css-ruby/Overview.src.html@e9426bf43628
css-ruby/Overview.src.html
Fri, 21 Jun 2013 16:19:24 -0700
- author
- fantasai <fantasai.cvs@inkedblade.net>
- date
- Fri, 21 Jun 2013 16:19:24 -0700
- changeset 8533
- e9426bf43628
- parent 8527
- 47abcae337d2
- child 8534
- db340cae813c
- permissions
- -rw-r--r--
[css-ruby] Define line-breaking. Delete old text wrt line-stacking.
1 <!--
3 Issues:
4 white space
5 line breaking
6 bidi
8 -->
10 <!DOCTYPE html>
11 <html lang="en">
12 <head>
13 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
14 <title>CSS Ruby Module Level 1</title>
15 <link rel=contents href="#contents">
16 <link rel=index href="#index">
17 <link rel="stylesheet" type="text/css" href="../default.css">
18 <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
19 <link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS].css">
20 </head>
22 <body class="h-entry">
24 <div class="head">
25 <!--logo-->
27 <h1 class="p-name">CSS Ruby Module Level 1</h1>
29 <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>
30 <dl>
31 <dt>This version:
32 <dd><a class="u-url" href="[VERSION]">[VERSION]</a>
34 <dt>Latest version:
35 <dd><a href="http://www.w3.org/TR/[SHORTNAME]/">http://www.w3.org/TR/css3-ruby/</a>
37 <dt>Editor's draft:
38 <dd><a href="http://dev.w3.org/csswg/[SHORTNAME]/">http://dev.w3.org/csswg/[SHORTNAME]/</a>
39 (<a href="https://dvcs.w3.org/hg/csswg/log/tip/[SHORTNAME]/Overview.src.html">change log</a>)
41 <dt>Previous version:
42 <dd><a href="http://www.w3.org/TR/2011/WD-css3-ruby-20110630/">
43 http://www.w3.org/TR/2011/WD-css3-ruby-20110630/</a>
45 <dt>Issue Tracking:</dt>
46 <dd><a rel="issues" href="http://www.w3.org/Style/CSS/Tracker/products/FIXME">http://www.w3.org/Style/CSS/Tracker/products/FIXME</a>
48 <dt>Feedback:</dt>
49 <dd><a href="mailto:www-style@w3.org?subject=%5BSHORTNAME%5D%20feedback"
50 >www-style@w3.org</a>
51 with subject line “<kbd>[[SHORTNAME]]
52 <var>… message topic …</var></kbd>”
53 (<a rel="discussion" href="http://lists.w3.org/Archives/Public/www-style/"
54 >archives</a>)
56 <dt>Editors:
57 <dd class="p-author h-card vcard">
58 <a class="p-name fn u-url url" rel="author"
59 href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>,
60 <a class="p-org org h-org" href="http://www.mozilla.org/">Mozilla</a>
61 <dd class="p-author h-card vcard">
62 <a class="p-name fn u-url url" rel="author"
63 href="mailto:koji.a.ishii@mail.rakuten.com">Koji Ishii</a>,
64 <span class="p-org org">Rakuten, Inc.</span>
65 <dd class="p-author h-card vcard">
66 <a class="p-name fn u-url url" rel="author"
67 href="mailto:ishida@w3.org">Richard Ishida</a>,
68 <span class="p-org org">W3C</span>
70 <dt>Former editors:
71 <dd>Michel Suignard, Microsoft
72 <dd>Marcin Sawicki, Microsoft
73 </dl>
75 <!--copyright-->
77 <hr title="Separator for header">
78 </div>
80 <h2 class="no-num no-toc" id="abstract">Abstract</h2>
82 <p>
83 <span class="p-summary">
84 “Ruby” are short runs of text alongside the base text,
85 typically used in East Asian documents to indicate pronunciation
86 or to provide a short annotation.
87 This module describes the rendering model and formatting controls
88 related to displaying ruby annotations in CSS.
89 </span>
91 <a href="http://www.w3.org/TR/CSS/">CSS</a> is a language for describing
92 the rendering of structured documents (such as HTML and XML) on screen, on
93 paper, in speech, etc.
95 <h2 class="no-num no-toc" id="status">Status of this document</h2>
97 <!--status-->
99 <p>The following features are at risk: …
101 <h2 class="no-num no-toc" id="contents">
102 Table of Contents</h2>
104 <!--toc-->
106 <h2 id="intro">
107 Introduction</h2>
109 <p><em>This section is not normative.</em>
111 <h3 id="placement">
112 Module interactions</h3>
114 <p>This module extends the inline box model of CSS Level 2 [[!CSS21]]
115 to support ruby.
117 <p>None of the properties in this module apply to the <code>::first-line</code> or
118 <code>::first-letter</code> pseudo-elements.
120 <h3 id="values">
121 Values</h3>
123 <p>This specification follows the
124 <a href="http://www.w3.org/TR/CSS21/about.html#property-defs">CSS property
125 definition conventions</a> from [[!CSS21]]. Value types not defined in
126 this specification are defined in CSS Level 2 Revision 1 [[!CSS21]].
127 Other CSS modules may expand the definitions of these value types: for
128 example [[CSS3VAL]], when combined with this module, expands the
129 definition of the <var><length></var> value type as used in this specification.</p>
131 <p>In addition to the property-specific values listed in their definitions,
132 all properties defined in this specification also accept the
133 <a href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>
134 keyword as their property value. For readability it has not been repeated
135 explicitly.
137 <h3 id="conventions">
138 Document conventions</h3>
140 <p>Many typographical conventions in East Asian typography depend
141 on whether the character rendered is wide (CJK) or narrow (non-CJK).
142 There are a number of illustrations in this document
143 for which the following legend is used:
145 <dl>
146 <dt><img alt="Symbolic wide-cell glyph representation" width="39" height="39" src="images/fullwidth.gif">
147 <dd>Wide-cell glyph (e.g. Han) that is the <var>n</var>th character in the text run.
148 They are typically sized to 50% when used as annotations.
149 <dt><img alt="Symbolic narrow-cell glyph representation" width="19" height="39" src="images/halfwidth.gif">
150 <dd>Narrow-cell glyph (e.g. Roman) which is the <var>n</var>th glyph in the text run.
151 </dl>
153 <p>The orientation which the above symbols assume in the diagrams
154 corresponds to the orientation that the glyphs they represent
155 are intended to assume when rendered by the user agent.
156 Spacing between these characters in the diagrams is incidental,
157 unless intentionally changed to make a point.
159 <h3 id="ruby-def">
160 What is ruby?</h3>
162 <p><dfn>Ruby</dfn> is the commonly-used name for a run of text
163 that appears alongside another run of text (referred to as the “base”)
164 and serves as an annotation or a pronunciation guide associated with that run of text.
166 <p>The following figures show two examples of Ruby,
167 a simple case and one with more complicated structure.
169 <div class="example">
170 <p>In this first example, a single annotation is used to annotate the base text.
171 <div class="figure">
172 <p><img src="images/licence.png"
173 alt="Example of ruby applied on top of a Japanese expression">
174 <p class="caption">Example of ruby used in Japanese (simple case)
175 </div>
176 <p>In Japanese typography, this case is sometimes called
177 <i lang="ja">taigo</i> ruby or group-ruby (per-word ruby),
178 because the annotation as a whole is associated
179 with multi-character word (as a whole).
180 </div>
182 <div class="example">
183 <p>In this second example,
184 two levels of annotations are attached to a base sequence:
185 the hiragana characters on top refer to the pronunciation of each of the base kanji characters,
186 while the words “Keio” and “University” on the bottom are annotations describing the English translation.
