--- a/ttml10/spec/ttaf1-dfxp.html Thu Jul 19 01:10:10 2012 -0600
+++ b/ttml10/spec/ttaf1-dfxp.html Thu Jul 19 01:11:21 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: 2012/06/28 06:05:43 $<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: 2012/07/19 07:10:10 $<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: 2012/06/28 06:05:43 $ @@ @@@@ @@@@</h2><dl><dt>This version:</dt><dd>
+<h2><a name="w3c-doctype" id="w3c-doctype"/>Editors' copy $Date: 2012/07/19 07:10:10 $ @@ @@@@ @@@@</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="#d3e17274">Element Derivation</a><br/>
- J.2 <a href="#d3e17753">Attribute Derivation</a><br/>
+ J.1 <a href="#d3e17321">Element Derivation</a><br/>
+ J.2 <a href="#d3e17800">Attribute Derivation</a><br/>
K <a href="#qa">QA Framework Compliance</a> (Non-Normative)<br/>
- K.1 <a href="#d3e18621">Requirements</a><br/>
- K.2 <a href="#d3e18785">Guidelines</a><br/>
+ K.1 <a href="#d3e18668">Requirements</a><br/>
+ K.2 <a href="#d3e18832">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">
@@ -3179,7 +3179,7 @@
3.2.4.1. If the value represented is less than 0.0,
then it must be interpreted as equal to 0.0; similarly, if the value
represented is greater than 1.0, then it must be interpreted as
-1.0. The value NaN shall be interpreted as 0.0.</p><p>If a presentation processor does not support a specific,
+1.0. The value NaN must be interpreted as 0.0.</p><p>If a presentation processor does not support a specific,
valid opacity value, then it must interpret it as being equal to the
closest supported value.</p></div><div class="div3">
<h4><a name="style-value-color" id="style-value-color"/>8.3.2 <color></h4><p>A <color> expression is used to specify a named color, exact RGB color triple,
@@ -3907,7 +3907,13 @@
<em>N</em> intermediate synchronic
document instances,
<em>DOC<sub><span>inter<sub>0</sub></span></sub></em> …
-<em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>.</p></div><div class="div3">
+<em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>.</p><div class="note"><p class="prefix"><b>Note:</b></p><p>Where an implementation is able to detect significant similarity between two
+adjacent synchronic document instances,
+<em>DOC<sub><span>inter<sub>0</sub></span></sub></em> …
+<em>DOC<sub><span>inter<sub>N−1</sub></span></sub></em>,
+then it is preferred that the implementation make the transition between
+presenting the two instances as smooth as possible, e.g., as described
+by <a href="#cea608c">[CEA-608-C]</a>, § C.3.</p></div></div><div class="div3">
<h4><a name="semantics-region-layout-step-2" id="semantics-region-layout-step-2"/>9.3.3 Synchronic Flow Processing</h4><p>Subsequent to performing a temporal (synchronic) slice and subsequent
remapping of regionally selected content hierarchy, the resulting intermediate
synchronic document is subjected to a flow transformation step that produces
@@ -4289,7 +4295,11 @@
then the temporal intervals of child elements are considered to apply in
parallel, i.e., simultaneously in time. Furthermore, the specification of
the time interval of each child element is considered to be relative to the temporal
-interval of the container element instance.</p><p>If the time container semantics of an element instance is <code>seq</code>,
+interval of the container element instance. For the purpose of determining the
+<a href="#smil21">[SMIL 2.1]</a> <code>endsync</code> semantics of a <code>par</code>
+time container, a default value of <code>all</code> applies.</p><div class="note"><p class="prefix"><b>Note:</b></p><p>The use of a default value of <code>all</code> for the <code>endsync</code>
+behavior is distinct from <a href="#smil21">[SMIL 2.1]</a> which uses a default value
+of <code>last</code>.</p></div><p>If the time container semantics of an element instance is <code>seq</code>,
then the temporal intervals of child elements are considered to apply in
sequence, i.e., sequentially in time. Furthermore, the specification of
the time interval of each child element is considered to be relative to the temporal
@@ -5080,7 +5090,7 @@
"bold"
TTAF.FrameRate.datatype =
- xsd:nonNegativeInteger
+ xsd:positiveInteger
TTAF.FrameRateMultiplier.datatype =
xsd:string { pattern = "\p{Nd}+\s+\p{Nd}+" }
@@ -6149,7 +6159,7 @@
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="frameRate">
- <xs:restriction base="xs:nonNegativeInteger"/>
+ <xs:restriction base="xs:positiveInteger"/>
</xs:simpleType>
<xs:simpleType name="frameRateMultiplier">
<xs:annotation>
@@ -8362,7 +8372,7 @@
<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="d3e17274" id="d3e17274"/>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="d3e17321" id="d3e17321"/>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
@@ -8417,7 +8427,7 @@
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="d3e17753" id="d3e17753"/>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="d3e17800" id="d3e17800"/>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
@@ -8489,9 +8499,9 @@
<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="d3e18621" id="d3e18621"/>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="d3e18668" id="d3e18668"/>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="d3e18785" id="d3e18785"/>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="d3e18832" id="d3e18832"/>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">