css-ruby/Overview.src.html@b0abc18cf23b
css-ruby/Overview.src.html
Fri, 13 Sep 2013 14:26:34 -0700
- author
- fantasai <fantasai.cvs@inkedblade.net>
- date
- Fri, 13 Sep 2013 14:26:34 -0700
- changeset 9172
- b0abc18cf23b
- parent 9169
- 614ea183fabe
- child 9173
- a509cde54544
- permissions
- -rw-r--r--
[css-ruby] Remove issue wrt ruby-align, as it is no longer relevant.
1 <!--
3 Issues:
4 bidi
5 box layout/sizing
6 clean up inter-character vs. parallel layout requirements
8 Redo all examples with consistent font. (M+ 2p?)
10 -->
12 <!DOCTYPE html>
13 <html lang="en">
14 <head>
15 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
16 <title>CSS Ruby Module Level 1</title>
17 <link rel=contents href="#contents">
18 <link rel=index href="#index">
19 <link rel="stylesheet" type="text/css" href="../default.css">
20 <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
21 <link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS].css">
22 </head>
24 <body class="h-entry">
26 <div class="head">
27 <!--logo-->
29 <h1 class="p-name">CSS Ruby Module Level 1</h1>
31 <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>
32 <dl>
33 <dt>This version:
34 <dd><a class="u-url" href="[VERSION]">[VERSION]</a>
36 <dt>Latest version:
37 <dd><a href="http://www.w3.org/TR/[SHORTNAME]/">http://www.w3.org/TR/css3-ruby/</a>
39 <dt>Editor's draft:
40 <dd><a href="http://dev.w3.org/csswg/[SHORTNAME]/">http://dev.w3.org/csswg/[SHORTNAME]/</a>
41 (<a href="https://dvcs.w3.org/hg/csswg/log/tip/[SHORTNAME]/Overview.src.html">change log</a>)
43 <dt>Previous version:
44 <dd><a href="http://www.w3.org/TR/2011/WD-css3-ruby-20110630/">
45 http://www.w3.org/TR/2011/WD-css3-ruby-20110630/</a>
47 <dt>Issue Tracking:</dt>
48 <dd><a rel="issues" href="http://www.w3.org/Style/CSS/Tracker/products/FIXME">http://www.w3.org/Style/CSS/Tracker/products/FIXME</a>
50 <dt>Feedback:</dt>
51 <dd><a href="mailto:www-style@w3.org?subject=%5BSHORTNAME%5D%20feedback"
52 >www-style@w3.org</a>
53 with subject line “<kbd>[[SHORTNAME]]
54 <var>… message topic …</var></kbd>”
55 (<a rel="discussion" href="http://lists.w3.org/Archives/Public/www-style/"
56 >archives</a>)
58 <dt>Editors:
59 <dd class="p-author h-card vcard">
60 <a class="p-name fn u-url url" rel="author"
61 href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>,
62 <a class="p-org org h-org" href="http://www.mozilla.org/">Mozilla</a>
63 <dd class="p-author h-card vcard">
64 <a class="p-name fn u-url url" rel="author"
65 href="mailto:koji.a.ishii@mail.rakuten.com">Koji Ishii</a>,
66 <span class="p-org org">Rakuten, Inc.</span>
67 <dd class="p-author h-card vcard">
68 <a class="p-name fn u-url url" rel="author"
69 href="mailto:ishida@w3.org">Richard Ishida</a>,
70 <span class="p-org org">W3C</span>
72 <dt>Former editors:
73 <dd>Michel Suignard, Microsoft
74 <dd>Marcin Sawicki, Microsoft
75 </dl>
77 <!--copyright-->
79 <hr title="Separator for header">
80 </div>
82 <h2 class="no-num no-toc" id="abstract">Abstract</h2>
84 <p>
85 <span class="p-summary">
86 “Ruby” are short runs of text alongside the base text,
87 typically used in East Asian documents to indicate pronunciation
88 or to provide a short annotation.
89 This module describes the rendering model and formatting controls
90 related to displaying ruby annotations in CSS.
91 </span>
93 <a href="http://www.w3.org/TR/CSS/">CSS</a> is a language for describing
94 the rendering of structured documents (such as HTML and XML) on screen, on
95 paper, in speech, etc.
97 <h2 class="no-num no-toc" id="status">Status of this document</h2>
99 <!--status-->
101 <p>The following features are at risk: …
103 <h2 class="no-num no-toc" id="contents">
104 Table of Contents</h2>
106 <!--toc-->
108 <h2 id="intro">
109 Introduction</h2>
111 <p><em>This section is not normative.</em>
113 <h3 id="placement">
114 Module interactions</h3>
116 <p>This module extends the inline box model of CSS Level 2 [[!CSS21]]
117 to support ruby.
119 <p>None of the properties in this module apply to the <code>::first-line</code> or
120 <code>::first-letter</code> pseudo-elements.
122 <h3 id="values">
123 Values</h3>
125 <p>This specification follows the
126 <a href="http://www.w3.org/TR/CSS21/about.html#property-defs">CSS property
127 definition conventions</a> from [[!CSS21]]. Value types not defined in
128 this specification are defined in CSS Level 2 Revision 1 [[!CSS21]].
129 Other CSS modules may expand the definitions of these value types: for
130 example [[CSS3VAL]], when combined with this module, expands the
131 definition of the <var><length></var> value type as used in this specification.</p>
133 <p>In addition to the property-specific values listed in their definitions,
134 all properties defined in this specification also accept the
135 <a href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>
136 keyword as their property value. For readability it has not been repeated
137 explicitly.
139 <h3 id="conventions">
140 Document conventions</h3>
142 <p>Many typographical conventions in East Asian typography depend
143 on whether the character rendered is wide (CJK) or narrow (non-CJK).
144 There are a number of illustrations in this document
145 for which the following legend is used:
147 <dl>
148 <dt><img alt="Symbolic wide-cell glyph representation" width="39" height="39" src="images/fullwidth.gif">
149 <dd>Wide-cell glyph (e.g. Han) that is the <var>n</var>th character in the text run.
150 They are typically sized to 50% when used as annotations.
151 <dt><img alt="Symbolic narrow-cell glyph representation" width="19" height="39" src="images/halfwidth.gif">
152 <dd>Narrow-cell glyph (e.g. Roman) which is the <var>n</var>th glyph in the text run.
153 </dl>
155 <p>The orientation which the above symbols assume in the diagrams
156 corresponds to the orientation that the glyphs they represent
157 are intended to assume when rendered by the user agent.
158 Spacing between these characters in the diagrams is incidental,
159 unless intentionally changed to make a point.
161 <h3 id="ruby-def">
162 What is ruby?</h3>
164 <p><dfn>Ruby</dfn> is the commonly-used name for a run of text
165 that appears alongside another run of text (referred to as the “base”)
166 and serves as an annotation or a pronunciation guide associated with that run of text.
168 <p>The following figures show two examples of Ruby,
169 a simple case and one with more complicated structure.
171 <div class="example">
172 <p>In this first example, a single annotation is used to annotate the base text.
173 <div class="figure">
174 <p><img src="images/licence.png"
175 alt="Example of ruby applied on top of a Japanese expression">
176 <p class="caption">Example of ruby used in Japanese (simple case)
177 </div>
178 <p>In Japanese typography, this case is sometimes called
179 <i lang="ja">taigo</i> ruby or group-ruby (per-word ruby),
180 because the annotation as a whole is associated
181 with multi-character word (as a whole).
182 </div>
184 <div class="example">
185 <p>In this second example,
186 two levels of annotations are attached to a base sequence:
187 the hiragana characters on top refer to the pronunciation of each of the base kanji characters,
188 while the words “Keio” and “University” on the bottom are annotations describing the English translation.
189 <div class="figure">
190 <p><img src="images/ruby-univ.gif"
191 alt="Example showing complex ruby with annotation text over and under the base characters">
192 <p class="caption">Complex ruby with annotation text over and under the base characters
193 </div>
194 <p>
195 <p>Notice that to allow correct association between the hiragana characters and
196 their corresponding Kanji base characters,
197 the spacing between these Kanji characters is adjusted.
198 (This happens around the fourth Kanji character in the figure above.)
199 To avoid variable spacing between the Kanji characters in the example above
200 the hiragana annotations can be styled as a <i>collapsed annotation</i>,
201 which will look more like the group-ruby example earlier.