187 <div class="figure">
188 <p><img src="images/ruby-univ.gif"
189 alt="Example showing complex ruby with annotation text over and under the base characters">
190 <p class="caption">Complex ruby with annotation text over and under the base characters
191 </div>
192 <p>
193 <p>Notice that to allow correct association between the hiragana characters and
194 their corresponding Kanji base characters,
195 the spacing between these Kanji characters is adjusted.
196 (This happens around the fourth Kanji character in the figure above.)
197 To avoid variable spacing between the Kanji characters in the example above
198 the hiragana annotations can be styled as a <i>collapsed annotation</i>,
199 which will look more like the group-ruby example earlier.
200 However because the base-annotation pairings are recorded in the ruby structure,
201 if the text breaks across lines, the annotation characters will stay
202 correctly paired with their respective base characters.
203 </div>
205 <p><i>Ruby</i> formatting as used in Japanese is described in JIS X-4051 [[JIS4051]] (in Japanese)
206 and in Requirements for Japanese Text Layout [[JLREQ]] (in English and Japanese)].
207 In HTML, ruby structure and markup to represent it is described
208 in the Ruby Markup Extension specification.
209 This module describes the CSS rendering model
210 and formatting controls relevant to ruby layout of such markup.
212 <h2 id="ruby-model">
213 Ruby Formatting Model</h2>
215 <p>The CSS ruby model is based on
216 the <a href="http://darobin.github.io/html-ruby/">HTML Ruby Markup Extension</a>
217 and <a href="http://www.w3.org/TR/ruby/">XHTML Ruby Annotation Recommendation</a> [[RUBY]].
218 In this model, a ruby structure consists of
219 one or more <dfn>ruby base</dfn> elements representing the base (annotated) text,
220 associated with one or more levels of <dfn>ruby annotation</dfn> elements representing the annotations.
221 The structure of ruby is similar to that of a table:
222 there are “rows” (the base text level, each annotation level)
223 and “columns” (each <i>ruby base</i> and its corresponding <i>ruby annotations</i>).
225 <p>Consecutive bases and annotations are grouped together into <dfn>ruby segments</dfn>.
226 Within a <i>ruby segment</i>, a <i>ruby annotation</i> may span multiple <i>ruby bases<i>.
228 <p class="note">In HTML, a single <code><ruby></code> element may contain multiple <i>ruby segments</i>.
229 (In the XHTML Ruby model, a single <code><ruby></code> element can only contain one <i>ruby segment</i>.)
231 <h3 id="ruby-display">
232 Ruby-specific 'display' property values</h3>
234 <p>For document languages (such as XML applications) that do not have pre-defined ruby elements,
235 authors must map document language elements to ruby elements;
236 this is done with the 'display' property.
238 <table class="propdef">
239 <tr>
240 <th>Name:
241 <td>display
242 <tr>
243 <th><a href="#values">New Values</a>:
244 <td>ruby | ruby-base | ruby-text | ruby-base-container | ruby-text-container
245 </table>
247 <p>The following new 'display' values assign ruby layout roles to an arbitrary element:
249 <dl>
250 <dt>''ruby''
251 <dd>Specifies that an element generates a <dfn title="ruby container | ruby container box">ruby container box</dfn>.
252 (Corresponds to HTML/XHTML <code><ruby></code> elements.)
253 <dt>''ruby-base''
254 <dd>Specifies that an element generates a <dfn title="ruby base box | ruby base">ruby base box</dfn>.
255 (Corresponds to HTML/XHTML <code><rb></code> elements.)
256 <dt>''ruby-text''
257 <dd>Specifies that an element generates a <dfn title="ruby annotation box | ruby annotation">ruby annotation box</dfn>.
258 (Corresponds to HTML/XHTML <code><rt></code> elements.)
259 <dt>''ruby-base-container''
260 <dd>Specifies that an element generates a <dfn title="ruby base container box | ruby base container">ruby base container box</dfn>.
261 (Corresponds to XHTML <code><rbc></code> elements; always implied in HTML.)
262 <dt>''ruby-text-container''
263 <dd>Specifies that an element generates a <dfn title="ruby annotation container box | ruby annotation container">ruby annotation container box</dfn>.
264 (Corresponds to HTML/XHTML <code><ruby></code> elements.)
265 </dl>
267 <h3 id="box-fixup">
268 Anonymous Ruby Box Generation</h3>
270 <p>The CSS model does not require that the document language
271 include elements that correspond to each of these components.
272 Missing parts of the structure are implied through the anonymous box generation rules
273 <a href="http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes">similar to those used to normalize tables</a>. [[!CSS21]]
275 <ol>
276 <li>Any in-flow block-level boxes directly contained by a
277 <i>ruby container</i>,
278 <i>ruby base container</i>,
279 <i>ruby annotation container</i>,
280 <i>ruby base box</i>,
281 or <i>ruby annotation box</i>
282 are forced to be inline-level boxes,
283 and their 'display' value computed accordingly.
284 For example,
285 the 'display' property of an in-flow element with ''display: block''
286 parented by an element with ''display: ruby-text''
287 computes to ''inline-block''.
288 This computation occurs after any intermediary anonymous-box fixup
289 (such as that required by internal table elements).
291 <li>Any consecutive sequence of <i>ruby bases</i> not parented by a <i>ruby base container</i>
292 is wrapped in an anonymous <i>ruby base container</i>.
293 Similarly, any consecutive sequence of <i>ruby annotations</i> not parented by a <i>ruby annotation container</i>
294 is wrapped in an anonymous <i>ruby annotation container</i>.
296 <li>Within each <i>ruby base container</i>,
297 each sequence of inline-level boxes is wrapped in an anonymous <i>ruby base box</i>.
298 Similarly, within each <i>ruby annotation container</i>,
299 each sequence of inline-level boxes is wrapped in an anonymous <i>ruby annotation box</i>.
301 <li>A sequence of <i>ruby base containers</i> and/or <i>ruby annotation containers</i>
302 not parented by a <i>ruby container</i>
303 is wrapped in an anonymous <i>ruby container</i>.
304 </ol>
306 <p>At this point, all ruby layout structures are properly parented,
307 and the UA can start to associate bases with their annotations.
309 <p class="note">
310 Note that the UA is not required to create any of these anonymous boxes in its internal structures,
311 as long as pairing and layout behaves as if they existed.
313 <h3 id="pairing">
314 Ruby Pairing and Annotation Levels</h3>
316 <p>Within a ruby structure,
317 each <i>ruby bases</i> are associated with <i>ruby annotations</i>
318 and vice versa.
319 A <i>ruby base</i> can be associated with at most one <i>ruby annotation</i> per annotation level.
320 If there are multiple annotation levels, it can therefore be associated with multiple <i>ruby annotations</i>.
321 A <i>ruby annotation</i> is associated with one or more <i>ruby bases</i>;
322 annotations can span multiple bases.
324 <p><dfn>Annotation pairing</dfn> is the process of associating
325 <i>ruby annotations</i> with <i>ruby bases</i>.
327 <ol>
328 <li>
329 <p>First, the ruby structure is divided into <i>ruby segments</i>,
330 each consisting of a single <i>ruby base container</i>
331 followed by one or more <i>ruby annotation containers</i>.
332 If the first child of a <i>ruby container</i> is a <i>ruby annotation container</i>,
333 an anonymous, empty <i>ruby base container</i> is assumed to exist before it.
334 Similarly, if the <i>ruby container</i> contains consecutive <i>ruby base containers</i>,
335 anonymous, empty <i>ruby annotation containers</i> are assumed to exist between them.
336 The <i>ruby base container</i> in each segment is thus associated
337 with each of the <i>ruby annotation containers</i> in that segment.
