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<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 name="title" id="title"></a>Timed Text (TT) Authoring Format 1.0 Use
Cases and Requirements</h1>

<h2><a name="w3c-doctype" id="w3c-doctype"></a>W3C Working Group Note 27
April 2006</h2>
<dl>
  <dt>This version:</dt>
    <dd><a
      href="http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/">http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/</a></dd>
  <dt>Latest version:</dt>
    <dd><a
      href="http://www.w3.org/TR/ttaf1-req/">http://www.w3.org/TR/ttaf1-req/</a></dd>
  <dt>Previous version:</dt>
    <dd><a
      href="http://www.w3.org/TR/2003/WD-tt-af-1-0-req-20030915/">http://www.w3.org/TR/2003/WD-tt-af-1-0-req-20030915/</a></dd>
  <dt>Editor:</dt>
    <dd>Glenn Adams, Extensible Formatting Systems, Inc. <a
      href="mailto:glenn@xfsi.com">&lt;glenn@xfsi.com&gt;</a></dd>
</dl>

<p class="copyright"><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
© 2006 <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.org/"><acronym
title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>,
<a href="http://www.keio.ac.jp/">Keio</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 name="abstract" id="abstract"></a>Abstract</h2>

<p>This document specifies usage scenarios and requirements for a timed text
authoring format. A timed text authoring format 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>
</div>

<div>
<h2><a name="status" 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 Working Group Note is the third publication of the Timed Text (TT)
Authoring Format 1.0 Use Cases and Requirements, and represents an editorial
revision from the previous version in order to transition from Working Draft
to Working Group Note. This document has been produced by the <a
href="http://www.w3.org/AudioVideo/TT/">Timed Text Working Group</a> as part
of the W3C <a href="http://www.w3.org/AudioVideo/Activity">Synchronized
Multimedia Activity</a>. The authors of this document are the TT Working
Group members, who consider this document to be stable, and do not expect
further revision.</p>

<p>Comments on this document should be sent to the email list <a
href="mailto:public-tt@w3.org">public-tt@w3.org</a>, which is the public
mailing list of Timed Text Working Group (<a
href="http://lists.w3.org/Archives/Public/public-tt/">list archives</a>). To
subscribe, send an email to <a
href="mailto:public-tt-request@w3.org">public-tt-request@w3.org</a> with the
word <code>subscribe</code> in the subject line.</p>

<p>Publication as a Working Group Note does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite this
document as other than work in progress.</p>

<p>As of this publication, the Working Group does not expect this document to
become a W3C Recommendation, and therefore it has no associated <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/">W3C Patent
Policy</a> licensing obligations. If this expectation changes, the Working
Group will have an opportunity to fulfill the associated patent policy
requirements with respect to a future draft.</p>

<p>This document was produced by a group operating under the <a
href="http://www.w3.org/TR/2002/NOTE-patent-practice-20020124">24 January
2002 CPP</a> as amended by the <a
href="http://www.w3.org/2004/02/05-pp-transition">W3C Patent Policy
Transition Procedure</a>. W3C maintains a <a rel="disclosure"
href="http://www.w3.org/2003/01/Timed-text-Patent-statements.html">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 name="contents" id="contents"></a>Table of Contents</h2>

<p class="toc">1 <a href="#intro">Introduction</a><br />
    1.1 <a href="#motivation">Motivation</a><br />
    1.2 <a href="#model">System Model</a><br />
2 <a href="#definitions">Definitions</a><br />
    2.1 <a href="#acronyms">Acronyms</a><br />
    2.2 <a href="#terms">Terminology</a><br />
    2.3 <a href="#notations">Notations</a><br />
3 <a href="#scenarios">Use Case Scenarios</a><br />
4 <a href="#requirements">Requirements</a><br />
    4.1 <a href="#general">General</a><br />
    4.2 <a href="#content">Content</a><br />
    4.3 <a href="#styling">Styling</a><br />
    4.4 <a href="#timing">Timing</a><br />
    4.5 <a href="#animation">Animation</a><br />
    4.6 <a href="#metadata">Metadata</a><br />
</p>

<h3><a name="appendices" id="appendices"></a>Appendices</h3>

<p class="toc">A <a href="#references">References</a><br />
B <a href="#other-references">Other References</a> (Non-Normative)<br />
C <a href="#acknowledgements">Acknowledgments</a> (Non-Normative)<br />
</p>
</div>
<hr />

<div class="body">

<div class="div1">
<h2><a name="intro" id="intro"></a>1 Introduction</h2>

<p>This document specifies usage scenarios and requirements for a timed text
authoring format. A timed text authoring format 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>

<div class="note">
<p class="prefix"><b>Note:</b></p>

<p>This document incorporates requirements regarding stylistic and timing
functionality that range from simple to relatively complex. It is expected
that the use of this functionality will be partitioned into one or more
profiles represented by document types of increasing complexity. It is not
expected that every authoring system or ultimate consumer of timed text
content will support all of this functionality.</p>
</div>

<div class="div2">
<h3><a name="motivation" id="motivation"></a>1.1 Motivation</h3>

<p>A principal motivation for the development of a common authoring format
for timed text is the lack of a standard content format that supports the
representation and interchange of textual information which is synchronized
with other media elements or which serves as a synchronization master
itself.</p>

<p>Popular proprietary multimedia systems and their corresponding player
components have defined distinct timed text formats for each proprietary use.
As a consequence there is no common authoring format that serves as a
portable interchange format between such systems. A goal of the present work
is to define such a portable interchange format to ease the burden of
authoring tool developers and users as well as enhance portability of timed
text content.</p>

<p>A side effect of the development and deployment of a common timed text
authoring format is that it simplifies the creation and distribution of
synchronized text for use with a multitude of devices, such as multimedia
players, caption, subtitle, and teletext encoders and decoders, character
generators, LED displays, and other text display devices.</p>
</div>

<div class="div2">
<h3><a name="model" id="model"></a>1.2 System Model</h3>

<p>The uses cases and requirements specified in this document are based upon
a system model, depicted in <a href="#model-graphic"><b>Figure 1 – System
Model</b></a>, wherein the timed text authoring format 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
to the target distribution formats as required.</p>

<table id="model-graphic" class="graphic">
  <caption>Figure 1 – System Model</caption>
  <tbody>
    <tr>
      <td rowspan="1" colspan="1"><img src="./images/model.png"
        alt="System Model" /></td>
    </tr>
  </tbody>
</table>

<div class="note">
<p class="prefix"><b>Note:</b></p>

<p>In the figure depicted above, the acronym <em>DFXP</em> refers to a
profile of the timed text authoring format known as the Distribution Format
Exchange Profile, which is intended primarily to satisfy interchange among
existing legacy formats, and which may also be distributed directly.</p>
</div>

<div class="note">
<p class="prefix"><b>Note:</b></p>

<p>This system model does not preclude the timed text authoring format from
being used as a distribution format in its own right.</p>
</div>
</div>
</div>

<div class="div1">
<h2><a name="definitions" id="definitions"></a>2 Definitions</h2>

<div class="div2">
<h3><a name="acronyms" id="acronyms"></a>2.1 Acronyms</h3>

<table class="acronyms">
  <tbody>
    <tr>
      <td class="label"><b>TT</b></td>
      <td class="def"><p>Timed Text</p>
      </td>
    </tr>
    <tr>
      <td class="label"><b>TT AS</b></td>
      <td class="def"><p>Timed Text Authoring System</p>
      </td>
    </tr>
    <tr>
      <td class="label"><b>TT AF</b></td>
      <td class="def"><p>Timed Text Authoring Format</p>
      </td>
    </tr>
    <tr>
      <td class="label"><b>TT WG</b></td>
      <td class="def"><p>Timed Text Working Group</p>
      </td>
    </tr>
  </tbody>
</table>
</div>