202 However because the base-annotation pairings are recorded in the ruby structure,
203 if the text breaks across lines, the annotation characters will stay
204 correctly paired with their respective base characters.
205 </div>
207 <p><i>Ruby</i> formatting as used in Japanese is described in JIS X-4051 [[JIS4051]] (in Japanese)
208 and in Requirements for Japanese Text Layout [[JLREQ]] (in English and Japanese)].
209 In HTML, ruby structure and markup to represent it is described
210 in the Ruby Markup Extension specification.
211 This module describes the CSS rendering model
212 and formatting controls relevant to ruby layout of such markup.
214 <h2 id="ruby-model">
215 Ruby Formatting Model</h2>
217 <p>The CSS ruby model is based on
218 the <a href="http://darobin.github.io/html-ruby/">HTML Ruby Markup Extension</a>
219 and <a href="http://www.w3.org/TR/ruby/">XHTML Ruby Annotation Recommendation</a> [[RUBY]].
220 In this model, a ruby structure consists of
221 one or more <dfn>ruby base</dfn> elements representing the base (annotated) text,
222 associated with one or more levels of <dfn>ruby annotation</dfn> elements representing the annotations.
223 The structure of ruby is similar to that of a table:
224 there are “rows” (the base text level, each annotation level)
225 and “columns” (each <i>ruby base</i> and its corresponding <i>ruby annotations</i>).
227 <p>Consecutive bases and annotations are grouped together into <dfn>ruby segments</dfn>.
228 Within a <i>ruby segment</i>, a <i>ruby annotation</i> may span multiple <i>ruby bases</i>.
230 <p class="note">In HTML, a single <code><ruby></code> element may contain multiple <i>ruby segments</i>.
231 (In the XHTML Ruby model, a single <code><ruby></code> element can only contain one <i>ruby segment</i>.)
233 <h3 id="ruby-display">
234 Ruby-specific 'display' property values</h3>
236 <p>For document languages (such as XML applications) that do not have pre-defined ruby elements,
237 authors must map document language elements to ruby elements;
238 this is done with the 'display' property.
240 <table class="propdef">
241 <tr>
242 <th>Name:
243 <td>display
244 <tr>
245 <th><a href="#values">New Values</a>:
246 <td>ruby | ruby-base | ruby-text | ruby-base-container | ruby-text-container
247 </table>
249 <p>The following new 'display' values assign ruby layout roles to an arbitrary element:
251 <dl>
252 <dt>''ruby''
253 <dd>Specifies that an element generates a <dfn title="ruby container | ruby container box">ruby container box</dfn>.
254 (Corresponds to HTML/XHTML <code><ruby></code> elements.)
255 <dt>''ruby-base''
256 <dd>Specifies that an element generates a <dfn title="ruby base box | ruby base">ruby base box</dfn>.
257 (Corresponds to HTML/XHTML <code><rb></code> elements.)
258 <dt>''ruby-text''
259 <dd>Specifies that an element generates a <dfn title="ruby annotation box | ruby annotation">ruby annotation box</dfn>.
260 (Corresponds to HTML/XHTML <code><rt></code> elements.)
261 <dt>''ruby-base-container''
262 <dd>Specifies that an element generates a <dfn title="ruby base container box | ruby base container">ruby base container box</dfn>.
263 (Corresponds to XHTML <code><rbc></code> elements; always implied in HTML.)
264 <dt>''ruby-text-container''
265 <dd>Specifies that an element generates a <dfn title="ruby annotation container box | ruby annotation container">ruby annotation container box</dfn>.
266 (Corresponds to HTML/XHTML <code><ruby></code> elements.)
267 </dl>
269 <h3 id="box-fixup">
270 Anonymous Ruby Box Generation</h3>
272 <p>The CSS model does not require that the document language
273 include elements that correspond to each of these components.
274 Missing parts of the structure are implied through the anonymous box generation rules
275 <a href="http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes">similar to those used to normalize tables</a>. [[!CSS21]]
277 <ol>
278 <li>Any in-flow block-level boxes directly contained by a
279 <i>ruby container</i>,
280 <i>ruby base container</i>,
281 <i>ruby annotation container</i>,
282 <i>ruby base box</i>,
283 or <i>ruby annotation box</i>
284 are forced to be inline-level boxes,
285 and their 'display' value computed accordingly.
286 For example,
287 the 'display' property of an in-flow element with ''display: block''
288 parented by an element with ''display: ruby-text''
289 computes to ''inline-block''.
290 This computation occurs after any intermediary anonymous-box fixup
291 (such as that required by internal table elements).
293 <li>Any consecutive sequence of <i>ruby bases</i> not parented by a <i>ruby base container</i>
294 is wrapped in an anonymous <i>ruby base container</i>.
295 Similarly, any consecutive sequence of <i>ruby annotations</i> not parented by a <i>ruby annotation container</i>
296 is wrapped in an anonymous <i>ruby annotation container</i>.
298 <li>Within each <i>ruby base container</i>,
299 each sequence of inline-level boxes is wrapped in an anonymous <i>ruby base box</i>.
300 Similarly, within each <i>ruby annotation container</i>,
301 each sequence of inline-level boxes is wrapped in an anonymous <i>ruby annotation box</i>.
303 <li>A sequence of <i>ruby base containers</i> and/or <i>ruby annotation containers</i>
304 not parented by a <i>ruby container</i>
305 is wrapped in an anonymous <i>ruby container</i>.
306 </ol>
308 <p>At this point, all ruby layout structures are properly parented,
309 and the UA can start to associate bases with their annotations.
311 <p class="note">
312 Note that the UA is not required to create any of these anonymous boxes in its internal structures,
313 as long as pairing and layout behaves as if they existed.
315 <h3 id="pairing">
316 Ruby Pairing and Annotation Levels</h3>
318 <p>Within a ruby structure,
319 each <i>ruby base</i> is associated with <i>ruby annotations</i>
320 and vice versa.
321 A <i>ruby base</i> can be associated with at most one <i>ruby annotation</i> per annotation level.
322 If there are multiple annotation levels, it can therefore be associated with multiple <i>ruby annotations</i>.
323 A <i>ruby annotation</i> is associated with one or more <i>ruby bases</i>;
324 annotations can span multiple bases.
326 <p><dfn>Annotation pairing</dfn> is the process of associating
327 <i>ruby annotations</i> with <i>ruby bases</i>.
329 <ol>
330 <li>
331 <p>First, the ruby structure is divided into <i>ruby segments</i>,
332 each consisting of a single <i>ruby base container</i>
333 followed by one or more <i>ruby annotation containers</i>.
334 If the first child of a <i>ruby container</i> is a <i>ruby annotation container</i>,
335 an anonymous, empty <i>ruby base container</i> is assumed to exist before it.
336 Similarly, if the <i>ruby container</i> contains consecutive <i>ruby base containers</i>,
337 anonymous, empty <i>ruby annotation containers</i> are assumed to exist between them.
338 The <i>ruby base container</i> in each segment is thus associated
339 with each of the <i>ruby annotation containers</i> in that segment.
341 <p>Each <i>ruby annotation containers</i> in a <i>ruby segment</i>
342 represents one <dfn title="annotation level | level">level</dfn> of annotation:
343 the first one represents the first level of annotation,
344 the second one represents the second level of annotation,
345 and so on.
347 <li>Within each <i>ruby segment</i>,
348 each <i>ruby base box</i> in the <i>ruby base container</i>
349 is paired with one <i>ruby annotation box</i>
350 from each <i>ruby annotation container</i> in its <i>ruby segment</i>.
351 If there are not enough <i>ruby annotations</i> in a <i>ruby annotation container</i>,
352 the last one is associated with any excess <i>ruby bases</i>.
353 (If there are not any in the <i>ruby annotation container</i>, an anonymous empty one is assumed to exist.)
354 If there are not enough <i>ruby bases</i>,
355 any remaining <i>ruby annotations</i> are assumed to be associated
356 with empty, anonymous bases inserted at the end of the <i>ruby base container</i>.
358 <p>If an implementation supports ruby markup with explicit spanning
359 (e.g. XHTML Complex Ruby Annotations),
360 it must adjust the pairing rules to pair spanning annotations to multiple bases
361 appropriately.