339 <p>Each <i>ruby annotation containers</i> in a <i>ruby segment</i>
340 represents one <dfn title="annotation level | level">level</dfn> of annotation:
341 the first one represents the first level of annotation,
342 the second one represents the second level of annotation,
343 and so on.
345 <li>Within each <i>ruby segment</i>,
346 each <i>ruby base box</i> in the <i>ruby base container</i>
347 is paired with one <i>ruby annotation box</i>
348 from each <i>ruby annotation container</i> in its <i>ruby segment</i>.
349 If there are not enough <i>ruby annotations</i> in a <i>ruby annotation container</i>,
350 the last one is associated with any excess <i>ruby bases</i>.
351 (If there are not any in the <i>ruby annotation container</i>, an anonymous empty one is assumed to exist.)
352 If there are not enough <i>ruby bases</i>,
353 any remaining <i>ruby annotations</i> are assumed to be associated
354 with empty, anonymous bases inserted at the end of the <i>ruby base container</i>.
356 <p>If an implementation supports ruby markup with explicit spanning
357 (e.g. XHTML Complex Ruby Annotations),
358 it must adjust the pairing rules to pair spanning annotations to multiple bases
359 appropriately.
360 </ol>
362 <p>A this point, ruby “columns” are defined,
363 each represented by a single <i>ruby base</i>
364 and associated with one <i>ruby annotation</i> (possibly an empty, anonymous one)
365 from each <i>annotation level</i>.
367 <h4 id="nested-pairing">
368 Nested Ruby</h4>
370 <p>When <i>ruby containers</i> are nested,
371 pairing begins with the deepest <i>ruby container</i>,
372 then expands out,
373 treating each <i>ruby container</i> nested within another <i>ruby container</i>
374 as a <i>ruby base</i>,
375 and associating each <i>ruby annotation</i>
376 associated with the nested <i>ruby container</i>
377 as being associated with (spanning) all of its <i>ruby bases</i>.
379 <p>Using nested <i>ruby containers</i> thus allows the representation
380 of complex spanning relationships.
382 <p class="issue">This shouldn't belong in Level 1. But HTML5 allows it, so we have to handle it. Yay HTML5.
384 <h3 id="ruby-line-breaking">
385 Ruby box and line breaking</h3>
387 <p>When there is not enough space for an entire <i>ruby container</i> to fit on the line,
388 the ruby may be broken wherever all levels allow a break.
389 In typical cases, line breaks are forbidden within each <i>ruby base</i> and <i>ruby annotation</i>,
390 so the <i>ruby container</i> can only break between adjacent <i>ruby bases</i>,
391 and only if no <i>ruby annotations</i> span those <i>ruby bases</i>.
392 Whenever ruby breaks across lines, <i>ruby annotations</i>
393 <em>must</i> stay with their respective bases.
395 <div class="figure">
396 <p><img src="images/r-break-a.gif"
397 alt="Diagram showing the line breaking opportunity in a complex ruby">
398 <p class="caption">Ruby line breaking opportunity
399 </div>
401 <p>Whether ruby can break between two adjacent <i>ruby bases</i>
402 is controlled by normal line-breaking rules for the affected text,
403 exactly as if the <i>ruby bases</i> were regular <i>inline</i> boxes.
405 <div class="example">
406 <p>For example, if two adjacent ruby bases are “蝴” and “蝶”,
407 the line may break between them,
408 because lines are normally allowed to break between two Han characters.
409 However, if 'word-break' is ''keep-all'', that line break is forbidden.
410 </div>
412 <p>Inter-base white space is significant for evaluating line break opportunities between <i>ruby bases</i>.
413 As with white space between inlines, it collapses when the line breaks there.
415 <div class="example">
416 <p>For example, given the following markup:
417 <pre><ruby><rb>one</rb> <rb>two</rb> <rt>1</rt> <rt>2</rt></ruby></pre>
418 <p>Due to the space, the line may break between “one” and “two“.
419 If the line breaks there, that space disappears,
420 in accordance with standard CSS white space processing rules. [[CSS3-TEXT]]
421 </div>
423 <p>The line <em>must not</em> break between a <i>ruby base</i> and its annotations.
425 <div class="figure">
426 <img src="images/r-break-b.gif"
427 alt='Diagram showing the line breaking opportunity in a "Bopomofo" ruby'>
428 <p class="caption">''inter-character'' ruby line breaking opportunity
429 </div>
431 <!-- <h3 id="ruby-line-height">
432 Ruby box and line stacking</h3>
434 <div class="figure">
435 <p>
436 <img class="example"
437 alt="Diagram showing the ruby text using 2 half leading"
438 src="images/rlh-a.gif" width="210" height="138" /></p>
440 <p><b>Figure 3.3.1</b>: Excluded Ruby text</p>
441 </div>
442 -->
444 <h2 id="ruby-props">
445 Ruby Properties</h2>
447 <p>The following properties are introduced to control ruby positioning and alignment.
449 <h3 id="rubypos">
450 Ruby positioning: the 'ruby-position' property</h3>
452 <table class="propdef">
453 <tr>
454 <th>Name:
455 <td><dfn>ruby-position</dfn>
456 <tr>
457 <th><a href="#values">Value</a>:
458 <td>[ over | under | inter-character ] && [ right | left ]
459 <tr>
460 <th>Initial:
461 <td>over right
462 <tr>
463 <th>Applies to:
464 <td>ruby annotation containers
465 <tr>
466 <th>Inherited:
467 <td>yes
468 <tr>
469 <th>Percentages:
470 <td>N/A
471 <tr>
472 <th>Media:
473 <td>visual
474 <tr>
475 <th>Computed value:
476 <td>specified value
477 <tr>
478 <th>Animatable:
479 <td>no
480 <tr>
481 <th>Canonical order:
482 <td><abbr title="follows order of property value definition">per grammar</abbr>
483 </table>
485 <p>This property controls position of the ruby text with respect to its base.
486 Values have the following meanings:
488 <p class="issue"><span class="issuehead">Issue-107: </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=&hdr-1-name=subject&hdr-1-query=ruby-position%3A+undesirable+default+value+%27before%27+for+complex+ruby&hdr-2-name=from&hdr-2-query=&hdr-3-name=message-id&hdr-3-query=&period_month=&period_year=&index-grp=Public__FULL&index-type=t&type-index=www-style&resultsperpage=20&sortby=date">this thread</a> and <a href="http://www.w3.org/Search/Mail/Public/advanced_search?keywords=&hdr-1-name=subject&hdr-1-query=Styling+of+complex+Ruby&hdr-2-name=from&hdr-2-query=&hdr-3-name=message-id&hdr-3-query=&period_month=&period_year=&index-grp=Public__FULL&index-type=t&type-index=public-i18n-core&resultsperpage=20&sortby=date">this one</a>.</p>
489 <dl>
490 <dt><dfn title="ruby-position:over">''over''</dfn>
491 <dd>The ruby text appears <i>over</i> the base in horizontal text.
493 <div class="figure">
494 <p><img src="images/shinkansen-top.gif"
495 alt="Diagram of ruby glyph layout in horizontal mode with ruby text appearing above the base">
496 <p class="caption">Ruby over Japanese base text in horizontal layout
497 </div>
498 </dd>
500 <dt><dfn title="ruby-position:right">''right''</dfn>
501 <dd>The ruby text appears on the right side of the base in vertical text.
502 <div class="figure">
503 <p><img src="images/shinkansen-right.gif" width="33"
504 alt="Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the right of the base">
505 <p class="caption">Ruby to the right of Japanese base text in vertical layout
506 </div>
507 </dd>
509 <dt><dfn title="ruby-position:under">''under''</dfn>
510 <dd>The ruby text appears under the base in horizontal text.
