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<p><a href="http://www.w3.org/"><img alt="W3C"
src="http://www.w3.org/Icons/w3c_home" width="72" height="48"></a></p>

<h1>Ruby Annotation</h1>

<h2><acronym title="World Wide Web Consortium">W3C</acronym> Recommendation
31 May 2001 (Markup errors corrected 25 June 2008)</h2>
<dl>
  <dt>This version:</dt>
    <dd><a
      href="http://www.w3.org/TR/2001/REC-ruby-20010531/">http://www.w3.org/TR/2001/REC-ruby-20010531</a>
      <br>
      (<a href="ruby.zip">ZIP archive</a>)</dd>
  <dt>Latest version:</dt>
    <dd><a href="http://www.w3.org/TR/ruby/">http://www.w3.org/TR/ruby</a><br>
    </dd>
  <dt>Previous version:</dt>
    <dd><a
      href="http://www.w3.org/TR/2001/PR-ruby-20010406/">http://www.w3.org/TR/2001/PR-ruby-20010406</a></dd>
  <dt>Editors:</dt>
    <dd>Marcin <span class="familyname">Sawicki</span> (until 10 October,
      1999)</dd>
    <dd><a href="mailto:michelsu@microsoft.com">Michel <span
      class="familyname">Suignard</span></a>, Microsoft</dd>
    <dd><a href="mailto:mimasa@w3.org">Masayasu <span
      class="familyname">Ishikawa</span></a>
      (<span lang="ja">石川 雅康</span>), <acronym
      title="World Wide Web Consortium">W3C</acronym></dd>
    <dd><a href="mailto:duerst@w3.org">Martin <span
      class="familyname">Dürst</span></a>, <acronym
      title="World Wide Web Consortium">W3C</acronym></dd>
    <dd><a href="mailto:texin@progress.com">Tex <span
      class="familyname">Texin</span></a>, Progress Software Corp.</dd>
    <dd>(See <a href="#ack">Acknowledgements</a> for additional
    contributors)</dd>
</dl>

<p class="copyright"><a
href="http://www.w3.org/Consortium/Legal/ipr-notice-20000612#Copyright">Copyright</a>
©1998-2001 <a href="http://www.w3.org/"><acronym
title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a
href="http://www.lcs.mit.edu/"><acronym
title="Massachusetts Institute of Technology">MIT</acronym></a>, <a
href="http://www.inria.fr/"><acronym lang="fr"
title="Institut National de Recherche en Informatique et Automatique">INRIA</acronym></a>,
<a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. <acronym
title="World Wide Web Consortium">W3C</acronym> <a
href="http://www.w3.org/Consortium/Legal/ipr-notice-20000612#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice-20000612#W3C_Trademarks">trademark</a>,
<a
href="http://www.w3.org/Consortium/Legal/copyright-documents-19990405">document
use</a> and <a
href="http://www.w3.org/Consortium/Legal/copyright-software-19980720">software
licensing</a> rules apply.</p>
<hr>
</div>

<div>
<h2><a id="Abstract" name="Abstract">Abstract</a></h2>

<p>"Ruby" are short runs of text alongside the base text, typically used in
East Asian documents to indicate pronunciation or to provide a short
annotation. This specification defines markup for ruby, in the form of an
XHTML module [<a href="#xhtmlmod">XHTMLMOD</a>].</p>
</div>

<div>
<h2><a id="Status" name="Status">Status of This Document</a></h2>

<p><em>This section describes the status of this document at the time of its
publication. Other documents may supersede this document. The <a
href="http://www.w3.org/TR/ruby/#Status">latest status</a> of this series of
documents is maintained at the W3C.</em></p>

<p>This document has been reviewed by W3C Members and other interested
parties and has been endorsed by the Director as a W3C Recommendation. It is
a stable document and may be used as reference material or cited as a
normative reference from another document. W3C's role in making the
Recommendation is to draw attention to the specification and to promote its
widespread deployment. This enhances the functionality and interoperability
of the Web.</p>

<p>This document has been produced as part of the W3C <a
href="http://www.w3.org/International/Activity">Internationalization
Activity</a> by the <a
href="http://www.w3.org/International/Group/">Internationalization Working
Group</a> (I18N WG, <a
href="http://cgi.w3.org/MemberAccess/AccessRequest">members only</a>) with
the help of the Internationalization Interest Group (I18N IG). Comments
should be sent to the <a
href="http://lists.w3.org/Archives/Public/www-i18n-comments/">publicly
archived</a> mailing list <a
href="mailto:www-i18n-comments@w3.org">www-i18n-comments@w3.org</a>. Comments
in languages other than English, in particular Japanese, are also welcome.
Public discussion of this document takes place on the <a
href="mailto:www-international@w3.org">www-international@w3.org</a> mailing
list (see <a
href="http://lists.w3.org/Archives/Public/www-international/">archive</a>).</p>

<p>Due to its subject matter, and to make the examples more realistic, this
document includes examples using a wide range of characters. Not all user
agents may be able to display all characters. Depending on the user agent,
changing the configuration can improve the situation. Also, great care has
been taken to serve this document in <a href="encodings">various character
encodings</a> to cover a wide range of user agents and configurations.</p>

<p>Information related to this document can be found on the <a
href="http://www.w3.org/International/O-HTML-ruby">public ruby page</a>
(http://www.w3.org/International/O-HTML-ruby). This includes <a
href="http://www.w3.org/International/O-HTML-ruby#Translations">translations</a>
of this specification as well as potential <a
href="http://www.w3.org/2001/05/ruby-errata">errata</a>. A list
of current <a href="http://www.w3.org/TR/">W3C Recommendations and other
technical documents</a> can be found at http://www.w3.org/TR.</p>

<p>There have been no declarations regarding patents related to this
specification within the Internationalization Working Group.</p>
<hr>
</div>

<h2><a id="Contents" name="Contents">Contents</a></h2>

<div class="toc">
<ul>
  <li class="informative">1.  <a href="#intro">Introduction</a>
    <ul>
      <li>1.1  <a href="#what">What is ruby?</a></li>
      <li>1.2  <a href="#markup-overview">Ruby markup overview</a>
        <ul>
          <li>1.2.1  <a href="#simple-ruby1">Simple ruby markup</a></li>
          <li>1.2.2  <a href="#simple-parenthesis">Simple ruby markup with
            parentheses</a></li>
          <li>1.2.3  <a href="#complex">Complex ruby markup</a></li>
          <li>1.2.4  <a href="#summary">Summary</a></li>
        </ul>
      </li>
    </ul>
  </li>
  <li class="normative">2.  <a href="#definition">Formal definition of ruby
    markup</a>
    <ul>
      <li>2.1  <a href="#abstract-def">Abstract definition of ruby
        markup</a></li>
      <li>2.2  <a href="#ruby">The <code>ruby</code> element</a></li>
      <li>2.3  <a href="#rbc">The <code>rbc</code> element</a></li>
      <li>2.4  <a href="#rtc">The <code>rtc</code> element</a></li>
      <li>2.5  <a href="#rb">The <code>rb</code> element</a></li>
      <li>2.6  <a href="#rt">The <code>rt</code> element</a></li>
      <li>2.7  <a href="#rp">The <code>rp</code> element</a></li>
    </ul>
  </li>
  <li>3. <a href="#rendering">Rendering and Styling Considerations</a>
    <ul>
      <li>3.1  <a href="#web">Ruby on the Web vs. traditional typographic
        usage</a></li>
      <li>3.2  <a href="#font">Font size of ruby text</a></li>
      <li>3.3  <a href="#positioning">Positioning of ruby text</a></li>
      <li>3.4  <a href="#presentation">Presentation of ruby markup</a></li>
      <li>3.5  <a href="#non-visual">Considerations for non-visual
        rendering</a></li>
      <li>3.6  <a href="#rp-alternatives">Alternatives to the
        <code>rp</code> element</a></li>
    </ul>
  </li>
  <li>4. <a href="#conformance">Conformance Criteria</a></li>
  <li><a href="#appendix">Appendices</a>
    <ul>
      <li class="normative">A.  <a href="#module">Ruby module for <acronym
        title="Extensible HyperText Markup Language">XHTML</acronym></a></li>
      <li class="informative">B.  <a href="#design">Notes on design
        decisions</a></li>
      <li class="informative">C.  <a href="#compatibility">Notes on
        backwards compatibility</a></li>
      <li class="informative">D.  <a href="#glossary">Glossary</a></li>
      <li class="informative">E.  <a href="#changes">Changes from Proposed
        Recommendation</a></li>
    </ul>
  </li>
  <li class="informative"><a href="#ack">Acknowledgements</a></li>
  <li class="informative ref"><a href="#ref">References</a></li>
</ul>
</div>
<hr>

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

<p>This section is <em>informative</em>.</p>

<p>This document presents an overview of ruby annotation and defines the
markup for it. Several examples are provided. However, this document does not
specify any mechanisms for presentation or styling of ruby annotation; this
is part of the respective style sheet languages.</p>