362 </ol>
364 <p>A this point, ruby “columns” are defined,
365 each represented by a single <i>ruby base</i>
366 and associated with one <i>ruby annotation</i> (possibly an empty, anonymous one)
367 from each <i>annotation level</i>.
369 <h4 id="nested-pairing">
370 Nested Ruby</h4>
372 <p>When <i>ruby containers</i> are nested,
373 pairing begins with the deepest <i>ruby container</i>,
374 then expands out,
375 treating each <i>ruby container</i> nested within another <i>ruby container</i>
376 essentially as a single <i>ruby base</i> in the outer <i>ruby container</i>,
377 and associating each <i>ruby annotation</i>
378 paired with the nested <i>ruby container</i>
379 as being associated with (spanning) all of its <i>ruby bases</i>.
381 <p>Using nested <i>ruby containers</i> thus allows the representation
382 of complex spanning relationships.
384 <p class="issue">This has to be Level 1 because HTML5 allows it, so we have to handle it. Yay HTML5.
386 <h3 id="autohide">
387 Autohiding Annotations</h3>
389 <p>If a <i>ruby annotation</i> has the exact same text content as its base,
390 it is <dfn title="hidden ruby annotation | hidden annotation">hidden</dfn>.
391 Hiding a <i>ruby annotation</i> does not affect annotation pairing
392 or the block-axis positioning of boxes in other <i>levels</i>.
393 However the <i>hidden annotation</i> is not visible,
394 and it has no impact on layout
395 other than to separate adjacent sequences of <i>ruby annotation boxes</i> within its level,
396 as if they belonged to separate segments
397 and the <i>hidden annotation</i>’s base were not a <i>ruby base</i> but an intervening inline.
399 <div class="example">
400 <p>This is to allow correct inlined display of annotations
401 for Japanese words that are a mix of kanji and hirangana.
402 For example, the word <i>振り仮名</i> should be inlined as
403 <p class="figure">振り仮名(ふりがな)
404 <p>and therefore marked up as
405 <pre>
406 <!-- --><ruby>
407 <!-- --> <rb>振</rb><rb>り</rb><rb>仮</rb><rb>名</rb>
408 <!-- --> <rp>(</rp><rt>ふ</rt><rt>り</rt><rt>が</rt><rt>な</rt><rp>)</rp>
409 <!-- --><ruby></pre>
410 <p>However, when displayed as ruby, the “り” should be hidden
411 <div class="figure">
412 <p><img src="images/furigana-separate.png"
413 alt="Hiragana annotations for 振り仮名 appear, each above its base character.">
414 <p class="caption">Hiragana ruby for 振り仮名
415 </div>
416 </div>
418 <p class="note">
419 Future levels of CSS Ruby may add controls for this,
420 but in this level it is always forced.
422 <p>The content comparison for this auto-hiding behavior
423 takes place prior to white space collapsing
424 and ignores elements (considers only the <code>textContent</code> of the boxes).
425 <span class="issue">Is before or after white space collapsing easier?We should do whatever is easier, as it really doesn't matter much which way to go.
427 <h3 id="white-space">
428 White Space</h3>
430 <p><i>Collapsible</i> white space within a ruby structure is discarded
431 <ul>
432 <li>at the beginning and end of a <i>ruby container</i>, <i>ruby annotation container</i>, or <i>ruby base container</i>,
433 <li>at the beginning/end of a <i>ruby annotation box</i> or <i>ruby base box</i> if white space is not its only contents,
434 <li>between a <i>ruby base container</i> and its following <i>ruby annotation container</i>,
435 <li>between <i>ruby annotation containers</i>.
436 </ul>
438 <p>Between <i>ruby segments</i>, between <i>ruby bases</i>, and between <i>ruby annotations</i>, however,
439 white space is not discarded.
441 <p>Where undiscarded white space is <i>collapsible</i>, it will collapse
442 following the standard <a href="http://www.w3.org/TR/css3-text/#white-space-rules">white space processing rules</a>. [[!CSS3TEXT]]
443 For <i>collapsible</i> white space between <i>ruby segments</i>, however,
444 the contextual text for determining collapsing behavior is given by the <i>ruby bases</i> on either side,
445 not the text on either side of the white space in the source document.
447 <div class="note">
448 <p>Note that the white space processing rules
449 cause a white space sequence containing a <i>segment break</i> (such as a line feed)
450 to <a href="http://www.w3.org/TR/css3-text/#line-break-transform">collapse to nothing</a> between CJK characters.
451 This means that CJK ruby can safely use white space for indentation of the ruby markup.
452 For example, the following markup will display without any spaces:
453 <pre>
454 <!-- --><ruby>
455 <!-- --> <rb>東</rb><rb>京</rb>
456 <!-- --> <rt>とう</rt><rt>きょう</rt>
457 <!-- --></ruby></pre>
458 <p>However, white space that does not contain a <i>segment break</i> does not collapse completely away,
459 so this markup will display with a space between the first and second ruby pairs:
460 <pre>
461 <!-- --><ruby>
462 <!-- --> <rb>東</rb> <rb>京</rb>
463 <!-- --> <rt>とう</rt> <rt>きょう</rt>
464 <!-- --></ruby></pre>
465 </div>
467 <p>Any preserved white space is then wrapped in an anonymous box belonging to
468 the <i>ruby base container</i> (if between <i>ruby bases</i>),
469 <i>ruby annotation container</i> (if between <i>ruby annotations</i>),
470 or <i>ruby container</i> (if between <i>ruby segments</i>).
471 In the latter case, the text is considered part of the <i>base level</i>.
472 Such anonynmous boxes do not take part in pairing.
473 They merely ensure separation between adjacent bases/annotations.
475 <p class="issue">Specify how these anonymous white space boxes impact layout.
477 <div class="example">
478 <p>These rules allow ruby to be used with space-separated scripts such as Latin.
479 For example,
480 <pre>
481 <!-- --><ruby>
482 <!-- --> <rb>W</rb><rb>W</rb><rb>W</rb>
483 <!-- --> <rt>World</rt> <rt>Wide</rt> <rt>Web</rt>
484 <!-- --></ruby></pre>
485 <p>They also ensure that annotated white space is preserved. For example,
486 <pre>
487 <!-- --><ruby>
488 <!-- --> <rb>Aerith</rb><rb> </rb><rb>Gainsboro</rb>
489 <!-- --> <rt>エアリス</rt><rt>・</rt><rt>ゲインズブール</rt>
490 <!-- --></ruby></pre>
491 </div>
493 <h3 id="ruby-layout">
494 Ruby layout</h3>
496 <p>When a ruby structure is laid out,
497 its base level is laid out on the line,
498 aligned according to its 'vertical-align' property
499 exactly as if its <i>bases</i> were a regular sequence of <i>inline</i> boxes.
500 Each <i>ruby base container</i> is sized and positioned
501 to contain exactly the full height of its <i>ruby bases</i>.
503 <p><i>Ruby annotations</i> associated with the base level
504 are then positioned with respect to their <i>ruby base boxes</i>
505 according to the applicable 'ruby-position' values.
506 <i>Ruby annotations</i> within a level (within a single <i>ruby container</i>)
507 are aligned to each other as if they were inline boxes
508 participating in the same inline formatting context.
509 Each <i>ruby annotation container</i> is sized and positioned
510 to contain exactly the full height of its <i>ruby annotations</i>.
512 <p>A ruby container (or fragment thereof)
513 measures as wide as the content of its widest level.
514 Similarly, <i>ruby base boxes</i> and <i>ruby annotation boxes</i>
515 within a ruby “column” have the measure of the widest content in that “column”.
516 In the case of spanning <i>annotations</i>
517 (whether actually spanning or pretending to span per 'ruby-collapse'),
518 the measures of the <i>ruby annotation box</i> and
519 the sum of its associated <i>ruby base boxes</i> must match.
521 <p>How the extra space is distributed
522 when ruby content is narrower than the measure of its box
523 is specified by the 'ruby-align' property.
525 <h4 id="inter-character-layout">
526 Inter-character ruby layout</h4>
528 <p>Inter-character annotations have special layout.
529 When 'ruby-position' indicates ''inter-character'' annotations,
530 the affected <i>annotation boxes</i>
531 are spliced into and measured as part of the layout of the base level.
532 The <i>ruby base container</i> must be sized to include both the <i>base boxes</i>
533 as well as the ''inter-character'' <i>annotation boxes</i>.