511 This is a relatively rare setting used in ideographic East Asian writing systems,
512 most easily found in educational text.
514 <div class="figure">
515 <p><img src="images/shinkansen-bottom.gif"
516 alt="Diagram of ruby glyph layout in horizontal mode with ruby text appearing below the base">
517 <p class="caption">Ruby under Japanese base text in horizontal layout
518 </div>
519 </dd>
521 <dt><dfn title="ruby-position:left">''left''</dfn>
522 <dd>The ruby text appears on the left side of the base in vertical text.
524 <div class="figure">
525 <p><img src="images/shinkansen-left.gif"
526 alt="Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the left of the base">
527 <p class="caption">Ruby to the left of Japanese base text in vertical layout
528 </div>
529 </dd>
531 <dt><dfn title="ruby-position:inter-character">''inter-character''</dfn></dt>
532 <dd>
533 <p>The ruby text appears on the right of the base in horizontal text.
534 This value forces the 'writing-mode' of the <i>ruby annotation</i> to be vertical.
536 <p>This value is provided for the special case of traditional Chinese
537 as used especially in Taiwan:
538 ruby (made of <a href="#g-bopomofo">bopomofo</a> glyphs) in that context
539 appears vertically along the right side of the base glyph,
540 even when the layout of the base characters is horizontal:
542 <div class="figure">
543 <p><img src="images/bopomofo.gif"
544 alt="Example of Taiwanese-style ruby">
545 <p class="caption">“Bopomofo” ruby in traditional Chinese
546 (ruby text shown in blue for clarity) in horizontal layout
547 </div>
548 <p class="note">
549 Note that the user agent is responsible for ensuring the correct relative alignment and positioning of the glyphs,
550 including those corresponding to the tone marks, when displaying.
551 Tone marks are spacing characters that occur (in memory) at the end of the ruby text for each base character.
552 They are usually displayed in a separate column to the right of the bopomofo characters,
553 and the height of the tone mark depends on the number of characters in the syllable.
554 One tone mark, however, is placed above the bopomofo, not to the right of it.
555 <!-- See Taiwanese requirements doc for EPUB at http://epub-revision.googlecode.com/files/EGLS_TW_eng.ppt -->
556 </dd>
557 </dl>
559 <p>If multiple <i>ruby annotation containers</i> have the same 'ruby-position',
560 they stack along the block axis,
561 with lower levels of annotation closer to the base text.
563 <h3 id="collapsed-ruby">
564 Collapsed Ruby Annotations: the 'ruby-merge' property</h3>
566 <table class="propdef">
567 <tr>
568 <th>Name:
569 <td><dfn>ruby-merge</dfn>
570 <tr>
571 <th><a href="#values">Value</a>:
572 <td>separate | collapse | auto
573 <tr>
574 <th>Initial:
575 <td>separate
576 <tr>
577 <th>Applies to:
578 <td>ruby annotation containers
579 <tr>
580 <th>Inherited:
581 <td>yes
582 <tr>
583 <th>Percentages:
584 <td>N/A
585 <tr>
586 <th>Media:
587 <td>visual
588 <tr>
589 <th>Computed value:
590 <td>specified value
591 <tr>
592 <th>Animatable:
593 <td>no
594 <tr>
595 <th>Canonical order:
596 <td><abbr title="follows order of property value definition">per grammar</abbr>
597 </table>
599 <p>
600 This property controls how ruby annotation boxes should be rendered
601 when there are more than one in a ruby container box.
603 <p>Possible values:</p>
604 <dl>
605 <dt><dfn title="ruby-merge:separate">''separate''</dfn>
606 <dd>
607 <p>
608 Each ruby annotation box is rendered in the same column(s) as its corresponding base box(es).
609 This style is called “mono ruby” in [[JLREQ]].
611 <div class="example">
612 <p>For example, the following two markups render the same:
613 <pre><ruby>無<rt>む</ruby><ruby>常<rt>じょう</ruby></pre>
614 <p>and:
615 <pre><ruby style="ruby-merge:separate"><rb>無<rb>常<rt>む<rt>じょう</ruby></pre>
616 </div>
617 </dd>
619 <dt><dfn title="ruby-merge:collapse">''collapse''</dfn>
620 <dd>
621 <p>
622 All <i>ruby annotation boxes</i> within the same <i>ruby segment</i> on the same line are concatenated,
623 and laid out as if their contents belonged to a single <i>ruby annotation box</i>
624 spanning all their associated <i>ruby base boxes.
625 This style renders similar to “group ruby” in [[JLREQ]],
626 except that <i>ruby annotations</i> are kept together with their respective <i>ruby bases</i> when breaking lines.
627 </p>
629 <div class="example">
630 <p>The following two markups render the same both characters fit on one line:
631 <pre><ruby>無常<rt>むじょう</ruby></pre>
632 <p>and:
633 <pre><ruby style="ruby-merge:collapse"><rb>無<rb>常<rt>む<rt>じょう</ruby></pre>
634 <p>However, the second one renders the same as ''ruby-position: separate''
635 when the two bases are split across lines.
636 </div>
637 </dd>
639 <dt><dfn title="ruby-merge:auto">''auto''</dfn></dt>
640 <dd>
641 <p>
642 The user agent may use any algorithm to determine how each ruby annotation box
643 is rendered to its corresponding base box.
644 <div class="example">
645 <p>
646 One possible algorithm is described as Jukugo-ruby in [[JLREQ]].
647 <p>
648 Another, more simplified algorithm of Jukugo-ruby is
649 to render as Mono-ruby if all ruby annotation boxes fit within
650 advances of their corresponding base boxes,
651 and render as Group-ruby otherwise.
652 </p>
653 </div>
654 </dd>
655 </dl>
657 <h3 id="rubyalign">
658 Ruby Text Distribution: the 'ruby-align' property</h3>
660 <table class="propdef">
661 <tr>
662 <th>Name:
663 <td><dfn>ruby-align</dfn>
664 <tr>
665 <th><a href="#values">Value</a>:
666 <td>auto | start | center |
667 distribute-letter | distribute-space
668 <tr>
669 <th>Initial:
670 <td>auto
671 <tr>
672 <th>Applies to:
673 <td>ruby bases, ruby annotations, ruby base containers, ruby annotation containers
674 <tr>
675 <th>Inherited:
676 <td>yes
677 <tr>
678 <th>Percentages:
679 <td>N/A
680 <tr>
681 <th>Media:
682 <td>visual
683 <tr>
684 <th>Computed value:
685 <td>specified value (except for initial and inherit)
686 </table>
688 <p>This property specifies how text is distributed within the various ruby boxes
689 when their text contents exactly fill their respective boxes.
691 <p>Values have the following meanings:
692 <p class="issue"><span class="issuehead">Issue: </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>
693 <dl>
694 <dt><dfn title="ruby-align:auto">''auto''</dfn></dt>
695 <dd>
696 <p>The user agent determines how the ruby contents are aligned.
