--- a/ttml10/spec/ttaf1-dfxp.html Wed Apr 25 22:20:47 2012 -0600
+++ b/ttml10/spec/ttaf1-dfxp.html Wed Apr 25 22:23:33 2012 -0600
@@ -70,9 +70,9 @@
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-</style><link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-ED.css"/></head><body>Last Modified: $Date: 2012/03/15 06:53:57 $<div id="revisions"/><div class="head">
+</style><link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-ED.css"/></head><body>Last Modified: $Date: 2012/04/26 04:20:47 $<div id="revisions"/><div class="head">
<h1><a name="title" id="title"/>Timed Text Markup Language (TTML) 1.0 (Second Edition)</h1>
-<h2><a name="w3c-doctype" id="w3c-doctype"/>Editors' copy $Date: 2012/03/15 06:53:57 $ @@ @@@@ @@@@</h2><dl><dt>This version:</dt><dd>
+<h2><a name="w3c-doctype" id="w3c-doctype"/>Editors' copy $Date: 2012/04/26 04:20:47 $ @@ @@@@ @@@@</h2><dl><dt>This version:</dt><dd>
<a href="ttaf1-dfxp.html">ttaf1-dfxp.html</a>
</dd><dt>Latest version:</dt><dd><a href="http://dvcs.w3.org/hg/ttml/raw-file/tip/ttml10/spec/ttaf1-dfxp.html?content-type=text/html;charset=utf-8">http://dvcs.w3.org/hg/ttml/raw-file/tip/ttml10/spec/ttaf1-dfxp.html?content-type=text/html;charset=utf-8</a></dd><dt>Previous version:</dt><dd>
<a href="http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/">http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/</a>
@@ -416,11 +416,11 @@
H <a href="#other-references">Other References</a> (Non-Normative)<br/>
I <a href="#requirements">Requirements</a> (Non-Normative)<br/>
J <a href="#derivation">Vocabulary Derivation</a> (Non-Normative)<br/>
- J.1 <a href="#d3e17042">Element Derivation</a><br/>
- J.2 <a href="#d3e17521">Attribute Derivation</a><br/>
+ J.1 <a href="#d3e17088">Element Derivation</a><br/>
+ J.2 <a href="#d3e17567">Attribute Derivation</a><br/>
K <a href="#qa">QA Framework Compliance</a> (Non-Normative)<br/>
- K.1 <a href="#d3e18389">Requirements</a><br/>
- K.2 <a href="#d3e18553">Guidelines</a><br/>
+ K.1 <a href="#d3e18435">Requirements</a><br/>
+ K.2 <a href="#d3e18599">Guidelines</a><br/>
L <a href="#streaming">Streaming TTML Content</a> (Non-Normative)<br/>
M <a href="#acknowledgments">Acknowledgments</a> (Non-Normative)<br/>
</p></div><hr/><div class="body"><div class="div1">
@@ -1544,8 +1544,25 @@
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>continuous</code>.</p><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>discontinuous</code> applies, then time
-expressions must not be converted to either media time or real time
+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.</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, 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
+as labeled synchronization events (markers), where some external
+synchronization context emits these events with implied constraints
+regarding time coordinate monoticity and resynchronization in
+the presence of dropped frames.</p><p>Use of <code>continuous</code> marker mode with the <code>smpte</code>
+time base is different from using the <code>media</code> time base
+because (1) the semantics of the <code>ttp:dropMode</code> parameter
+apply to the former, but not the latter, and (2) <a href="#smpte12m">[SMPTE 12M]</a>
+time coordinates may be applied monotonically to media which has been
+subjected to dilation in time, constriction in time, or reversal in
+time.</p></div><p>If a value of <code>discontinuous</code> applies, then time
+expressions must not be converted to real time
coordinates, arithmetical operators (addition, multiplication) are not
defined on time expressions, and, consequently, any expression of a
duration must be considered to be invalid.</p><div class="note"><p class="prefix"><b>Note:</b></p><p>When operating with <code>smpte</code> time base and
@@ -1658,7 +1675,11 @@
then a time expression denotes a <a href="#smpte12m">[SMPTE 12M]</a> time
coordinate with which the content of a document instance 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><p>If the time base is designated as <code>clock</code>, then the time
+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)
@@ -8310,7 +8331,7 @@
<h2><a name="derivation" id="derivation"/>J Vocabulary Derivation (Non-Normative)</h2><p>This appendix provides information about the derivation of TTML
vocabulary, separately describing derivation of elements and
attributes.</p><div class="div2">
-<h3><a name="d3e17042" id="d3e17042"/>J.1 Element Derivation</h3><p>The first column of <a href="#element-vocab-derivation-table"><b>Table K-1 – Elements</b></a>
+<h3><a name="d3e17088" id="d3e17088"/>J.1 Element Derivation</h3><p>The first column of <a href="#element-vocab-derivation-table"><b>Table K-1 – Elements</b></a>
specifies a TTML element vocabulary item; the second column specifies the
syntactic and/or semantic model on which the vocabulary item is based;
the third column specifies the reference that defines
@@ -8365,7 +8386,7 @@
and <code>@requiredFeatures</code> on the <code>svg:svg</code> element,