534 The affected <i>ruby annotation container</i> is similarly sized
535 so that its content box coincides with that of the <i>ruby base container</i>.
537 <p>For the purpose of laying out other levels of annotations,
538 an ''inter-character'' annotation effectively becomes part of its base.
539 <span class="issue">Or should it become a quasi-base between two bases?</span>
540 A spanning ''inter-character'' annotation is placed after
541 all the bases that it spans.
543 <h3 id="box-style">
544 Styling Ruby Boxes</h4>
546 <p>In most respects, ruby boxes can be styled similar to inline boxes.
547 However, the UA is not required to support
548 any of the box properties (borders, margins, padding),
549 any of the background properties or outline properties,
550 or any other property that illustrates the bounds of the box
551 on <i>ruby base container boxes</i>, <i>ruby annotation container boxes</i>,
552 or <a href="#nested-pairing">ruby-internal <i>ruby container boxes</i></a>.
553 The UA may implement these boxes simply as abstractions for inheritance
554 and control over the layout of their contents.
556 <p class="issue">
557 Alternatively... use margins to control offsets?
558 Or could line-height be adequate? Its centering behavior can be awkward.
560 <h3 id="line-breaks">
561 Ruby box and line breaking</h3>
563 <p>When there is not enough space for an entire <i>ruby container</i> to fit on the line,
564 the ruby may be broken wherever all levels simultaneously allow a break.
565 Ruby most often breaks between base-annotation sets,
566 but if the line-breaking rules allow it, can also break within a <i>ruby base</i>
567 (and, in parallel, its associated <i>annotation boxes</i>).
569 <p>Whenever ruby breaks across lines, <i>ruby annotations</i> must stay
570 with their respective <i>bases</i>.
571 The line <em>must not</em> break between a <i>ruby base</i> and its <i>annotations</i>,
572 even in the case of ''inter-character'' <i>annotations</i>.
574 <div class="figure">
575 <img src="images/r-break-b.gif"
576 alt='Diagram showing the line breaking opportunity in a "Bopomofo" ruby'>
577 <p class="caption">''inter-character'' ruby line breaking opportunity
578 </div>
580 <h4 id="break-between">
581 Breaking between bases</h4>
583 <p>In typical cases, <i>ruby base boxes</i> and <i>ruby annotation boxes</i>
584 are styled to forbid internal line wrapping and do not contain forced breaks.
585 (See <a href="#default-stylesheet">Appendix A</a>.)
586 In such cases the <i>ruby container</i> can only break between adjacent <i>ruby bases</i>,
587 and only if no <i>ruby annotations</i> span those <i>ruby bases</i>.
589 <div class="figure">
590 <p><img src="images/r-break-a.gif"
591 alt="Diagram showing the line breaking opportunity in a complex ruby">
592 <p class="caption">Ruby line breaking opportunity
593 </div>
595 <p>Whether ruby can break between two adjacent <i>ruby bases</i>
596 is controlled by normal line-breaking rules for the base text,
597 exactly as if the <i>ruby bases</i> were adjacent <i>inline</i> boxes.
598 (The annotations are ignored when determining soft wrap opportunities for the base level.)
600 <div class="example">
601 <p>For example, if two adjacent ruby bases are “蝴” and “蝶”,
602 the line may break between them,
603 because lines are normally allowed to break between two Han characters.
604 However, if 'word-break' is ''keep-all'', that line break is forbidden.
605 <pre><ruby>蝴<rt>hú</rt>蝶<rt>dié</rt></pre>
606 </div>
608 <p>Inter-base white space is significant for evaluating line break opportunities between <i>ruby bases</i>.
609 As with white space between inlines, it collapses when the line breaks there.
610 Similarly, annotation white space is also trimmed at a line break.
612 <div class="example">
613 <p>For example, given the following markup:
614 <pre><ruby><rb>one</rb> <rb>two</rb> <rt>1</rt> <rt>2</rt></ruby></pre>
615 <p>Due to the space, the line may break between “one” and “two“.
616 If the line breaks there, that space—and the space between “1” and “2”—disappears,
617 in accordance with standard CSS white space processing rules. [[CSS3TEXT]]
618 </div>
620 <h4 id="break-within">
621 Breaking within bases</h4>
623 <p>For longer base texts, it is sometimes appropriate to allow breaking within a base-annotation pair.
624 For example, if an English sentence is annotated with its Japanese translation,
625 allowing the text to wrap allows for reasonable line breaking behavior in the paragraph.
627 <p class="issue">
628 Insert scanned example so people don't think this is just the ramblings of an insane spec-writer.
630 <p>Line-breaking within a <i>ruby base</i> is only allowed if the 'white-space' property
631 of the <i>ruby base</i> and all its parallel <i>annotations</i> allow it,
632 and there exists a <i>soft wrap opportunity</i> <em>within</em> (i.e. not at the start or end)
633 the content of each base/annotation box.
634 Since there is no structural correspondance between fragments of content
635 within <i>ruby bases</i> and <i>annotations</i>,
636 the UA may break at any set of opportunities;
637 but it is recommended that the UA attempt to proportionally balance
638 the amount of content inside each fragment.
640 <p>There are no line breaking opportunities within ''inter-character'' <i>annotations</i>.
642 <p>Ruby alignment takes place within each fragment, after line-breaking.
644 <h3 id="ruby-bidi">
645 Bidi Reordering</h3>
647 <p class="issue">
648 Constraints:
649 Text within a ruby base must remain contiguous,
650 and bases belonging to a single annotation must remain contiguous.
651 Still figuring out exactly to enforce these limitations in a sensible manner.
653 <!--
655 <p>The Unicode bidirectional algorithm orders logically-stored text for visual presentation
656 when characters from scripts of opposing directionalities are mixed
657 within a single paragraph.
658 (See [[CSS3-WRITING-MODES]] for a more in-depth discussion of bidirectional text in CSS.)
659 Bidi reordering of ruby-annotation pairs is controlled by the ordering of the base text, as follows:
661 <h4 id="bidi-B">Proposal A</h4>
663 <p class="note">This proposal is simpler, but will require more frequent tagging of mixed-directionality content.
665 <p>To avoid the interference of the <i>annotations</i> in the ordering of base text,
666 all annotations are ignored for the purpose of resolving neutral characters in the base level.
668 <p>To preserve the correspondance of <i>ruby annotations</i>
669 to their respective <i>ruby bases</i>,
670 a few restrictions are imposed:
671 <ul>
672 <li>The contents of a <i>ruby base</i> or <i>ruby annotation</i> must remain contiguous.
673 To this end, the contents of each <i>ruby base</i> and <i>ruby annotation</i> are treated as if within a <i>bidi isolation</i>.
674 <li>For the purpose of ordering <i>ruby bases</i> within a <i>ruby container</i>,
675 each <i>ruby base</i> is treated as a strong character of its specified 'direction'.
676 (<i>Ruby annotations</i> are positioned with respect to their <i>bases</i>,
677 so are affected by reordering, but do not themselves participate in reordering.)
678 <li>All <i>bases</i> spanned by a single <i>annotation</i> must remain contiguous.
679 To this end, the embedding level of all bases spanned by a spanning <i>annotation</i>
680 is increased by two prior to reordering.
681 </ul>
683 <h4 id="bidi-B">Proposal B</h4>
685 <p class="note">This preserves some aspects of implicit bidi.
686 For example, annotating each half of "first-second" would not cause the word to reverse itself to "second-first" within an opposite-order paragraph.
688 <p>To avoid the interference of the <i>annotations</i> in the ordering of the base text,
689 all annotations are ignored for the purpose of resolving neutral characters in the base text;
690 and the base text is resolved exactly as if each <i>ruby base</i> were
691 just a normal <i>inline box</i> embedded in the <i>ruby container</i>'s inline formatting context.
693 <p>Furthermore, to preserve the correspondance of <i>ruby annotations</i>
694 to their respective <i>ruby bases</i>,
695 a few restrictions are imposed:
696 <ul>
697 <li>The contents of a <i>ruby base</i> must remain contiguous.
698 <li>All <i>bases</i> spanned by a single <i>annotation</i> must remain contiguous.
699 </ul>
700 <p>To this end, the text of <i>ruby base</i> boxes that are not <i>bidi-isolated</i>
701 must have its embedding level increased by two;
702 and if an <i>annotation</i> spans more than one <i>ruby base</i>,
703 the spanned text's embedding level
704 (or the embedding level assigned to the isolation, if the <i>ruby base</i> is <i>bidi-isolated</i>)
705 is further increased by two.