<div class="div2">
<h3><a name="terms" id="terms"></a>2.2 Terminology</h3>
<dl>
  <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 Authoring Format</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 authoring format content.</p>
    </dd>
</dl>
</div>

<div class="div2">
<h3><a name="notations" id="notations"></a>2.3 Notations</h3>

<p>The following notations are employed in this document:</p>
<ul>
  <li><p><span class="strong">SXXX</span>– use case scenario
    <em>XXX</em></p>
  </li>
  <li><p><span class="strong">RXXX</span>– requirement <em>XXX</em></p>
  </li>
  <li><p><span class="strong">RX9X</span>– solution space requirement
    <em>X9X</em></p>
  </li>
  <li><p><span class="strong">NXXX</span>– non-requirement <em>XXX</em></p>
  </li>
</ul>
</div>
</div>

<div class="div1">
<h2><a name="scenarios" id="scenarios"></a>3 Use Case Scenarios</h2>
<dl>
  <dt><a name="S000" id="S000"></a>S000 – Captioning Audio</dt>
    <dd>
      <div class="use">
      <p>A caption service provider needs a common content authoring format
      by means of which a textual expression of audio information may be
      associated with such audio information in a time synchronized
      manner.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>In the context of captioning an aggregate audio/video service, both
      audio and caption information are typically synchronized to the video
      track as the timebase master.</p>
      </div>
      </div>
    </dd>
  <dt><a name="S001" id="S001"></a>S001 – Subtitling Audio</dt>
    <dd>
      <div class="use">
      <p>A subtitle service provider needs a common content authoring format
      by means of which a textual expression of the original or a translation
      of the original natural language (speech) audio information may be
      associated with such audio information in a time synchronized
      manner.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>In the context of subtitling an aggregate audio/video service, both
      audio and subtitle information are typically synchronized to the video
      track as the timebase master.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The distinction between <em>captioning</em> and <em>subtitling</em>
      is best expressed as follows: captioning is expressly intended to serve
      the needs of deaf and hard of hearing users, and typically contains
      transcriptions of speech and non-speech audio information; in contrast,
      subtitling is generally intended to serve the needs of hearing users
      who don't have access to an audio track (e.g., in muting situations) or
      don't understand the natural language of the speech contained in the
      audio track. Subtitling is often viewed as a paraphrase or a
      translation of speech information, as opposed to a transcription of all
      audio information.</p>
      <p>In the absence of captioning information, subtitling information may
      also be used by deaf and hard of hearing users, provided that it is
      available in the original natural language.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>Some user communities use the term <em>subtitling</em> to encompass
      both captioning and subtitling uses as distinguished in the previous
      note.</p>
      </div>
      </div>
    </dd>
  <dt><a name="S002" id="S002"></a>S002 – Description</dt>
    <dd>
      <div class="use">
      <p>A description service provider needs a common content authoring
      format in which a textual description of video information or a textual
      expression of an audio description of video information may be
      associated with such video information in a time synchronized
      manner.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>When a description is rendered by an audio track, such a description
      is commonly referred to as an <em>Audio Description</em>.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>In the use of aural forms of visual description, it may be the case
      that the duration of an aural form of a description exceeds the
      duration of the visual information being described. In a presentation
      device, this necessitates manual or automatic pausing of the video
      track in order to fully render the aural form of description. It is
      likely that similar modes of presentation will be required for timed
      text representations of video descriptions.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>This use case scenario is not intended to serve as a general form of
      <em>metadata</em> description of related video or audio content.</p>
      </div>
      </div>
    </dd>
  <dt><a name="S003" id="S003"></a>S003 – Generic Timed Text</dt>
    <dd>
      <div class="use">
      <p>A generic timed text service provider needs a common content
      authoring format in which textual information can be presented in a
      time synchronized manner.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>In the context of using a generic timed text service, timed text
      information serves as the timebase master, with which other possible
      timed media may be associated.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>Examples of the use of generic timed text include (but are not
      limited to): marquee signs, timed text oriented presentations,
      scrolling text presentation, etc.</p>
      </div>
      </div>
    </dd>
</dl>
</div>

<div class="div1">
<h2><a name="requirements" id="requirements"></a>4 Requirements</h2>

<div class="div2">
<h3><a name="general" id="general"></a>4.1 General</h3>
<dl>
  <dt><a name="R100" id="R100"></a>R100 – Specification Format</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be authored using XML and XSL
      Stylesheets based on <a href="#xmlspec">[XML Spec]</a> and shall adhere
      to best current practices in the W3C for specification style and
      quality assurance.</p>
      </div>
    </dd>
  <dt><a name="R101" id="R101"></a>R101 – Specification Modularity</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in a modular manner that
      logically separates significant areas of functionality to as great
      extent as is practical.</p>
      </div>
    </dd>
  <dt><a name="R102" id="R102"></a>R102 – Specification Organization</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be organized in such a manner as to
      separate the following aspects:</p>
      <ul>
        <li><p>TT Framework</p>
        </li>
        <li><p>TT Core Vocabulary</p>
        </li>
        <li><p>TT Core Document Types</p>
        </li>
        <li><p>TT Extension Vocabulary(ies)</p>
        </li>
        <li><p>TT Extension Document Type(s)</p>
        </li>
      </ul>
      <p></p>
      </div>
    </dd>
  <dt><a name="R103" id="R103"></a>R103 – Core and Periphery</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner that
      core functionality is logically separated from peripheral
      functionality.</p>
      </div>
    </dd>
  <dt><a name="R104" id="R104"></a>R104 – Evolution of Core</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner that
      core functionality can evolve over time, e.g., by the specification of
      multiple levels (or versions) of core functionality.</p>
      </div>
    </dd>
  <dt><a name="R105" id="R105"></a>R105 – Ownership of Core</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner that
      core functionality be specified soley by the TT WG or, in the event
      that the TT WG is terminated, its successors within the W3C.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is assumed that one or more appropriate namespace mechanisms will
      be used to segregate core functionality defined or adopted in the TT AF
      from peripheral functionality defined or adopted by clients of the TT
      AF.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R106" id="R106"></a>R106 – Surjection of Core</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner that
      for every item in the TT AF core vocabulary, there shall be at least
      one TT AF core document type that makes use of that item, i.e., there
      exists a surjection from the set of TT AF core document types to the
      set of TT AF vocabulary items referenced by those document types.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The TT AF specification(s) may define standardized peripheral
      vocabulary that is not referenced by any TT AF core document type.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R107" id="R107"></a>R107 – Evolution of Periphery</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner that
      peripheral functionality can evolve over time, e.g., by the future
      specification of one or more peripheral functionality modules.</p>
      </div>
    </dd>
  <dt><a name="R108" id="R108"></a>R108 – Ownership of Periphery</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner that
      peripheral functionality need not be specified by the TT WG or the W3C,
      but may be specified by other W3C WGs as well as non-W3C clients of the
      TT AF.</p>
      </div>
    </dd>
  <dt><a name="R109" id="R109"></a>R109 – Transformability</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of being transformed, without undue
      complexity, into one or more legacy timed text content formats, e.g.,
      <a href="#threegpp">[3GPP]</a>, <a href="#qtext">[QText]</a>, <a
      href="#realtext">[RealText]</a>, <a href="#sami">[SAMI]</a>, etc.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The above list of potential target timed text content formats is
      strictly informative, and is not intended to be exhuastive.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R110" id="R110"></a>R110 – Streamable Tranformation</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of being transformed into an idealized
      streamable representation format.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is not required that an idealized streamable representation
      format be defined by the TT AF specification(s); however, the
      definition of such a format may be the subject of future activities by
      the TT WG.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is intended that existing closed captioning and subtitle
      streaming formats used by analog and digital television services as
      well as timed text used in the context of streaming audio and motion
      video formats be potentially targeted by one or more transformations of
      the TT AF. These formats include <a href="#eia608b">[EIA-608B]</a>, <a
      href="#eia708b">[EIA-708B]</a>, <a href="#en300706">[EN 300 706]</a>,
      <a href="#en300743">[EN 300 743]</a>, etc.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R111" id="R111"></a>R111 – Accessibility – Content</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall include the following accessibility related
      features:</p>
      <ul>
        <li><p>Support for a mechanism to explicitly associate <em>Equivalent
          Alternatives</em> to the textual information in the TT presentation
          in accordance with <a href="#xmlaccess">[WAI XML AG]</a> Guideline
          1.</p>
        </li>
        <li><p>Support for <em>Content Rendering Adaption</em> in accordance
          with <a href="#smilaccess">[WAI SMIL AG]</a>, Section 5. See also
          <a href="#R207"><b>Conditional Content</b></a>.</p>
        </li>
        <li><p>Use of a default text vocabulary that satisfies guideline 2 of
          <a href="#xmlaccess">[WAI XML AG]</a> regarding structural and
          semantical stringency.</p>
        </li>
        <li><p>Ability to extend or replace the default text vocabulary with
          other XML dialects to represent the textual information of the TT
          presentation. See also <a href="#R205"><b>Intrinsic and Extrinsic
          Text Content</b></a>.</p>
        </li>
        <li><p>Support for explicit definition of a <em>Navigational
          Structure</em> associated with the TT presentation in accordance
          with <a href="#smilaccess">[WAI SMIL AG]</a>, Section 4.3.</p>
        </li>
      </ul>
      <p></p>
      </div>
    </dd>
  <dt><a name="R112" id="R112"></a>R112 – Accessibility – Authoring
  System</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner as to
      require a TT AS to adhere to all applicable aspects of <a
      href="#atag10">[ATAG 1.0]</a>.</p>
      </div>
    </dd>
</dl>
</div>