<p>This document is organized as follows:</p>

<p><a href="#what">Section 1.1</a> gives an overview of ruby annotation.</p>

<p><a href="#markup-overview">Section 1.2</a> gives an overview of the
markup for ruby annotation.</p>

<p><a href="#definition">Section 2</a> provides the normative definition of
ruby markup.</p>

<p><a href="#rendering">Section 3</a> discusses typical rendering and
styling of ruby text.</p>

<p><a href="#conformance">Section 4</a> provides conformance criteria.</p>

<div>
<h3><a id="what" name="what">1.1 What is ruby?</a></h3>

<p><em>Ruby</em> is the term used for a run of text that is associated with
another run of text, referred to as the <em>base text</em>. Ruby text is used
to provide a short annotation of the associated base text. It is most often
used to provide a <em>reading</em> (pronunciation guide). Ruby annotations
are used frequently in Japan in many kinds of publications, including books
and magazines. Ruby is also used in China, especially in schoolbooks.</p>

<p>Ruby text is usually presented alongside the base text, using a smaller
typeface. The name "ruby" in fact originated from the name of the 5.5<abbr
title="points">pt</abbr> font size in British printing, which is about half
the 10<abbr title="points">pt</abbr> font size commonly used for normal text.
<a href="#fig1.1">Figure 1.1</a> shows an example, with three ideographs
(kanji) as base text, and six hiragana giving the reading (shinkansen -
Japanese bullet train).</p>

<div class="figure">
<p><a id="fig1.1" name="fig1.1"><img
alt="At the bottom left, three Japanese ideographs from left to right. On top of them, six hiragana characters at half size. To the right, arrows and text saying 'ruby base' (bottom) and 'ruby text' (top)."
class="example" height="33" width="140" src="shinkansen-top.gif"></a></p>

<p><strong>Figure 1.1</strong>: Ruby text giving the reading of each
character of the base text.</p>
</div>

<p>East Asian typography has developed various features that do not appear in
western typography. Most of these can be addressed appropriately with style
sheet languages such as <acronym title="Cascading Style Sheets">CSS</acronym>
or <acronym title="Extensible Style Language">XSL</acronym>. However,
additional markup is required to define the association between base text and
ruby text.</p>

<p>This specification defines such markup, designed to be usable with
<acronym title="Extensible HyperText Markup Language">XHTML</acronym>, so
that ruby text is available on the Web without using special workarounds or
graphics. Although this specification gives examples of actual rendering to
make it easier for most readers to understand the markup, all such examples
are informational only. This document does not specify any mechanisms for
presentation or styling; this is part of the respective style sheet
languages.</p>

<p>Sometimes more than one ruby text is associated with the same base text. A
typical example is to indicate both meaning as well as reading for the same
base text. In such cases, ruby texts may appear on both sides of the base
text. Ruby text before the base text is often used to indicate reading; ruby
text after the base text is often used to indicate meaning. <a
href="#fig1.2">Figure 1.2</a> shows an example of base text with two ruby
texts, giving reading using hiragana and Latin letters.</p>

<div class="figure">
<p><a id="fig1.2" name="fig1.2"><img
alt="At the left, three Japanese ideographs from left to right. On top of them, six hiragana characters at half size. Below the ideographs, the text 'shinkansen'. To the right, arrows and text saying 'ruby base' (middle), 'ruby text' (top), and 'ruby text 2' (bottom)."
class="example" height="49" width="149"
src="shinkansen-top-bottom.gif"></a></p>

<p><strong>Figure 1.2</strong>: Two ruby texts applied to the same base
text.</p>
</div>

<p>In addition, each ruby text may be associated with different, but
overlapping, parts of the base text, such as <a id="fig1.3" name="fig1.3">in
the following example:</a></p>

<div class="figure">

<table>
  <tbody>
    <tr class="rt" style="text-align: center">
      <td>Month</td>
      <td>Day</td>
      <td>Year</td>
    </tr>
    <tr class="rb" style="text-align: center">
      <td><strong>10</strong></td>
      <td><strong>31</strong></td>
      <td><strong>2002</strong></td>
    </tr>
    <tr class="rt" style="text-align: center">
      <td colspan="3">Expiration Date</td>
    </tr>
  </tbody>
</table>

<p><strong>Figure 1.3</strong>: Base text with two ruby texts using different
associations</p>
</div>

<p>In this example, the base text is the date "10 31 2002". One ruby text is
the phrase "Expiration Date". This ruby text is associated with the entire
base text. The other ruby text has 3 parts: "Month", "Day" and "Year". Each
part is associated with a different part of the base text. "Month" is
associated with "10", "Day" is associated with "31", and "Year" is associated
with "2002".</p>
</div>

<div>
<h3><a id="markup-overview" name="markup-overview">1.2 Ruby markup
overview</a></h3>

<p>The markup defined in this specification is designed to cover all the
above cases, namely markup for one or two ruby texts associated with the same
base text and markup for associations of substrings of the ruby text(s) with
components of the base text.</p>

<p>There are two variants of ruby markup, called <em>simple ruby markup</em>
and <em>complex ruby markup</em>. Simple ruby markup associates a single ruby
text with a run of base text. Simple ruby markup can also specify a fallback
mechanism to allow display of ruby text by (older) browsers that do not know
about ruby markup. Complex ruby markup can associate two ruby texts with one
base text, and can define a more fine-grained association between components
of the ruby text and the base text. However, complex ruby markup does not
provide a fallback mechanism for browsers that do not understand ruby
markup.</p>

<p>This section gives an overview of the markup for ruby defined in this
specification. A full formal definition can be found in <a
href="#definition">Section 2</a>.</p>

<div>
<h4><a id="simple-ruby1" name="simple-ruby1">1.2.1 Simple ruby markup</a></h4>

<p>In the simplest case, ruby markup defines a <code>ruby</code> element
which contains one <code>rb</code> element for the base text and one
<code>rt</code> element for the ruby text. This <code>ruby</code> element
therefore creates an association between the base text and the ruby text, and
is sufficient for most cases.<a id="fig1.4" name="fig1.4"> Here is an example
of simple ruby markup:</a></p>

<div class="figure">
<pre class="xml">&lt;ruby&gt;
  &lt;rb&gt;WWW&lt;/rb&gt;
  &lt;rt&gt;World Wide Web&lt;/rt&gt;
&lt;/ruby&gt;</pre>

<p><strong>Figure 1.4</strong>: Example of simple ruby markup</p>
</div>

<p><a id="fig1.5" name="fig1.5">This may be rendered as follows:</a></p>

<div class="figure">
<p><img
alt="At the bottom left, three large letters reading 'WWW'. On top of them, in smaller letters, the text 'World Wide Web'. To the right, arrows and text saying 'ruby base' (bottom) and 'ruby text' (top)."
class="example" height="30" width="145" src="ruby-en-ex.gif"></p>

<p><strong>Figure 1.5</strong>: Example of rendering for simple ruby markup
in <a href="#fig1.4">Figure 1.4</a></p>
</div>

<p class="note"><strong>Note</strong>: The name of this enclosing element,
"&lt;<code>ruby</code>&gt;", should be interpreted to mean that its contents
are <em>associating</em> ruby text with base text. It must not be
misunderstood to mean that everything inside, including the base text,
<em>is</em> ruby. The name of the enclosing element was chosen to compactly
and clearly identify the function of the markup construct; the names for the
other elements were chosen to keep the overall length short.</p>
</div>

<div>
<h4><a id="simple-parenthesis" name="simple-parenthesis">1.2.2 Simple ruby
markup with parentheses</a></h4>

<p>Some user agents might not understand ruby markup, or may not be able to
render ruby text appropriately. In either situation, it is generally
preferable to render ruby text, so that information is not lost. A generally
acceptable fallback is to place the ruby text immediately after the base
text, and to enclose the ruby text in parentheses. The parentheses reduce the
potential for confusing the ruby text with other text. (It should be noted
that text in parentheses in Japanese typography is never called "ruby".)</p>

<p>For compatibility with older user agents that do not understand ruby
markup and simply render the content of elements they do not understand,
<code>rp</code> elements can be added to simple ruby markup to distinguish
ruby text.</p>

<p>The element name <code>rp</code> stands for "ruby parenthesis". The
<code>rp</code> elements and the parentheses (or other characters) inside
them are provided as a fallback mechanism only. User agents that ignore
unknown elements, but render their contents, will display the contents of
each <code>rp</code> element. Therefore the <code>rp</code> element can be
used to denote both the beginning and end of ruby text.</p>

<p>User agents that do know about ruby markup will recognize the
<code>rp</code> element, and intentionally not display its contents. Instead,
they will render the simple ruby markup in a more appropriate way.</p>

<p><a id="fig1.6" name="fig1.6">The following example demonstrates the use of
the <code>rp</code> element:</a></p>

<div class="figure">
<pre class="xml">&lt;ruby&gt;
  &lt;rb&gt;WWW&lt;/rb&gt;
  &lt;rp&gt;(&lt;/rp&gt;&lt;rt&gt;World Wide Web&lt;/rt&gt;&lt;rp&gt;)&lt;/rp&gt;
&lt;/ruby&gt;</pre>