707 -->
709 <h3 id="line-height">
710 Ruby box and line stacking</h3>
712 <p>The 'line-height' property controls spacing between lines in CSS.
713 When inline content on line is shorter than the 'line-height',
714 half-leading is added on either side of the content,
715 as specificed in <a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">CSS2.1§10.8</a>. [[!CSS21]]
717 <p>In order to ensure consistent spacing of lines,
718 documents with ruby typically ensure that the 'line-height' is large enough
719 to accommodate ruby between lines of text.
720 Therefore, ordinarily, <i>ruby annotation containers</i> and <i>ruby annotation boxes</i>
721 do not contribute to the measured height of a line's inline contents;
722 any alignment (see 'vertical-align') and line-height calculations
723 are performed using only the <i>ruby base container</i>,
724 exactly as if it were a normal inline.
726 <p>However, if the 'line-height' specified on the <i>ruby container</i>
727 is less than the distance between
728 the top of the top <i>ruby annotation container</i>
729 and the bottom of the bottom <i>ruby annotation container</i>,
730 then additional leading is added
731 on the appropriate side of the <i>ruby base container</i>
732 such that if a block consisted of three lines
733 each containing ruby identical to this,
734 none of the <i>ruby containers</i> would overlap.
736 <p class="note">Note that this does not ensure that the <i>ruby annotations</i> remain within the line box.
737 It merely ensures that <em>if all lines had equal spacing</em>
738 and equivalent amounts and positioning of <i>ruby annotations</i>,
739 there would be enough room to avoid overlap.
741 <p>Authors should ensure appropriate 'line-height' and 'padding' to accommodate ruby,
742 and be particularly careful at the beginning or end of a block
743 and when a line contains inline-level content
744 (such as images, inline blocks, or elements shifted with 'vertical-align')
745 taller than the paragraph's default font size.
747 <div class="figure">
748 <p><img src="images/rlh-a.gif"
749 alt="The content of each line sits in the middle of its line height;
750 the additional space on each side is called half-leading.
751 Ruby fits between lines if it is smaller than twice the half-leading,
752 but this means that it occupies space belonging to the half-leading of the previous line.">
753 <p class="caption">Ruby annotations will often overflow the line;
754 authors should ensure content over/under a ruby-annotated line
755 is adequately spaced to leave room for the ruby.
756 </div>
758 <p class="note">More control over how ruby affects alignment and line layout
759 will be part of the CSS Line Layout Module Level 3.
760 Note, it is currently in the process of being rewritten;
761 the current drafts should not be relied upon.
763 <h2 id="ruby-props">
764 Ruby Properties</h2>
766 <p>The following properties are introduced to control ruby positioning and alignment.
768 <h3 id="rubypos">
769 Ruby positioning: the 'ruby-position' property</h3>
771 <table class="propdef">
772 <tr>
773 <th>Name:
774 <td><dfn>ruby-position</dfn>
775 <tr>
776 <th><a href="#values">Value</a>:
777 <td>[ over | under | inter-character ] && [ right | left ]
778 <tr>
779 <th>Initial:
780 <td>over right
781 <tr>
782 <th>Applies to:
783 <td>ruby annotation containers
784 <tr>
785 <th>Inherited:
786 <td>yes
787 <tr>
788 <th>Percentages:
789 <td>N/A
790 <tr>
791 <th>Media:
792 <td>visual
793 <tr>
794 <th>Computed value:
795 <td>specified value
796 <tr>
797 <th>Animatable:
798 <td>no
799 <tr>
800 <th>Canonical order:
801 <td><abbr title="follows order of property value definition">per grammar</abbr>
802 </table>
804 <p>This property controls position of the ruby text with respect to its base.
805 Values have the following meanings:
807 <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>
808 <dl>
809 <dt><dfn title="ruby-position:over">''over''</dfn>
810 <dd>The ruby text appears <i>over</i> the base in horizontal text.
812 <div class="figure">
813 <p><img src="images/shinkansen-top.gif"
814 alt="Diagram of ruby glyph layout in horizontal mode with ruby text appearing above the base">
815 <p class="caption">Ruby over Japanese base text in horizontal layout
816 </div>
817 </dd>
819 <dt><dfn title="ruby-position:right">''right''</dfn>
820 <dd>The ruby text appears on the right side of the base in vertical text.
821 <div class="figure">
822 <p><img src="images/shinkansen-right.gif" width="33"
823 alt="Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the right of the base">
824 <p class="caption">Ruby to the right of Japanese base text in vertical layout
825 </div>
826 </dd>
828 <dt><dfn title="ruby-position:under">''under''</dfn>
829 <dd>The ruby text appears under the base in horizontal text.
830 This is a relatively rare setting used in ideographic East Asian writing systems,
831 most easily found in educational text.
833 <div class="figure">
834 <p><img src="images/shinkansen-bottom.gif"
835 alt="Diagram of ruby glyph layout in horizontal mode with ruby text appearing below the base">
836 <p class="caption">Ruby under Japanese base text in horizontal layout
837 </div>
838 </dd>
840 <dt><dfn title="ruby-position:left">''left''</dfn>
841 <dd>The ruby text appears on the left side of the base in vertical text.
843 <div class="figure">
844 <p><img src="images/shinkansen-left.gif"
845 alt="Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the left of the base">
846 <p class="caption">Ruby to the left of Japanese base text in vertical layout
847 </div>
848 </dd>
850 <dt><dfn title="ruby-position:inter-character">''inter-character''</dfn></dt>
851 <dd>
852 <p>The ruby text appears on the right of the base in horizontal text.
853 This value forces the 'writing-mode' of the <i>ruby annotation</i> to be vertical.
855 <p>This value is provided for the special case of traditional Chinese
856 as used especially in Taiwan:
857 ruby (made of <a href="#g-bopomofo">bopomofo</a> glyphs) in that context
858 appears vertically along the right side of the base glyph,
859 even when the layout of the base characters is horizontal:
861 <div class="figure">
862 <p><img src="images/bopomofo.gif"
863 alt="Example of Taiwanese-style ruby">
864 <p class="caption">“Bopomofo” ruby in traditional Chinese
865 (ruby text shown in blue for clarity) in horizontal layout
866 </div>
867 <p class="note">
868 Note that the user agent is responsible for ensuring the correct relative alignment and positioning of the glyphs,
869 including those corresponding to the tone marks, when displaying.
870 Tone marks are spacing characters that occur (in memory) at the end of the ruby text for each base character.
871 They are usually displayed in a separate column to the right of the bopomofo characters,
872 and the height of the tone mark depends on the number of characters in the syllable.
873 One tone mark, however, is placed above the bopomofo, not to the right of it.
874 <!-- See Taiwanese requirements doc for EPUB at http://epub-revision.googlecode.com/files/EGLS_TW_eng.ppt -->
875 </dd>
876 </dl>
878 <p>If multiple <i>ruby annotation containers</i> have the same 'ruby-position',
879 they stack along the block axis,
880 with lower levels of annotation closer to the base text.
882 <h3 id="collapsed-ruby">
883 Collapsed Ruby Annotations: the 'ruby-merge' property</h3>
885 <table class="propdef">
886 <tr>
887 <th>Name:
888 <td><dfn>ruby-merge</dfn>
889 <tr>
890 <th><a href="#values">Value</a>:
891 <td>separate | collapse | auto
892 <tr>
893 <th>Initial:
894 <td>separate
895 <tr>
896 <th>Applies to:
897 <td>ruby annotation containers
898 <tr>
899 <th>Inherited:
900 <td>yes
901 <tr>
902 <th>Percentages:
903 <td>N/A
904 <tr>
905 <th>Media:
906 <td>visual
907 <tr>
908 <th>Computed value:
909 <td>specified value
910 <tr>
911 <th>Animatable:
912 <td>no
913 <tr>
914 <th>Canonical order:
915 <td><abbr title="follows order of property value definition">per grammar</abbr>
916 </table>
918 <p>
919 This property controls how ruby annotation boxes should be rendered
920 when there are more than one in a ruby container box.