but extended to support distinct specification of optionality.</p></li><li><p>Derived from the use of <code>@baseProfile</code>
and <code>@version</code> on the <code>svg:svg</code> element.</p></li></ol></div></div><div class="div2">
-<h3><a name="d3e17521" id="d3e17521"/>J.2 Attribute Derivation</h3><p>The first column of <a href="#attribute-vocab-derivation-table"><b>Table K-2 – Attributes</b></a>
+<h3><a name="d3e17567" id="d3e17567"/>J.2 Attribute Derivation</h3><p>The first column of <a href="#attribute-vocab-derivation-table"><b>Table K-2 – Attributes</b></a>
specifies a TTML attribute vocabulary item; the second column specifies the
syntactic and/or semantic model on which the vocabulary item is based;
the third column specifies the reference that defines
@@ -8437,9 +8458,9 @@
<h2><a name="qa" id="qa"/>K QA Framework Compliance (Non-Normative)</h2><p>This appendix specifies the compliance of this specification with the
requirements and guidelines defined by <a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/">QA
Framework Specifications Guidelines</a> <a href="#qaf-sg">[QAF SG]</a>.</p><div class="div2">
-<h3><a name="d3e18389" id="d3e18389"/>K.1 Requirements</h3><table summary="HTML Table" id="qa-framework-requirements-table" class="common"><caption>Table L-1 – QA Framework Requirements Checklist</caption><col width="76%" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><tbody><tr><td><span class="strong">Requirement</span></td><td><span class="strong">YES</span></td><td><span class="strong">NO</span></td><td><span class="strong">N/A</span></td><td><span class="strong">Notes</span></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#include-conformance-clause-principle">Requirement 01: Include a conformance
+<h3><a name="d3e18435" id="d3e18435"/>K.1 Requirements</h3><table summary="HTML Table" id="qa-framework-requirements-table" class="common"><caption>Table L-1 – QA Framework Requirements Checklist</caption><col width="76%" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><tbody><tr><td><span class="strong">Requirement</span></td><td><span class="strong">YES</span></td><td><span class="strong">NO</span></td><td><span class="strong">N/A</span></td><td><span class="strong">Notes</span></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#include-conformance-clause-principle">Requirement 01: Include a conformance
clause</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-scope-principle">Requirement 02: Define the scope.</a></td><td><a href="#intro">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#implement-principle">Requirement 03: Identify who or what will implement the specification.</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-norm-principle">Requirement 04: Make a list of normative references.</a></td><td><a href="#references">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-principle">Requirement 05: Define the terms used in the normative parts of the specification.</a></td><td><a href="#definitions">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conf-label-principle">Requirement 06: Create conformance labels for each part of the conformance model.</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#consistent-style-principle">Requirement 07: Use a consistent style for conformance requirements and explain how to distinguish them.</a></td><td><a href="#conventions">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#req-opt-conf-principle">Requirement 08: Indicate which conformance requirements are mandatory, which are recommended, and which are optional.</a></td><td><a href="#conventions">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-mandatory-principle">Requirement 09: If the technology is subdivided, then indicate which subdivisions are mandatory for conformance.</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdiv-constraints-principle">Requirement 10: If the technology is subdivided, then address subdivision constraints.</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#likehood-extension-principle">Requirement 11: Address Extensibility.</a></td><td><a href="#doctypes">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#deprecated-feature-principle">Requirement 12: Identify deprecated features.</a></td><td/><td/><td>N/A</td><td>1</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#degree-support-principle">Requirement 13: Define how each class of product handles each deprecated feature.</a></td><td/><td/><td>N/A</td><td>1</td></tr></tbody></table><div class="note"><p class="prefix"><b>Note:</b></p><ol class="enumar"><li><p>No feature is deprecated by this version of this specification.</p></li></ol></div></div><div class="div2">