<div class="div2">
<h3><a name="content" id="content"></a>4.2 Content</h3>
<dl>
  <dt><a name="R200" id="R200"></a>R200 – Authorability</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of being created and modified using a
      plain text editor, e.g., emacs, vi, etc.</p>
      </div>
    </dd>
  <dt><a name="R201" id="R201"></a>R201 – Multiple Natural Languages</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of representing content of different
      natural languages, where the content of distinct languages may be
      segregated into separate document instances or may be integrated into a
      single document instance.</p>
      </div>
    </dd>
  <dt><a name="R202" id="R202"></a>R202 – Natural Language Coverage</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of representing content of at least those
      specific natural languages that may be represented with <a
      href="#unicode32">[Unicode 3.2]</a>.</p>
      </div>
    </dd>
  <dt><a name="R203" id="R203"></a>R203 – Natural Language Association
  Granularity</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of associating natural language binding
      information with plain text information at the granularity of a single
      coded character.</p>
      </div>
    </dd>
  <dt><a name="R204" id="R204"></a>R204 – Minimum Character
  Representability</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of representing every coded character
      available in <a href="#unicode32">[Unicode 3.2]</a> by using only those
      characters in <a href="#ascii">[ASCII (ANSI X3.4)]</a>.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>This requirement facilitates the entry and editing of characters in
      a TT AF document instance that would otherwise not be permitted due to
      lack of an appropriate character input method or lack of support for a
      non-ASCII character encoding system.</p>
      <p>It is assumed that every TT AS will provide a means to enter and
      edit TT AF document instances represented in the ASCII character
      set.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R205" id="R205"></a>R205 – Intrinsic and Extrinsic Text
  Content</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing text content intrinsically
      within a TT AF document instance, extrinsically by referencing from a
      TT AF document instance to text content in one or more external
      resources, or in any combination of these two modes.</p>
      </div>
    </dd>
  <dt><a name="R206" id="R206"></a>R206 – Markup Association</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of associating structural markup with
      intrinsic and extrinsic text content, where such markup may denote
      either or both semantic (functional) and presentational (formal)
      properties of the content.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>In this context, <em>presentational</em> properties designate both
      stylistic and timing related presentation information.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R207" id="R207"></a>R207 – Conditional Content</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing conditional content, where
      each alternative content choice is governed by one or more test
      expressions such that exactly one or zero content choice is selected
      when evaluating each choice in a predefined order.</p>
      </div>
    </dd>
  <dt><a name="R208" id="R208"></a>R208 – Flowed Text</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing authorial intention to flow
      (layout) text content in an idealized, but unspecified user agent.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>In this context, the concept of <em>flow</em> refers to an implied
      process by means of which textual information expressed in the
      character domain is mapped to a positioned glyph codomain.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is not required that an idealized user agent or behavior of such
      a user agent be defined by the TT AF specification(s); however, the
      definition of such a user agent or user agent behavior may be the
      subject of future activities by the TT WG.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R209" id="R209"></a>R209 – Logical Flowed Text
  Vocabulary</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing the following vocabulary as
      pertains to logical flowed text content:</p>
      <ul>
        <li><p>body</p>
        </li>
        <li><p>division</p>
        </li>
        <li><p>paragraph</p>
        </li>
        <li><p>phrase</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>A generic <em>role</em> attribute is expected to be provided for use
      with these items in order to express distinct stylistic and semantic
      roles, e.g., a <em>paragraph</em> role may be associated with a
      <em>division</em> item to indicate that the logical division expressed
      corresponds to a stylistic and semantic paragraph.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>One possible mapping for this vocabulary is to
      <code>xhtml:body</code>, <code>xhtml:div</code>, <code>xhtml:p</code>,
      and <code>xhtml:span</code>, respectively, as defined by <a
      href="#xhtml1">[XHTML 1.0]</a>.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R210" id="R210"></a>R210 – Presentational Flowed Text
  Vocabulary</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing the following vocabulary as
      pertains to presentational flowed text content:</p>
      <ul>
        <li><p>block</p>
        </li>
        <li><p>block container</p>
        </li>
        <li><p>character</p>
        </li>
        <li><p>flow</p>
        </li>
        <li><p>forced line break</p>
        </li>
        <li><p>inline</p>
        </li>
        <li><p>inline container</p>
        </li>
        <li><p>region</p>
        </li>
        <li><p>viewport</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The items enumerated above are drawn in part from similarly named
      items defined by <a href="#xsl">[XSL 1.0]</a>, Section 6,
      <em>Formatting Objects</em>.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The <em>forced line break</em> item may be expressed in terms of the
      <em>character</em> item, where the specified character has line
      separator or line break semantics.</p>
      <p>The use of this item in combination with a <em>wrap option</em>
      style parameter with the value <code>nowrap</code> permits an
      intermediate mode of text representation with formatting semantics that
      fall between flowed text and non-flowed text.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The <em>viewport</em> and <em>region</em> items are intended to be
      analogous to the <a href="#xsl">[XSL 1.0]</a> vocabulary
      <code>fo:simple-page-master</code> and <code>fo:region-*</code>,
      respectively.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R211" id="R211"></a>R211 – Flowed Text Vocabulary
  Relationship</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be defined in such a manner that a default
      relationship between logical and presentational flowed text vocabulary
      may be assumed as follows:</p>
      <ul>
        <li><p>body ⇔ flow</p>
        </li>
        <li><p>division (display: block) ⇔ block container</p>
        </li>
        <li><p>paragraph ⇔ block</p>
        </li>
        <li><p>division (display: inline) ⇔ inline container</p>
        </li>
        <li><p>phrase ⇔ inline</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>Parsed character data (<code>#PCDATA</code>) that appears in logical
      flowed text content should be assumed to map by default to parsed
      character data or <em>character</em> in presentational flowed text
      content.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R212" id="R212"></a>R212 – Flowed Text Vocabulary
  Separation</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be defined in such a manner that use of logical
      flowed text vocabulary is separated from use of presentational flowed
      text vocabulary.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is not required that the TT AF specification(s) define a document
      type that supports the simultaneous use of both logical and
      presentational flowed text vocabulary.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R213" id="R213"></a>R213 – Non-Flowed Text</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing authorial intention to
      render non-flowed text content in an idealized, but unspecified user
      agent.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>In this context, the concept of <em>non-flowed text</em> refers to
      textual information that is explicitly associated with positioned glyph
      information at authoring time; i.e., all bidirectional processing and
      character to glyph substitution processing and glyph position
      assignment has already occurred.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is not required that an idealized user agent or behavior of such
      a user agent be defined by the TT AF specification(s); however, the
      definition of such a user agent or user agent behavior may be the
      subject of future activities by the TT WG.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R214" id="R214"></a>R214 – Non-Flowed Text Vocabulary</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing the following vocabulary as
      pertains to non-flowed text content:</p>
      <ul>
        <li><p>area</p>
        </li>
        <li><p>glyph</p>
        </li>
        <li><p>glyph sequence</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The glyph and glyph sequence vocabulary items are intended to make
      direct reference to specific glyphs in specific fonts, having already
      been transformed from the character domain to the glyph domain.
      References to glyphs would typically take the form of a glyph
      identifier or a glyph code. For further information on character to the
      glyph mapping process, see <a href="#charmod">[CharMod]</a>, Section
      3.1.3, <em>Units of Visual Rendering</em>.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R215" id="R215"></a>R215 – Hybrid Flowed and Non-Flowed
  Text</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing authorial intention to
      create a hybrid of flowed and non-flowed text content; however, such an
      expression may require that these two types of content be segregated at
      a specific level of granularity.</p>
      </div>
    </dd>
  <dt><a name="R216" id="R216"></a>R216 – Hyperlinking</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing simple hyperlinks, where
      the ending (destination) resource is either the starting (source)
      resource or an external resource.</p>
      </div>
    </dd>
  <dt><a name="R217" id="R217"></a>R217 – Embedded Graphics</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing block and inline, embedded
      graphics of both bitmap and vector or outline formats.</p>
      <p>If block or inline graphics are used for the purpose of expressing
      pre-rasterized text in a bitmap format, then the original text that
      produced such a pre-rasterized form shall also be required to be
      present in TT AF content.</p>
      </div>
    </dd>
  <dt><a name="R218" id="R218"></a>R218 – Non-Embedded Graphics</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing block and inline,
      non-embedded graphics of both bitmap and vector or outline formats,
      where a graphic is represented by an external resource.</p>
      <p>If block or inline graphics are used for the purpose of expressing
      pre-rasterized text in a bitmap format, then the original text that
      produced such a pre-rasterized form shall also be required to be
      present in TT AF content.</p>
      </div>
    </dd>
  <dt><a name="R219" id="R219"></a>R219 – Embedded Fonts</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing embedded fonts of both
      bitmap and outline formats.</p>
      </div>
    </dd>
  <dt><a name="R220" id="R220"></a>R220 – Non-Embedded Fonts</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing non-embedded fonts of both
      bitmap and outline formats, where a font is represented by an external
      resource.</p>
      </div>
    </dd>
  <dt><a name="R221" id="R221"></a>R221 – Descriptive Vocabulary</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of associating text content with
      descriptive information from an appropriate domain of discourse.</p>
      <p></p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>See <a href="#tei">[TEI]</a>, Chapter 10, <em>Base Tag Set for
      Drama</em>, and Chapter 11, <em>Transcription of Speech</em>, for
      examples of descriptive vocabulary pertaining to drama and the
      transcription of speech, respectively.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R222" id="R222"></a>R222 – Embedded Audio</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing embedded audio that is
      intended to be played or rendered in sequence or in parallel with
      associated text content.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The use of embedded audio is intended to support aural cues that may
      accompany text.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R223" id="R223"></a>R223 – Non-Embedded Audio</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing non-embedded audio that is
      intended to be played or rendered in sequence or in parallel with
      associated text content, where the audio content is represented by an
      external resource.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The use of non-embedded audio is intended to support aural cues that
      may accompany text.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R290" id="R290"></a>R290 – Markup Format</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall support the use of both <a href="#xml10">[XML
      1.0]</a> and <a href="#xml11">[XML 1.1]</a> as serialized forms of a TT
      AF XML information set.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>See <a href="#infoset">[XML InfoSet]</a> for further information on
      an <em>XML information set</em>.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R291" id="R291"></a>R291 – Markup Format and Unicode
  Interaction</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall require or recommend adherence to the practices
      recommended by <a href="#uxml">[Unicode in XML]</a>.</p>
      </div>
    </dd>
  <dt><a name="R292" id="R292"></a>R292 – Extrinsic Resource References</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall support the use of <a href="#xlink">[XLink]</a> for
      the purpose of referencing external resources.</p>
      </div>
    </dd>
  <dt><a name="R293" id="R293"></a>R293 – Schema Validity Specification</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner that
      the normative validity of markup content be specified in terms of
      either or both <a href="#rng">[RELAX NG]</a> and <a href="#xsd-1">[XML
      Schema Part 1]</a> in combination with <a href="#xsd-2">[XML Schema
      Part 2]</a>.</p>
      </div>
    </dd>
</dl>
</div>