<p><strong>Figure 1.6</strong>: Example of simple ruby markup including
<code>rp</code> elements for fallback</p>
</div>

<p>User agents that either:</p>
<ul>
  <li>do not know about ruby markup but render the contents of unknown
    elements, or</li>
  <li>cannot render the ruby text alongside the base text,</li>
</ul>

<p><a id="fig1.7" name="fig1.7">will render the above markup as:</a></p>

<div class="figure">
<p><strong>WWW (World Wide Web)</strong></p>

<p><strong>Figure 1.7</strong>: Rendering of simple ruby markup using
fallback parentheses</p>
</div>

<p>User agents that do know about ruby markup, and that have more
sophisticated presentation styles for ruby text, will choose to not render
the parentheses. For example, the markup of <a href="#fig1.6">figure 1.6</a>
can be rendered as shown in the next figure.</p>

<div class="figure">
<p><a id="fig1.8" name="fig1.8"><img
alt="EAt the bottom left, three large letters reading 'WWW'. On top of them, in smaller letters, the text 'World Wide Web'. To the right, arrows and text saying 'ruby base' (bottom) and 'ruby text' (top)."
class="example" height="30" width="145" src="ruby-en-ex.gif"></a></p>

<p><strong>Figure 1.8</strong>: <code>rp</code> element ignored in favor of
more sophisticated rendering</p>
</div>
</div>

<div>
<h4><a id="complex" name="complex">1.2.3 Complex ruby markup</a></h4>

<p>Complex ruby markup is used to associate more than one ruby text with a
base text, or to associate parts of ruby text with parts of base text.</p>

<p>Complex ruby markup provides for multiple <code>rb</code> and
<code>rt</code> elements. This specification defines container elements that
make the association between the individual elements clear. The ruby base
container element, <code>rbc</code>, encloses <code>rb</code> elements. There
can be one or two ruby text container elements, <code>rtc</code>, that
enclose <code>rt</code> elements. This allows association of two ruby text
containers with the same base text. With complex ruby markup it is also
possible to associate parts of the base text with parts of a ruby text by
using a number of <code>rb</code> elements, and a corresponding number of
<code>rt</code> elements. In addition, the <code>rt</code> element may use
the <code>rbspan</code> attribute to indicate that a single <code>rt</code>
element spans (is associated with) multiple <code>rb</code> elements. This is
similar to the <a
href="http://www.w3.org/TR/html4/struct/tables.html#adef-colspan"><code>colspan</code></a>
attribute of the <code>th</code> and <code>td</code> elements in tables ([<a
href="#html4">HTML4</a>], section 11.2.6).</p>

<p>Where and how each part of complex ruby markup is rendered is defined as
part of the respective style sheet languages; see also section 3 for further
information.</p>

<p><a id="fig1.9" name="fig1.9">The following example shows all these
features.</a></p>

<div class="figure">
<pre class="xml">&lt;ruby&gt;
  &lt;rbc&gt;
    &lt;rb&gt;10&lt;/rb&gt;
    &lt;rb&gt;31&lt;/rb&gt;
    &lt;rb&gt;2002&lt;/rb&gt;
  &lt;/rbc&gt;
  &lt;rtc&gt;
    &lt;rt&gt;Month&lt;/rt&gt;
    &lt;rt&gt;Day&lt;/rt&gt;
    &lt;rt&gt;Year&lt;/rt&gt;
  &lt;/rtc&gt;
  &lt;rtc&gt;
    &lt;rt rbspan="3"&gt;Expiration Date&lt;/rt&gt;
  &lt;/rtc&gt;
&lt;/ruby&gt;</pre>

<p><strong>Figure 1.9</strong>: Complex ruby markup to associate two ruby
texts with different parts of the same base text.</p>
</div>

<p>In this example, the first ruby text container encloses 3 components
("Month", "Day", "Year"). Each of these components is associated with a
corresponding component in the base text ("10", "31", "2002"). The second
ruby text container ("Expiration Date") consists of a single ruby text, and
is associated with the entire base text ("10 31 2002"). <a id="fig1.10"
name="fig1.10">It may be rendered as shown in figure 1.10.</a></p>

<div class="figure">

<table>
  <tbody>
    <tr class="rt" style="text-align: center">
      <td>Month</td>
      <td>Day</td>
      <td>Year</td>
    </tr>
    <tr class="rb" style="text-align: center">
      <td><strong>10</strong></td>
      <td><strong>31</strong></td>
      <td><strong>2002</strong></td>
    </tr>
    <tr class="rt" style="text-align: center">
      <td colspan="3">Expiration Date</td>
    </tr>
  </tbody>
</table>

<p><strong>Figure 1.10</strong>: Rendering of the complex ruby markup in <a
href="#fig1.9">figure 1.9</a></p>
</div>

<p>The example shows that the  association of ruby text with base text can be
more or less granular as needed. For example, the ruby text can be associated
with the entire base text in cases where:</p>
<ul>
  <li>a more detailed relationship is unknown, or</li>
  <li>when the reading or annotation only applies to the whole unit and
    cannot be split into pieces.</li>
</ul>

<p>More fine-grained associations can also be made when the relationships are
known. For these situations, an improved rendering can therefore be provided.
For example, a person's name can be decomposed into family name and given
name, or a <span lang="ja">kanji</span> compound or phrase can be decomposed
into semantic subparts or individual characters. With either fine or course
granularity, the spans of the ruby text can be set with the corresponding
spacing in the base text, and better readability and a more balanced layout
may be achieved.</p>

<p>The <code>rp</code> element is not available in the case of complex ruby
markup. There are two reasons for this. First, the <code>rp</code> element is
only a fallback mechanism, and it was considered that this is much more
important for the more frequent simple case. Second, for the more complex
cases, it is difficult to come up with a reasonable fallback display, and
constructing markup for such cases can be even more difficult if not
impossible.</p>
</div>

<div>
<h4><a id="summary" name="summary">1.2.4 Summary</a></h4>

<p>In summary, the <code>ruby</code> element serves as a container for one of
the following:</p>
<ul>
  <li>a combination of <code>rb</code>, <code>rt</code> and possibly
    <code>rp</code> elements (<strong>simple ruby markup</strong>) for:
    <ul>
      <li>Association of a single ruby text with a single base text</li>
      <li>Fallback in case the ruby markup is not understood.</li>
    </ul>
  </li>
  <li>a combination of a single <code>rbc</code> and one or two
    <code>rtc</code> container elements (<strong>complex ruby
    markup</strong>) for:
    <ul>
      <li>Associating two ruby texts with the same base text</li>
      <li>Defining more fine-grained associations between parts of a ruby
        text and parts of the base text.</li>
    </ul>
  </li>
</ul>
</div>
</div>
</div>

<div class="normative">
<h2><a id="definition" name="definition">2.  Formal definition of ruby
markup</a></h2>

<p>This section is <em>normative</em>.</p>

<p>This section contains the formal syntax definition and the specification
of the functionality of the ruby markup. Some familiarity with the <acronym
title="Extensible HyperText Markup Language">XHTML</acronym> Modularization
framework, in particular the "<cite>Modularization of <acronym
title="Extensible HyperText Markup Language">XHTML</acronym></cite>" [<a
href="#xhtmlmod">XHTMLMOD</a>] specification, is assumed.</p>

<div>
<h3><a id="abstract-def" name="abstract-def">2.1  Abstract definition of
ruby markup</a></h3>

<p>The following is the abstract definition of the elements for ruby markup,
which is consistent with the <acronym
title="Extensible HyperText Markup Language">XHTML</acronym> Modularization
framework [<a href="#xhtmlmod">XHTMLMOD</a>]. Further definitions of <acronym
title="Extensible HyperText Markup Language">XHTML</acronym> abstract modules
can be found in [<a href="#xhtmlmod">XHTMLMOD</a>].</p>

<table border="1" summary="Elements and Attributes for Ruby Module">
  <thead>
    <tr>
      <th scope="col">Elements</th>
      <th scope="col">Attributes</th>
      <th scope="col">Minimal Content Model</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td abbr="element"><a id="ruby-abstract" name="ruby-abstract"
        href="#ruby">ruby</a></td>
      <td abbr="attribute">Common</td>
      <td abbr="content" class="content">(rb, (rt | (rp, rt, rp)))</td>
    </tr>
    <tr>
      <td abbr="element"><a id="rbc-abstract" name="rbc-abstract"
        href="#rbc">rbc</a></td>
      <td abbr="attribute">Common</td>
      <td abbr="content" class="content">rb+</td>
    </tr>
    <tr>
      <td abbr="element"><a id="rtc-abstract" name="rtc-abstract"
        href="#rtc">rtc</a></td>
      <td abbr="attribute">Common</td>
      <td abbr="content" class="content">rt+</td>
    </tr>
    <tr>
      <td abbr="element"><a id="rb-abstract" name="rb-abstract"
        href="#rb">rb</a></td>
      <td abbr="attribute">Common</td>
      <td abbr="content" class="content">(PCDATA | Inline - ruby)*</td>
    </tr>
    <tr>
      <td abbr="element"><a id="rt-abstract" name="rt-abstract"
        href="#rt">rt</a></td>
      <td abbr="attribute">Common, rbspan (CDATA)</td>
      <td abbr="content" class="content">(PCDATA | Inline - ruby)*</td>
    </tr>
    <tr>
      <td abbr="element"><a id="rp-abstract" name="rp-abstract"
        href="#rp">rp</a></td>
      <td abbr="attribute">Common</td>
      <td abbr="content" class="content">PCDATA*</td>
    </tr>
  </tbody>
</table>