697 This is the initial value.
698 The behavior recommended by [[JLREQ]] is for wide-cell ruby to be aligned in the 'distribute-space' mode:
699 <div class="figure">
700 <p><img width="145" height="91"
701 alt="Diagram of glyph layout in auto aligned ruby when ruby text is shorter than base"
702 src="images/ra-ds.gif" /><img width="145" height="91"
703 alt="Diagram of glyph layout in auto aligned ruby when ruby text is longer than base"
704 src="images/ra-ds-rb.gif" /></p>
705 <p><b>Figure 4.2.1</b>: Wide-cell text in 'auto' ruby alignment is
706 'distribute-space' justified</p>
707 </div>
709 <p>The recommended behavior for narrow-cell glyph ruby is to be
710 aligned in the 'center' mode.</p>
711 <div class="figure">
712 <p><img
713 alt="Diagram of glyph layout in auto aligned ruby when halfwidth ruby text is shorter than base"
714 width="145" height="91"
715 src="images/ra-c-h.gif" /><img
716 alt="Diagram of character layout in auto aligned ruby when ruby text is longer than narrow-width base"
717 width="145" height="91"
718 src="images/ra-c-rb-h.gif" /></p>
719 <p><b>Figure 4.2.2</b>: Narrow-width ruby text in 'auto' ruby alignment
720 is centered</p>
721 </div>
722 </dd>
724 <dt><dfn title="ruby-align:start">''start''</dfn></dt>
725 <dd>The ruby annotation content is aligned with the start edge of the base.
726 <div class="figure">
727 <p><img
728 alt="Diagram of glyph layout in left aligned ruby when ruby text is shorter than base"
729 width="145" height="91" src="images/ra-l.gif" /><img
730 width="145" height="91"
731 alt="Diagram of glyph layout in left aligned ruby when ruby text is longer than base"
732 src="images/ra-l-rb.gif" /></p>
733 <p><b>Figure 4.2.3</b>: Start ruby alignment</p>
734 </div>
735 </dd>
737 <dt><dfn title="ruby-align:center">''center''</dfn></dt>
738 <dd>The ruby text content is centered within the width of the base. If the
739 length of the base is smaller than the length of the ruby text, then the
740 base is centered within the width of the ruby text.
742 <div class="figure">
743 <p><img width="145" height="91"
744 alt="Diagram of glyph layout in center aligned ruby when ruby text is shorter than base"
745 src="images/ra-c.gif" /><img width="145" height="91"
746 alt="Diagram of glyph layout in center aligned ruby when ruby text is longer than base"
747 src="images/ra-c-rb.gif" /></p>
748 <p><b>Figure 4.2.4</b>: Center ruby alignment</p>
749 </div>
750 </dd>
752 <!--
753 <dt><strong>right</strong></dt>
754 <dd>The ruby text content is aligned with the end edge of the base.
755 <p class="issue"><span class="issuehead">Issue: </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=&hdr-1-name=subject&hdr-1-query=[CSS3+Ruby]%20left/start+and+right/end&hdr-2-name=from&hdr-2-query=&hdr-3-name=message-id&hdr-3-query=&index-grp=Member__FULL+Public__FULL&index-type=t&type-index=public-i18n-core%40w3.org&resultsperpage=20&sortby=date">this thread</a>.</p>
756 <div class="figure">
757 <p><img class="example" width="145" height="91"
758 alt="Diagram of glyph layout in right aligned ruby when ruby text is shorter than base"
759 src="images/ra-r.gif" /><img class="example" width="145" height="91"
760 alt="Diagram of glyph layout in right aligned ruby when ruby text is longer than base"
761 src="images/ra-r-rb.gif" /></p>
762 <p><b>Figure 4.2.5</b>: End ruby alignment</p>
763 </div>
764 </dd>
765 -->
767 <dt><dfn title="ruby-align:distribute-letter">''distribute-letter''</dfn></dt>
768 <dd>If the width of the ruby text is smaller than that of the base, then
769 the ruby text contents are evenly distributed across the width of the
770 base, with the first and last ruby text glyphs lining up with the
771 corresponding first and last base glyphs. If the width of the ruby text
772 is at least the width of the base, then the letters of the base are
773 evenly distributed across the width of the ruby text.
775 <div class="figure">
776 <p><img width="145" height="91"
777 alt="Diagram of glyph layout in distribute-letter aligned ruby when ruby text is shorter than base"
778 src="images/ra-dl.gif" /><img width="145" height="91"
779 alt="Diagram of glyph layout in distribute-letter aligned ruby when ruby text is longer than base"
780 src="images/ra-dl-rb.gif" /></p>
781 <p><b>Figure 4.2.6</b>: Distribute-letter ruby alignment</p>
782 </div>
783 </dd>
785 <dt><dfn title="ruby-align:distribute-space">''distribute-space''</dfn></dt>
786 <dd>If the width of the ruby text is smaller than that of the base, then
787 the ruby text contents are evenly distributed across the width of the
788 base, with a certain amount of white space preceding the first and
789 following the last character in the ruby text. That amount of white
790 space is normally equal to half the amount of inter-character space of
791 the ruby text. If the width of the ruby text is at least the width of
792 the base, then the same type of space distribution applies to the base.
793 In other words, if the base is shorter than the ruby text, the base is
794 distribute-space aligned. This type of alignment
795 is described by [[JLREQ]].
797 <div class="figure">
798 <p><img width="145" height="91"
799 alt="Diagram of glyph layout in distribute-space aligned ruby when ruby text is shorter than base"
800 src="images/ra-ds.gif" /><img width="145" height="91"
801 alt="Diagram of glyph layout in distribute-space aligned ruby when ruby text is longer than base"
802 src="images/ra-ds-rb.gif" /></p>
803 <p><b>Figure 4.2.7</b>: Distribute-space ruby alignment</p>
804 </div>
805 </dd>
807 <!--
808 <dt><strong>line-edge</strong></dt>
809 <dd>If the ruby text is not adjacent to a line edge, it is aligned as in
810 'auto'. If it is adjacent to a line edge, then it is still aligned as in
811 auto, but the side of the ruby text that touches the end of the line is
812 lined up with the corresponding edge of the base. This type of alignment
813 is described by [[JLREQ]]. This type of alignment is
814 relevant only to the scenario where the ruby text is longer than the
815 ruby base. In the other scenarios, this is just 'auto'.
816 <div class="figure">
817 <p><img class="example" width="146" height="109"
818 alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is shorter than base"
819 src="images/ra-le-l.gif" /><img class="example" width="146"
820 height="110"
821 alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is longer than base"
822 src="images/ra-le-r.gif" /></p>
823 <p><b>Figure 4.2.8</b>: Line edge ruby alignment</p>
824 </div>
825 </dd>
826 -->
827 </dl>
829 <p>For a complex ruby with spanning elements, one additional consideration is
830 required. If the spanning element spans multiple 'rows' (other rbc or rtc
831 elements), and the ruby alignment requires space distribution among the
832 'spanned' elements, a ratio must be determined among the 'columns' of spanned
833 elements. This ratio is computed by taking into consideration the widest
834 element within each column.</p>
836 <h2 id="edge-effects">
837 Edge Effects</h2>
839 <h3 id="ruby-overhang">
840 Overhanging Ruby</h3>
842 <p>
843 When <i>ruby annotation box</i> is longer than its corresponding <i>ruby base box</i>,
844 the <i>ruby annotation box</i> may partially overhang adjacent boxes.
845 </p>
846 <p>
847 This level of the specification does not define
848 how much the overhang may be allowed, and under what conditions.
849 </p>
851 <p>If the ruby text is not allowed to overhang,
852 then the ruby behaves like a traditional inline box,
853 i.e. only its own contents are rendered within its boundaries
854 and adjacent elements do not cross the box boundary:
856 <div class="figure">
857 <p><img src="images/ro-n.gif"
858 alt="Diagram showing the ruby boxes interacting with adjacent text">
859 <p class="caption">Simple ruby whose text is not allowed to overhang adjacent text
860 </div>
862 <p>However, if <i>ruby annotation</i> content is allowed to overhang adjacent elements
863 and it happens to be wider than its base,
864 then the adjacent content is partially rendered within the area of the <i>ruby container box</i>,
865 while the <i>ruby annotation</i> may partially overlap the upper blank parts of the adjacent content:
867 <div class="figure">
868 <p><img src="images/ro-a.gif"
869 alt="Diagram showing the ruby boxes interacting with adjacent text">
870 <p class="caption">Simple ruby whose text is allowed to overhang adjacent text
871 </div>
873 <p>The <i>ruby annotations</i> related to a <i>ruby base</i>
874 must never overhang another <i>ruby base</i>.
