css-ruby/Overview.src.html

Wed, 19 Jun 2013 15:45:39 +0900

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Wed, 19 Jun 2013 15:45:39 +0900
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     1 <!DOCTYPE html>
     2 <html lang="en">
     3 <head>
     4 	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
     5 	<title>CSS Ruby Module Level 1</title>
     6 	<link rel=contents href="#contents">
     7 	<link rel=index href="#index">
     8 	<link rel="stylesheet" type="text/css" href="../default.css">
     9 	<link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
    10 	<link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS].css">
    11 </head>
    13 <body class="h-entry">
    15 <div class="head">
    16 <!--logo-->
    18 <h1 class="p-name">CSS Ruby Module Level 1</h1>
    20 <h2 class="no-num no-toc">[LONGSTATUS] <time class="dt-updated" datetime="[CDATE]">[DATE]</time> <!-- for HTML4 doctype: <span class="value-title" title="[CDATE]">[DATE]</span></span> --> </h2>
    21 <dl>
    22 	<dt>This version:
    23 		<dd><a class="u-url" href="[VERSION]">[VERSION]</a>
    25 	<dt>Latest version:
    26 		<dd><a href="http://www.w3.org/TR/[SHORTNAME]/">http://www.w3.org/TR/css3-ruby/</a>
    28 	<dt>Editor's draft:
    29 		<dd><a href="http://dev.w3.org/csswg/[SHORTNAME]/">http://dev.w3.org/csswg/[SHORTNAME]/</a>
    30 		(<a href="https://dvcs.w3.org/hg/csswg/log/tip/[SHORTNAME]/Overview.src.html">change log</a>)
    32 	<dt>Previous version:
    33 		<dd><a href="http://www.w3.org/TR/2011/WD-css3-ruby-20110630/">
    34 		http://www.w3.org/TR/2011/WD-css3-ruby-20110630/</a>
    36 	<dt>Issue Tracking:</dt>
    37 		<dd><a rel="issues" href="http://www.w3.org/Style/CSS/Tracker/products/FIXME">http://www.w3.org/Style/CSS/Tracker/products/FIXME</a>
    39 	<dt>Feedback:</dt>
    40 		<dd><a href="mailto:www-style@w3.org?subject=%5BSHORTNAME%5D%20feedback"
    41 				 >www-style@w3.org</a> 
    42 				 with subject line &ldquo;<kbd>[[SHORTNAME]] 
    43 				 <var>&hellip; message topic &hellip;</var></kbd>&rdquo;
    44 				 (<a rel="discussion" href="http://lists.w3.org/Archives/Public/www-style/"
    45 					 >archives</a>)
    47 	<dt>Editors:
    48 		<dd class="p-author h-card vcard">
    49 			<a class="p-name fn u-url url" rel="author"
    50 				 href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>,
    51 			<a class="p-org org h-org" href="http://www.mozilla.org/">Mozilla</a>
    52 		<dd class="p-author h-card vcard">
    53 			<a class="p-name fn u-url url" rel="author"
    54 				 href="mailto:koji.a.ishii@mail.rakuten.com">Koji Ishii</a>,
    55 			<span class="p-org org">Rakuten, Inc.</span>
    56 		<dd class="p-author h-card vcard">
    57 			<a class="p-name fn u-url url" rel="author"
    58 				 href="mailto:ishida@w3.org">Richard Ishida</a>,
    59 			<span class="p-org org">W3C</span>
    61 	<dt>Former editors:
    62 		<dd>Michel Suignard, Microsoft
    63 		<dd>Marcin Sawicki, Microsoft
    64 </dl>
    66 <!--copyright-->
    68 <hr title="Separator for header">
    69 </div>
    71 <h2 class="no-num no-toc" id="abstract">Abstract</h2>
    73 	<p>
    74 	<span class="p-summary">
    75 		“Ruby” are short runs of text alongside the base text,
    76 		typically used in East Asian documents to indicate pronunciation
    77 		or to provide a short annotation.
    78 		This module describes the rendering model and formatting controls
    79 		related to displaying ruby annotations in CSS.
    80 	</span>
    82 	<a href="http://www.w3.org/TR/CSS/">CSS</a> is a language for describing
    83 	the rendering of structured documents (such as HTML and XML) on screen, on
    84 	paper, in speech, etc.
    86 <h2 class="no-num no-toc" id="status">Status of this document</h2>
    88 <!--status-->
    90 <p>The following features are at risk: &hellip;
    92 <h2 class="no-num no-toc" id="contents">
    93 Table of Contents</h2>
    95 <!--toc-->
    97 <h2 id="intro">
    98 Introduction</h2>
   100 	<p><em>This section is not normative.</em>
   102 <h3 id="placement">
   103 Module interactions</h3>
   105 	<p>This module extends the inline box model of CSS Level 2 [[!CSS21]]
   106 	to support ruby.
   108 	<p>None of the properties in this module apply to the <code>::first-line</code> or
   109 	<code>::first-letter</code> pseudo-elements.
   111 <h3 id="values">
   112 Values</h3>
   114 	<p>This specification follows the
   115 	<a href="http://www.w3.org/TR/CSS21/about.html#property-defs">CSS property
   116 	definition conventions</a> from [[!CSS21]]. Value types not defined in
   117 	this specification are defined in CSS Level 2 Revision 1 [[!CSS21]].
   118 	Other CSS modules may expand the definitions of these value types: for
   119 	example [[CSS3VAL]], when combined with this module, expands the
   120 	definition of the <var>&lt;length&gt;</var> value type as used in this specification.</p>
   122 	<p>In addition to the property-specific values listed in their definitions,
   123 	all properties defined in this specification also accept the
   124 	<a href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>
   125 	keyword as their property value. For readability it has not been repeated
   126 	explicitly.
   128 <h3 id="conventions">
   129 Document conventions</h3>
   131 	<p>Many typographical conventions in East Asian typography depend
   132 	on whether the character rendered is wide (CJK) or narrow (non-CJK).
   133 	There are a number of illustrations in this document
   134 	for which the following legend is used:
   136 	<dl>
   137 		<dt><img alt="Symbolic wide-cell glyph representation" width="39" height="39" src="images/fullwidth.gif">
   138 		<dd>Wide-cell glyph (e.g. Han) that is the <var>n</var>th character in the text run.
   139 		They are typically sized to 50% when used as annotations.
   140 		<dt><img alt="Symbolic narrow-cell glyph representation" width="19" height="39" src="images/halfwidth.gif">
   141 		<dd>Narrow-cell glyph (e.g. Roman) which is the <var>n</var>th glyph in the text run.
   143 	<p>The orientation which the above symbols assume in the diagrams
   144 	corresponds to the orientation that the glyphs they represent
   145 	are intended to assume when rendered by the user agent.
   146 	Spacing between these characters in the diagrams is incidental,
   147 	unless intentionally changed to make a point.
   149 <h3 id="ruby-def">
   150 What is ruby?</h3>
   152 	<p><dfn>Ruby</dfn> is the commonly-used name for a run of text
   153 	that appears alongside another run of text (referred to as the “base”)
   154 	and serves as an annotation or a pronunciation guide associated with that run of text.
   156 	<p>The following figures show two examples of Ruby,
   157 	a simple case and one with more complicated structure.
   159 	<div class="example">
   160 		<p>In this first example, a single annotation is used to annotate the base text.
   161 		<div class="figure">
   162 			<p><img src="images/licence.png"
   163 			        alt="Example of ruby applied on top of a Japanese expression">
   164 			<p class="caption">Example of ruby used in Japanese (simple case)
   165 		</div>
   166 		<p>In Japanese typography, this case is sometimes called
   167 		<i lang="ja">taigo</i> ruby or group-ruby (per-word ruby),
   168 		because the annotation as a whole is associated
   169 		with multi-character word (as a whole).
   170 	</div>
   172 	<div class="example">
   173 		<p>In this second example,
   174 		two levels of annotations are attached to a base sequence:
   175 		the hiragana characters on top refer to the pronunciation of each of the base kanji characters,
   176 		while the words “Keio” and “University” on the bottom are annotations describing the English translation.
   177 		<div class="figure">
   178 			<p><img src="images/ruby-univ.gif"
   179 			        alt="Example showing complex ruby with annotation text over and under the base characters">
   180 			<p class="caption">Complex ruby with annotation text over and under the base characters
   181 		</div>
   182 		<p>
   183 		<p>Notice that to allow correct association between the hiragana characters and 
   184 		their corresponding Kanji base characters,
   185 		the spacing between these Kanji characters is adjusted.
   186 		(This happens around the fourth Kanji character in the figure above.)
   187 		To avoid variable spacing between the Kanji characters in the example above
   188 		the hiragana annotations can be styled as a <i>collapsed annotation</i>,
   189 		which will look more like the group-ruby example earlier.
   190 		However because the base-annotation pairings are recorded in the ruby structure,
   191 		if the text breaks across lines, the annotation characters will stay
   192 		correctly paired with their respective base characters.
   193 	</div>
   195 	<i>Ruby</i> formatting as used in Japanese is described in JIS X-4051 [[JIS4051]] (in Japanese)
   196 	and in Requirements for Japanese Text Layout [[JLREQ]] (in English and Japanese)].
   197 	In HTML, ruby structure and markup to represent it is described
   198 	in the Ruby Markup Extension specification.
   199 	This module describes the CSS rendering model
   200 	and formatting controls relevant to ruby layout of such markup.
   202 <h2 id="ruby-model">
   203 Ruby Formatting Model</h2>
   205 	<p>The CSS ruby model is based on
   206 	the <a href="http://darobin.github.io/html-ruby/">HTML Ruby Markup Extension</a>
   207 	and <a href="http://www.w3.org/TR/ruby/">XHTML Ruby Annotation Recommendation</a> [[RUBY]].
   208 	In this model, a ruby structure consists of
   209 	one or more <dfn>ruby base</dfn> elements representing the base (annotated) text,
   210 	associated with one or more levels of <dfn>ruby annotation</dfn> elements representing the annotations.