<div class="div2">
<h3><a name="styling" id="styling"></a>4.3 Styling</h3>
<dl>
  <dt><a name="R300" id="R300"></a>R300 – Inline Styling</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of inline styling, where inline styling
      means the inclusion of stylistic presentation information in a TT AF
      document instance.</p>
      </div>
    </dd>
  <dt><a name="R301" id="R301"></a>R301 – Inline Styling Form</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of specifying inline styling by means of
      (1) distinct attributes, (2) a generic attribute, e.g.,
      <code>style</code>, and (3) one or more inline stylesheets.</p>
      </div>
    </dd>
  <dt><a name="R302" id="R302"></a>R302 – Out-of-Line Styling</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of out-of-line styling, where out-of-line
      styling means the association of stylistic presentation information
      with TT AF content via some mechanism external to a TT AF document
      instance.</p>
      </div>
    </dd>
  <dt><a name="R303" id="R303"></a>R303 – Out-Of-Line Styling Form</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of specifying out-of-line styling by
      means of one or more external stylesheets.</p>
      </div>
    </dd>
  <dt><a name="R304" id="R304"></a>R304 – Styling Prioritization</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of associating priorities with stylistic
      presentation information in order to permit the resolution of multiple
      style specifications that apply to the same content.</p>
      </div>
    </dd>
  <dt><a name="R305" id="R305"></a>R305 – Style Parameters – Aural</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of associating the following aural style
      parameters with timed text content:</p>
      <ul>
        <li><p>azimuth</p>
        </li>
        <li><p>cue before, during, after</p>
        </li>
        <li><p>elevation</p>
        </li>
        <li><p>pause before, after</p>
        </li>
        <li><p>pitch</p>
        </li>
        <li><p>pitch range</p>
        </li>
        <li><p>richness</p>
        </li>
        <li><p>speaking mode</p>
        </li>
        <li><p>speech rate</p>
        </li>
        <li><p>stress</p>
        </li>
        <li><p>voice family</p>
        </li>
        <li><p>volume</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>For further information on these style parameters, see <a
      href="#xsl">[XSL 1.0]</a>, Section 7.6, <em>Common Aural
      Properties</em> and <a href="#css2">[CSS Level 2]</a>.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>For further information on the <em>speaking mode</em> aural style
      parameter, see discussion of <code>speak</code>,
      <code>speak-numeral</code>, and <code>speak-punctuation</code>
      properties described in <a href="#xsl">[XSL 1.0]</a>, Section 7.6.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R306" id="R306"></a>R306 – Style Parameters – Visual</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of associating the following visual style
      parameters with timed text content:</p>
      <ul>
        <li><p>absolute position</p>
        </li>
        <li><p>background color</p>
        </li>
        <li><p>baseline alignment point</p>
        </li>
        <li><p>baseline alignment</p>
        </li>
        <li><p>baseline dominance</p>
        </li>
        <li><p>baseline shift</p>
        </li>
        <li><p>bidirectional treatment</p>
        </li>
        <li><p>block progression dimension</p>
        </li>
        <li><p>block scroll amount</p>
        </li>
        <li><p>border before, after, start, end</p>
        </li>
        <li><p>break before, after</p>
        </li>
        <li><p>clear</p>
        </li>
        <li><p>color</p>
        </li>
        <li><p>color profile name</p>
        </li>
        <li><p>display none, block, inline</p>
        </li>
        <li><p>display alignment</p>
        </li>
        <li><p>float</p>
        </li>
        <li><p>font family</p>
        </li>
        <li><p>font size</p>
        </li>
        <li><p>font style</p>
        </li>
        <li><p>font weight</p>
        </li>
        <li><p>height</p>
        </li>
        <li><p>indent start, end</p>
        </li>
        <li><p>inline progression dimension</p>
        </li>
        <li><p>inline scroll amount</p>
        </li>
        <li><p>intrusion-displace</p>
        </li>
        <li><p>line feed treatment</p>
        </li>
        <li><p>line height</p>
        </li>
        <li><p>line stacking strategy</p>
        </li>
        <li><p>line wrapping option</p>
        </li>
        <li><p>opacity</p>
        </li>
        <li><p>origin (top, left)</p>
        </li>
        <li><p>overflow</p>
        </li>
        <li><p>padding before, after, start, end</p>
        </li>
        <li><p>reference orientation</p>
        </li>
        <li><p>relative position</p>
        </li>
        <li><p>space before, after, start, end</p>
        </li>
        <li><p>text alignment</p>
        </li>
        <li><p>text altitude (ascent)</p>
        </li>
        <li><p>text decoration</p>
        </li>
        <li><p>text depth (descent)</p>
        </li>
        <li><p>text indent (first line)</p>
        </li>
        <li><p>text shadow</p>
        </li>
        <li><p>visibility</p>
        </li>
        <li><p>white space collapse</p>
        </li>
        <li><p>white space treatment</p>
        </li>
        <li><p>width</p>
        </li>
        <li><p>writing mode</p>
        </li>
        <li><p>z-index</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>For further information on these style parameters, see <a
      href="#xsl">[XSL 1.0]</a>, Section 7, <em>Formatting Properties</em>
      and <a href="#css2">[CSS Level 2]</a>.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>The style parameters <em>break before</em> and <em>break after</em>
      are intended to model the like named style properties defined by <a
      href="#xsl">[XSL 1.0]</a>, Section 7.19, <em>Keeps and Breaks
      Properties</em>, except that the possible values of these parameters
      are expected to be restricted to <code>auto</code>, <code>line</code>,
      and <code>inherit</code>. The new value <code>line</code> is intended
      to denote a line area context in order to express that a line break
      should precede or follow the element associated with this parameter.</p>
      <p>Unlike XSL, these parameters apply only to inline vocabulary, and
      not block vocabulary.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>A <em>style parameter</em> is intended to convey the notion of any
      type of style specification or declaration whether it is expressed as
      an attribute or a property.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R307" id="R307"></a>R307 – Style Parameters – Visual –
  Temporal Fill Mode</dt>
    <dd>
      <div class="req">
      <p>The TT AF may be capable of associating the following visual style
      parameters that pertain to temporal filling (flowing) of timed text
      content:</p>
      <ul>
        <li><p>temporal fill mode</p>
        </li>
        <li><p>temporal fill direction</p>
        </li>
        <li><p>temporal block clear mode</p>
        </li>
        <li><p>temporal fill interval</p>
        </li>
        <li><p>temporal inter-fill interval</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>These parameters are intended to permit the expression of authorial
      intent with respect to the temporal filling (stacking) of glyph areas
      within a line area and line areas within a block area.</p>
      <p>The <em>temporal fill mode</em> parameter permits specifying the
      granularity of temporal filling, e.g., line, word, character. The
      <em>temporal fill direction</em> parameter permits specifying the
      direction of fill (stacking) independently from the writing mode. The
      <em>temporal block clear mode</em> parameter permits specifying whether
      the containing block is cleared or is automatically scrolled, and by
      what extent, when the block is filled. The <em>temporal fill
      interval</em> parameter permits specifying the interval that a filled
      area should remain static before processing the next fill. The
      <em>temporal inter-fill interval</em> parameter permits specifying the
      interval between the end of a prior fill interval and the start of a
      subsequent fill interval.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R390" id="R390"></a>R390 – Style Parameter Symmetry</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be defined in such a manner that if a stylistic
      presentation parameter may be specified as a style property, then that
      parameter shall also be specifiable as a style attribute, and
      vice-versa.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>In this context, a style <em>attribute</em> refers to an attribute
      expressed in a markup language (e.g., an XML attribute), while a style
      <em>property</em> refers to a property expressed in a style language
      (e.g., a CSS property).</p>
      </div>
      </div>
    </dd>
  <dt><a name="R391" id="R391"></a>R391 – Style Parameter Definitions</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be defined in such a manner that if there is a
      conflict when adopting the name or value semantics of a style parameter
      specification, then the following order shall hold for resolving such a
      conflict:</p>
      <ol type="1">
        <li><p>XSL FO</p>
        </li>
        <li><p>SVG</p>
        </li>
        <li><p>SMIL</p>
        </li>
        <li><p>CSS Level 2</p>
        </li>
        <li><p>CSS Level 3</p>
        </li>
      </ol>
      <p></p>
      </div>
    </dd>
  <dt><a name="R392" id="R392"></a>R392 – Style Element Type Shorthand
  Equivalence</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be defined in such a manner that to the extent that
      stylistic oriented markup element types are defined or adopted, then
      such element types shall be defined as shorthand equivalents of
      non-stylistic oriented element types in combination with specific style
      parameters.</p>
      </div>
    </dd>
</dl>
</div>