-<h3><a name="d3e18553" id="d3e18553"/>K.2 Guidelines</h3><table summary="HTML Table" id="qa-framework-guidelines-table" class="common"><caption>Table L-2 – QA Framework Guidelines Checklist</caption><col width="76%" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><tbody><tr><td><span class="strong">Guideline</span></td><td><span class="strong">YES</span></td><td><span class="strong">NO</span></td><td><span class="strong">N/A</span></td><td><span class="strong">Notes</span></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-model-gp">Good Practice 01: Define the specification's conformance model in the conformance clause.</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#norm-informative-gp">Good Practice 02: Specify in the conformance clause how to distinguish normative from informative content.</a></td><td><a href="#conventions">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-claim-gp">Good Practice 03: Provide the wording for conformance claims.</a></td><td><a href="#claims">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-gp">Good Practice 04: Provide an Implementation Conformance Statement Pro Forma.</a></td><td/><td>NO</td><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-claim-gp">Good Practice 05: Require an Implementation Conformance Statement as part of valid conformance claims.</a></td><td><a href="#claims">YES</a></td><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#use-example-gp">Good Practice 06: Provide examples, use cases, and graphics.</a></td><td><a href="#example">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-sample-gp">Good Practice 07: Write sample code or tests.</a></td><td>YES</td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-define-practice">Good Practice 08: When imposing requirements by normative references, address conformance dependencies.</a></td><td><a href="#references">YES</a></td><td/><td/><td>1</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-inline-gp">Good Practice 09: Define unfamiliar terms in-line and consolidate the definitions in a glossary section.</a></td><td><a href="#definitions">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#reuse-terms-gp">Good Practice 10: Use terms already defined without changing their definition.</a></td><td><a href="#definitions">YES</a></td><td/><td/><td>2</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#formal-language-gp">Good Practice 11: Use formal languages when possible.</a></td><td><a href="#schemas">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-assertion-gp">Good Practice 12: Write Test Assertions.</a></td><td/><td>NO</td><td/><td>3</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-foster-gp">Good Practice 13: Create subdivisions of the technology when warranted.</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#rules-profiles-gp">Good Practice 14: If the technology is profiled, define rules for creating new profiles.</a></td><td><a href="#vocabulary-profiles">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#need-option-gp">Good Practice 15:Use optional features as warranted.</a></td><td>YES</td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#label-options-gp">Good Practice 16: Clearly identify optional features.</a></td><td>YES</td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#constraints-gp">Good Practice 17: Indicate any limitations or constraints on optional features.</a></td><td>YES</td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#extensions-prohibited-gp">Good Practice 18: If extensibility is allowed, define an extension mechanism.</a></td><td><a href="#extension-vocabulary-overview">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#breaking-conformance-gp">Good Practice 19: Warn extension creators to create extensions that do not interfere with conformance.</a></td><td><a href="#extension-vocabulary-overview">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-error-gp">Good Practice 20: Define error-handling for unknown extensions.</a></td><td><a href="#conformance-processor">YES</a></td><td/><td/><td>4</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#workaround-gp">Good Practice 21: Explain how to avoid using a deprecated feature.</a></td><td/><td/><td>N/A</td><td>5</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#obsolete-gp">Good Practice 22: Identify obsolete features.</a></td><td/><td/><td>N/A</td><td>5</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#error-handling-gp">Good Practice 23: Define an error handling mechanism.</a></td><td><a href="#reduced-infoset">YES</a></td><td/><td/><td/></tr></tbody></table><div class="note"><p class="prefix"><b>Note:</b></p><ol class="enumar"><li><p>When making normative references to external specifications,