   211 	The structure of ruby is similar to that of a table:
   212 	there are “rows” (the base text level, each annotation level)
   213 	and “columns” (each <i>ruby base</i> and its corresponding <i>ruby annotations</i>).
   215 	<p>Consecutive bases and annotations are grouped together into <dfn>ruby segments</dfn>.
   216 	Within a <i>ruby segment</i>, a <i>ruby annotation</i> may span multiple <i>ruby bases<i>.
   218 	<p class="note">In HTML, a single <code>&lt;ruby&gt;</code> element may contain multiple <i>ruby segments</i>.
   219 	(In the XHTML Ruby model, a single <code>&lt;ruby&gt;</code> element can only contain one <i>ruby segment</i>.)
   221 <h3 id="ruby-display">
   222 Ruby-specific 'display' property values</h3>
   224 	<p>For document languages (such as XML applications) that do not have pre-defined ruby elements,
   225 	authors must map document language elements to ruby elements;
   226 	this is done with the 'display' property.
   228 	<table class="propdef">
   229 		<tr>
   230 			<th>Name:
   231 			<td>display
   232 		<tr>
   233 			<th><a href="#values">New Values</a>:
   234 			<td>ruby | ruby-base | ruby-text | ruby-base-container | ruby-text-container
   235 	</table>
   237 	<p>The following new 'display' values assign ruby layout roles to an arbitrary element:
   239 	<dl>
   240 		<dt>''ruby''
   241 			<dd>Specifies that an element generates a <dfn title="ruby container | ruby container box">ruby container box</dfn>.
   242 			(Corresponds to HTML/XHTML <code>&lt;ruby&gt;</code> elements.)
   243 		<dt>''ruby-base''
   244 			<dd>Specifies that an element generates a <dfn title="ruby base box | ruby base">ruby base box</dfn>.
   245 			(Corresponds to HTML/XHTML <code>&lt;rb&gt;</code> elements.)
   246 		<dt>''ruby-text''
   247 			<dd>Specifies that an element generates a <dfn title="ruby annotation box | ruby annotation">ruby annotation box</dfn>.
   248 			(Corresponds to HTML/XHTML <code>&lt;rt&gt;</code> elements.)
   249 		<dt>''ruby-base-container''
   250 			<dd>Specifies that an element generates a <dfn title="ruby base container box | ruby base container">ruby base container box</dfn>.
   251 			(Corresponds to XHTML <code>&lt;rbc&gt;</code> elements; always implied in HTML.)
   252 		<dt>''ruby-text-container''
   253 			<dd>Specifies that an element generates a <dfn title="ruby annotation container box | ruby annotation container">ruby annotation container box</dfn>.
   254 			(Corresponds to HTML/XHTML <code>&lt;ruby&gt;</code> elements.)
   255 	</dl>
   257 <h3 id="box-fixup">
   258 Anonymous Ruby Box Generation</h3>
   260 	<p>The CSS model does not require that the document language
   261 	include elements that correspond to each of these components.
   262 	Missing parts of the structure are implied through the anonymous box generation rules
   263 	<a href="http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes">similar to those used to normalize tables</a>. [[!CSS21]]
   265 	<ol>
   266 		<li>Any in-flow block-level boxes directly contained by a
   267 		<i>ruby container</i>,
   268 		<i>ruby base container</i>,
   269 		<i>ruby annotation container</i>,
   270 		<i>ruby base box</i>,
   271 		or <i>ruby annotation box</i>
   272 		are forced to be inline-level boxes,
   273 		and their 'display' value computed accordingly.
   274 		For example,
   275 		the 'display' property of an in-flow element with ''display: block''
   276 		parented by an element with ''display: ruby-text''
   277 		computes to ''inline-block''.
   278 		This computation occurs after any intermediary anonymous-box fixup
   279 		(such as that required by internal table elements).
   281 		<li>Any consecutive sequence of <i>ruby bases</i> not parented by a <i>ruby base container</i>
   282 		is wrapped in an anonymous <i>ruby base container</i>.
   283 		Similarly, any consecutive sequence of <i>ruby annotations</i> not parented by a <i>ruby annotation container</i>
   284 		is wrapped in an anonymous <i>ruby annotation container</i>.
   286 		<li>Within each <i>ruby base container</i>,
   287 		each sequence of inline-level boxes is wrapped in an anonymous <i>ruby base box</i>.
   288 		Similarly, within each <i>ruby annotation container</i>,
   289 		each sequence of inline-level boxes is wrapped in an anonymous <i>ruby annotation box</i>.
   291 		<li>A sequence of <i>ruby base containers</i> and/or <i>ruby annotation containers</i>
   292 		not parented by a <i>ruby container</i>
   293 		is wrapped in an anonymous <i>ruby container</i>.
   294 	</ol>
   296 	<p>At this point, all ruby layout structures are properly parented,
   297 	and the UA can start to associate bases with their annotations.
   299 	<p class="note">
   300 	Note that the UA is not required to create any of these anonymous boxes in its internal structures,
   301 	as long as pairing and layout behaves as if they existed.
   303 <h3 id="pairing">
   304 Ruby Pairing and Annotation Levels</h3>
   306 	<p>Within a ruby structure,
   307 	each <i>ruby bases</i> are associated with <i>ruby annotations</i>
   308 	and vice versa.
   309 	A <i>ruby base</i> can be associated with at most one <i>ruby annotation</i> per annotation level.
   310 	If there are multiple annotation levels, it can therefore be associated with multiple <i>ruby annotations</i>.
   311 	A <i>ruby annotation</i> is associated with one or more <i>ruby bases</i>;
   312 	annotations can span multiple bases.
   314 	<p><dfn>Annotation pairing</dfn> is the process of associating
   315 	<i>ruby annotations</i> with <i>ruby bases</i>.
   317 	<ol>
   318 		<li>
   319 		<p>First, the ruby structure is divided into <i>ruby segments</i>,
   320 		each consisting of a single <i>ruby base container</i>
   321 		followed by one or more <i>ruby annotation containers</i>.
   322 		If the first child of a <i>ruby container</i> is a <i>ruby annotation container</i>,
   323 		an anonymous, empty <i>ruby base container</i> is assumed to exist before it.
   324 		Similarly, if the <i>ruby container</i> contains consecutive <i>ruby base containers</i>,
   325 		anonymous, empty <i>ruby annotation containers</i> are assumed to exist between them.
   326 		The <i>ruby base container</i> in each segment is thus associated
   327 		with each of the <i>ruby annotation containers</i> in that segment.
   329 		<p>Each <i>ruby annotation containers</i> in a <i>ruby segment</i>
   330 		represents one <dfn title="annotation level | level">level</dfn> of annotation:
   331 		the first one represents the first level of annotation,
   332 		the second one represents the second level of annotation,
   333 		and so on.
   335 		<li>Within each <i>ruby segment</i>,
   336 		each <i>ruby base box</i> in the <i>ruby base container</i>
   337 		is paired with one <i>ruby annotation box</i>
   338 		from each <i>ruby annotation container</i> in its <i>ruby segment</i>.
   339 		If there are not enough <i>ruby annotations</i> in a <i>ruby annotation container</i>,
   340 		the last one is associated with any excess <i>ruby bases</i>.
   341 		(If there are not any in the <i>ruby annotation container</i>, an anonymous empty one is assumed to exist.)
   342 		If there are not enough <i>ruby bases</i>,
   343 		any remaining <i>ruby annotations</i> are assumed to be associated
   344 		with empty, anonymous bases inserted at the end of the <i>ruby base container</i>.
   346 		<p>If an implementation supports ruby markup with explicit spanning
   347 		(e.g. XHTML Complex Ruby Annotations),
   348 		it must adjust the pairing rules to pair spanning annotations to multiple bases
   349 		appropriately.
   350 	</ol>
   352 	<p>A this point, ruby “columns” are defined,
   353 	each represented by a single <i>ruby base</i>
   354 	and associated with one <i>ruby annotation</i> (possibly an empty, anonymous one)
   355 	from each <i>annotation level</i>.
   357 <h4 id="nested-pairing">
   358 Nested Ruby</h4>
   360 	<p>When <i>ruby containers</i> are nested,
   361 	pairing begins with the deepest <i>ruby container</i>,
   362 	then expands out,
   363 	treating each <i>ruby container</i> nested within another <i>ruby container</i>
   364 	as a <i>ruby base</i>,
   365 	and associating each <i>ruby annotation</i>
   366 	associated with the nested <i>ruby container</i>
   367 	as being associated with (spanning) all of its <i>ruby bases</i>.
   369 	<p>Using nested <i>ruby containers</i> thus allows the representation
   370 	of complex spanning relationships.
   372 	<p class="issue">This shouldn't belong in Level 1. But HTML5 allows it, so we have to handle it. Yay HTML5.
   374 <h3 id="box-model">
   375 Generating Ruby Structure</h3>
   377 	<p>
   379 <h3 id="box-model">
   380 Ruby box model</h3>
   382 <p>In the following description, the elements specified by   Ruby 
   383 Annotation [[RUBY]] are used to describe the box model. As mentioned
   384 earlier, a user agent can obtain the same results by using the Ruby specific 'display' 
   385 property values. </p>
   387 <p>For a user agent that supports the ruby markup, the ruby structure consists of three or more
   388 boxes. The outermost container is the <a
   389 href="http://www.w3.org/TR/ruby/#ruby"><samp>ruby</samp></a> element itself.