<div class="div2">
<h3><a name="timing" id="timing"></a>4.4 Timing</h3>
<dl>
  <dt><a name="R401" id="R401"></a>R401 – Inline Timing</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of inline timing, where inline timing
      means the inclusion of temporal presentation markup in a TT AF document
      instance.</p>
      </div>
    </dd>
  <dt><a name="R402" id="R402"></a>R402 – Out-of-Line Timing</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of out-of-line timing, where out-of-line
      timing means the association of temporal presentation information with
      TT AF content via some mechanism external to a TT AF document
      instance.</p>
      </div>
    </dd>
  <dt><a name="R403" id="R403"></a>R403 – Synchronization Parameters</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing the following
      synchronization parameters in terms of any legal combination that
      expresses a possibly repeated or restarted, single, simple interval:</p>
      <ul>
        <li><p>begin</p>
        </li>
        <li><p>dur</p>
        </li>
        <li><p>end</p>
        </li>
        <li><p>endsync</p>
        </li>
        <li><p>fill</p>
        </li>
        <li><p>fillDefault</p>
        </li>
        <li><p>repeatCount</p>
        </li>
        <li><p>repeatDur</p>
        </li>
        <li><p>restart</p>
        </li>
        <li><p>restartDefault</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>For further information on these synchronization parameters, see <a
      href="#smil20">[SMIL 2.0]</a>, Section 10, <em>The SMIL 2.0 Timing and
      Synchronization Module</em>.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is not required that the TT AF support the specification of
      multiple simple intervals, i.e., multiple start, duration, or begin
      values.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R404" id="R404"></a>R404 – Synchronization Parameter Value
  Space Semantics</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing the following
      synchronization parameter value space semantics:</p>
      <ul>
        <li><p><em>Offset Values</em> – a clock offset from an implied or
          explicit synchronization timebase;</p>
        </li>
        <li><p><em>Event Values</em> – a clock offset from a named event
          associated with an implied or explicit element node, including, at
          a minimum, named events that indicate the beginning or end of a
          timed element's active interval;</p>
        </li>
        <li><p><em>Access Key Values</em> – a clock offset from a specific
          key press event;</p>
        </li>
        <li><p><em>Media Marker Values</em> – a clock offset from a media
          marker, including, at a minimum, a media marker that denotes a
          SMPTE time code;</p>
        </li>
        <li><p><em>Wallclock Values</em> – a clock offset from an absolute
          wallclock time in an implied or explicit time zone.</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is not required that the TT AF support the specification of
      negative offset values.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R405" id="R405"></a>R405 – Time Containment Semantics</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing sequential, parallel, and
      exclusive time containment semantics of consituent timed text
      content.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>For further information on these time containment semantics, see <a
      href="#smil20">[SMIL 2.0]</a>, Section 10, <em>The SMIL 2.0 Timing and
      Syncrhonization Module</em>.</p>
      </div>
      </div>
    </dd>
</dl>
</div>