876 <p>The alignment of the contents of the base or the ruby text
877 is not affected by overhanging behavior.
878 The alignment is achieved the same way regardless of the overhang behavior setting
879 and it is computed before the space available for overlap is determined.
880 It is controlled by the 'ruby-align' property.
882 <p>This entire logic applies the same way in vertical ideographic layout,
883 only the dimension in which it works in such a layout is vertical,
884 instead of horizontal.
886 <div class="example">
887 <p>
888 The user agent may use [[JIS4051]] recommendation of
889 using one ruby text character length as the maximum overhang length.
890 Detailed rules for how ruby text can overhang adjacent characters for Japanese are described by [[JLREQ]].
891 </p>
892 </div>
894 <h3 id="line-edge">
895 Line-edge Alignment</h3>
897 <p>
898 When a <i>ruby annotation box</i> that is longer than its <i>ruby base</i>
899 is at the start or end edge of a line,
900 the user agent <em>may</em> force the side of the <i>ruby annotation</i> that touches the edge of the line
901 to align to the corresponding edge of the base.
902 This type of alignment is described by [[JLREQ]].
903 </p>
904 <p>
905 This level of the specification does not provide a mechanism to control this behavior.
906 </p>
907 <div class="figure">
908 <p><img src="images/ra-le-l.gif"
909 alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is shorter than base">
910 <img src="images/ra-le-r.gif"
911 alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is longer than base">
912 <p class="caption">Line-edge alignment
913 </div>
915 <!--
916 <h3 id="rubyover">
917 Ruby overhanging: the 'ruby-overhang' property</h3>
919 <table class="propdef">
920 <tr>
921 <th>Name:
922 <td><dfn>ruby-overhang</dfn>
923 <tr>
924 <th>Value:
925 <td>auto | start | end | none
926 <tr>
927 <th>Initial:
928 <td>none
929 <tr>
930 <th>Applies to:
931 <td>the parent of elements with display: ruby-text
932 <tr>
933 <th>Inherited:
934 <td>yes
935 <tr>
936 <th>Percentages:
937 <td>N/A
938 <tr>
939 <th>Media:
940 <td>visual
941 <tr>
942 <th>Computed value:
943 <td>specified value (except for initial and inherit)
944 </table>
946 <p>This property determines whether, and on which side, ruby text is allowed
947 to partially overhang any adjacent text in addition to its own base, when the
948 ruby text is wider than the ruby base. Note that ruby text is never allowed to
949 overhang glyphs belonging to another ruby base. <span class="issue"><span class="issuehead">Issue: </span> This rule must be broken if we are to allow support for jukugo ruby.</span> Also the user agent is free to assume
950 a maximum amount by which ruby text may overhang adjacent text. The user agent may use
951 the [[JIS4051]] recommendation of using one ruby text character
952 length as the maximum overhang length. Detailed rules for how ruby text can overhang adjacent characters for Japanese are described by [[JLREQ]].</p>
954 <p>Possible values:</p>
955 <dl>
956 <dt><strong>auto</strong></dt>
957 <dd>The ruby text can overhang text adjacent to the base on either side. [[JLREQ]] and [[JIS4051]] specify the categories of characters that
958 ruby text can overhang. The user agent is free to follow those recommendations or specify its own classes of
959 characters to overhang. This is the initial value.
960 <div class="figure">
961 <p><img class="example" width="177" height="91"
962 alt="Diagram of glyph layout in overhanging ruby" src="images/ro-a.gif" /></p>
963 <p><b>Figure 4.3.1</b>: Ruby overhanging adjacent text</p>
964 </div>
965 </dd>
966 <dt><strong>start</strong></dt>
967 <dd>The ruby text can only overhang the text that precedes it. That means, for
968 example, that ruby cannot overhang text that is to the right of it in
969 horizontal LTR layout, and it cannot overhang text that is below it in
970 vertical-ideographic layout.
971 <div class="figure">
972 <p><img class="example" width="199" height="91"
973 alt="Diagram of glyph layout when ruby overhangs the preceding glyphs only"
974 src="images/ro-s.gif" /></p>
975 <p><b>Figure 4.3.2</b>: Ruby overhanging preceding text only</p>
976 </div>
977 </dd>
978 <dt><strong>end</strong></dt>
979 <dd>The ruby text can only overhang the text that follows it. That means, for
980 example, that ruby cannot overhang text that is to the left of it in
981 horizontal LTR layout, and it cannot overhang text that is above it in
982 vertical-ideographic layout.
983 <div class="figure">
984 <p><img class="example" width="198" height="91"
985 alt="Diagram of glyph layout when ruby overhangs the following characters only"
986 src="images/ro-e.gif" /></p>
987 <p><b>Figure 4.3.3</b>: Ruby overhanging following text only</p>
988 </div>
989 </dd>
990 <dt><strong>none</strong></dt>
991 <dd>The ruby text cannot overhang any text adjacent to its base, only its
992 own base.
994 <div class="figure">
995 <p><img class="example" width="220" height="91"
996 alt="Diagram of glyph layout in non-overhanging ruby"
997 src="images/ro-n.gif" /></p>
998 <p><b>Figure 4.3.4</b>: Ruby not allowed to overhang adjacent text</p>
999 </div>
1000 </dd>
1001 </dl>
1003 <h3 id="rubyspan">
1004 Ruby annotation spanning: the 'ruby-span' property</h3>
1006 <table class="propdef">
1007 <tr>
1008 <th>Name:
1009 <td><dfn>ruby-span</dfn>
1010 <tr>
1011 <th>Value:
1012 <td>attr(x) | none
1013 <tr>
1014 <th>Initial:
1015 <td>none
1016 <tr>
1017 <th>Applies to:
1018 <td>elements with display: ruby-text
1019 <tr>
1020 <th>Inherited:
1021 <td>no
1022 <tr>
1023 <th>Percentages:
1024 <td>N/A
1025 <tr>
1026 <th>Media:
1027 <td>visual
1028 <tr>
1029 <th>Computed value:
1030 <td><number>
1031 </table>
1033 <p>This property controls the spanning behavior of annotation elements. </p>
1035 <p class="note"><span class="note-label">Note:</span> A XHTML user agent may also use the <samp>rbspan</samp>
1036 attribute to get the same effect.</p>
1038 <p>Possible values:</p>
1040 <dl>
1041 <dt><strong>attr(x)</strong></dt>
1042 <dd>The value of attribute 'x' as a string value. The string value is
1043 evaluated as a <number> to determine the number of ruby base elements to be
1044 spanned by the annotation element. If the <number> is '0', it is replaced by
1045 '1'.The <number> is the computed value. </dd>
1046 <dt>none</dt>
1047 <dd>No spanning. The computed value is '1'.</dd>
1048 </dl>
1050 <p>The following example shows an XML example using the 'display' property
1051 values associated with the 'ruby structure and the 'ruby-span' property</p>
1052 <pre class="xml">myruby { display: ruby; }
1053 myrbc { display: ruby-base-container; }
1054 myrb { display: ruby-base; }
1055 myrtc.before { display: ruby-text-container; ruby-position: before}
1056 myrtc.after { display: ruby-text-container; ruby-position: after}
1057 myrt { display: ruby-text; ruby-span: attr(rbspan); }
1058 ...