   390 In the simple case, it is a container for two non-overlapping boxes: the ruby
   391 text box (<a href="http://www.w3.org/TR/ruby/#rt"><samp>rt</samp></a> element)
   392 and the ruby base box (<a
   393 href="http://www.w3.org/TR/ruby/#rb"><samp>rb</samp></a> element). The
   394 positioning of these two boxes relative to each other is controlled by the <a
   395 href="#rubypos">'ruby-position'</a> property.</p>
   397 <div class="figure">
   398 <img class="example" width="223" height="93"
   399 alt="Diagram of the ruby box model    consisting of two boxes, one on top of the other, enclosed within a third box representing the ruby element"
   400 src="images/r-box-t.gif" />
   402 <p><b>Figure 3.2.1</b>: Ruby box model (simple case)</p>
   403 </div>
   405 <p>In the case of complex ruby, the ruby element is a container for two or
   406 three non-overlapping boxes: one ruby base collection (<a
   407 href="http://www.w3.org/TR/ruby/#rbc"><samp>rbc</samp></a> element), and one
   408 or two ruby text collections (<a
   409 href="http://www.w3.org/TR/ruby/#rtc"><samp>rtc</samp></a> element). The
   410 <samp>rbc</samp> element is itself a container for one or several ruby base
   411 box (<samp>rb</samp> element), while each <samp>rtc</samp> element is a
   412 container for one or several ruby text box (rt element). The position of the
   413 <samp>rtc</samp> element in relation to the related <samp>rbc</samp> element
   414 is controlled by the <a href="#rubypos">'ruby-position'</a> property. The two
   415 following figures show examples of these complex ruby.</p>
   417 <div class="figure">
   418 <img src="images/r-box-g.gif"
   419 alt="Diagram of a group ruby with a full ruby    text above and partial ruby text below" width="408" height="170" />
   421 <p><b>Figure 3.2.2</b>: Ruby box model (complex ruby with an empty rt element
   422 after)</p>
   423 </div>
   425 <p>In the example above, the ruby text after (below) the ruby bases contains two <samp>rt</samp> elements with the first one
   426 being empty, the empty <samp>rt</samp> element corresponds to the first part
   427 of the ruby base collection (the first part is identified by the first <samp>rb</samp>  element
   428 within the <samp> rbc</samp> element).</p>
   430 <div class="figure">
   431 <img src="images/r-box-h.gif"
   432 alt="Diagram of a group ruby with a spanning    ruby text above and partial ruby text below" width="400" height="173" />
   434 <p><b>Figure 3.2.3</b>: Ruby box model (complex ruby with a spanning ruby text
   435 element)</p>
   436 </div>
   438 <p>In the example above, the ruby text before (above) the ruby bases spans the whole ruby base collection. The 
   439 ruby text after (below) the ruby bases still contain two <samp>rt</samp> elements, one of
   440 which is empty. The spanning behavior of <samp>rt</samp> text elements is
   441 controlled by the <a
   442 href="http://www.w3.org/TR/ruby/#ruby"><samp>rbspan</samp></a> attribute in a
   443 way similar to the <samp>colspan</samp> attribute used for table column.</p>
   445 <p class="issue"><span class="issuehead">Issue:&nbsp;</span> The examples above contain the term 'group ruby', which is not used elsewhere in this specification. It appears to be used in a way that is different to the use of the term in JLREQ. I propose to replace it with just 'ruby'.</p>
   446 <p class="note"><span class="note-label">Note:</span> The visual description of the ruby elements does not refer 
   447 necessarily to the logical orders of the elements</p>
   449 <p>The width of the ruby box is by default determined by its widest child
   450 element, whose width in turn is determined by its content. The width of all direct
   451 children of the <samp>ruby</samp> element is the width of the widest children. In this respect, the ruby
   452 box is much like a two or three row <samp>table</samp> element, with the
   453 following exceptions:</p>
   454 <ul>
   455   <li>the ruby box is an inline element, like an image, even though it itself,
   456     like a table, is a container of other boxes</li>
   457   <li>the equivalent of the cells: the <samp>rb</samp> element and the
   458     <samp>rt</samp> text element can only contain inline-level elements.</li>
   459   <li>the content of each 'cell' is always measured at its maximum width</li>
   460   <li>unlike a table, a ruby element doesn't have to fit in a line, the ruby
   461     box may be split into several boxes at line boundary, depending of the
   462     spanning of the ruby texts. This is however only possible for the complex
   463     ruby and can only happen at the boundary of non spanning elements.</li>
   464   <li>both the ruby text and the ruby base boxes may overlap with adjacent
   465     text (outside of the ruby element) if an appropriate <a
   466     href="#rubyover">'ruby-overhang'</a> parameter is set via CSS. Note
   467     however that the actual content of the ruby base cannot overlap with that
   468     adjacent text. The distribution of the content of the ruby base within the
   469     ruby base box is controlled by the <a href="#rubyalign">'ruby-align'</a>
   470     property.</li>
   471 </ul>
   473 <p>If the ruby text is not allowed to overhang, then the ruby behaves like a
   474 traditional box, i.e. only its contents are rendered within its boundaries and
   475 adjacent elements do not cross the box boundary:</p>
   477 <div class="figure">
   478 <p><img class="example" width="220" height="91"
   479 alt="Diagram showing the ruby boxes interacting with adjacent text"
   480 src="images/ro-n.gif" /></p>
   482 <p><b>Figure 3.2.4</b>: Simple ruby whose text is not allowed to overhang
   483 adjacent text</p>
   484 </div>
   486 <p>However, if ruby text is allowed to overhang adjacent elements and it
   487 happens to be wider than its base, then the adjacent content is partially
   488 rendered within the area of the ruby base box, while the ruby text may be
   489 partially overlapping with the upper blank parts of the adjacent content:</p>
   491 <div class="figure">
   492 <p><img class="example" width="177" height="91"
   493 alt="Diagram showing the ruby boxes interacting with adjacent text"
   494 src="images/ro-a.gif" /></p>
   496 <p><b>Figure 3.2.5</b>: Simple ruby whose text is allowed to overhang adjacent
   497 text</p>
   498 </div>
   500 <p>The ruby text related to a ruby base can never overhang another ruby
   501 base.</p>
   503 <p>The alignment of the contents of the base or the ruby text is not affected
   504 by the overhanging behavior. The alignment is achieved the same way regardless
   505 of the overhang behavior setting and it is computed before the space available
   506 for overlap is determined. It is controlled by the <a
   507 href="#rubyalign">'ruby-align'</a> property.</p>
   509 <p>The exact circumstances in which the ruby text will overhang other
   510 elements, and to what degree it will do so, will be controlled by the <a
   511 href="#rubyover">'ruby-overhang'</a> property.</p>
   513 <p>This entire logic applies the same way in vertical ideographic layout, only
   514 the dimension in which it works in such a layout is vertical, instead of
   515 horizontal.</p>
   517 <p class="note"><span class="note-label">Note:</span> Because the purpose of the XHTML <samp>rp</samp> element
   518 [[RUBY]] is to allow pre-existing user agents
   519 to parenthesize ruby text content, an XHTML user agent should use a styling rule 
   520 for these elements that avoids rendering them such as&nbsp; <samp>rp {display: 
   521 none}</samp>.</p>
   523 <h3 id="ruby-line-height">
   524 Ruby box and line stacking</h3>
   526 <p>The interaction of the ruby box and line stacking is controlled by the 
   527 'line-stacking-ruby' property described in the CSS3 Line Module. That property 
   528 takes two values: 'include-ruby' and 'exclude-ruby. Depending on the property 
   529 value, the ruby box is considered or excluded for line stacking. Even if the 
   530 ruby box is considered for line stacking, some values of the 
   531 'line-stacking-strategy' property (also described in the CSS3 Line module) can 
   532 still create occurrences where a the ruby box will eventually be ignored (e.g. 
   533 case where the 'line-stacking-strategy' value is 'block-line-height').</p>
   535 <p>In the following figure, each line box is shown with leading space 
   536 distributed before and after the two text segments ('Previous line' and 'Ruby 
   537 base'); the dotted lines show the line box for each line. The 
   538 'line-stacking-ruby' property is set to 'exclude-ruby'. The achieved effect is 
   539 that the ruby box does not affect the line to line spacing. It is however the 
   540 responsibility of the style author to avoid 'bleeding' effects between the ruby 
   541 text and the surrounding text of images.</p>
   543 <div class="figure">
   544 <p>
   545 <img class="example" 
   546 alt="Diagram showing the ruby text using 2 half leading"
   547 src="images/rlh-a.gif" width="210" height="138" /></p>
   549 <p><b>Figure 3.3.1</b>: Excluded Ruby text</p>
   550 </div>
   553 <p>In the following figure, the line boxes have no extra leading space. The 
   554 'line-stacking-ruby' property is set to 'include-ruby' and the 
   555 'line-stacking-strategy' property is set to a value where inline boxes are 
   556 considered for line stacking. In this case, the line box with 
   557 the ruby text is affected and has its 'stack-height' increased by the amount 
   558 necessary to fit the ruby text.</p>
   560 <div class="figure">
   561 <p>
   562 <img class="example" 
   563 alt="Diagram showing the ruby text expanding above base text"
   564 src="images/rlh-b.gif" width="210" height="111" /></p>
   566 <p><b>Figure 3.3.2</b>: Ruby text increasing line height</p>
   567 </div>
   568 <p>This mechanism allows rendering of evenly spaced lines of text within a
   569 block-level element, whether a line contains ruby or not. The authors need
   570 only to set for the block-level element a line height value larger than the
   571 computed line-height of the largest ruby element within the block.</p>
   573 <h3 id="ruby-line-breaking">
   574 Ruby box and line breaking</h3>
   576 <p>When a ruby falls at the end of a line where there is not sufficient room for the entire ruby to fit on the line, the complex ruby may be broken at locations where boxes of the ruby container align. Some examples are provided below to provide more clarity.</p>
   578 <p>
   579 <img class="example" 
   580 alt="Diagram showing the line breaking opportunity in a complex ruby"
   581 src="images/r-break-a.gif" width="408" height="201" /></p>
   583 <p><b>Figure 3.4.1</b>: Complex ruby line breaking opportunity</p>
   585 <p>
   586 <img class="example" 
   587 alt='Diagram showing the line breaking opportunity in a "Bopomofo" ruby'
   588 src="images/r-break-b.gif" width="300" height="90" /></p>
   590 <p><b>Figure 3.4.1</b>: "Bopomofo" ruby line breaking opportunity</p>
   591 <p class="issue"><span class="issuehead">Issue:&nbsp;</span> Line breaks should only be allowed within ruby if the ruby base text can be broken at that point. E.g. if complex Ruby is used to annotate the two morphemes of &quot;butterfly&quot;, the fact that we have added ruby annotations should not cause a line breaking opportunity to be present between &quot;butter&quot; and &quot;fly&quot; </p>
   592 <h2 id="ruby-props">
   593 Ruby Properties</h2>
   595 <h3 id="rubypos">
   596 Ruby positioning: the 'ruby-position' property</h3>
   598 	<table class="propdef">
   599 		<tr>
   600 			<th>Name:
   601 			<td><dfn>ruby-position</dfn>
   602 		<tr>
   603 			<th><a href="#values">Value</a>:
   604 			<td>[ over | under | inter-character ] && [ right | left ]
   605 		<tr>
   606 			<th>Initial:
   607 			<td>over right
   608 		<tr>
   609 			<th>Applies to:
   610 			<td>the parent of elements with display: ruby-text.