<p>The maximal content model for the <code>ruby</code> element is as
follows:</p>
<pre class="content">((rb, (rt | (rp, rt, rp))) | (rbc, rtc, rtc?))</pre>

<p>The minimal content model for the <code>ruby</code> element corresponds to
simple ruby markup. The <code>(rbc, rtc, rtc?)</code> alternative of the
maximal content model for the <code>ruby</code> element corresponds to
complex ruby markup.</p>

<p>An implementation of this abstract definition as an <acronym
title="Extensible HyperText Markup Language">XHTML</acronym> <acronym
title="Document Type Definition">DTD</acronym> module can be found in <a
href="#module">Appendix A</a>. An <abbr
title="Extensible Markup Language">XML</abbr> Schema [<a
href="#xmlschema">XMLSchema</a>] implementation is being worked on (see [<a
href="#ModSchema">ModSchema</a>]).</p>
</div>

<div>
<h3><a id="ruby" name="ruby">2.2  The <code>ruby</code> element</a></h3>

<p>The <code>ruby</code> element is an inline (or text-level) element that
serves as an overall container. It contains either the <a
href="#rb"><code>rb</code></a>, <a href="#rt"><code>rt</code></a> and
optional <a href="#rp"><code>rp</code></a> elements (simple ruby markup) or
the <a href="#rbc"><code>rbc</code></a> and <a
href="#rtc"><code>rtc</code></a> elements (complex ruby markup).</p>

<p>In the case of simple ruby markup, the <code>ruby</code> element contains
either an <a href="#rb"><code>rb</code></a> element followed by an <a
href="#rt"><code>rt</code></a> element, or a sequence of an <a
href="#rb"><code>rb</code></a> element, an <a href="#rp"><code>rp</code></a>
element, an <a href="#rt"><code>rt</code></a> element and another <a
href="#rp"><code>rp</code></a> element. The content of the <a
href="#rt"><code>rt</code></a> element is taken as ruby text and associated
with the content of the <code><a href="#rb"><code>rb</code></a></code>
element as the base text. The content of the <a
href="#rp"><code>rp</code></a> elements, if present, is ignored.</p>

<p>In the case of complex ruby markup, the <code>ruby</code> element contains
an <a href="#rbc"><code>rbc</code></a> element followed by one or two <a
href="#rtc"><code>rtc</code></a> elements. The content of the subelements of
each <a href="#rtc"><code>rtc</code></a> element is taken as ruby text and
associated with the content of the subelements of the <a
href="#rbc"><code>rbc</code></a> element as the base text.</p>

<p>The <code>ruby</code> element has common attributes only. Examples of
common attributes include: <code>id</code>, <code>class</code> or
<code>xml:lang</code>. Common attributes depend on the markup language with
which ruby markup is used. In the case of [<a href="#xhtml11">XHTML 1.1</a>],
these are defined in <a
href="http://www.w3.org/TR/xhtml-modularization/abstract_modules.html#s_commonatts">XHTML
Modularization, Section 5.1</a> [<a href="#xhtmlmod">XHTMLMOD</a>].</p>
</div>

<div>
<h3><a id="rbc" name="rbc">2.3  The <code>rbc</code> element</a></h3>

<p>The <code>rbc</code> (ruby base container) element serves as the container
for <a href="#rb"><code>rb</code></a> elements in the case of complex ruby
markup. Only one <code>rbc</code> element may appear inside a <a
href="#ruby"><code>ruby</code></a> element.</p>

<p>The <code>rbc</code> element has common attributes only.</p>
</div>

<div>
<h3><a id="rtc" name="rtc">2.4  The <code>rtc</code> element</a></h3>

<p>The <code>rtc</code> (ruby text container) element serves as the container
for <a href="#rt"><code>rt</code></a> elements in the case of complex ruby
markup. One or two <code>rtc</code> elements may appear inside a <a
href="#ruby"><code>ruby</code></a> element to associate ruby texts with a
single base text, represented by an <a href="#rbc"><code>rbc</code></a>
element. More than two <code>rtc</code> elements MUST NOT appear inside a <a
href="#ruby"><code>ruby</code></a> element.</p>

<p>The <code>rtc</code> element has common attributes only.</p>
</div>

<div>
<h3><a id="rb" name="rb">2.5  The <code>rb</code> element</a></h3>

<p>The <code>rb</code> (ruby base) element serves to markup the base text.
For simple ruby markup, only one <code>rb</code> element may appear. For
complex ruby markup, multiple <code>rb</code> elements may appear inside an
<a href="#rbc"><code>rbc</code></a> element. Each <code>rb</code> element is
associated with a corresponding <a href="#rt"><code>rt</code></a> element,
for fine-grained control of ruby presentation.</p>

<p>The <code>rb</code> element may contain inline elements or character data
as its content, but the <a href="#ruby"><code>ruby</code></a> element is not
allowed as its descendant element.</p>

<p>The <code>rb</code> element has common attributes only.</p>
</div>

<div>
<h3><a id="rt" name="rt">2.6  The <code>rt</code> element</a></h3>

<p>The <code>rt</code> element is the markup for ruby text. For simple ruby
markup, only one <code>rt</code> element may appear. For complex ruby markup,
multiple <code>rt</code> elements may appear inside an <a
href="#rtc"><code>rtc</code></a> element, and each <code>rt</code> element
contains the ruby text for the relevant base text, represented by the
corresponding <a href="#rb"><code>rb</code></a> element.</p>

<p>The <code>rt</code> element may contain inline elements or character data
as its content, but the <a href="#ruby"><code>ruby</code></a> element is not
allowed as its descendant element.</p>

<p>The <code>rt</code> element has common attributes and the
<code>rbspan</code> attribute. In complex ruby markup, the
<code>rbspan</code> attribute allows an <code>rt</code> element to span
multiple <a href="#rb"><code>rb</code></a> elements. The value shall be an
integer value greater than zero ("0"). The default value of this attribute is
one ("1"). The <code>rbspan</code> attribute should not be used in simple
ruby markup, and user agents should ignore the <code>rbspan</code> attribute
when it appears in simple ruby markup.</p>
</div>

<div>
<h3><a id="rp" name="rp">2.7  The <code>rp</code> element</a></h3>

<p>The <code>rp</code> element can be used in the case of simple ruby markup
to specify characters that can denote the beginning and end of ruby text when
user agents do not have other ways to present ruby text distinctively from
the base text. Parentheses (or similar characters) can provide an acceptable
fallback. In this situation, ruby text will only degrade to be rendered
inline and enclosed in the fallback parentheses. This is the least
inappropriate rendering under the condition that only inline rendering is
available. The <code>rp</code> element cannot be used with complex ruby
markup.</p>

<p>The <code>rp</code> element has common attributes only.</p>

<p>Using parentheses for the fallback may lead to confusion between runs of
text intended to be ruby text and other runs that happen to be enclosed
within parentheses. The document or style sheet author should be aware of the
potential for that confusion and is advised to choose an unambiguous
delimiter for the fallback.</p>
</div>
</div>

<div class="informative">
<h2><a id="rendering" name="rendering">3. Rendering and styling
considerations</a></h2>

<p>This section is <em>informative</em>.</p>

<p>This section discusses various aspects of rendering and styling in the
context of ruby markup as defined in this document. However, this document
does not specify any mechanisms for presentation/styling; this is left to the
respective style sheet languages. Formatting properties for styling ruby are
under development for <acronym title="Cascading Style Sheets">CSS</acronym>
and <acronym title="Extensible Style Language">XSL</acronym>. See for example
"<cite>CSS3 module: Ruby</cite>" [<a href="#css3-ruby">CSS3-RUBY</a>]
(<em>work in progress</em>) for more details.</p>

<p>Details of ruby formatting in a Japanese print context can be found in
JIS-X-4051 [<a href="#jis">JIS4051</a>].</p>

<div>
<h3><a id="web" name="web">3.1 Ruby on the Web vs. traditional typographic
usage</a></h3>