1059 <myruby>
1060 <myrbc>
1061 <myrb>10</myrb>
1062 <myrb>31</myrb>
1063 <myrb>2002</myrb>
1064 </myrbc>
1065 <myrtc class="before">
1066 <myrt>Month</myrt>
1067 <myrt>Day</myrt>
1068 <myrt>Year</myrt>
1069 </myrtc>
1070 <myrtc class="after">
1071 <myrt rbspan="3">Expiration Date</myrt>
1072 </myrtc>
1073 </myruby></pre>
1074 -->
1076 <h2 id="default-stylesheet" class="no-num">
1077 Appendix A: Default Style Sheet</h2>
1079 <p><em>This section is informative.</em>
1081 <h3 id="default-ua-ruby" class="no-num">
1082 <span class="secno">A.1</span> Supporting Ruby Layout</h3>
1084 <p>The following represents a default UA style sheet
1085 for rendering HTML and XHTML ruby markup as ruby layout:
1087 <pre>
1088 <!-- -->ruby { display: ruby; }
1089 <!-- -->rb { display: ruby-base; white-space: nowrap; }
1090 <!-- -->rt { display: ruby-text; white-space: nowrap; font-size: 50%; }
1091 <!-- -->rbc { display: ruby-base-container; }
1092 <!-- -->rtc { display: ruby-text-container; }</pre>
1094 <p>Additional rules for UAs supporting the relevant features of [[CSS3-TEXT-DECOR]] and [[CSS3-FONTS]]:
1095 <pre>rt { font-variant-east-asian: ruby; text-emphasis: none; }</pre>
1097 <p class="note">Authors should not use the above rules;
1098 a UA that supports ruby layout should provide these by default.
1100 <h3 id="default-inline" class="no-num">
1101 <span class="secno">A.2</span> Inlining Ruby Annotations</h3>
1103 <p>The following represents a sample style sheet
1104 for rendering HTML and XHTML ruby markup as inline annotations:
1106 <pre>ruby, rb, rt, rbc, rtc, rp {
1107 <!-- --> display: inline; white-space: inherit;
1108 <!-- --> font-variant-east-asian: inherit; text-emphasis: inherit; }</pre>
1110 <h3 id="default-parens" class="no-num">
1111 <span class="secno">A.3</span> Generating Parentheses</h3>
1113 <p>Unfortunately, because Selectors cannot match against text nodes,
1114 it's not possible with CSS to express rules that will automatically and correctly
1115 add parentheses to unparenthesized ruby annotations in HTML.
1116 (This is because HTML ruby allows implying the <i>ruby base</i> from raw text, without a corresponding element.)
1117 However, these rules will handle cases where either <code><rb></code>
1118 or <code><rtc></code> is used rigorously.
1120 <pre>
1121 <!-- -->/* Parens around <rtc> */
1122 <!-- -->rtc::before { content: "("; }
1123 <!-- -->rtc::after { content: ")"; }
1125 <!-- -->/* Parens before first <rt> not inside <rtc> */
1126 <!-- -->rb + rt::before,
1127 <!-- -->rtc + rt::before { content: "("; }
1129 <!-- -->/* Parens after <rt> not inside <rtc> */
1130 <!-- -->rb ~ rt:last-child::after,
1131 <!-- -->rt + rb::before { content: ")"; }
1132 <!-- -->rt + rtc::before { content: ")("; }</pre>
1134 <h2 id="glossary">
1135 Glossary</h2>
1136 <dl>
1137 <dt><a id="g-bopomofo"><strong><span
1138 lang="zh">Bopomofo</span></strong></a></dt>
1139 <dd>37 characters and 4 tone markings used as phonetics in Chinese,
1140 especially standard Mandarin.</dd>
1141 <dt><a id="g-hanja"><strong><span
1142 lang="ko">Hanja</span></strong></a></dt>
1143 <dd>Subset of the Korean writing system that utilizes ideographic
1144 characters borrowed or adapted from the Chinese writing system. Also see
1145 <a href="#g-kanji"><span lang="ja">Kanji</span></a>.</dd>
1146 <dt><a id="g-hiragana"><strong><span
1147 lang="ja">Hiragana</span></strong></a></dt>
1148 <dd>Japanese syllabic script, or character of that script. Rounded and
1149 cursive in appearance. Subset of the Japanese writing system, used together
1150 with kanji and katakana. In recent times, mostly used to write Japanese
1151 words when kanji are not available or appropriate, and word endings and
1152 particles. Also see <a
1153 href="#g-katakana"><span lang="ja">Katakana</span></a>.</dd>
1154 <dt><a id="g-ideogram"><strong>Ideograph</strong></a></dt>
1155 <dd>A character that is used to represent an idea, word, or word component,
1156 in contrast to a character from an alphabetic or syllabic script. The most
1157 well-known ideographic script is used (with some variation) in East Asia
1158 (China, Japan, Korea,...).</dd>
1159 <dt><a id="g-kana"><strong><span lang="ja">Kana</span></strong></a></dt>
1160 <dd>Collective term for hiragana and katakana.</dd>
1161 <dt><a id="g-kanji"><strong>Kanji</strong></a></dt>
1162 <dd>Japanese term for ideographs; ideographs used in Japanese. Subset of the
1163 Japanese writing system, used together with hiragana and katakana. Also see <a
1164 href="#g-hanja"><span lang="ko">Hanja</span></a>.</dd>
1165 <dt><a id="g-katakana"><strong><span
1166 lang="ja">Katakana</span></strong></a></dt>
1167 <dd>Japanese syllabic script, or character of that script. Angular in
1168 appearance. Subset of the Japanese writing system, used together with
1169 kanji and hiragana. In recent times, mainly used to write foreign words. Also see <a
1170 href="#g-hiragana"><span lang="ja">Hiragana</span></a>.</dd>
1171 <dt><a id="g-monoruby" name="g-monoruby"><strong>Mono-ruby</strong></a></dt>
1172 <dd>In Japanese typography: Ruby associated with a single character of
1173 the base text.</dd>
1174 <dt><a id="g-ruby"><strong>Ruby</strong></a></dt>
1175 <dd>A run of text that appears in the vicinity of another run of text and
1176 serves as an annotation or a pronunciation guide for that text.</dd>
1177 </dl>
1179 <h2 id="conformance">
1180 Conformance</h2>
1182 <h3 id="conventions">
1183 Document conventions</h3>
1185 <p>Conformance requirements are expressed with a combination of
1186 descriptive assertions and RFC 2119 terminology. The key words “MUST”,
1187 “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”,
1188 “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this
1189 document are to be interpreted as described in RFC 2119.
1190 However, for readability, these words do not appear in all uppercase
1191 letters in this specification.
1193 <p>All of the text of this specification is normative except sections
1194 explicitly marked as non-normative, examples, and notes. [[!RFC2119]]</p>
1196 <p>Examples in this specification are introduced with the words “for example”
1197 or are set apart from the normative text with <code>class="example"</code>,
1198 like this:
1200 <div class="example">
1201 <p>This is an example of an informative example.</p>
1202 </div>
1204 <p>Informative notes begin with the word “Note” and are set apart from the
1205 normative text with <code>class="note"</code>, like this:
1207 <p class="note">Note, this is an informative note.</p>
1209 <h3 id="conformance-classes">
1210 Conformance classes</h3>
1212 <p>Conformance to CSS Ruby Module
1213 is defined for three conformance classes:
1214 <dl>
1215 <dt><dfn title="style sheet!!as conformance class">style sheet</dfn>
1216 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
1217 style sheet</a>.
1218 <dt><dfn>renderer</dfn></dt>
1219 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
1220 that interprets the semantics of a style sheet and renders
1221 documents that use them.