   611 		<tr>
   612 			<th>Inherited:
   613 			<td>yes
   614 		<tr>
   615 			<th>Percentages:
   616 			<td>N/A
   617 		<tr>
   618 			<th>Media:
   619 			<td>visual
   620 		<tr>
   621 			<th>Computed value:
   622 			<td>specified value (except for initial and inherit)
   623 		<tr>
   624 			<th>Animatable:
   625 			<td>no
   626 		<tr>
   627 			<th>Canonical order:
   628 			<td><abbr title="follows order of property value definition">per grammar</abbr>
   629 	</table>
   630 	<p class="issue"><span class="issuehead">Issue:&nbsp;</span> We replaced 'right' with 'inter-character', since that was its original intended purpose and such removes potential ambiguity with 'inline' or 'before'.  Bopomofo ruby needs special handling by the implementation, if ruby is to always appear to the right. (Note that the user may also choose to position bopomofo ruby before the base, in which case they would use the normal 'before' setting.)</p>
   631 	<p>This property is used by the parent of elements with display: ruby-text to
   632 		control the position of the ruby text with respect to its base. Such parents
   633 		are typically either the <samp>ruby</samp> element itself (simple ruby) or the
   634 		<samp>rtc</samp> element (complex ruby). This assures that all parts of a <samp>rtc</samp> 
   635 		element will be displayed in the same position. Possible values:</p>
   636 	<p class="issue"><span class="issuehead">Issue-107:&nbsp;</span> Roland Steiner has requested the addition of an auto value as default. See <a href="http://www.w3.org/Search/Mail/Public/advanced_search?keywords=&amp;hdr-1-name=subject&amp;hdr-1-query=ruby-position%3A+undesirable+default+value+%27before%27+for+complex+ruby&amp;hdr-2-name=from&amp;hdr-2-query=&amp;hdr-3-name=message-id&amp;hdr-3-query=&amp;period_month=&amp;period_year=&amp;index-grp=Public__FULL&amp;index-type=t&amp;type-index=www-style&amp;resultsperpage=20&amp;sortby=date">this thread</a> and <a href="http://www.w3.org/Search/Mail/Public/advanced_search?keywords=&amp;hdr-1-name=subject&amp;hdr-1-query=Styling+of+complex+Ruby&amp;hdr-2-name=from&amp;hdr-2-query=&amp;hdr-3-name=message-id&amp;hdr-3-query=&amp;period_month=&amp;period_year=&amp;index-grp=Public__FULL&amp;index-type=t&amp;type-index=public-i18n-core&amp;resultsperpage=20&amp;sortby=date">this one</a>.</p>
   637 	<dl>
   638 		<dt><dfn title="ruby-position:over">''over''</dfn></dt>
   639 		<dd>The ruby text appears over the base in horizontal text.
   640 			This is the most common setting used in ideographic East Asian writing systems.
   641 			This is the initial value.
   643 			<div class="figure">
   644 				<p>
   645 				<img
   646 					alt="Diagram of ruby glyph layout in horizontal mode with ruby text appearing above the base"
   647 					src="images/shinkansen-top.gif" width="140" height="33" /></p>
   648 				<p><b>Figure 4.1.1</b>: Top ruby in horizontal layout applied to
   649 				Japanese text</p>
   650 			</div>
   651 		</dd>
   653 		<dt><dfn title="ruby-position:right">''right''</dfn></dt>
   654 		<dd>The ruby text appears on the right side of the base in vertical text.
   656 			<div class="figure">
   657 				<p>
   658 				<img
   659 					alt="Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the right of the base"
   660 					src="images/shinkansen-right.gif" width="33" height="141" /></p>
   661 				<p><b>Figure 4.1.2</b>: Top ruby in vertical ideographic layout applied
   662 				to Japanese text</p>
   663 			</div>
   664 		</dd>
   666 		<dt><dfn title="ruby-position:under">''under''</dfn></dt>
   667 		<dd>The ruby text appears under the base in horizontal text.
   668 			This is a relatively rare setting used in ideographic East Asian writing systems,
   669 			most easily found in educational text.
   671 			<div class="figure">
   672 				<p>
   673 				<img
   674 					alt="Diagram of ruby glyph layout in horizontal mode with ruby text appearing below the base"
   675 					src="images/shinkansen-bottom.gif" width="142" height="36" /></p>
   676 				<p><b>Figure 4.1.3</b>: Bottom ruby in horizontal layout applied to Japanese text</p>
   677 			</div>
   678 		</dd>
   680 		<dt><dfn title="ruby-position:left">''left''</dfn></dt>
   681 		<dd>The ruby text appears on the left side of the base in vertical text.
   683 			<div class="figure">
   684 				<p>
   685 				<img
   686 					alt="Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the left of the base"
   687 					src="images/shinkansen-left.gif" width="37" height="141" /></p>
   688 				<p><b>Figure 4.1.4</b>: Bottom ruby in vertical ideographic layout applied to Japanese text</p>
   689 			</div>
   690 		</dd>
   692 		<dt><dfn title="ruby-position:inter-character">''inter-character''</dfn></dt>
   693 		<dd>
   694 			<p class="issue"><span class="issuehead">Issue:&nbsp;</span> We replaced 'right' with 'inter-character', since that was its original intended purpose and such removes potential ambiguity with 'inline' or 'before'.  Bopomofo ruby needs special handling by the implementation, if ruby is to always appear to the right. (Note that the user may also choose to position bopomofo ruby before the base, in which case they would use the normal 'before' setting.)  See <a href="http://www.w3.org/Search/Mail/Public/advanced_search?keywords=&amp;hdr-1-name=subject&amp;hdr-1-query=[CSS3+Ruby]%20Vertical+layout+not+enough+for+bopomofo&amp;hdr-2-name=from&amp;hdr-2-query=&amp;hdr-3-name=message-id&amp;hdr-3-query=&amp;index-grp=Member__FULL+Public__FULL&amp;index-type=t&amp;type-index=public-i18n-core%40w3.org&amp;resultsperpage=20&amp;sortby=date">this thread</a> following a request from the i18n WG.</p>
   695 			<p>The ruby text appears on the right of the base in horizontal text.
   697 			<p>This value is provided for the special case of traditional Chinese as used especially in
   698 				Taiwan: ruby (made of <a href="#g-bopomofo"><span
   699 				lang="zh">bopomofo</span></a> glyphs) in that context  appears vertically along
   700 				the right side of the base glyph,
   701 				even when the layout of the base characters is horizontal:</p>
   703 				<div class="figure">
   704 					<p><img alt="Example of Taiwanese-style ruby"
   705 						width="138" height="42" src="images/bopomofo.gif" /></p>
   706 					<p><b>Figure 4.1.5</b>: "<span lang="zh">Bopomofo</span>" ruby in
   707 						traditional Chinese (ruby text shown in blue for clarity) in horizontal
   708 						layout</p>
   709 				</div>
   710 				<p class="note"><span class="note-label">Note:</span> The bopomofo 
   711 				transcription is written in the normal way as part of the ruby text. 
   712 				The user agent is responsible for ensuring the correct relative alignment 
   713 				and positioning of the glyphs, including those corresponding to the 
   714 				tone marks, when displaying. Tone marks are spacing characters that occur in memory at the end of the ruby text for each base character. They are usually displayed in a separate column to the right of the bopomofo characters, and the height of the tone mark depends on the number of characters in the syllable. One tone mark, however, is placed above the bopomofo, not to the right of it.</p>
   715 				<p class="note"><span class="note-label">Note:</span> To make bopomofo annotations appear before or after the base text, like annotations for most other East Asian writing systems, use the 'before' and 'after' values of ruby-position.</p>
   716 			<p>It is not defined how a user-agent should handle ruby text that is not bopomofo
   717 				when the value of ruby-position is set to 'inter-character'.</p>
   718 			<!-- See Taiwanese requirements doc for EPUB at http://epub-revision.googlecode.com/files/EGLS_TW_eng.ppt -->
   719 		</dd>
   721 		<!--
   722 <dt><strong>inline</strong></dt>
   723 <dd>
   724 <p>Ruby text follows the ruby base with no special styling.  The value can be used to disable  ruby text positioning.</p>
   725 <p>If the author has used the XHTML <samp>rp</samp> element [[RUBY]] they should set the <samp>display</samp> value for that element to <samp>inline</samp>, so that the ruby text is distinguishable from the base text.  If no <samp>rp</samp> element has been used, the author can use the <samp>content</samp> property with the <samp>:before</samp> and <samp>:after</samp> pseudo-elements to set off the ruby text. </p>
   726 <p class="issue"><span class="issuehead">Issue:&nbsp;</span> Here is a <a href="http://www.w3.org/Search/Mail/Public/advanced_search?keywords=&amp;hdr-1-name=subject&amp;hdr-1-query=[CSS3+Ruby]%20inline+value+description+missing&amp;hdr-2-name=from&amp;hdr-2-query=&amp;hdr-3-name=message-id&amp;hdr-3-query=&amp;index-grp=Member__FULL+Public__FULL&amp;index-type=t&amp;type-index=public-i18n-core%40w3.org&amp;resultsperpage=20&amp;sortby=date">request </a>for this section to be added, from the i18n WG..</p>
   727 </dd>
   728 		-->
   729 	</dl>
   731 <p>If two rtc elements are set with the same ruby-position value, (for example 
   732 both &#39;before&#39;), the relative position of the two elements is undefined. This 
   733 setting should not be used.</p>
   735 <h3 id="rubymerge">Ruby merge: the 'ruby-merge' property</h3>
   737 	<table class="propdef">
   738 		<tr>
   739 			<th>Name:
   740 			<td><dfn>ruby-merge</dfn>
   741 		<tr>
   742 			<th><a href="#values">Value</a>:
   743 			<td>separate | collapse | auto
   744 		<tr>
   745 			<th>Initial:
   746 			<td>separate
   747 		<tr>
   748 			<th>Applies to:
   749 			<td>all elements and generated content
   750 		<tr>
   751 			<th>Inherited:
   752 			<td>yes
   753 		<tr>
   754 			<th>Percentages:
   755 			<td>N/A
   756 		<tr>
   757 			<th>Media:
   758 			<td>visual
   759 		<tr>
   760 			<th>Computed value:
   761 			<td>specified value (except for initial and inherit)
   762 	</table>
   764 	<p>
   765 		This property controls how ruby annotation boxes should be rendered
   766 		when there are more than one in a ruby container box.