922 <p>Possible values:</p>
923 <dl>
924 <dt><dfn title="ruby-merge:separate">''separate''</dfn>
925 <dd>
926 <p>
927 Each ruby annotation box is rendered in the same column(s) as its corresponding base box(es).
928 This style is called “mono ruby” in [[JLREQ]].
930 <div class="example">
931 <p>For example, the following two markups render the same:
932 <pre><ruby>無<rt>む</ruby><ruby>常<rt>じょう</ruby></pre>
933 <p>and:
934 <pre><ruby style="ruby-merge:separate"><rb>無<rb>常<rt>む<rt>じょう</ruby></pre>
935 </div>
936 </dd>
938 <dt><dfn title="ruby-merge:collapse">''collapse''</dfn>
939 <dd>
940 <p>
941 All <i>ruby annotation boxes</i> within the same <i>ruby segment</i> on the same line are concatenated,
942 and laid out as if their contents belonged to a single <i>ruby annotation box</i>
943 spanning all their associated <i>ruby base boxes</i>.
944 This style renders similar to “group ruby” in [[JLREQ]],
945 except that <i>ruby annotations</i> are kept together with their respective <i>ruby bases</i> when breaking lines.
946 </p>
948 <div class="example">
949 <p>The following two markups render the same both characters fit on one line:
950 <pre><ruby>無常<rt>むじょう</ruby></pre>
951 <p>and:
952 <pre><ruby style="ruby-merge:collapse"><rb>無<rb>常<rt>む<rt>じょう</ruby></pre>
953 <p>However, the second one renders the same as ''ruby-position: separate''
954 when the two bases are split across lines.
955 </div>
956 </dd>
958 <dt><dfn title="ruby-merge:auto">''auto''</dfn></dt>
959 <dd>
960 <p>
961 The user agent may use any algorithm to determine how each ruby annotation box
962 is rendered to its corresponding base box,
963 with the intention that if all annotations fit over their respective bases,
964 the result is identical to “mono ruby”,
965 but if some annotations are wider than their bases
966 the space is shared in some way
967 to avoid forcing space between bases.
968 <div class="example">
969 <p>
970 One possible algorithm is described as “jukugo ruby” in [[JLREQ]].
971 <p>
972 Another, more simplified algorithm of “jukugo ruby” is
973 to render as ''separate'' if all ruby annotation boxes fit
974 within the advances of their corresponding base boxes,
975 and render as ''collapse'' otherwise.
976 </p>
977 </div>
978 </dd>
979 </dl>
981 <h3 id="ruby-align-property"><a name="rubyalign"></a>
982 Ruby Text Distribution: the 'ruby-align' property</h3>
984 <table class="propdef">
985 <tr>
986 <th>Name:
987 <td><dfn>ruby-align</dfn>
988 <tr>
989 <th><a href="#values">Value</a>:
990 <td>start | center | space-between | space-around
991 <tr>
992 <th>Initial:
993 <td>space-around
994 <tr>
995 <th>Applies to:
996 <td>ruby bases, ruby annotations, ruby base containers, ruby annotation containers
997 <tr>
998 <th>Inherited:
999 <td>yes
1000 <tr>
1001 <th>Percentages:
1002 <td>N/A
1003 <tr>
1004 <th>Media:
1005 <td>visual
1006 <tr>
1007 <th>Computed value:
1008 <td>specified value (except for initial and inherit)
1009 </table>
1011 <p>This property specifies how text is distributed within the various ruby boxes
1012 when their contents do not exactly fill their respective boxes.
1013 Note that space distributed by 'ruby-align' is unrelated to, and independent of,
1014 any space distributed due to justification.
1016 <p>Values have the following meanings:
1017 <dl>
1018 <dt><dfn title="ruby-align:start">''start''</dfn></dt>
1019 <dd>The ruby content is aligned with the start edge of its box.
1020 <div class="figure">
1021 <p><img
1022 alt="Diagram of glyph layout in left aligned ruby when ruby text is shorter than base"
1023 width="145" height="91" src="images/ra-l.gif" /><img
1024 width="145" height="91"
1025 alt="Diagram of glyph layout in left aligned ruby when ruby text is longer than base"
1026 src="images/ra-l-rb.gif" />
1027 <p class="caption">''start'' ruby distribution
1028 </div>
1029 </dd>
1031 <dt><dfn title="ruby-align:center">''center''</dfn></dt>
1032 <dd>The ruby content is centered within its box.
1033 <div class="figure">
1034 <p><img width="145" height="91"
1035 alt="Diagram of glyph layout in center aligned ruby when ruby text is shorter than base"
1036 src="images/ra-c.gif" /><img width="145" height="91"
1037 alt="Diagram of glyph layout in center aligned ruby when ruby text is longer than base"
1038 src="images/ra-c-rb.gif" />
1039 <p class="caption">''center'' ruby distribution
1040 </div>
1041 </dd>
1043 <dt><dfn title="ruby-align:space-between">''space-between''</dfn></dt>
1044 <dd>
1045 <p>The ruby content expands as defined for normal text justification
1046 (as defined by 'text-justify'),
1047 except that if there are no <a href="http://www.w3.org/TR/css3-text/#expansion-opportunity"><i>expansion opportunities</i></a>
1048 the content is centered.
1049 <div class="figure">
1050 <p><img width="145" height="91"
1051 alt="Diagram of glyph layout in distribute-letter aligned ruby when ruby text is shorter than base"
1052 src="images/ra-dl.gif" /><img width="145" height="91"
1053 alt="Diagram of glyph layout in distribute-letter aligned ruby when ruby text is longer than base"
1054 src="images/ra-dl-rb.gif" />
1055 <p class="caption">''space-between'' ruby distribution
1056 </div>
1057 </dd>
1059 <dt><dfn title="ruby-align:space-around">''space-around''</dfn></dt>
1060 <dd>
1061 <p>As for ''space-between''
1062 except that there exists an extra <a href="http://www.w3.org/TR/css3-text/#expansion-opportunity"><i>expansion opportunity</i></a>
1063 whose space is distributed half before and half after the ruby content.
1064 <div class="example">
1065 <p>Since a typical implementation will by default define <i>expansion opportunities</i>
1066 between every adjacent pair of CJK <i>characters</i>
1067 and not between adjacent pairs of Latin <i>characters</i>,
1068 this should result in the behavior recommended by [[JLREQ]]:
1069 for wide-cell ruby content to be distributed...
1070 <div class="figure">
1071 <p><img width="145" height="91"
1072 alt="Diagram of glyph layout in auto aligned ruby when ruby text is shorter than base"
1073 src="images/ra-ds.gif" /><img width="145" height="91"
1074 alt="Diagram of glyph layout in auto aligned ruby when ruby text is longer than base"
1075 src="images/ra-ds-rb.gif" />
1076 <p class="caption">Wide-cell text in ''space-around'' ruby distribution is spaced apart
1077 </div>
1078 <p>... and narrow-cell glyph ruby to be centered.
1079 <div class="figure">
1080 <p><img
1081 alt="Diagram of glyph layout in auto aligned ruby when halfwidth ruby text is shorter than base"
1082 width="145" height="91"
1083 src="images/ra-c-h.gif" /><img
1084 alt="Diagram of character layout in auto aligned ruby when ruby text is longer than narrow-width base"
1085 width="145" height="91"
1086 src="images/ra-c-rb-h.gif" />
1087 <p class="caption">Narrow-width ruby text in ''space-around'' ruby distribution is centered
1088 </div>
1089 </div>
1090 </dd>
1091 </dl>
1093 <p class="issue">Add a paragraph explaining how to distribute space in situations with spanning annotations.
1094 <!--
1095 <p>For a complex ruby with spanning elements, one additional consideration is
1096 required. If the spanning element spans multiple 'rows' (other rbc or rtc
1097 elements), and the ruby alignment requires space distribution among the
1098 'spanned' elements, a ratio must be determined among the 'columns' of spanned
1099 elements. This ratio is computed by taking into consideration the widest
1100 element within each column.</p>
1101 -->
1102 <h2 id="edge-effects">
1103 Edge Effects</h2>
1105 <h3 id="ruby-overhang">
1106 Overhanging Ruby</h3>
1108 <p>
1109 When <i>ruby annotation box</i> is longer than its corresponding <i>ruby base box</i>,
1110 the <i>ruby annotation box</i> may partially overhang adjacent boxes.
1111 </p>
1112 <p>
1113 This level of the specification does not define
1114 how much the overhang may be allowed, and under what conditions.