<div class="div2">
<h3><a name="animation" id="animation"></a>4.5 Animation</h3>
<dl>
  <dt><a name="R500" id="R500"></a>R500 – Animation Modes</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing animation according to the
      following modes:</p>
      <ul>
        <li><p>continuous – linear</p>
        </li>
        <li><p>continuous – non-linear</p>
        </li>
        <li><p>discrete</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>By <em>animation</em> is meant the ability to alter some parameter
      or value over time.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R501" id="R501"></a>R501 – Scroll Animation</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing animated scrolling of
      content, both in block and inline progression directions, with
      independent expression of scroll in, scroll out, and scroll
      repetition.</p>
      </div>
    </dd>
  <dt><a name="R502" id="R502"></a>R502 – Highlight Animation</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing animated highlighting of
      content, with granularity at the level of individual characters or
      glyphs.</p>
      </div>
    </dd>
  <dt><a name="R503" id="R503"></a>R503 – Fade Transition Animation</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing animated fade transitions
      of content, with granularity at the level of individual regions or
      areas.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>See <a href="#R210"><b>Presentational Flowed Text Vocabulary</b></a>
      and <a href="#R214"><b>Non-Flowed Text Vocabulary</b></a> for
      information on <em>region</em> and <em>area</em> vocabulary items,
      respectively.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R504" id="R504"></a>R504 – Animated Style Parameters –
  Aural</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of animating the following aural style
      parameters:</p>
      <ul>
        <li><p>azimuth</p>
        </li>
        <li><p>elevation</p>
        </li>
        <li><p>speaking mode</p>
        </li>
        <li><p>speech rate</p>
        </li>
        <li><p>volume</p>
        </li>
      </ul>
      <p></p>
      </div>
    </dd>
  <dt><a name="R505" id="R505"></a>R505 – Animated Style Parameters –
  Visual</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of animating the following visual style
      parameters:</p>
      <ul>
        <li><p>background color</p>
        </li>
        <li><p>block scroll amount</p>
        </li>
        <li><p>border color</p>
        </li>
        <li><p>color</p>
        </li>
        <li><p>display</p>
        </li>
        <li><p>inline scroll amount</p>
        </li>
        <li><p>opacity</p>
        </li>
        <li><p>origin</p>
        </li>
        <li><p>visibility</p>
        </li>
      </ul>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is possible to express fade-in and fade-out transitions by means
      of animating the <em>opacity</em> style parameter.</p>
      </div>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>Animation of the <em>display</em> style parameter may cause reflow
      (reformatting) of content in a user agent at each animation step.</p>
      </div>
      </div>
    </dd>
  <dt><a name="N506" id="N506"></a>N506 – Animated Content</dt>
    <dd>
      <div class="req">
      <p>The TT AF is not required to support the animation of content.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>By <em>animation of content</em> is meant the dynamic addition or
      changing of element content by means of animation functionality, e.g.,
      replacing the text content of an element.</p>
      </div>
      </div>
    </dd>
</dl>
</div>

<div class="div2">
<h3><a name="metadata" id="metadata"></a>4.6 Metadata</h3>
<dl>
  <dt><a name="R600" id="R600"></a>R600 – Metadata Item Association</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of associating arbitrary metadata,
      expressed as <em>metadata items</em>, with (1) a TT AF document
      instance and (2) any element contained within a TT AF document
      instance.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>It is not required that metadata be able to be associated with an
      element's attributes or with any other child of an element other than a
      child that is characterized as an element itself.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R601" id="R601"></a>R601 – Metadata Item Constituents</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing the following constituents
      of individual metadata items:</p>
      <ul>
        <li><p>name</p>
        </li>
        <li><p>value type</p>
        </li>
        <li><p>value</p>
        </li>
      </ul>
      <p></p>
      </div>
    </dd>
  <dt><a name="R602" id="R602"></a>R602 – Metadata Item Value
  Representation</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall give preference to the representation of metadata
      item values as element content as opposed to attribute content.</p>

      <div class="note">
      <p class="prefix"><b>Note:</b></p>
      <p>By <em>element content</em> is meant those children of an element
      information item that are characterized as elements or as character
      data. By <em>attribute content</em> is meant the normalized values of
      the attributes of an element information item.</p>
      </div>
      </div>
    </dd>
  <dt><a name="R603" id="R603"></a>R603 – Metadata Item Extensibility</dt>
    <dd>
      <div class="req">
      <p>The TT AF shall be capable of expressing metadata items whose names,
      value types, and semantics are defined externally to the TT AF
      specification(s).</p>
      </div>
    </dd>
  <dt><a name="R604" id="R604"></a>R604 – Metadata Item Validation</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner as to
      permit and potentially require the ability to validate metadata.</p>
      </div>
    </dd>
  <dt><a name="R690" id="R690"></a>R690 – Dublin Core Preference</dt>
    <dd>
      <div class="req">
      <p>The TT AF specification(s) shall be defined in such a manner as to
      give preference to those metadata items defined by <a
      href="#dcmes">[DCMES 1.1]</a> in case that a conflict exists with
      another candidate metadata representation.</p>
      </div>
    </dd>
</dl>
</div>
</div>
</div>