   767 	</p>
   769 	<p>Possible values:</p>
   770 	<dl>
   771 		<dt><dfn title="ruby-merge:separate">''separate''</dfn></dt>
   772 		<dd>
   773 			<p>
   774 				Each ruby annotation box is rendered in the same column as its corresponding base box.
   775 				This style is called Mono-ruby in [[JLREQ]].
   776 			</p>
   778 			<div class="example">
   779 				<p>The following two markups render the same:</p>
   780 				<pre>&lt;ruby&gt;無&lt;rt&gt;む&lt;/ruby&gt;&lt;ruby&gt;常&lt;rt&gt;じょう&lt;/ruby&gt;</pre>
   781 				<p>and:</p>
   782 				<pre>&lt;ruby style="ruby-merge:separate"&gt;&lt;rb&gt;無&lt;rb&gt;常&lt;rt&gt;む&lt;rt&gt;じょう&lt;/ruby&gt;</pre>
   783 			</div>
   784 		</dd>
   786 		<dt><dfn title="ruby-merge:collapse">''collapse''</dfn></dt>
   787 		<dd>
   788 			<p>
   789 				All ruby annotation boxes are concatenated,
   790 				and rendered to the concatenated ruby base boxes.
   791 				This style renders similar to Group-ruby in [[JLREQ]],
   792 				except that it allows line break between annotation pairs.
   793 			</p>
   795 			<div class="example">
   796 				<p>The following two markups render the same if fit in a line:</p>
   797 				<pre>&lt;ruby&gt;無常&lt;rt&gt;むじょう&lt;/ruby&gt;</pre>
   798 				<p>and:</p>
   799 				<pre>&lt;ruby style="ruby-merge:collapse"&gt;&lt;rb&gt;無&lt;rb&gt;常&lt;rt&gt;む&lt;rt&gt;じょう&lt;/ruby&gt;</pre>
   800 			</div>
   801 		</dd>
   803 		<dt><dfn title="ruby-merge:auto">''auto''</dfn></dt>
   804 		<dd>
   805 			<p>
   806 				The user agent may use any algorithm to determine how each ruby annotation box
   807 				is rendered to its corresponding base box.
   808 			</p>
   809 			<div class="example">
   810 			<p>
   811 				One possible algorithm is described as Jukugo-ruby in [[JLREQ]].
   812 			</p>
   813 			<p>
   814 				Another, more simplified algorithm of Jukugo-ruby is
   815 				to render as Mono-ruby if all ruby annotation boxes fit within
   816 				advances of their corresponding base boxes,
   817 				and render as Group-ruby otherwise.
   818 			</p>
   819 			</div>
   820 		</dd>
   821 	</dl>
   823 <h3 id="rubyalign">
   824 Ruby alignment: the 'ruby-align' property</h3>
   826 	<table class="propdef">
   827 		<tr>
   828 			<th>Name:
   829 			<td><dfn>ruby-align</dfn>
   830 		<tr>
   831 			<th><a href="#values">Value</a>:
   832 			<td>auto | start | center |
   833 				distribute-letter | distribute-space
   834 		<tr>
   835 			<th>Initial:
   836 			<td>auto
   837 		<tr>
   838 			<th>Applies to:
   839 			<td>all elements and generated content
   840 		<tr>
   841 			<th>Inherited:
   842 			<td>yes
   843 		<tr>
   844 			<th>Percentages:
   845 			<td>N/A
   846 		<tr>
   847 			<th>Media:
   848 			<td>visual
   849 		<tr>
   850 			<th>Computed value:
   851 			<td>specified value (except for initial and inherit)
   852 	</table>
   854 	<p>This property can be used on any element to control the text alignment of
   855 		the ruby text and ruby base contents relative to each other. It applies to all
   856 		the rubys in the element. For simple ruby, the alignment is applied to the
   857 		ruby child element whose content is shorter: either the <a
   858 		href="http://www.w3.org/TR/ruby/#rb"><samp>rb</samp></a>   element or the <a
   859 		href="http://www.w3.org/TR/ruby/#rt"><samp>rt</samp></a> element [[RUBY]].
   860 		For complex ruby, the alignment is also applied to the
   861 		ruby child elements whose content is shorter: either the <samp>rb</samp>
   862 		element and/or one or two <samp>rt</samp> elements for each related ruby text
   863 		and ruby base element within the <samp>rtc</samp> and <samp>rbc</samp>
   864 		element.</p>
   866 	<p>Possible values:</p>
   867 	<p class="issue"><span class="issuehead">Issue:&nbsp;</span> Tony Graham has <a href="http://www.w3.org/Style/XSL/Group/FO/wiki/Ruby#Treat_CSS3_.22ruby-align.22_As_Shorthand.3F">suggested </a>that distribute-letter and distribute-space be values of a ruby-group-distribution property, and line-edge be moved to a ruby-alignment-edge property, and that the rest be gathered under a ruby-alignment property. And that ruby-align become a shorthand.</p>
   868 	<dl>
   869 		<dt><dfn title="ruby-align:auto">''auto''</dfn></dt>
   870 		<dd>
   871 			<p>The user agent determines how the ruby contents are aligned.
   872 				This is the initial value.
   873 				The behavior recommended by [[JLREQ]] is for  wide-cell ruby  to be aligned in the 'distribute-space' mode:
   874 				<div class="figure">
   875 					<p><img width="145" height="91"
   876 					alt="Diagram of glyph layout in auto aligned ruby when ruby text is shorter than base"
   877 					src="images/ra-ds.gif" /><img width="145" height="91"
   878 					alt="Diagram of glyph layout in auto aligned ruby when ruby text is longer than base"
   879 					src="images/ra-ds-rb.gif" /></p>
   880 					<p><b>Figure 4.2.1</b>: Wide-cell text in 'auto' ruby alignment is
   881 					'distribute-space' justified</p>
   882 				</div>
   884 			<p>The recommended behavior for  narrow-cell glyph ruby is to be
   885 				aligned in the 'center' mode.</p>
   886 				<div class="figure">
   887 					<p><img
   888 					alt="Diagram of glyph layout in auto aligned ruby when halfwidth ruby text is shorter than base"
   889 					width="145" height="91"
   890 					src="images/ra-c-h.gif" /><img
   891 					alt="Diagram of character layout in auto aligned ruby when ruby text is longer than narrow-width base"
   892 					width="145" height="91"
   893 					src="images/ra-c-rb-h.gif" /></p>
   894 					<p><b>Figure 4.2.2</b>: Narrow-width ruby text in 'auto' ruby alignment
   895 					is centered</p>
   896 				</div>
   897 		</dd>
   899 		<dt><dfn title="ruby-align:start">''start''</dfn></dt>
   900 		<dd>The ruby text content is aligned with the start edge of the base.
   901 			<p class="issue"><span class="issuehead">Issue:&nbsp;</span> The i18n WG feels that start and left should not be synonymous, and proposed to drop left (there is no left/right in overhang)? See <a href="http://www.w3.org/Search/Mail/Public/advanced_search?keywords=&amp;hdr-1-name=subject&amp;hdr-1-query=[CSS3+Ruby]%20left/start+and+right/end&amp;hdr-2-name=from&amp;hdr-2-query=&amp;hdr-3-name=message-id&amp;hdr-3-query=&amp;index-grp=Member__FULL+Public__FULL&amp;index-type=t&amp;type-index=public-i18n-core%40w3.org&amp;resultsperpage=20&amp;sortby=date">this thread</a>.</p>
   903 			<div class="figure">
   904 				<p><img
   905 					alt="Diagram of glyph layout in left aligned ruby when ruby text is shorter than base"
   906 					width="145" height="91" src="images/ra-l.gif" /><img
   907 					width="145" height="91"
   908 					alt="Diagram of glyph layout in left aligned ruby when ruby text is longer than base"
   909 					src="images/ra-l-rb.gif" /></p>
   910 				<p><b>Figure 4.2.3</b>: Start ruby alignment</p>
   911 			</div>
   912 		</dd>
   914 		<dt><dfn title="ruby-align:center">''center''</dfn></dt>
   915 		<dd>The ruby text content is centered within the width of the base. If the
   916 			length of the base is smaller than the length of the ruby text, then the
   917 			base is centered within the width of the ruby text.
   919 			<div class="figure">
   920 				<p><img width="145" height="91"
   921 					alt="Diagram of glyph layout in center aligned ruby when ruby text is shorter than base"
   922 					src="images/ra-c.gif" /><img width="145" height="91"
   923 					alt="Diagram of glyph layout in center aligned ruby when ruby text is longer than base"
   924 					src="images/ra-c-rb.gif" /></p>
   925 				<p><b>Figure 4.2.4</b>: Center ruby alignment</p>
   926 			</div>
   927 		</dd>
   929 		<!--
   930   <dt><strong>right</strong></dt>
   931     <dd>The ruby text content is aligned with the end edge of the base.