1115 </p>
1117 <p>If the ruby text is not allowed to overhang,
1118 then the ruby behaves like a traditional inline box,
1119 i.e. only its own contents are rendered within its boundaries
1120 and adjacent elements do not cross the box boundary:
1122 <div class="figure">
1123 <p><img src="images/ro-n.gif"
1124 alt="Diagram showing the ruby boxes interacting with adjacent text">
1125 <p class="caption">Simple ruby whose text is not allowed to overhang adjacent text
1126 </div>
1128 <p>However, if <i>ruby annotation</i> content is allowed to overhang adjacent elements
1129 and it happens to be wider than its base,
1130 then the adjacent content is partially rendered within the area of the <i>ruby container box</i>,
1131 while the <i>ruby annotation</i> may partially overlap the upper blank parts of the adjacent content:
1133 <div class="figure">
1134 <p><img src="images/ro-a.gif"
1135 alt="Diagram showing the ruby boxes interacting with adjacent text">
1136 <p class="caption">Simple ruby whose text is allowed to overhang adjacent text
1137 </div>
1139 <p>The <i>ruby annotations</i> related to a <i>ruby base</i>
1140 must never overhang another <i>ruby base</i>.
1142 <p>The alignment of the contents of the base or the ruby text
1143 is not affected by overhanging behavior.
1144 The alignment is achieved the same way regardless of the overhang behavior setting
1145 and it is computed before the space available for overlap is determined.
1146 It is controlled by the 'ruby-align' property.
1148 <p class="issue">
1149 I suspect overhanging interacts with alignment in some cases;
1150 might need to look into this later.
1152 <p>This entire logic applies the same way in vertical ideographic layout,
1153 only the dimension in which it works in such a layout is vertical,
1154 instead of horizontal.
1156 <div class="example">
1157 <p>
1158 The user agent may use [[JIS4051]] recommendation of
1159 using one ruby text character length as the maximum overhang length.
1160 Detailed rules for how ruby text can overhang adjacent characters for Japanese are described by [[JLREQ]].
1161 </p>
1162 </div>
1164 <h3 id="line-edge">
1165 Line-edge Alignment</h3>
1167 <p>
1168 When a <i>ruby annotation box</i> that is longer than its <i>ruby base</i>
1169 is at the start or end edge of a line,
1170 the user agent <em>may</em> force the side of the <i>ruby annotation</i> that touches the edge of the line
1171 to align to the corresponding edge of the base.
1172 This type of alignment is described by [[JLREQ]].
1173 </p>
1174 <p>
1175 This level of the specification does not provide a mechanism to control this behavior.
1176 </p>
1177 <div class="figure">
1178 <p><img src="images/ra-le-l.gif"
1179 alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is shorter than base">
1180 <img src="images/ra-le-r.gif"
1181 alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is longer than base">
1182 <p class="caption">Line-edge alignment
1183 </div>
1185 <!--
1186 <h3 id="rubyover">
1187 Ruby overhanging: the 'ruby-overhang' property</h3>
1189 <table class="propdef">
1190 <tr>
1191 <th>Name:
1192 <td><dfn>ruby-overhang</dfn>
1193 <tr>
1194 <th>Value:
1195 <td>auto | start | end | none
1196 <tr>
1197 <th>Initial:
1198 <td>none
1199 <tr>
1200 <th>Applies to:
1201 <td>the parent of elements with display: ruby-text
1202 <tr>
1203 <th>Inherited:
1204 <td>yes
1205 <tr>
1206 <th>Percentages:
1207 <td>N/A
1208 <tr>
1209 <th>Media:
1210 <td>visual
1211 <tr>
1212 <th>Computed value:
1213 <td>specified value (except for initial and inherit)
1214 </table>
1216 <p>This property determines whether, and on which side, ruby text is allowed
1217 to partially overhang any adjacent text in addition to its own base, when the
1218 ruby text is wider than the ruby base. Note that ruby text is never allowed to
1219 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
1220 a maximum amount by which ruby text may overhang adjacent text. The user agent may use
1221 the [[JIS4051]] recommendation of using one ruby text character
1222 length as the maximum overhang length. Detailed rules for how ruby text can overhang adjacent characters for Japanese are described by [[JLREQ]].</p>
1224 <p>Possible values:</p>
1225 <dl>
1226 <dt><strong>auto</strong></dt>
1227 <dd>The ruby text can overhang text adjacent to the base on either side. [[JLREQ]] and [[JIS4051]] specify the categories of characters that
1228 ruby text can overhang. The user agent is free to follow those recommendations or specify its own classes of
1229 characters to overhang. This is the initial value.
1230 <div class="figure">
1231 <p><img class="example" width="177" height="91"
1232 alt="Diagram of glyph layout in overhanging ruby" src="images/ro-a.gif" /></p>
1233 <p><b>Figure 4.3.1</b>: Ruby overhanging adjacent text</p>
1234 </div>
1235 </dd>
1236 <dt><strong>start</strong></dt>
1237 <dd>The ruby text can only overhang the text that precedes it. That means, for
1238 example, that ruby cannot overhang text that is to the right of it in
1239 horizontal LTR layout, and it cannot overhang text that is below it in
1240 vertical-ideographic layout.
1241 <div class="figure">
1242 <p><img class="example" width="199" height="91"
1243 alt="Diagram of glyph layout when ruby overhangs the preceding glyphs only"
1244 src="images/ro-s.gif" /></p>
1245 <p><b>Figure 4.3.2</b>: Ruby overhanging preceding text only</p>
1246 </div>
1247 </dd>
1248 <dt><strong>end</strong></dt>
1249 <dd>The ruby text can only overhang the text that follows it. That means, for
1250 example, that ruby cannot overhang text that is to the left of it in
1251 horizontal LTR layout, and it cannot overhang text that is above it in
1252 vertical-ideographic layout.
1253 <div class="figure">
1254 <p><img class="example" width="198" height="91"
1255 alt="Diagram of glyph layout when ruby overhangs the following characters only"
1256 src="images/ro-e.gif" /></p>
1257 <p><b>Figure 4.3.3</b>: Ruby overhanging following text only</p>
1258 </div>
1259 </dd>
1260 <dt><strong>none</strong></dt>
1261 <dd>The ruby text cannot overhang any text adjacent to its base, only its
1262 own base.
1264 <div class="figure">
1265 <p><img class="example" width="220" height="91"
1266 alt="Diagram of glyph layout in non-overhanging ruby"
1267 src="images/ro-n.gif" /></p>
1268 <p><b>Figure 4.3.4</b>: Ruby not allowed to overhang adjacent text</p>
1269 </div>
1270 </dd>
1271 </dl>
1273 <h3 id="rubyspan">
1274 Ruby annotation spanning: the 'ruby-span' property</h3>
1276 <table class="propdef">
1277 <tr>
1278 <th>Name:
1279 <td><dfn>ruby-span</dfn>
1280 <tr>
1281 <th>Value:
1282 <td>attr(x) | none
1283 <tr>
1284 <th>Initial:
1285 <td>none
1286 <tr>
1287 <th>Applies to:
1288 <td>elements with display: ruby-text
1289 <tr>
1290 <th>Inherited:
1291 <td>no
1292 <tr>
1293 <th>Percentages:
1294 <td>N/A
1295 <tr>
1296 <th>Media:
1297 <td>visual
1298 <tr>
1299 <th>Computed value:
1300 <td><number>
1301 </table>
1303 <p>This property controls the spanning behavior of annotation elements. </p>
1305 <p class="note"><span class="note-label">Note:</span> A XHTML user agent may also use the <samp>rbspan</samp>
1306 attribute to get the same effect.</p>
1308 <p>Possible values:</p>
1310 <dl>
1311 <dt><strong>attr(x)</strong></dt>
1312 <dd>The value of attribute 'x' as a string value. The string value is
1313 evaluated as a <number> to determine the number of ruby base elements to be
1314 spanned by the annotation element. If the <number> is '0', it is replaced by
1315 '1'.The <number> is the computed value. </dd>
1316 <dt>none</dt>
1317 <dd>No spanning. The computed value is '1'.</dd>
1318 </dl>
1320 <p>The following example shows an XML example using the 'display' property
1321 values associated with the 'ruby structure and the 'ruby-span' property</p>
1322 <pre class="xml">myruby { display: ruby; }
1323 myrbc { display: ruby-base-container; }
1324 myrb { display: ruby-base; }
1325 myrtc.before { display: ruby-text-container; ruby-position: before}
1326 myrtc.after { display: ruby-text-container; ruby-position: after}
1327 myrt { display: ruby-text; ruby-span: attr(rbspan); }
1328 ...
