syntax-br"></a><table class="syntax"><caption>XML Representation – Element Information Item: br</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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
+            <a href="#element-vocab-type-content">Content</a> 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>
+
+          <p>Any metadata specified by children in the <code>Metadata.class</code>
+          element group applies semantically to the <code>br</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>br</code> element.</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
@@ -2079,86 +4907,256 @@
   {<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>*
+  <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"></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"></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"></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"></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"></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"></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"></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"></a><table class="syntax"><caption>XML Representation – Element Information Item: styling</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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>*
+  <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"></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><a id="elt-syntax-style"></a><table class="syntax"><caption>XML Representation – Element Information Item: style</caption><tbody><tr><td>
-<div class="exampleInner"><pre>
+</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><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
@@ -2168,63 +5166,334 @@
   {<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"></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 <a href="#element-vocab-type-content">Content</a> 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 <a href="#element-vocab-type-content">Content</a> 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
-<a href="#element-vocab-type-content">Content</a> 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="note"><p class="prefix"><b>Note:</b></p><p>Due to the general syntax of this specification (and the schemas it references) with respect
-to how style attributes are specified, particularly for the purpose of supporting inheritance,
-it is possible for an author to inadvertently specify a non-inheritable style attribute on
-an element that applies neither to that element or any of its descendants while still remaining
-conformant from a content validity perspective. Content authors may wish to make use of TTML
-content verification tools that detect and warn about such usage.</p></div><div class="div3">
-<h4><a id="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"></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"></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>&l