<p>The term "ruby" in Japanese is only used for text visually rendered
alongside the base text. Considerations for such cases are given in <a
href="#font">section 3.2</a> (font size), <a href="#positioning">section
3.3</a> (positioning), and <a href="#presentation">section 3.4</a>
(presentation of ruby markup). This kind of presentation should be used
wherever possible. However, introducing ruby to the Web may lead to some
phenomena and problems that are not present in traditional typography.
Structural markup for ruby, as defined in this specification, cannot
guarantee that ruby text will always be rendered alongside the base text.
There are a very wide variety of current and future output devices for
documents marked up with <acronym
title="Extensible HyperText Markup Language">XHTML</acronym>. The following
are possible scenarios and reasons for different rendering:</p>
<ul>
  <li>On non-visual user agents such as voice browsers and braille user
    agents, only sequential rendering is possible. See <a
    href="#non-visual">section 3.5</a> for more consideration on non-visual
    rendering.</li>
  <li>On display devices with low resolution, displaying ruby text at the
    usual size may not be feasible. Fallbacks may be used. See <a
    href="#rp-alternatives">section 3.6</a> for additional details.</li>
  <li>For educational purposes, it may in some cases be interesting to hide
    the ruby text and make it available as a pop-up. This is impossible on
    paper, but easily possible on a dynamic display device.</li>
</ul>
</div>

<div>
<h3><a id="font" name="font">3.2 Font size of ruby text</a></h3>

<p>In typical usage, the font size of ruby text is normally about half the
font size of the base text. In fact, the name "ruby" originated from the name
of the 5.5<abbr title="points">pt</abbr> font size in British printing, which
is about half the 10<abbr title="points">pt</abbr> font size commonly used
for normal text.</p>
</div>

<div>
<h3><a id="positioning" name="positioning">3.3 Positioning of ruby
text</a></h3>

<p>There are several positions where the ruby text can appear relative to its
base text. Because East Asian text may be rendered vertically as well as
horizontally, the terms "before" and "after" are used here rather than
"above" and "below" or "right side" and "left side". The words "before" and
"after" should be understood as "before"/"after" the line containing the base
text. The correspondence is shown in the following table:</p>

<table border="1" cellpadding="8" class="rendering">
  <tbody>
    <tr>
      <th>terminology</th>
      <td><strong>Horizontal Layout</strong><br>
        (left-to-right, top-to-bottom)</td>
      <td><strong>Vertical Layout</strong><br>
        (top-to-bottom, right-to-left)</td>
    </tr>
    <tr>
      <th abbr='position'>before</th>
      <td abbr='horizontal'>above</td>
      <td abbr='vertical'>right-side</td>
    </tr>
    <tr>
      <th abbr='position'>after</th>
      <td abbr='horizontal'>below</td>
      <td abbr='vertical'>left-side</td>
    </tr>
  </tbody>
</table>

<p>Ruby texts are most frequently placed before the base text (see <a
href="#fig1.1">figure 1.1</a> and <a href="#fig3.2">figure 3.2</a>).
Sometimes, especially in horizontal educational documents, ruby text may
appear after the base text, i.e. below (see <a href="#fig3.1">figure
3.1</a>). In Chinese, it is rather common that <span lang="zh">Pinyin</span>
ruby text appears after the base text. Ruby text may also appear after the
base text in vertical layout (see <a href="#fig3.3">figure 3.3</a>). In all
these cases, the writing direction of the ruby text is the same as that of
its base text, that is vertical if the base text is vertical, and horizontal
if the base text is horizontal.</p>

<div class="figure">
<p><a id="fig3.1" name="fig3.1"><img
alt="At the top left, three Japanese ideographs from left to right. Below them, the text 'shinkansen'. To the right, arrows and text saying 'ruby base' (top) and 'ruby text' (bottom)."
class="example" height="36" width="142" src="shinkansen-bottom.gif"></a></p>

<p><strong>Figure 3.1</strong>: Ruby text (Latin letters) after/below the
base text (Japanese ideographs)</p>
</div>

<div class="figure">
<p><a id="fig3.2" name="fig3.2"><img
alt="At the top left, three Japanese ideographs from top to bottom. To their right, six hiragana characters at half size. At the bottom, arrows and text saying 'ruby base' (left) and 'ruby text' (right)."
class="example" height="141" width="33" src="shinkansen-right.gif"></a></p>

<p><strong>Figure 3.2</strong>: Ruby text in vertical writing (before/to the
right)</p>
</div>

<div class="figure">
<p><a id="fig3.3" name="fig3.3"><img
alt="Example showing ruby on the left side of vertical Japanese text"
class="example" height="141" width="37" src="shinkansen-left.gif"></a></p>

<p><strong>Figure 3.3</strong>: Ruby text in vertical writing (after/to the
left).</p>
</div>

<p>In traditional Chinese texts, "<span lang="zh">Bopomofo</span>" ruby text
can appear along the right side of the base text even in horizontal
layout.</p>

<div class="figure">
<p><a id="fig3.4" name="fig3.4"><img
alt="From the right, a large Chinese ideograph, three smaller bopomofo letters from top to bottom (in blue), a bopomofo accent mark (in red), another large Chinese ideograph, two smaller bopomofo letters from top to bottom (in blue) and another bopomofo accent mark (in red)."
class="example" height="42" width="138" src="bopomofo.gif"></a></p>

<p><strong>Figure 3.4</strong>: "<span lang="zh">Bopomofo</span>" ruby text
in traditional Chinese (ruby text shown in blue/red for clarity) in
horizontal layout</p>
</div>

<p>Note that <span lang="zh">Bopomofo</span> tone marks (in the above example
shown in red for clarity) seem to appear in a separate column (along the
right side of the <span lang="zh">Bopomofo</span> ruby text) and therefore
might be seen as "ruby on ruby". However, they are simply encoded as part of
the ruby text. The details of this encoding are not addressed in this
document.</p>
</div>

<div>
<h3><a id="presentation" name="presentation">3.4 Presentation of ruby
markup</a></h3>

<p>This specification does not prescribe how ruby markup will be displayed.
Style sheets, in general, will be used to specify the exact behavior of ruby
markup.</p>

<div class="note">
<p><strong>Note.</strong> Although the rendering of the ruby texts should be
controlled by style sheets, in case no style information is provided by the
author or the user, it is recommended that visual user agents place the ruby
text before the base text when only one ruby text is used. This is also the
case for simple ruby. When there are two ruby texts, the first ruby text
should be placed before the base text, and the second ruby text should be
placed after the base text. A sample user agent default style sheet which
describes this formatting will be provided by [<a
href="#css3-ruby">CSS3-RUBY</a>] or its successor document.</p>

<p>For non-visual rendering, in the absence of style sheet information, it is
recommended that both the base text and the ruby text(s) should be rendered,
with an indication (e.g. different voice, different pitch, ...) of the status
of each.</p>
</div>

<p><a id="fig3.5" name="fig3.5">In order for style sheets to be able to apply
styling, or for other mechanisms to render ruby text appropriately, it is
very important to provide enough information on the function of each
component. The following example illustrates the use of the class attribute
to allow style sheets to define the exact presentation of the ruby text. The
class "<samp>reading</samp>" is used for a ruby text that indicates reading.
The class "<samp>annotation</samp>" is used to indicate ruby text that is
used for annotation. The <code>xml:lang</code> attribute indicates the
language of the text.</a></p>

<div class="figure">
<pre class="xml">&lt;ruby xml:lang="ja"&gt;
  &lt;rbc&gt;
    &lt;rb&gt;斎&lt;/rb&gt;
    &lt;rb&gt;藤&lt;/rb&gt;
    &lt;rb&gt;信&lt;/rb&gt;
    &lt;rb&gt;男&lt;/rb&gt;
  &lt;/rbc&gt;
  &lt;rtc class="reading"&gt;
    &lt;rt&gt;さい&lt;/rt&gt;
    &lt;rt&gt;とう&lt;/rt&gt;
    &lt;rt&gt;のぶ&lt;/rt&gt;
    &lt;rt&gt;お&lt;/rt&gt;
  &lt;/rtc&gt;
  &lt;rtc class="annotation"&gt;
    &lt;rt rbspan="4" xml:lang="en"&gt;W3C Associate Chairman&lt;/rt&gt;
  &lt;/rtc&gt;
&lt;/ruby&gt;</pre>

<p><strong>Figure 3.5</strong>: Ruby markup with <code>class</code> and
<code>xml:lang</code> attributes.</p>
</div>

<p>Using a style sheet specifying horizontal text, rendering of the reading
before the base text, and rendering of the annotation after the base text,
the markup above could be rendered like this:</p>

<div class="figure">
<p><a id="fig3.6" name="fig3.6"><img src="chairman.gif"
alt="In the middle, four Japanese ideographs from left to right. On top of that, hiragana letters in smaller size (two hiragana for each of the three first ideographs, one hiragana for the latest ideograph). At the bottom, the text 'W3C Associate Chairman'."></a></p>

<p><strong>Figure 3.6</strong>: Horizontal rendering of two ruby texts
associated with a single base text.</p>
</div>
</div>

<div>
<h3><a id="non-visual" name="non-visual">3.5 Considerations for non-visual
rendering</a></h3>