<div class="back">

<div class="div1">
<h2><a name="references" id="references"></a>A References</h2>
<dl>
  <dt class="label"><a name="ascii" id="ascii"></a>ASCII (ANSI X3.4)</dt>
    <dd>American National Standards Institute. <cite>ANSI X3.4: Coded
      character set – 7-bit American national code for information
      interchange</cite>. New York, 1986.</dd>
  <dt class="label"><a name="atag10" id="atag10"></a>ATAG 1.0</dt>
    <dd>Jutta Treviranus, Charles McCathieNevile, Ian Jacobs, Jan Richards,
      Eds., <a href="http://www.w3.org/TR/ATAG10/"><cite>Authoring Tool
      Accessibility Guidelines 1.0</cite></a>, W3C Recommendation, 3 February
      2000. (See <a
      href="http://www.w3.org/TR/ATAG10/">http://www.w3.org/TR/ATAG10/</a>.)</dd>
  <dt class="label"><a name="dcmes" id="dcmes"></a>DCMES 1.1</dt>
    <dd>Dublin Core Metadata Initiative, <a
      href="http://dublincore.org/documents/dces/"><cite>Dublin Core Metadata
      Element Set, Version 1.1: Reference Description</cite></a>. (See <a
      href="http://dublincore.org/documents/dces/">http://dublincore.org/documents/dces/</a>.)</dd>
  <dt class="label"><a name="rng" id="rng"></a>RELAX NG</dt>
    <dd>James Clark and Makato Murata, Eds., <a
      href="http://www.relaxng.org/spec-20011203.html"><cite>RELAX NG
      Specification</cite></a>, OASIS Committee Specification, 3 December
      2001. (See <a
      href="http://www.relaxng.org/spec-20011203.html">http://www.relaxng.org/spec-20011203.html</a>.)</dd>
  <dt class="label"><a name="unicode32" id="unicode32"></a>Unicode 3.2</dt>
    <dd>The Unicode Consortium, <cite>The Unicode Standard, Version
      3.2.0</cite> is defined by <cite>The Unicode Standard, Version
      3.0</cite> (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-61633-5), as
      amended by the <cite>Unicode Standard Annex #27: Unicode 3.1</cite>
      (see <a
      href="http://www.unicode.org/reports/tr27/">http://www.unicode.org/reports/tr27</a>)
      and by the <cite>Unicode Standard Annex #28: Unicode 3.2</cite> (see <a
      href="http://www.unicode.org/reports/tr28/">http://www.unicode.org/reports/tr28</a>).</dd>
  <dt class="label"><a name="uxml" id="uxml"></a>Unicode in XML</dt>
    <dd>Martin J. Dürst and Asums Freytag, <a
      href="http://www.w3.org/TR/unicode-xml/"><cite>Unicode in XML and other
      Markup Languages</cite></a>, W3C Note. (See <a
      href="http://www.w3.org/TR/unicode-xml/">http://www.w3.org/TR/unicode-xml/</a>.)</dd>
  <dt class="label"><a name="smilaccess" id="smilaccess"></a>WAI SMIL AG</dt>
    <dd>Marja-Riitta Koivunen, <a
      href="http://www.w3.org/TR/SMIL-access/"><cite>Accessibility Features
      of SMIL</cite></a>, W3C Note, 21 September 1999. (See <a
      href="http://www.w3.org/TR/SMIL-access/">http://www.w3.org/TR/SMIL-access/</a>.)</dd>
  <dt class="label"><a name="xmlaccess" id="xmlaccess"></a>WAI XML AG</dt>
    <dd>Daniel Dardailler, Sean B. Palmer, Charles McCathieNevile, Eds., <a
      href="http://www.w3.org/TR/xag.html"><cite>XML Accessibility
      Guidelines</cite></a>, W3C Working Draft, 3 October 2002. (See <a
      href="http://www.w3.org/TR/xag.html">http://www.w3.org/TR/xag.html</a>.)</dd>
  <dt class="label"><a name="xlink" id="xlink"></a>XLink</dt>
    <dd>Steve DeRose, Eve Maler, David Orchard, Eds., <a
      href="http://www.w3.org/TR/xlink/"><cite>XML Linking Language (XLink)
      Version 1.0</cite></a>, W3C Recommendation. (See <a
      href="http://www.w3.org/TR/xlink/">http://www.w3.org/TR/xlink/</a>.)</dd>
  <dt class="label"><a name="xml10" id="xml10"></a>XML 1.0</dt>
    <dd>Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, Eds., <a
      href="http://www.w3.org/TR/REC-xml"><cite>Extensible Markup Language
      (XML) 1.0 (Second Edition)</cite></a>, W3C Recommendation. (See <a
      href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a>.)</dd>
  <dt class="label"><a name="xml11" id="xml11"></a>XML 1.1</dt>
    <dd>John Cowan, <a
      href="http://www.w3.org/TR/2002/CR-xml11-20021015/"><cite>Extensible
      Markup Language (XML) 1.1</cite></a>, W3C Candidate Recommendation, 15
      October 2002. (See <a
      href="http://www.w3.org/TR/2002/CR-xml11-20021015/">http://www.w3.org/TR/2002/CR-xml11-20021015/</a>.)</dd>
  <dt class="label"><a name="infoset" id="infoset"></a>XML InfoSet</dt>
    <dd>John Cowan and Richard Tobin, <a
      href="http://www.w3.org/TR/xml-infoset/"><cite>XML Information
      Set</cite></a>, W3C Recommendation, 24 Oct 2001. (See <a
      href="http://www.w3.org/TR/xml-infoset/">http://www.w3.org/TR/xml-infoset/</a>.)</dd>
  <dt class="label"><a name="xsd-1" id="xsd-1"></a>XML Schema Part 1</dt>
    <dd>Henry S. Thompson, David Beech, Murray Maloney, Noah Mendelsohn,
      Eds., <a href="http://www.w3.org/TR/xmlschema-1/"><cite>XML Schema Part
      1: Structures</cite></a>, W3C Recommendation. (See <a
      href="http://www.w3.org/TR/xmlschema-1/">http://www.w3.org/TR/xmlschema-1/</a>.)</dd>
  <dt class="label"><a name="xsd-2" id="xsd-2"></a>XML Schema Part 2</dt>
    <dd>Paul Biron and Ashok Malhotra, <a
      href="http://www.w3.org/TR/xmlschema-2/"><cite>XML Schema Part 2:
      Datatypes</cite></a>, W3C Recommendation. (See <a
      href="http://www.w3.org/TR/xmlschema-2/">http://www.w3.org/TR/xmlschema-2/</a>.)</dd>
  <dt class="label"><a name="xmlspec" id="xmlspec"></a>XML Spec</dt>
    <dd>Norman Walsh, <a href="http://www.w3.org/2002/xmlspec/"><cite>The XML
      Spec Schema and Stylesheets</cite></a>, W3C. (See <a
      href="http://www.w3.org/2002/xmlspec/">http://www.w3.org/2002/xmlspec/</a>).</dd>
</dl>
</div>