+<h3><a name="d3e18599" id="d3e18599"/>K.2 Guidelines</h3><table summary="HTML Table" id="qa-framework-guidelines-table" class="common"><caption>Table L-2 – QA Framework Guidelines Checklist</caption><col width="76%" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><col width="6%" align="center" span="1"/><tbody><tr><td><span class="strong">Guideline</span></td><td><span class="strong">YES</span></td><td><span class="strong">NO</span></td><td><span class="strong">N/A</span></td><td><span class="strong">Notes</span></td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-model-gp">Good Practice 01: Define the specification's conformance model in the conformance clause.</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#norm-informative-gp">Good Practice 02: Specify in the conformance clause how to distinguish normative from informative content.</a></td><td><a href="#conventions">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#conformance-claim-gp">Good Practice 03: Provide the wording for conformance claims.</a></td><td><a href="#claims">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-gp">Good Practice 04: Provide an Implementation Conformance Statement Pro Forma.</a></td><td/><td>NO</td><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ics-claim-gp">Good Practice 05: Require an Implementation Conformance Statement as part of valid conformance claims.</a></td><td><a href="#claims">YES</a></td><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#use-example-gp">Good Practice 06: Provide examples, use cases, and graphics.</a></td><td><a href="#example">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-sample-gp">Good Practice 07: Write sample code or tests.</a></td><td>YES</td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#ref-define-practice">Good Practice 08: When imposing requirements by normative references, address conformance dependencies.</a></td><td><a href="#references">YES</a></td><td/><td/><td>1</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-terms-inline-gp">Good Practice 09: Define unfamiliar terms in-line and consolidate the definitions in a glossary section.</a></td><td><a href="#definitions">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#reuse-terms-gp">Good Practice 10: Use terms already defined without changing their definition.</a></td><td><a href="#definitions">YES</a></td><td/><td/><td>2</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#formal-language-gp">Good Practice 11: Use formal languages when possible.</a></td><td><a href="#schemas">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#write-assertion-gp">Good Practice 12: Write Test Assertions.</a></td><td/><td>NO</td><td/><td>3</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#subdivide-foster-gp">Good Practice 13: Create subdivisions of the technology when warranted.</a></td><td><a href="#conformance">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#rules-profiles-gp">Good Practice 14: If the technology is profiled, define rules for creating new profiles.</a></td><td><a href="#vocabulary-profiles">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#need-option-gp">Good Practice 15:Use optional features as warranted.</a></td><td>YES</td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#label-options-gp">Good Practice 16: Clearly identify optional features.</a></td><td>YES</td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#constraints-gp">Good Practice 17: Indicate any limitations or constraints on optional features.</a></td><td>YES</td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#extensions-prohibited-gp">Good Practice 18: If extensibility is allowed, define an extension mechanism.</a></td><td><a href="#extension-vocabulary-overview">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#breaking-conformance-gp">Good Practice 19: Warn extension creators to create extensions that do not interfere with conformance.</a></td><td><a href="#extension-vocabulary-overview">YES</a></td><td/><td/><td/></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#define-error-gp">Good Practice 20: Define error-handling for unknown extensions.</a></td><td><a href="#conformance-processor">YES</a></td><td/><td/><td>4</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#workaround-gp">Good Practice 21: Explain how to avoid using a deprecated feature.</a></td><td/><td/><td>N/A</td><td>5</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#obsolete-gp">Good Practice 22: Identify obsolete features.</a></td><td/><td/><td>N/A</td><td>5</td></tr><tr><td><a href="http://www.w3.org/TR/2005/REC-qaframe-spec-20050817/#error-handling-gp">Good Practice 23: Define an error handling mechanism.</a></td><td><a href="#reduced-infoset">YES</a></td><td/><td/><td/></tr></tbody></table><div class="note"><p class="prefix"><b>Note:</b></p><ol class="enumar"><li><p>When making normative references to external specifications,
specific clauses or sections are cited.</p></li><li><p>See also <a href="#derivation"><b>J Vocabulary Derivation</b></a>.</p></li><li><p>Test assertions and test suites will be provided prior to entering
Proposed Recommendation (PR) phase.</p></li><li><p>See criterion #3 in <a href="#conformance-processor"><b>3.2 Processor Conformance</b></a> and definition of
<a href="#doctypes">TTML Abstract Document Instance</a>.</p></li><li><p>No feature is deprecated or obsoleted by this version of this specification.</p></li></ol></div></div></div><div class="div1">