   932     	<p class="issue"><span class="issuehead">Issue:&nbsp;</span> The i18n WG feels that end and right should not be synonymous, and proposed to drop right (there is no left/right in overhang)? See <a href="http://www.w3.org/Search/Mail/Public/advanced_search?keywords=&amp;hdr-1-name=subject&amp;hdr-1-query=[CSS3+Ruby]%20left/start+and+right/end&amp;hdr-2-name=from&amp;hdr-2-query=&amp;hdr-3-name=message-id&amp;hdr-3-query=&amp;index-grp=Member__FULL+Public__FULL&amp;index-type=t&amp;type-index=public-i18n-core%40w3.org&amp;resultsperpage=20&amp;sortby=date">this thread</a>.</p>
   933 <div class="figure">
   934 	<p><img class="example" width="145" height="91"
   935       alt="Diagram of glyph layout in right aligned ruby when ruby text is shorter than base"
   936       src="images/ra-r.gif" /><img class="example" width="145" height="91"
   937       alt="Diagram of glyph layout in right aligned ruby when ruby text is longer than base"
   938       src="images/ra-r-rb.gif" /></p>
   939 	<p><b>Figure 4.2.5</b>: End ruby alignment</p>
   940 </div>
   941     </dd>
   942 		-->
   944 		<dt><dfn title="ruby-align:distribute-letter">''distribute-letter''</dfn></dt>
   945 		<dd>If the width of the ruby text is smaller than that of the base, then
   946 			the ruby text contents are evenly distributed across the width of the
   947 			base, with the first and last ruby text glyphs lining up with the
   948 			corresponding first and last base glyphs. If the width of the ruby text
   949 			is at least the width of the base, then the letters of the base are
   950 			evenly distributed across the width of the ruby text.
   952 			<div class="figure">
   953 				<p><img width="145" height="91"
   954 				alt="Diagram of glyph layout in distribute-letter aligned ruby when ruby text is shorter than base"
   955 				src="images/ra-dl.gif" /><img width="145" height="91"
   956 				alt="Diagram of glyph layout in distribute-letter aligned ruby when ruby text is longer than base"
   957 				src="images/ra-dl-rb.gif" /></p>
   958 				<p><b>Figure 4.2.6</b>: Distribute-letter ruby alignment</p>
   959 			</div>
   960 		</dd>
   962 		<dt><dfn title="ruby-align:distribute-space">''distribute-space''</dfn></dt>
   963 		<dd>If the width of the ruby text is smaller than that of the base, then
   964 			the ruby text contents are evenly distributed across the width of the
   965 			base, with a certain amount of white space preceding the first and
   966 			following the last character in the ruby text. That amount of white
   967 			space is normally equal to half the amount of inter-character space of
   968 			the ruby text. If the width of the ruby text is at least the width of
   969 			the base, then the same type of space distribution applies to the base.
   970 			In other words, if the base is shorter than the ruby text, the base is
   971 			distribute-space aligned. This type of alignment
   972 			is described by [[JLREQ]].
   974 			<div class="figure">
   975 				<p><img width="145" height="91"
   976 					alt="Diagram of glyph layout in distribute-space aligned ruby when ruby text is shorter than base"
   977 					src="images/ra-ds.gif" /><img width="145" height="91"
   978 					alt="Diagram of glyph layout in distribute-space aligned ruby when ruby text is longer than base"
   979 					src="images/ra-ds-rb.gif" /></p>
   980 				<p><b>Figure 4.2.7</b>: Distribute-space ruby alignment</p>
   981 			</div>
   982 		</dd>
   984 		<!--
   985   <dt><strong>line-edge</strong></dt>
   986     <dd>If the ruby text is not adjacent to a line edge, it is aligned as in
   987       'auto'. If it is adjacent to a line edge, then it is still aligned as in
   988       auto, but the side of the ruby text that touches the end of the line is
   989       lined up with the corresponding edge of the base. This type of alignment
   990       is described by [[JLREQ]]. This type of alignment is
   991       relevant only to the scenario where the ruby text is longer than the
   992       ruby base. In the other scenarios, this is just 'auto'.
   993 		<div class="figure">
   994       <p><img class="example" width="146" height="109"
   995       alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is shorter than base"
   996       src="images/ra-le-l.gif" /><img class="example" width="146"
   997       height="110"
   998       alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is longer than base"
   999       src="images/ra-le-r.gif" /></p>
  1000       <p><b>Figure 4.2.8</b>: Line edge ruby alignment</p>
  1001       </div>
  1002     </dd>
  1003 		-->
  1004 	</dl>
  1006 	<p>For a complex ruby with spanning elements, one additional consideration is
  1007 		required. If the spanning element spans multiple 'rows' (other rbc or rtc
  1008 		elements), and the ruby alignment requires space distribution among the
  1009 		'spanned' elements, a ratio must be determined among the 'columns' of spanned
  1010 		elements. This ratio is computed by taking into consideration the widest
  1011 		element within each column.</p>
  1013 <h2 id="rubyover">
  1014 Ruby Overhang and Edge Effects</h2>
  1016 	<p>
  1017 		When <i>ruby annotation box</i> is longer than its corresponding <i>ruby base box</i>,
  1018 		the <i>ruby annotation box</i> may partially overhang adjacent boxes.
  1019 	</p>
  1020 	<p>
  1021 		This level of the specificaiton does not define
  1022 		how much the overhang may be allowed, and under what conditions.
  1023 	</p>
  1024 	<div class="example">
  1025 	<p>
  1026 		The user agent may use [[JIS4051]] recommendation of
  1027 		using one ruby text character length as the maximum overhang length.
  1028 		Detailed rules for how ruby text can overhang adjacent characters for Japanese are described by [[JLREQ]].
  1029 	</p>
  1030 	</div>
  1032 	<p>
  1033 		When such <i>ruby annotation box</i> is at the start or end edge of a line,
  1034 		user agent may align the side of the ruby text that touches the edge of the line
  1035 		to the corresponding edge of the base.
  1036 		This type of alignment is described by [[JLREQ]].
  1037 	</p>
  1038 	<p>
  1039 		This level of the specificaiton does not provide a mechanism to control this behavior.
  1040 	</p>
  1041 	<div class="figure">
  1042 		<p><img width="146" height="109"
  1043 			alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is shorter than base"
  1044 			src="images/ra-le-l.gif" /><img width="146"
  1045 			height="110"
  1046 			alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is longer than base"
  1047 			src="images/ra-le-r.gif" /></p>
  1048 		<p><b>Figure 4.2.8</b>: Line edge ruby alignment</p>
  1049 	</div>
  1051 	<!--
  1052 <h3 id="rubyover">
  1053 Ruby overhanging: the 'ruby-overhang' property</h3>
  1055   <table class="propdef">
  1056     <tr>
  1057       <th>Name:
  1058       <td><dfn>ruby-overhang</dfn>
  1059     <tr>
  1060       <th>Value:
  1061       <td>auto | start | end | none
  1062     <tr>
  1063       <th>Initial:
  1064       <td>none
  1065     <tr>
  1066       <th>Applies to:
  1067       <td>the parent of elements with display: ruby-text
  1068     <tr>
  1069       <th>Inherited:
  1070       <td>yes
  1071     <tr>
  1072       <th>Percentages:
  1073       <td>N/A
  1074     <tr>
  1075       <th>Media:
  1076       <td>visual
  1077     <tr>
  1078       <th>Computed value:
  1079       <td>specified value (except for initial and inherit)
  1080   </table>
  1082 <p>This property determines whether, and on which side, ruby text is allowed
  1083 to partially overhang any adjacent text in addition to its own base, when the
  1084 ruby text is wider than the ruby base. Note that ruby text is never allowed to
  1085 overhang glyphs belonging to another ruby base. <span class="issue"><span class="issuehead">Issue:&nbsp;</span> This rule must be broken if we are to allow support for jukugo ruby.</span> Also the user agent is free to assume
  1086 a maximum amount by which ruby text may overhang adjacent text. The user agent may use
  1087 the [[JIS4051]] recommendation of using one ruby text character
  1088 length as the maximum overhang length. Detailed rules for how ruby text can overhang adjacent characters for Japanese are described by [[JLREQ]].</p>
  1090 <p>Possible values:</p>
  1091 <dl>
  1092   <dt><strong>auto</strong></dt>
  1093     <dd>The ruby text can overhang text adjacent to the base on either side.   	  [[JLREQ]] and [[JIS4051]] specify the categories of characters that
  1094       ruby text can overhang. The user agent is free to follow those recommendations or specify its own classes of
  1095       characters to overhang. This is the initial value.
  1096 		<div class="figure">
  1097       <p><img class="example" width="177" height="91"
  1098       alt="Diagram of glyph layout in overhanging ruby" src="images/ro-a.gif" /></p>
  1099       <p><b>Figure 4.3.1</b>: Ruby overhanging adjacent text</p>
  1100       </div>
  1101     </dd>
  1102   <dt><strong>start</strong></dt>
  1103     <dd>The ruby text can only overhang the text that precedes it. That means, for
  1104       example, that ruby cannot overhang text that is to the right of it in
  1105       horizontal LTR layout, and it cannot overhang text that is below it in
  1106       vertical-ideographic layout.
  1107 		<div class="figure">
  1108       <p><img class="example" width="199" height="91"
  1109       alt="Diagram of glyph layout when ruby overhangs the preceding glyphs only"
  1110       src="images/ro-s.gif" /></p>
  1111       <p><b>Figure 4.3.2</b>: Ruby overhanging preceding text only</p>
  1112       </div>
  1113     </dd>
  1114   <dt><strong>end</strong></dt>
  1115     <dd>The ruby text can only overhang the text that follows it. That means, for
  1116       example, that ruby cannot overhang text that is to the left of it in
  1117       horizontal LTR layout, and it cannot overhang text that is above it in
  1118       vertical-ideographic layout.