<p>Documents containing ruby markup may in some cases need to be rendered by
non-visual user agents such as voice browsers and braille user agents. For
such rendering scenarios, it is important to understand that:</p>
<ul>
  <li>Depending on the user and the situation, different ways of rendering
    may be appropriate.</li>
  <li>Ruby text that represents reading may have to be treated differently
    from ruby text that contains other information.</li>
  <li>For appropriate non-visual rendering, it is important to indicate the
    function of each ruby text.</li>
  <li>There often are some differences between the reading indicated by the
    ruby text and the actual pronunciation.</li>
  <li>The reader may be interested in getting information about the
    (ideographic) base text.</li>
</ul>

<p>Depending on a user's needs, the way a text should be read may vary from
very quick and 'cursory' reading to very careful and detailed reading. This
may lead to different ways of treating ruby text in non-visual rendering,
from skipping ruby text in fast reading to detailed exploration of the ruby
structure and the actual characters used in careful reading.</p>

<p>In the frequent case that ruby texts represent reading, rendering both the
base text and the ruby text may produce annoying duplications. A speech
synthesizer may be able to correctly pronounce the base text based on a large
dictionary, or it may in other cases be able to select the right
pronunciation based on the reading given by the ruby text.</p>

<p>Not all ruby texts represent pronunciations. Authors should distinguish
ruby texts used for different purposes by using the <code>class</code>
attribute. This is demonstrated above by using <samp>class="reading"</samp>
for ruby text used to indicate reading.</p>

<p>Ruby text indicating reading may not produce the correct pronunciation
even in cases where the script used at first glance seems perfectly phonetic.
For example, <span lang="zh">Bopomofo</span> is associated independently for
each character of the base text; context-dependent sound or tone changes are
not reflected. Similarly, in Japanese, spelling irregularities can occur,
such as using "<span lang='ja'>は</span>" (<span lang='ja'>hiragana ha</span>) for the topic suffix pronounced "<span lang='ja'>わ</span>" (<span lang='ja'>wa</span>),
or using vowels for indicating lengthening. For such cases, authors may want
to supply the actual pronunciation with special markup designed for that
purpose, or may rely on the aural rendering system being able to handle such
cases correctly.</p>
</div>

<div>
<h3><a id="rp-alternatives" name="rp-alternatives">3.6 Alternatives to the
<code>rp</code> element</a></h3>

<p>If the author is not concerned about fallbacks for user agents that
neither know about ruby markup nor support <acronym
title="Cascading Style Sheets, level 2">CSS2</acronym> [<a
href="#css2">CSS2</a>] or <acronym
title="Extensible Style Language">XSL</acronym> [<a href="#xsl">XSL</a>]
style sheets, then the <code>rp</code> elements are not needed.</p>

<p>Nevertheless, it is possible to parenthesize ruby text as a fallback if
for example the device resolution is not appropriate for traditional ruby
rendering. Using [<a href="#css2">CSS2</a>], the parentheses can be generated
using the <a
href="http://www.w3.org/TR/1998/REC-CSS2-19980512/generate.html#content">'content'
property</a> ([<a href="#css2">CSS2</a>], section 12.2) with the <a
href="http://www.w3.org/TR/1998/REC-CSS2-19980512/generate.html#before-after-content">:before
and :after pseudo-elements</a> ([<a href="#css2">CSS2</a>], section 12.1), <a
id="fig3.8" name="fig3.8">as for example in the following style
fragment:</a></p>

<div class="figure">
<pre class="style">rt:before { content: "(" }
rt:after { content: ")" }</pre>

<p><strong>Figure 3.8</strong>: <acronym
title="Cascading Style Sheets, level 2">CSS2</acronym> style fragment to
generate parentheses around an <code>rt</code> element</p>
</div>

<p>In the above example, parentheses will be automatically generated around
the <code>rt</code> element. It is assumed that the above style rules are
used together with style rules that position the ruby text inline. Generation
of parentheses is straightforward with <acronym
title="XSL Transformations">XSLT</acronym> [<a href="#xslt">XSLT</a>].</p>
</div>
</div>

<div class="normative">
<h2><a name="conformance">4. Conformance Criteria</a></h2>

<p>This section is <em>normative</em>.</p>

<p>Within the context of this specification, conformance can be claimed for
markup, document types, module implementations,  documents, generators, and
interpreters. In most of these cases, two levels of conformance are
available: simple conformance and full conformance. Simple conformance means
that the conforming object supports the minimal content model of the ruby
element in <a href="#abstract-def">section
2.1</a>, i.e. only simple ruby markup. Full conformance means that the
conforming object supports the maximal content model of the ruby element in
<a href="#abstract-def">section 2.1</a>,
i.e. that both simple and complex ruby markup are supported.</p>

<p>Markup is <em>conforming simple ruby markup</em> if it contains one or
more <code>ruby</code> elements and the content of all those elements
(including their children) conforms to the minimal content model in <a
href="#abstract-def">section 2.1</a> (i.e.
only simple ruby markup is allowed). Markup is <em>conforming full ruby
markup</em> if it contains one or more <code>ruby</code> elements and the
content of all those elements (including their children) conforms to the
maximal content model in <a
href="#abstract-def">section 2.1</a> (i.e.
both simple and complex ruby markup is allowed).</p>

<p>A document type is a <em>conforming simple ruby markup document type</em>
if it integrates conforming simple ruby markup by adding the
<code>ruby</code> element to the appropriate elements (such as inline
elements) and by defining the necessary elements and attributes. A document
type is a <em>conforming full ruby markup document type</em> if it integrates
conforming full ruby markup by adding the <code>ruby</code> element to the
appropriate elements (such as inline elements) and by defining the necessary
elements and attributes.</p>

<p>A module implementation (e.g. with DTD or XML Schema technology) is a
<em>conforming simple ruby module implementation</em> if it is designed to
integrate simple ruby markup with other modules into document types as
described above. A module implementation is a <em>conforming complex ruby
module implementation</em> if it is designed to integrate full ruby markup
with other modules into document types as described above. A module
implementation is a <em>conforming full ruby module implementation</em> if it
is designed to integrate either simple or full ruby markup with other modules
into document types as described above (e.g. by providing a switch, or by
providing two separate module implementations).</p>

<p>A document is a <em>conforming simple ruby markup document</em> if it
contains conforming simple ruby markup and does not contain complex ruby
markup or non-conforming ruby markup. A document is a <em>conforming full
ruby markup document</em> if it contains conforming full ruby markup and does
not contain non-conforming ruby markup.</p>

<p>A generator is a <em>conforming simple ruby markup generator</em> if it
generates conforming simple ruby markup and does not generate complex ruby
markup or non-conforming ruby markup. A generator is a <em>conforming full
ruby markup generator</em> if it generates conforming full ruby markup and
does not generate non-conforming ruby markup.</p>

<p>An interpreter is a <em>conforming simple ruby markup interpreter</em> if
it rejects nonconforming simple ruby markup, accepts conforming simple ruby
markup, and, where it interprets ruby markup, does so in accordance with this
specification. An interpreter is a <em>conforming full ruby markup
interpreter</em> if it rejects nonconforming ruby markup, accepts conforming
full ruby markup, and, where it interprets ruby markup, does so in accordance
with this specification. Examples of interpreters are server-side analysis or
transformation tools and renderers.</p>

<p>For XHTML Modularization conformance, please see section 3 of [<a
href="#xhtmlmod">XHTMLMOD</a>].</p>
</div>
<hr>

<div>
<h2><a id="appendix" name="appendix">Appendices</a></h2>

<div class="informative">
<h2><a id="module" name="module">A.  Ruby module for <acronym
title="Extensible HyperText Markup Language">XHTML</acronym></a></h2>

<p>This appendix is <em>informative</em>.</p>

<p>The following is a link to the Ruby <acronym
title="Document Type Definition">DTD</acronym> module that is used in
<acronym title="Extensible HyperText Markup Language">XHTML</acronym> 1.1 [<a
href="#xhtml11">XHTML11</a>].</p>
<ul>
  <li><a href="xhtml-ruby-1.mod"><acronym
    title="Extensible HyperText Markup Language">XHTML</acronym> Ruby
    Module</a></li>
</ul>
</div>

<div class="informative">
<h2><a id="design" name="design">B. Notes on design decisions</a></h2>

<p>This appendix is <em>informative</em>. This appendix contains some notes
on design decisions, based on questions and comments received during the Last
Call review.</p>

<p>There were proposals to change e.g. &lt;rbc&gt;&lt;rb&gt;...&lt;/rbc&gt;
to &lt;rb&gt;&lt;rbc&gt;...&lt;/rb&gt; (and similar for rt/rtc). This looks
in some way more natural. However, in XML, the content of an element is
either mixed content (both character data and elements, without sequence or
occurrence restrictions) or element content (only elements, with
restrictions). This means that it is impossible to say that &lt;rb&gt;
contains either only &lt;rbc&gt; elements or only character data and inline
elements.</p>