<div class="div1">
<h2><a name="other-references" id="other-references"></a>B Other References
(Non-Normative)</h2>
<dl>
  <dt class="label"><a name="threegpp" id="threegpp"></a>3GPP</dt>
    <dd>3rd Generation Partnership Project, <a
      href="http://www.3gpp.org/ftp/Specs/html-info/26234.htm"><cite>Technical
      Specification Group Services and System Aspects; Transparent End-To-End
      Packet-Switched Streaming Service (PSS); Protocols and
      Codecs</cite></a>, 3GPP Organizational Partners. (See <a
      href="http://www.3gpp.org/ftp/Specs/html-info/26234.htm">http://www.3gpp.org/ftp/Specs/html-info/26234.htm</a>.)</dd>
  <dt class="label"><a name="charmod" id="charmod"></a>CharMod</dt>
    <dd>Martin J. Dürst et al., Eds., <a
      href="http://www.w3.org/TR/charmod/"><cite>Character Model for the
      World Wide Web 1.0: Fundamentals</cite></a>, W3C Recommendation, 15
      February 2005. (See <a
      href="http://www.w3.org/TR/charmod/">http://www.w3.org/TR/charmod/</a>.)</dd>
  <dt class="label"><a name="css2" id="css2"></a>CSS Level 2</dt>
    <dd>Bert Bos, Håkon Wium Lie, Chris Lilley, Ian Jacobs, Eds., <a
      href="http://www.w3.org/TR/REC-CSS2/"><cite>Cascading Style Sheets,
      Level 2</cite></a>, W3C Recommendation. (See <a
      href="http://www.w3.org/TR/REC-CSS2/">http://www.w3.org/TR/REC-CSS2/</a>.)</dd>
  <dt class="label"><a name="dcmi-terms" id="dcmi-terms"></a>DCMI Terms</dt>
    <dd>Dublin Core Metadata Initiative, <a
      href="http://dublincore.org/documents/2003/03/04/dcmi-terms/"><cite>DCMI
      Metadata Terms</cite></a>. (See <a
      href="http://dublincore.org/documents/2003/03/04/dcmi-terms/">http://dublincore.org/documents/2003/03/04/dcmi-terms/</a>.)</dd>
  <dt class="label"><a name="eia608b" id="eia608b"></a>EIA-608B</dt>
    <dd>Electronics Industry Alliance (EIA), <a
      href="http://www.ce.org/"><cite>Line 21 Data Services</cite></a>. (See
      <a href="http://www.ce.org/">http://www.ce.org/</a>.)</dd>
  <dt class="label"><a name="eia708b" id="eia708b"></a>EIA-708B</dt>
    <dd>Electronics Industry Alliance (EIA), <a
      href="http://www.ce.org/"><cite>Digital Television (DTV) Closed
      Captioning</cite></a>. (See <a
      href="http://www.ce.org/">http://www.ce.org/</a>.)</dd>
  <dt class="label"><a name="en300706" id="en300706"></a>EN 300 706</dt>
    <dd>European Telecommunications Standards Institute, <a
      href="http://webapp.etsi.org/action%5COP/OP20030411/en_300706v010201o.pdf"><cite>Enhanced
      Teletext Specification</cite></a>. (See <a
      href="http://webapp.etsi.org/action%5COP/OP20030411/en_300706v010201o.pdf">http://webapp.etsi.org/action%5COP/OP20030411/en_300706v010201o.pdf</a>.)</dd>
  <dt class="label"><a name="en300743" id="en300743"></a>EN 300 743</dt>
    <dd>European Telecommunications Standards Institute, <a
      href="http://webapp.etsi.org/action%5COP/OP20021004/en_300743v010201o.pdf"><cite>Digital
      Video Broadcasting (DVB); Subtitling Systems</cite></a>. (See <a
      href="http://webapp.etsi.org/action%5COP/OP20021004/en_300743v010201o.pdf">http://webapp.etsi.org/action%5COP/OP20021004/en_300743v010201o.pdf</a>.)</dd>
  <dt class="label"><a name="qtext" id="qtext"></a>QText</dt>
    <dd>Apple Computers, Inc., <a
      href="http://www.apple.com/quicktime/tutorials/texttracks.html"><cite>QuickTime
      Text</cite></a>. (See <a
      href="http://www.apple.com/quicktime/tutorials/texttracks.html">http://www.apple.com/quicktime/tutorials/texttracks.html</a>).</dd>
  <dt class="label"><a name="realtext" id="realtext"></a>RealText</dt>
    <dd>RealNetworks, Inc., <a
      href="http://www.realnetworks.com/resources/howto/realtext/index.html"><cite>RealText
      Markup</cite></a>. (See <a
      href="http://www.realnetworks.com/resources/howto/realtext/index.html">http://www.realnetworks.com/resources/howto/realtext/index.html</a>).</dd>
  <dt class="label"><a name="sami" id="sami"></a>SAMI</dt>
    <dd>Microsoft Corporation, <a
      href="http://www.msdn.microsoft.com/library/default.asp?url=/library/en-us/dnacc/html/atg_samiarticle.asp"><cite>SAMI
      – Synchronized Accessible Media Interchange for Windows Media
      Player</cite></a>. (See <a
      href="http://www.msdn.microsoft.com/library/default.asp?url=/library/en-us/dnacc/html/atg_samiarticle.asp">http://www.msdn.microsoft.com/library/default.asp?url=/library/en-us/dnacc/html/atg_samiarticle.asp</a>.)</dd>
  <dt class="label"><a name="smil20" id="smil20"></a>SMIL 2.0</dt>
    <dd>Jeff Ayars, Dick Bulterman, et al., Eds., <a
      href="http://www.w3.org/TR/smil20/"><cite>Synchronized Multimedia
      Integration Language (SMIL 2.0)</cite></a>, W3C Recommendation. (See <a
      href="http://www.w3.org/TR/smil20/">http://www.w3.org/TR/smil20/</a>.)</dd>
  <dt class="label"><a name="tei" id="tei"></a>TEI</dt>
    <dd>C. M. Sperberg-McQueen and Lou Burnard, Eds., <a
      href="http://www.tei-c.org/Guidelines2/index.html"><cite>TEI P4:
      Guidelines for Electronic Text Encoding and Interchange</cite></a>,
      Text Encoding Initiative Consortium, Oxford, 2002. (See <a
      href="http://www.tei-c.org/Guidelines2/index.html">http://www.tei-c.org/Guidelines2/index.html</a>.)</dd>
  <dt class="label"><a name="xhtml1" id="xhtml1"></a>XHTML 1.0</dt>
    <dd>Steven Pemberton, et al., Eds., <a
      href="http://www.w3.org/TR/xhtml1/"><cite>XHTML™ 1.0 Extensible
      Hypertext Markup Language (Second Edition)</cite></a>, W3C
      Recommendation. (See <a
      href="http://www.w3.org/TR/xhtml1/">http://www.w3.org/TR/xhtml1/</a>.)</dd>
  <dt class="label"><a name="xsl" id="xsl"></a>XSL 1.0</dt>
    <dd>Sharon Adler, Anders Berglund, et al., Eds., <a
      href="http://www.w3.org/TR/xsl/"><cite>Extensible Stylesheet Language,
      Version 1.0</cite></a>, W3C Recommendation. (See <a
      href="http://www.w3.org/TR/xsl/">http://www.w3.org/TR/xsl/</a>.)</dd>
</dl>
</div>

<div class="div1">
<h2><a name="acknowledgements" id="acknowledgements"></a>C Acknowledgments
(Non-Normative)</h2>

<p>The editor acknowledges the members of the Timed Text Working Group, the
members of other W3C Working Groups, and industry experts in other forums who
have contributed directly or indirectly to the process or content of creating
this document.</p>

<p>The current and former members of the Timed Text Working Group are: Glenn
Adams, Extensible Formatting Systems, Inc. (chair); Kees Blom, CWI; Brad
Botkin, WGBH; Dick Bulterman, CWI; Michael Dolan, Invited Expert; Gerry
Fields, WGBH; Geoff Freed, WGBH; Markus Gylling, DAISY Consortium; Markku
Hakkinen, Japanese Society for Rehabilitation of Persons with Disabilities;
Sean Hayes, Microsoft; Erik Hodge, RealNetworks; Masahiko Kaneko, Microsoft;
George Kerscher, DAISY Consortium; David Kirby, BBC; Thierry Michel, W3C
(team contact); Patrick Schmitz, Invited Expert; and, Dave Singer, Apple
Computer.</p>

<p>The Timed Text Working Group has benefited in its work from the
participation and contributions of a number of people not currently members
of the Working Group, including in particular those named below. Affiliations
given are those current at the time of their work with the WG.</p>

<p>John Birch, Screen Subtitling Systems; Bert Bos, W3C (chair, CSS WG);
Martin Dürst, W3C (leader, I18N Activity); Al Gilman (chair, WAI Protocol
and Formats WG); Philipp Hoschka, W3C (leader, Interaction Domain); Chris
Lilley, W3C (chair, SVG WG).</p>
</div>
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