  1119 		<div class="figure">
  1120       <p><img class="example" width="198" height="91"
  1121       alt="Diagram of glyph layout when ruby overhangs the following characters only"
  1122       src="images/ro-e.gif" /></p>
  1123       <p><b>Figure 4.3.3</b>: Ruby overhanging following text only</p>
  1124       </div>
  1125     </dd>
  1126   <dt><strong>none</strong></dt>
  1127     <dd>The ruby text cannot overhang any text adjacent to its base, only its
  1128       own base.
  1130       <div class="figure">
  1131       <p><img class="example" width="220" height="91"
  1132       alt="Diagram of glyph layout in non-overhanging ruby"
  1133       src="images/ro-n.gif" /></p>
  1134       <p><b>Figure 4.3.4</b>: Ruby not allowed to overhang adjacent text</p>
  1135       </div>
  1136     </dd>
  1137 </dl>
  1139 <h3 id="rubyspan">
  1140 Ruby annotation spanning: the 'ruby-span' property</h3>
  1142   <table class="propdef">
  1143     <tr>
  1144       <th>Name:
  1145       <td><dfn>ruby-span</dfn>
  1146     <tr>
  1147       <th>Value:
  1148       <td>attr(x) |  none
  1149     <tr>
  1150       <th>Initial:
  1151       <td>none
  1152     <tr>
  1153       <th>Applies to:
  1154       <td>elements with display: ruby-text
  1155     <tr>
  1156       <th>Inherited:
  1157       <td>no
  1158     <tr>
  1159       <th>Percentages:
  1160       <td>N/A
  1161     <tr>
  1162       <th>Media:
  1163       <td>visual
  1164     <tr>
  1165       <th>Computed value:
  1166       <td>&lt;number&gt;
  1167   </table>
  1169 <p>This property controls the spanning behavior of annotation elements. </p>
  1171 <p class="note"><span class="note-label">Note:</span> A XHTML user agent may also use the <samp>rbspan</samp> 
  1172 attribute to get the same effect.</p>
  1174 <p>Possible values:</p>
  1176 <dl>
  1177   <dt><strong>attr(x)</strong></dt>
  1178     <dd>The value of attribute 'x' as a string value. The string value is 
  1179     evaluated as a &lt;number&gt; to determine the number of ruby base elements to be 
  1180     spanned by the annotation element. If the &lt;number&gt; is &#39;0&#39;, it is replaced by 
  1181     &#39;1&#39;.The &lt;number&gt; is the computed value. </dd>
  1182   <dt>none</dt>
  1183   <dd>No spanning. The computed value is &#39;1&#39;.</dd>
  1184 </dl>
  1186 <p>The following example shows an XML example using the 'display' property 
  1187 values associated with the 'ruby structure and the 'ruby-span' property</p>
  1188 <pre class="xml">myruby       { display: ruby; }
  1189 myrbc        { display: ruby-base-container; }
  1190 myrb         { display: ruby-base; }
  1191 myrtc.before { display: ruby-text-container; ruby-position: before}
  1192 myrtc.after  { display: ruby-text-container; ruby-position: after}
  1193 myrt         { display: ruby-text; ruby-span: attr(rbspan); }
  1194 ...
  1195 &lt;myruby&gt;
  1196   &lt;myrbc&gt;
  1197     &lt;myrb&gt;10&lt;/myrb&gt;
  1198     &lt;myrb&gt;31&lt;/myrb&gt;
  1199     &lt;myrb&gt;2002&lt;/myrb&gt;
  1200   &lt;/myrbc&gt;
  1201   &lt;myrtc class=&quot;before&quot;&gt;
  1202     &lt;myrt&gt;Month&lt;/myrt&gt;
  1203     &lt;myrt&gt;Day&lt;/myrt&gt;
  1204     &lt;myrt&gt;Year&lt;/myrt&gt;
  1205   &lt;/myrtc&gt;
  1206   &lt;myrtc class=&quot;after&quot;&gt;
  1207     &lt;myrt rbspan=&quot;3&quot;&gt;Expiration Date&lt;/myrt&gt;
  1208   &lt;/myrtc&gt;
  1209 &lt;/myruby&gt;</pre>
  1210 	-->
  1212 <h2 id="default-stylesheet" class="no-num">
  1213 Appendix A: Default Style Sheet</h2>
  1215 	<p><em>This section is informative.</em>
  1217 <h3 id="default-ua-ruby" class="no-num">
  1218 <span class="secno">A.1</span> Supporting Ruby Layout</h3>
  1220 	<p>The following represents a default UA style sheet
  1221 	for rendering HTML and XHTML ruby markup as ruby layout:
  1223 	<pre>
  1224 <!--	-->ruby { display: ruby; }
  1225 <!--	-->rb   { display: ruby-base; white-space: nowrap; }
  1226 <!--	-->rt   { display: ruby-text; white-space: nowrap; font-size: 50%; }
  1227 <!--	-->rbc  { display: ruby-base-container; }
  1228 <!--	-->rtc  { display: ruby-text-container; }</pre>
  1230 	<p>Additional rules for UAs supporting the relevant features of [[CSS3-TEXT-DECOR]] and [[CSS3-FONTS]]:
  1231 	<pre>rt { font-variant-east-asian: ruby; text-emphasis: none; }</pre>
  1233 	<p class="note">Authors should not use the above rules;
  1234 	a UA that supports ruby layout should provide these by default.
  1236 <h3 id="default-inline" class="no-num">
  1237 <span class="secno">A.2</span> Inlining Ruby Annotations</h3>
  1239 	<p>The following represents a sample style sheet
  1240 	for rendering HTML and XHTML ruby markup as inline annotations:
  1242 	<pre>ruby, rb, rt, rbc, rtc, rp {
  1243 <!--	-->  display: inline; white-space: inherit;
  1244 <!--	-->  font-variant-east-asian: inherit; text-emphasis: inherit; }</pre>
  1246 <h3 id="default-parens" class="no-num">
  1247 <span class="secno">A.3</span> Generating Parentheses</h3>
  1249 	<p>Unfortunately, because Selectors cannot match against text nodes,
  1250 	it's not possible with CSS to express rules that will automatically and correctly
  1251 	add parentheses to unparenthesized ruby annotations in HTML.
  1252 	(This is because HTML ruby allows implying the <i>ruby base</i> from raw text, without a corresponding element.)
  1253 	However, these rules will handle cases where either <code>&lt;rb&gt;</code>
  1254 	or <code>&lt;rtc&gt;</code> is used rigorously.
  1256 	<pre>
  1257 <!--	-->/* Parens around &lt;rtc> */
  1258 <!--	-->rtc::before { content: "("; }
  1259 <!--	-->rtc::after  { content: ")"; }
  1261 <!--	-->/* Parens before first &lt;rt> not inside &lt;rtc> */
  1262 <!--	-->rb  + rt::before,
  1263 <!--	-->rtc + rt::before { content: "("; }
  1265 <!--	-->/* Parens after &lt;rt> not inside &lt;rtc> */
  1266 <!--	-->rb ~ rt:last-child::after,
  1267 <!--	-->rt + rb::before  { content: ")"; }
  1268 <!--	-->rt + rtc::before { content: ")("; }</pre>
  1270 <h2 id="glossary">
  1271 Glossary</h2>
  1272 <dl>
  1273   <dt><a id="g-bopomofo"><strong><span
  1274   lang="zh">Bopomofo</span></strong></a></dt>
  1275     <dd>37 characters and 4 tone markings used as phonetics in Chinese,
  1276       especially standard Mandarin.</dd>
  1277   <dt><a id="g-hanja"><strong><span
  1278   lang="ko">Hanja</span></strong></a></dt>
  1279     <dd>Subset of the Korean writing system that utilizes ideographic
  1280       characters borrowed or adapted from the Chinese writing system. Also see
  1281       <a href="#g-kanji"><span lang="ja">Kanji</span></a>.</dd>
  1282   <dt><a id="g-hiragana"><strong><span
  1283   lang="ja">Hiragana</span></strong></a></dt>
  1284     <dd>Japanese syllabic script, or character of that script. Rounded and 
  1285     cursive in appearance. Subset of the Japanese writing system, used together 
  1286     with kanji and katakana. In recent times, mostly used to write Japanese 
  1287     words when kanji are not available or appropriate, and word endings and 
  1288     particles. Also see <a
  1289       href="#g-katakana"><span lang="ja">Katakana</span></a>.</dd>
  1290   <dt><a id="g-ideogram"><strong>Ideograph</strong></a></dt>
  1291     <dd>A character that is used to represent an idea, word, or word component, 
  1292     in contrast to a character from an alphabetic or syllabic script. The most 
  1293     well-known ideographic script is used (with some variation) in East Asia 
  1294     (China, Japan, Korea,...).</dd>
  1295   <dt><a id="g-kana"><strong><span lang="ja">Kana</span></strong></a></dt>
  1296     <dd>Collective term for hiragana and katakana.</dd>
  1297   <dt><a id="g-kanji"><strong>Kanji</strong></a></dt>
  1298     <dd>Japanese term for ideographs; ideographs used in Japanese. Subset of the 
  1299     Japanese writing system, used together with hiragana and katakana. Also see <a
  1300       href="#g-hanja"><span lang="ko">Hanja</span></a>.</dd>
  1301   <dt><a id="g-katakana"><strong><span
  1302   lang="ja">Katakana</span></strong></a></dt>
  1303     <dd>Japanese syllabic script, or character of that script. Angular in 
  1304     appearance. Subset of the Japanese writing system,&nbsp; used together with 
  1305     kanji and hiragana. In recent times, mainly used to write foreign words. Also see <a
  1306       href="#g-hiragana"><span lang="ja">Hiragana</span></a>.</dd>
  1307   <dt><a id="g-monoruby" name="g-monoruby"><strong>Mono-ruby</strong></a></dt>
  1308     <dd>In Japanese typography: Ruby associated with a single character of
  1309       the base text.</dd>
  1310   <dt><a id="g-ruby"><strong>Ruby</strong></a></dt>
  1311     <dd>A run of text that appears in the vicinity of another run of text and
  1312       serves as an annotation or a pronunciation guide for that text.</dd>
  1313 </dl>
  1315 <h2 id="conformance">
  1316 Conformance</h2>
  1318 <h3 id="conventions">
  1319 Document conventions</h3>
  1321   <p>Conformance requirements are expressed with a combination of
  1322   descriptive assertions and RFC 2119 terminology. The key words “MUST”,
  1323   “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”,
  1324   “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this
  1325   document are to be interpreted as described in RFC 2119.