1222 <dt><dfn id="authoring-tool">authoring tool</dfn></dt>
1223 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
1224 that writes a style sheet.
1225 </dl>
1227 <p>A style sheet is conformant to CSS Ruby Module
1228 if all of its statements that use syntax defined in this module are valid
1229 according to the generic CSS grammar and the individual grammars of each
1230 feature defined in this module.
1232 <p>A renderer is conformant to CSS Ruby Module
1233 if, in addition to interpreting the style sheet as defined by the
1234 appropriate specifications, it supports all the features defined
1235 by CSS Ruby Module by parsing them correctly
1236 and rendering the document accordingly. However, the inability of a
1237 UA to correctly render a document due to limitations of the device
1238 does not make the UA non-conformant. (For example, a UA is not
1239 required to render color on a monochrome monitor.)
1241 <p>An authoring tool is conformant to CSS Ruby Module
1242 if it writes style sheets that are syntactically correct according to the
1243 generic CSS grammar and the individual grammars of each feature in
1244 this module, and meet all other conformance requirements of style sheets
1245 as described in this module.
1247 <h3 id="partial">
1248 Partial implementations</h3>
1250 <p>So that authors can exploit the forward-compatible parsing rules to
1251 assign fallback values, CSS renderers <strong>must</strong>
1252 treat as invalid (and <a href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore
1253 as appropriate</a>) any at-rules, properties, property values, keywords,
1254 and other syntactic constructs for which they have no usable level of
1255 support. In particular, user agents <strong>must not</strong> selectively
1256 ignore unsupported component values and honor supported values in a single
1257 multi-value property declaration: if any value is considered invalid
1258 (as unsupported values must be), CSS requires that the entire declaration
1259 be ignored.</p>
1261 <h3 id="experimental">
1262 Experimental implementations</h3>
1264 <p>To avoid clashes with future CSS features, the CSS2.1 specification
1265 reserves a <a href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
1266 syntax</a> for proprietary and experimental extensions to CSS.
1268 <p>Prior to a specification reaching the Candidate Recommendation stage
1269 in the W3C process, all implementations of a CSS feature are considered
1270 experimental. The CSS Working Group recommends that implementations
1271 use a vendor-prefixed syntax for such features, including those in
1272 W3C Working Drafts. This avoids incompatibilities with future changes
1273 in the draft.
1274 </p>
1276 <h3 id="testing">
1277 Non-experimental implementations</h3>
1279 <p>Once a specification reaches the Candidate Recommendation stage,
1280 non-experimental implementations are possible, and implementors should
1281 release an unprefixed implementation of any CR-level feature they
1282 can demonstrate to be correctly implemented according to spec.
1284 <p>To establish and maintain the interoperability of CSS across
1285 implementations, the CSS Working Group requests that non-experimental
1286 CSS renderers submit an implementation report (and, if necessary, the
1287 testcases used for that implementation report) to the W3C before
1288 releasing an unprefixed implementation of any CSS features. Testcases
1289 submitted to W3C are subject to review and correction by the CSS
1290 Working Group.
1292 <p>Further information on submitting testcases and implementation reports
1293 can be found from on the CSS Working Group's website at
1294 <a href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
1295 Questions should be directed to the
1296 <a href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
1297 mailing list.
1299 <h2 class=no-num id="acknowledgments">
1300 Acknowledgments</h2>
1302 <p>This specification would not have been possible without the help from:</p>
1304 <p>Stephen Deach, Martin Dürst, Hideki Hiura(<span lang="ja">樋浦 秀樹</span>), Masayasu Ishikawa(<span lang="ja">石川
1305 雅康</span>), Chris
1306 Pratley, Takao Suzuki(<span lang="ja">鈴木 孝雄</span>), Frank Yung-Fong Tang, Chris Thrasher, Masafumi Yabe<span lang="ja">家辺
1307 勝文</span>), Steve Zilles.</p>
1309 <h2 class="no-num" id="changes">
1310 Changes</h2>
1312 <p>The following major changes have been made since the previous Working Draft:
1313 <dl>
1314 <dt>Remove 'ruby-span' and mentions of <code>rbspan</code>.
1315 <dd>
1316 Explicit spanning is not used in HTML ruby in favor of implicit spanning.
1317 This can't handle some pathological double-sided spanning cases,
1318 but there seems to be no requirement for these at the moment.
1319 (For implementations that support full complex XHTML Ruby,
1320 they can imply spanning from the markup the same magic way
1321 that we handle cell spanning from tables. It doesn't seem
1322 necessary to include controls this in Level 1.)
1324 <dt>Defer 'ruby-overhang' and ''ruby-align: line-end'' to Level 2.
1325 <dd>
1326 It's somewhat complicated, advanced feature.
1327 Proposal is to make this behavior UA-defined
1328 and provide some examples of acceptable options.
1330 <dt>Close issue requesting 'display: rp': use ''display: none''.
1331 <dd>
1332 The i18nwg added an issue requesting a display value for <rp> elements.
1333 They're supposed to be hidden when &tl;ruby> is displayed as ruby.
1334 But this is easily accomplished already with ''display: none''.
1336 <dt>Change 'ruby-position' values to match 'text-emphasis-position'.
1337 <dd>
1338 Other than ''inter-character'', which we need to keep,
1339 it makes more sense to align ruby positions with 'text-emphasis-position',
1340 which can correctly handle various combinations of horizontal/vertical preferences.
1342 <dt>Remove unused values of 'ruby-align'.
1343 <dd>
1344 'left', 'right', and 'end' are not needed.
1346 <dt>Added 'ruby-merge' property to control jukugo rendering.
1347 <dd>
1348 This is a stylistic effect, not a structural one;
1349 the previous model assumed that it was structural and suggested handling it by changing markup. :(
1351 <dt>Remove ''inline'' from 'ruby-position'.
1352 <dd>
1353 This is do-able via ''display: inline'' on all the ruby-related elements,
1354 see <a href="#default-inline">Appendix A</a>
1356 <dt>Added <a href="#default-style">Default Style</a> rules
1357 <dd>
1358 As requested by i18nwg.
1360 <dt>Wrote anonymous box generation rules
1361 <dd>
1362 And defined pairing of bases and annotations.
1363 Should now handle all the crazy proposed permutations of HTML ruby markup.
1364 </dl>
1366 <h2 class=no-num id="references">
1367 References</h2>
1369 <h3 class="no-num" id="normative-references">
1370 Normative references</h3>
1371 <!--normative-->
1373 <h3 class="no-num" id="other-references">
1374 Other references</h3>
1375 <!--informative-->
1377 <h2 class="no-num" id="index">
1378 Index</h2>
1379 <!--index-->
1381 <h2 class="no-num" id="property-index">
1382 Property index</h2>
1383 <!-- properties -->
1385 </body>
1386 </html>
1387 <!-- Keep this comment at the end of the file
1388 Local variables:
1389 mode: sgml
1390 sgml-declaration:"~/SGML/HTML4.decl"
1391 sgml-default-doctype-name:"html"
1392 sgml-minimize-attributes:t
1393 sgml-nofill-elements:("pre" "style" "br")
1394 sgml-live-element-indicator:t
1395 sgml-omittag:nil
1396 sgml-shorttag:nil
1397 sgml-namecase-general:t
1398 sgml-general-insert-case:lower
1399 sgml-always-quote-attributes:t
1400 sgml-indent-step:nil
1401 sgml-indent-data:t
1402 sgml-parent-document:nil
1403 sgml-exposed-tags:nil
1404 sgml-local-catalogs:nil
1405 sgml-local-ecat-files:nil
1406 End:
1407 -->