<p>There were various proposals for removing the <code><a
href="#rp">rp</a></code> element from the minimal content model. They were
considered, but rejected for the following reasons:</p>
<ul>
  <li>Recognition and removal of the <code><a href="#rp">rp</a></code>
    elements by a receiver understanding ruby markup is extremely simple to
    implement; the burden on implementations is minimal. Both CSS and XSL
    provide easy mechanisms to remove the <code><a href="#rp">rp</a></code>
    elements or to avoid displaying them.</li>
  <li>Displaying ruby text in parentheses is not desirable, because it can be
    confused with ordinary parenthesized text, but such a confusion is highly
    preferable to the confusion created should ruby text appear inline, as
    part of the actual text, without any distinguishing features.</li>
</ul>

<p>It was suggested to change the names of the elements, in particular to
change &lt;ruby&gt; to &lt;gloss&gt;.  However, while ruby markup is indeed
in some way similar to the markup that would be needed for glosses, it is not
designed for that purpose.</p>
</div>

<div class="informative">
<h2><a id="compatibility" name="compatibility">C.  Notes on backwards
compatibility</a></h2>

<p>This appendix is <em>informative</em>.</p>

<p>For historical reasons, some authoring tools might generate ruby markup
without the start and end tags of the <code>rb</code> element, like:</p>

<div class="figure">
<pre class="sgml">&lt;ruby&gt;
  A
  &lt;rp&gt;(&lt;/rp&gt;&lt;rt&gt;aaa&lt;/rt&gt;&lt;rp&gt;)&lt;/rp&gt;
&lt;/ruby&gt;</pre>
</div>

<p>rather than the following:</p>

<div class="figure">
<pre class="xml">&lt;ruby&gt;
  &lt;rb&gt;A&lt;/rb&gt;
  &lt;rp&gt;(&lt;/rp&gt;&lt;rt&gt;aaa&lt;/rt&gt;&lt;rp&gt;)&lt;/rp&gt;
&lt;/ruby&gt;</pre>
</div>

<p>The former markup is not conforming to this specification, but user agents
that care about compatibility with documents generated by such authoring
tools may treat the former markup as if it were written like the latter.</p>
</div>

<div class="informative">
<h2><a id="glossary" name="glossary">D.  Glossary</a></h2>

<p>This appendix is <em>informative</em>.</p>
<dl>
  <dt><a id="g-RB" name="g-RB"><strong>Base text</strong></a></dt>
    <dd>Run of text that has a <a href="#g-RT">ruby text</a> associated with
      it.</dd>
  <dt><a id="g-bopomofo" name="g-bopomofo"><strong
  lang="zh">Bopomofo</strong></a></dt>
    <dd>37 characters and 4 tone marks used as phonetics in Chinese,
      especially standard Mandarin.</dd>
  <dt><a href="#complex" id="g-complex" name="g-complex"><strong>Complex ruby
  markup</strong></a></dt>
    <dd>In this specification: Ruby markup that allows association of two <a
      href="#g-RT">ruby texts</a> with a single <a href="#g-RB">base text</a>
      as well as fine-grained associations between parts of the <a
      href="#g-RT">ruby texts</a> and the <a href="#g-RB">base text</a>.</dd>
  <dt><a id="g-GR" name="g-GR"><strong>Group ruby</strong></a></dt>
    <dd>In Japanese typography: Ruby text associated with more than one
      character of the base text.</dd>
  <dt><a id="g-hiragana" name="g-hiragana"><strong
  lang="ja">Hiragana</strong></a></dt>
    <dd>Japanese syllabic script, or character of that script. Rounded and
      cursive in appearance. Subset of the Japanese writing system, used
      together with kanji and katakana. In recent times, mostly used to write
      Japanese words when kanji are not available or appropriate, and word
      endings and particles.</dd>
  <dt><a id="g-ideograph"
  name="g-ideograph"><strong>Ideograph</strong></a></dt>
    <dd>A character that is used to represent an idea, word, or word
      component, in contrast to a character from an alphabetic or syllabic
      script. The most well-known ideographic script is used (with some
      variation) in East Asia (China, Japan, Korea,...).</dd>
  <dt><a id="g-kana" name="g-kana"><strong lang="ja">Kana</strong></a></dt>
    <dd>Collective term for hiragana and katakana.</dd>
  <dt><a id="g-katakana" name="g-katakana"><strong
  lang="ja">Katakana</strong></a></dt>
    <dd>Japanese syllabic script, or character of that script. Angular in
      appearance. Subset of the Japanese writing system, used together with
      kanji and hiragana. In recent times, mainly used to write foreign
    words.</dd>
  <dt><a id="g-kanji" name="g-kanji"><strong lang="ja">Kanji</strong></a></dt>
    <dd>Japanese term for ideographs; ideographs used in Japanese. Subset of
      the Japanese writing system, used together with hiragana and
    katakana.</dd>
  <dt><a id="g-monoruby" name="g-monoruby"><strong>Monoruby</strong></a></dt>
    <dd>In Japanese typography: Ruby associated with a single character of
      the base text.</dd>
  <dt><a id="g-reading" name="g-reading"><strong>Reading</strong></a></dt>
    <dd>For ideographs: Technical term; indication of possible pronunciation.
      Different from pronunciation in various respects: script used may not
      be fully phonetic; actual pronunciation is speaker-dependent;
      pronunciation may not be realized when reading a text silently. In
      Chinese or Korean, some ideographs have several readings. In Japanese,
      most ideographs have at least two readings, and some have a lot more.
      Readings also may depend on context.</dd>
  <dt><a id="g-RT" name="g-RT"><strong>Ruby text</strong></a></dt>
    <dd>Run of text that appears in the immediate vicinity of another run of
      text (called <a href="#g-RB">"ruby base"</a>) and serves as an
      annotation or a pronunciation guide associated with the base.</dd>
  <dt><a href="#simple-ruby1" id="g-SR" name="g-SR"><strong>Simple ruby
  markup</strong></a></dt>
    <dd>In this specification: Ruby markup that associates a single <a
      href="#g-RT">ruby text</a> with a single <a href="#g-RB">ruby base</a>,
      optionally providing some delimiters such as parentheses for
    fallback.</dd>
</dl>
</div>

<div class="informative">
<h2><a id="changes" name="changes">E.  Changes from Proposed
Recommendation</a></h2>

<p>This appendix is <em>informative</em>.</p>

<p>Changes from the <a
href="http://www.w3.org/TR/2001/PR-ruby-20010406/">Proposed
Recommendation</a> (http://www.w3.org/TR/2001/PR-ruby-20010406):</p>
<ul>
  <li>Added conformance section</li>
  <li>Streamlined terms 'ruby text' and 'base text'</li>
  <li>Changed 'part of' to 'used by' in <a href='#module'>Appendix A</a>
      ([<a href='#xhtml11'>XHTML11</a>] does not contain any module definitions)</li>
  <li>Added link to [<a href='#ModSchema'>ModSchema</a>]
  <li>Fixed Appendix numbering and table of contents</li>
  <li>Fixed link in Section 3.3 (to fig. 1.1 rather than 1.3)</li>
  <li>Added Japanese titles for [<a href="#jis">JIS4051</a>] and [<a
    href="#jdcm">JIS4052</a>]</li>
  <li>Fixed various typos and minor grammatical mistakes</li>
</ul>
</div>
</div>

<div class="informative">
<h2><a id="ack" name="ack">Acknowledgements</a></h2>

<p>This section is <em>informative</em>.</p>

<p>Takao <span class="familyname">Suzuki</span> (<span
lang="ja">鈴木 孝雄</span>) and Chris <span
class="familyname">Wilson</span> have contributed to previous drafts as
editors.</p>

<p>This specification would not have been possible without the help from the
members of the W3C I18N WG, in particular Mark <span
class="familyname">Davis</span> and Hideki <span
class="familyname">Hiura</span> (<span lang="ja">樋浦 秀樹</span>), and
the members of the W3C I18N IG.</p>

<p>Additional contributors include Murray <span
class="familyname">Altheim</span>, Laurie Anna <span
class="familyname">Edlund</span>, Arye <span
class="familyname">Gittelma</span>, Koji <span
class="familyname">Ishii</span>, Rick <span
class="familyname">Jelliffe</span>, Eric <span
class="familyname">LeVine</span>, Chris <span
class="familyname">Lilley</span>, Charles <span
class="familyname">McCathieNevile</span>, Shigeki <span
class="familyname">Moro</span> (<span lang="ja">師 茂樹</span>), Chris
<span class="familyname">Pratley</span>, Nobuo <span
class="familyname">Saito</span> (<span lang="ja">斎藤 信男</span>), Rahul
<span class="familyname">Sonnad</span>, Chris <span
class="familyname">Thrasher</span>.</p>

<p>The markup defined in this specification was coordinated with the ruby
markup in [<a href="#jdcm">JIS4052</a>], developed by WG 2 (Typesetting) of
the Electronic Document Processing System Standardization Investigation and
Research Committee of the Japanese Standards Association. We would like to
thank the members of WG 2, in particular Kohji <span
class="familyname">Shibano</span> (<span lang="ja">芝野 耕司</span>,
chair), and Masafumi <span class="familyname">Yabe</span> (<span
lang="ja">家辺 勝文, liaison</span>), for their collaboration.
Technically, the markup for ruby in [<a href="#jdcm">JIS4052</a>] differs
from the markup in this specification in two points: First, there is an
alternative form of markup not compatible with XML, based on special symbols,
and second, the <a href="#rp"><code>rp</code></a> element is not
permitted.</p>