  1326   However, for readability, these words do not appear in all uppercase
  1327   letters in this specification.
  1329   <p>All of the text of this specification is normative except sections
  1330   explicitly marked as non-normative, examples, and notes. [[!RFC2119]]</p>
  1332   <p>Examples in this specification are introduced with the words “for example”
  1333   or are set apart from the normative text with <code>class="example"</code>,
  1334   like this:
  1336   <div class="example">
  1337     <p>This is an example of an informative example.</p>
  1338   </div>
  1340   <p>Informative notes begin with the word “Note” and are set apart from the
  1341   normative text with <code>class="note"</code>, like this:
  1343   <p class="note">Note, this is an informative note.</p>
  1345 <h3 id="conformance-classes">
  1346 Conformance classes</h3>
  1348   <p>Conformance to CSS Ruby Module
  1349   is defined for three conformance classes:
  1350   <dl>
  1351     <dt><dfn title="style sheet!!as conformance class">style sheet</dfn>
  1352       <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
  1353       style sheet</a>.
  1354     <dt><dfn>renderer</dfn></dt>
  1355       <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  1356       that interprets the semantics of a style sheet and renders
  1357       documents that use them.
  1358     <dt><dfn id="authoring-tool">authoring tool</dfn></dt>
  1359       <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  1360       that writes a style sheet.
  1361   </dl>
  1363   <p>A style sheet is conformant to CSS Ruby Module
  1364   if all of its statements that use syntax defined in this module are valid
  1365   according to the generic CSS grammar and the individual grammars of each
  1366   feature defined in this module.
  1368   <p>A renderer is conformant to CSS Ruby Module
  1369   if, in addition to interpreting the style sheet as defined by the
  1370   appropriate specifications, it supports all the features defined
  1371   by CSS Ruby Module by parsing them correctly
  1372   and rendering the document accordingly. However, the inability of a
  1373   UA to correctly render a document due to limitations of the device
  1374   does not make the UA non-conformant. (For example, a UA is not
  1375   required to render color on a monochrome monitor.)
  1377   <p>An authoring tool is conformant to CSS Ruby Module
  1378   if it writes style sheets that are syntactically correct according to the
  1379   generic CSS grammar and the individual grammars of each feature in
  1380   this module, and meet all other conformance requirements of style sheets
  1381   as described in this module.
  1383 <h3 id="partial">
  1384 Partial implementations</h3>
  1386   <p>So that authors can exploit the forward-compatible parsing rules to
  1387   assign fallback values, CSS renderers <strong>must</strong>
  1388   treat as invalid (and <a href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore
  1389   as appropriate</a>) any at-rules, properties, property values, keywords,
  1390   and other syntactic constructs for which they have no usable level of
  1391   support. In particular, user agents <strong>must not</strong> selectively
  1392   ignore unsupported component values and honor supported values in a single
  1393   multi-value property declaration: if any value is considered invalid
  1394   (as unsupported values must be), CSS requires that the entire declaration
  1395   be ignored.</p>
  1397 <h3 id="experimental">
  1398 Experimental implementations</h3>
  1400   <p>To avoid clashes with future CSS features, the CSS2.1 specification
  1401   reserves a <a href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
  1402   syntax</a> for proprietary and experimental extensions to CSS.
  1404   <p>Prior to a specification reaching the Candidate Recommendation stage
  1405   in the W3C process, all implementations of a CSS feature are considered
  1406   experimental. The CSS Working Group recommends that implementations
  1407   use a vendor-prefixed syntax for such features, including those in
  1408   W3C Working Drafts. This avoids incompatibilities with future changes
  1409   in the draft.
  1410   </p>
  1412 <h3 id="testing">
  1413 Non-experimental implementations</h3>
  1415   <p>Once a specification reaches the Candidate Recommendation stage,
  1416   non-experimental implementations are possible, and implementors should
  1417   release an unprefixed implementation of any CR-level feature they
  1418   can demonstrate to be correctly implemented according to spec.
  1420   <p>To establish and maintain the interoperability of CSS across
  1421   implementations, the CSS Working Group requests that non-experimental
  1422   CSS renderers submit an implementation report (and, if necessary, the
  1423   testcases used for that implementation report) to the W3C before
  1424   releasing an unprefixed implementation of any CSS features. Testcases
  1425   submitted to W3C are subject to review and correction by the CSS
  1426   Working Group.
  1428   <p>Further information on submitting testcases and implementation reports
  1429   can be found from on the CSS Working Group's website at
  1430   <a href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
  1431   Questions should be directed to the
  1432   <a href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
  1433   mailing list.
  1435 <h2 class=no-num id="acknowledgments">
  1436 Acknowledgments</h2>
  1438 <p>This specification would not have been possible without the help from:</p>
  1440 <p>Stephen Deach, Martin Dürst,  Hideki Hiura(<span lang="ja">樋浦 秀樹</span>), Masayasu Ishikawa(<span lang="ja">石川
  1441 雅康</span>), Chris
  1442 Pratley, Takao Suzuki(<span lang="ja">鈴木 孝雄</span>), Frank Yung-Fong Tang, Chris Thrasher, Masafumi Yabe<span lang="ja">家辺
  1443 勝文</span>), Steve Zilles.</p>
  1445 <h2 class="no-num" id="changes">
  1446 Changes</h2>
  1448 	<p>The following major changes have been made since the previous Working Draft:
  1449 	<dl>
  1450 		<dt>Remove 'ruby-span' and mentions of <code>rbspan</code>.
  1451 		<dd>
  1452 			Explicit spanning is not used in HTML ruby in favor of implicit spanning.
  1453 			This can't handle some pathological double-sided spanning cases,
  1454 			but there seems to be no requirement for these at the moment.
  1455 			(For implementations that support full complex XHTML Ruby,
  1456 			they can imply spanning from the markup the same magic way
  1457 			that we handle cell spanning from tables. It doesn't seem
  1458 			necessary to include controls this in Level 1.)
  1460 		<dt>Defer 'ruby-overhang' and ''ruby-align: line-end'' to Level 2.
  1461 		<dd>
  1462 			It's somewhat complicated, advanced feature.
  1463 			Proposal is to make this behavior UA-defined
  1464 			and provide some examples of acceptable options.
  1466 		<dt>Close issue requesting 'display: rp': use ''display: none''.
  1467 		<dd>
  1468 			The i18nwg added an issue requesting a display value for &lt;rp> elements.
  1469 			They're supposed to be hidden when &tl;ruby> is displayed as ruby.
  1470 			But this is easily accomplished already with ''display: none''.
  1472 		<dt>Change 'ruby-position' values to match 'text-emphasis-position'.
  1473 		<dd>
  1474 			Other than ''inter-character'', which we need to keep,
  1475 			it makes more sense to align ruby positions with 'text-emphasis-position',
  1476 			which can correctly handle various combinations of horizontal/vertical preferences.
  1478 		<dt>Remove unused values of 'ruby-align'.
  1479 		<dd>
  1480 			'left', 'right', and 'end' are not needed.
  1482 		<dt>Added 'ruby-merge' property to control jukugo rendering.
  1483 		<dd>
  1484 			This is a stylistic effect, not a structural one;
  1485 			the previous model assumed that it was structural and suggested handling it by changing markup. :(
  1487 		<dt>Remove ''inline'' from 'ruby-position'.
  1488 		<dd>
  1489 			This is do-able via ''display: inline'' on all the ruby-related elements,
  1490 			see <a href="#default-inline">Appendix A</a>
  1492 		<dt>Added <a href="#default-style">Default Style</a> rules
  1493 		<dd>
  1494 			As requested by i18nwg.
  1496 		<dt>Wrote anonymous box generation rules
  1497 		<dd>
  1498 			And defined pairing of bases and annotations.
  1499 			Should now handle all the crazy proposed permutations of HTML ruby markup.
  1500 	</dl>
  1502 <h2 class=no-num id="references">
  1503 References</h2>
  1505 <h3 class="no-num" id="normative-references">
  1506 Normative references</h3>
  1507 <!--normative-->
  1509 <h3 class="no-num" id="other-references">
  1510 Other references</h3>
  1511 <!--informative-->
  1513 <h2 class="no-num" id="index">
  1514 Index</h2>
  1515 <!--index-->
  1517 <h2 class="no-num" id="property-index">
  1518 Property index</h2>
  1519 <!-- properties -->
  1521 </body>
  1522 </html>
  1523 <!-- Keep this comment at the end of the file
  1524 Local variables:
  1525 mode: sgml
  1526 sgml-declaration:"~/SGML/HTML4.decl"
  1527 sgml-default-doctype-name:"html"
  1528 sgml-minimize-attributes:t
  1529 sgml-nofill-elements:("pre" "style" "br")
  1530 sgml-live-element-indicator:t
  1531 sgml-omittag:nil
  1532 sgml-shorttag:nil
  1533 sgml-namecase-general:t
  1534 sgml-general-insert-case:lower
  1535 sgml-always-quote-attributes:t
  1536 sgml-indent-step:nil
  1537 sgml-indent-data:t
  1538 sgml-parent-document:nil
  1539 sgml-exposed-tags:nil
  1540 sgml-local-catalogs:nil
  1541 sgml-local-ecat-files:nil
  1542 End:
  1543 -->

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