<p>Valuable Last Call comments were also received from: The HTML WG, the CSS
WG, the XSL WG, the WAI P&amp;F WG, Steven <span
class="familyname">Pemberton</span>, Trevor <span
class="familyname">Hill</span>, Susan <span class="familyname">Lesch</span>,
and Frank Yung-Fong <span class="familyname">Tang</span>. Akira <span
class="familyname">Uchida</span> (内田 明) provided feedback from a
translator's viewpoint.</p>

<p>An earlier proposal for markup for ruby, using attributes, is described in
[<a href="#dur97">DUR97</a>].</p>
</div>

<div class="informative ref">
<h2><a id="ref" name="ref">References</a></h2>

<h3>Normative References</h3>
<dl>
  <dt>[<a id="xhtml11" name="xhtml11">XHTML11</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/2001/REC-xhtml11-20010531/"><acronym
      title="Extensible HyperText Markup Language">XHTML</acronym><sup>&trade;</sup>
      1.1 - Module-based <acronym
      title="Extensible HyperText Markup Language">XHTML</acronym></a></cite>",
      <acronym title="World Wide Web Consortium">W3C</acronym>
      Recommendation</em></dd>
    <dd>M. Altheim, S. McCarron, <abbr title="Editors">eds.</abbr>, 31 May
      2001<br>
      Available at: http://www.w3.org/TR/2001/REC-xhtml11-20010531<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/xhtml11/">http://www.w3.org/TR/xhtml11</a></dd>
</dl>
<dl>
  <dt>[<a id="xhtmlmod" name="xhtmlmod">XHTMLMOD</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/2001/REC-xhtml-modularization-20010410/">Modularization
      of <acronym
      title="Extensible HyperText Markup Language">XHTML</acronym><sup>&trade;</sup></a></cite>",
      <acronym title="World Wide Web Consortium">W3C</acronym>
      Recommendation</em></dd>
    <dd>M. Altheim <em>et al.</em>, <abbr title="editors">eds.</abbr>, 10
      April 2001 <br>
      Available at:
      http://www.w3.org/TR/2001/REC-xhtml-modularization-20010410<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/xhtml-modularization/">http://www.w3.org/TR/xhtml-modularization</a></dd>
  <dt>[<a id="xml1" name="xml1">XML</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/2000/REC-xml-20001006">Extensible Markup
      Language (<abbr title="Extensible Markup Language">XML</abbr>) 1.0
      (Second Edition)</a></cite>", <acronym
      title="World Wide Web Consortium">W3C</acronym> Recommendation</em></dd>
    <dd>T. Bray, J. Paoli, C. M. Sperberg-McQueen, E. Maler, <abbr
      title="editors">eds.</abbr>, 6 October 2000<br>
      Available at: http://www.w3.org/TR/2000/REC-xml-20001006<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></dd>
</dl>

<h3>Informative References</h3>
<dl>
  <dt>[<a id="css2" name="css2">CSS2</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/1998/REC-CSS2-19980512/">Cascading Style
      Sheets, level 2 (<acronym
      title="Cascading Style Sheets, level 2">CSS2</acronym>)
      Specification</a></cite>", <acronym
      title="World Wide Web Consortium">W3C</acronym> Recommendation</em></dd>
    <dd>B. Bos, H. W. Lie, C. Lilley and I. Jacobs, <abbr
      title="editors">eds.</abbr>, 12 May 1998<br>
      Available at: http://www.w3.org/TR/1998/REC-CSS2-19980512<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/REC-CSS2/">http://www.w3.org/TR/REC-CSS2</a></dd>
  <dt>[<a id="css3-ruby" name="css3-ruby">CSS3-RUBY</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/2001/WD-css3-ruby-20010216/">CSS3 module:
      Ruby</a></cite>", <acronym
      title="World Wide Web Consortium">W3C</acronym> Working Draft</em></dd>
    <dd>M. Suignard, <abbr title="editor">ed.</abbr>, 16 February 2001<br>
      Available at: http://www.w3.org/TR/2001/WD-css3-ruby-20010216/<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/css3-ruby/">http://www.w3.org/TR/css3-ruby</a></dd>
  <dt>[<a id="dur97" name="dur97">DUR97</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/International/draft-duerst-ruby-01">Ruby in the
      Hypertext Markup Language</a></cite>", Internet Draft</em></dd>
    <dd>Martin Dürst, 28 February 1997, <em>expired</em><br>
      Available at: http://www.w3.org/International/draft-duerst-ruby-01</dd>
  <dt>[<a id="html4" name="html4">HTML4</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/1999/REC-html401-19991224/"><acronym
      title="HyperText Markup Language">HTML</acronym> 4.01
      Specification</a></cite>", <acronym
      title="World Wide Web Consortium">W3C</acronym> Recommendation</em></dd>
    <dd>D. Raggett, A. Le Hors, I. Jacobs, <abbr
      title="editors">eds.</abbr>, 24 December 1999<br>
      Available at: http://www.w3.org/TR/1999/REC-html401-19991224<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/html4/">http://www.w3.org/TR/html4</a></dd>
  <dt>[<a id="jis" name="jis">JIS4051</a>]</dt>
    <dd><em>"<cite>Line composition rules for Japanese documents</cite>"</em>
      (<span lang="ja">日本語文書の行組版方法</span>)</dd>
    <dd>JIS X 4051-1995, Japanese Standards Association, 1995 (in
    Japanese)</dd>
  <dt>[<a id="jdcm" name="jdcm">JIS4052</a>]</dt>
    <dd><em>"<cite>Exchange format for Japanese documents with composition
      markup</cite>"</em> (<span
      lang="ja">日本語文書の組版指定交換形式</span>)</dd>
    <dd>JIS X 4052:2000, Japanese Standards Association, 2000 (in
    Japanese)</dd>
<dt>[<a id='ModSchema' name='ModSchema'>ModSchema</a>]</dt>
    <dd><em>"<cite><a
      href='http://www.w3.org/TR/2001/WD-xhtml-m12n-schema-20010322/'>Modularization
      of XHTML&#8482; in XML Schema</a></cite>", <acronym
      title="World Wide Web  Consortium">W3C</acronym> Working Draft</em></dd>
    <dd>Daniel Austin and Shane McCarron, <abbr
      title="editors">eds.</abbr>, 22 March 2001<br>
      Available at: http://www.w3.org/TR/2001/WD-xhtml-m12n-schema-20010322<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/xhtml-m12n-schema/">http://www.w3.org/TR/xhtml-m12n-schema</a></dd>
<dt>[<a id="xmlschema" name="xmlschema">XMLSchema</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/"><abbr
      title="Extensible Markup Language">XML</abbr> Schema Part 1:
      Structures</a></cite>", <acronym
      title="World Wide Web  Consortium">W3C</acronym>
    Recommendation</em></dd>
    <dd>H. S. Thompson, D. Beech, M. Maloney, N. Mendelsohn, <abbr
      title="editors">eds.</abbr>, 2 May 2001<br>
      Available at: http://www.w3.org/TR/2001/REC-xmlschema-1-20010502<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/xmlschema-1/">http://www.w3.org/TR/xmlschema-1</a></dd>
    <dd>See also "<cite><abbr title="Extensible Markup Language">XML</abbr>
      Schema Part 2: Datatypes</cite>", available at: <a
      href="http://www.w3.org/TR/xmlschema-2/">http://www.w3.org/TR/xmlschema-2</a></dd>
  <dt>[<a id="xsl" name="xsl">XSL</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/2000/CR-xsl-20001121/">Extensible Style
      Language (<acronym
      title="Extensible Style Language">XSL</acronym>)</a></cite>", <acronym
      title="World Wide Web Consortium">W3C</acronym> Candidate
      Recommendation</em></dd>
    <dd>S. Adler <em>et al.</em>, <abbr title="editors">eds.</abbr>, 21
      November 2000<br>
      Available at: http://www.w3.org/TR/2000/CR-xsl-20001121<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/xsl/">http://www.w3.org/TR/xsl</a></dd>
  <dt>[<a id="xslt" name="xslt">XSLT</a>]</dt>
    <dd><em>"<cite><a
      href="http://www.w3.org/TR/1999/REC-xslt-19991116"><acronym
      title="Extensible Style Language">XSL</acronym> Transformations
      (<acronym title="XSL Transformations">XSLT</acronym>) Version
      1.0</a></cite>", <acronym
      title="World Wide Web Consortium">W3C</acronym> Recommendation</em></dd>
    <dd>J. Clark, <abbr title="editor">ed.</abbr>, 16 November 1999<br>
      Available at: http://www.w3.org/TR/1999/REC-xslt-19991116<br>
      The latest version is available at: <a
      href="http://www.w3.org/TR/xslt">http://www.w3.org/TR/xslt</a></dd>
</dl>
</div>
</body>
</html>