1329 <myruby>
1330 <myrbc>
1331 <myrb>10</myrb>
1332 <myrb>31</myrb>
1333 <myrb>2002</myrb>
1334 </myrbc>
1335 <myrtc class="before">
1336 <myrt>Month</myrt>
1337 <myrt>Day</myrt>
1338 <myrt>Year</myrt>
1339 </myrtc>
1340 <myrtc class="after">
1341 <myrt rbspan="3">Expiration Date</myrt>
1342 </myrtc>
1343 </myruby></pre>
1344 -->
1346 <h2 id="default-stylesheet" class="no-num">
1347 Appendix A: Default Style Sheet</h2>
1349 <p><em>This section is informative.</em>
1351 <h3 id="default-ua-ruby" class="no-num">
1352 <span class="secno">A.1</span> Supporting Ruby Layout</h3>
1354 <p>The following represents a default UA style sheet
1355 for rendering HTML and XHTML ruby markup as ruby layout:
1357 <pre>
1358 <!-- -->ruby { display: ruby; }
1359 <!-- -->rb { display: ruby-base; white-space: nowrap; }
1360 <!-- -->rt { display: ruby-text; white-space: nowrap; font-size: 50%; }
1361 <!-- -->rbc { display: ruby-base-container; }
1362 <!-- -->rtc { display: ruby-text-container; }
1363 <!-- -->ruby, rb, rt, rbc, rtc { unicode-bidi: isolate; }</pre>
1365 <p>Additional rules for UAs supporting the relevant features of [[CSS3-TEXT-DECOR]] and [[CSS3-FONTS]]:
1366 <pre>rt { font-variant-east-asian: ruby; text-emphasis: none; }</pre>
1368 <p class="note">Authors should not use the above rules;
1369 a UA that supports ruby layout should provide these by default.
1371 <h3 id="default-inline" class="no-num">
1372 <span class="secno">A.2</span> Inlining Ruby Annotations</h3>
1374 <p>The following represents a sample style sheet
1375 for rendering HTML and XHTML ruby markup as inline annotations:
1377 <pre>ruby, rb, rt, rbc, rtc, rp {
1378 <!-- --> display: inline; white-space: inherit;
1379 <!-- --> font-variant-east-asian: inherit; text-emphasis: inherit; }</pre>
1381 <h3 id="default-parens" class="no-num">
1382 <span class="secno">A.3</span> Generating Parentheses</h3>
1384 <p>Unfortunately, because Selectors cannot match against text nodes,
1385 it's not possible with CSS to express rules that will automatically and correctly
1386 add parentheses to unparenthesized ruby annotations in HTML.
1387 (This is because HTML ruby allows implying the <i>ruby base</i> from raw text, without a corresponding element.)
1388 However, these rules will handle cases where either <code><rb></code>
1389 or <code><rtc></code> is used rigorously.
1391 <pre>
1392 <!-- -->/* Parens around <rtc> */
1393 <!-- -->rtc::before { content: "("; }
1394 <!-- -->rtc::after { content: ")"; }
1396 <!-- -->/* Parens before first <rt> not inside <rtc> */
1397 <!-- -->rb + rt::before,
1398 <!-- -->rtc + rt::before { content: "("; }
1400 <!-- -->/* Parens after <rt> not inside <rtc> */
1401 <!-- -->rb ~ rt:last-child::after,
1402 <!-- -->rt + rb::before { content: ")"; }
1403 <!-- -->rt + rtc::before { content: ")("; }</pre>
1405 <h2 id="glossary">
1406 Glossary</h2>
1407 <dl>
1408 <dt><a id="g-bopomofo"><strong><span
1409 lang="zh">Bopomofo</span></strong></a></dt>
1410 <dd>37 characters and 4 tone markings used as phonetics in Chinese,
1411 especially standard Mandarin.</dd>
1412 <dt><a id="g-hanja"><strong><span
1413 lang="ko">Hanja</span></strong></a></dt>
1414 <dd>Subset of the Korean writing system that utilizes ideographic
1415 characters borrowed or adapted from the Chinese writing system. Also see
1416 <a href="#g-kanji"><span lang="ja">Kanji</span></a>.</dd>
1417 <dt><a id="g-hiragana"><strong><span
1418 lang="ja">Hiragana</span></strong></a></dt>
1419 <dd>Japanese syllabic script, or character of that script. Rounded and
1420 cursive in appearance. Subset of the Japanese writing system, used together
1421 with kanji and katakana. In recent times, mostly used to write Japanese
1422 words when kanji are not available or appropriate, and word endings and
1423 particles. Also see <a
1424 href="#g-katakana"><span lang="ja">Katakana</span></a>.</dd>
1425 <dt><a id="g-ideogram"><strong>Ideograph</strong></a></dt>
1426 <dd>A character that is used to represent an idea, word, or word component,
1427 in contrast to a character from an alphabetic or syllabic script. The most
1428 well-known ideographic script is used (with some variation) in East Asia
1429 (China, Japan, Korea,...).</dd>
1430 <dt><a id="g-kana"><strong><span lang="ja">Kana</span></strong></a></dt>
1431 <dd>Collective term for hiragana and katakana.</dd>
1432 <dt><a id="g-kanji"><strong>Kanji</strong></a></dt>
1433 <dd>Japanese term for ideographs; ideographs used in Japanese. Subset of the
1434 Japanese writing system, used together with hiragana and katakana. Also see <a
1435 href="#g-hanja"><span lang="ko">Hanja</span></a>.</dd>
1436 <dt><a id="g-katakana"><strong><span
1437 lang="ja">Katakana</span></strong></a></dt>
1438 <dd>Japanese syllabic script, or character of that script. Angular in
1439 appearance. Subset of the Japanese writing system, used together with
1440 kanji and hiragana. In recent times, mainly used to write foreign words. Also see <a
1441 href="#g-hiragana"><span lang="ja">Hiragana</span></a>.</dd>
1442 <dt><a id="g-monoruby" name="g-monoruby"><strong>Mono-ruby</strong></a></dt>
1443 <dd>In Japanese typography: Ruby associated with a single character of
1444 the base text.</dd>
1445 <dt><a id="g-ruby"><strong>Ruby</strong></a></dt>
1446 <dd>A run of text that appears in the vicinity of another run of text and
1447 serves as an annotation or a pronunciation guide for that text.</dd>
1448 </dl>
1450 <h2 id="conformance">
1451 Conformance</h2>
1453 <h3 id="conventions">
1454 Document conventions</h3>
1456 <p>Conformance requirements are expressed with a combination of
1457 descriptive assertions and RFC 2119 terminology. The key words “MUST”,
1458 “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”,
1459 “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this
1460 document are to be interpreted as described in RFC 2119.
1461 However, for readability, these words do not appear in all uppercase
1462 letters in this specification.
1464 <p>All of the text of this specification is normative except sections
1465 explicitly marked as non-normative, examples, and notes. [[!RFC2119]]</p>
1467 <p>Examples in this specification are introduced with the words “for example”
1468 or are set apart from the normative text with <code>class="example"</code>,
1469 like this:
1471 <div class="example">
1472 <p>This is an example of an informative example.</p>
1473 </div>
1475 <p>Informative notes begin with the word “Note” and are set apart from the
1476 normative text with <code>class="note"</code>, like this:
1478 <p class="note">Note, this is an informative note.</p>
1480 <h3 id="conformance-classes">
1481 Conformance classes</h3>
1483 <p>Conformance to CSS Ruby Module
1484 is defined for three conformance classes:
1485 <dl>
1486 <dt><dfn title="style sheet!!as conformance class">style sheet</dfn>
1487 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
1488 style sheet</a>.
1489 <dt><dfn>renderer</dfn></dt>
1490 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
1491 that interprets the semantics of a style sheet and renders
1492 documents that use them.
1493 <dt><dfn id="authoring-tool">authoring tool</dfn></dt>
1494 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
1495 that writes a style sheet.
1496 </dl>
1498 <p>A style sheet is conformant to CSS Ruby Module
1499 if all of its statements that use syntax defined in this module are valid
1500 according to the generic CSS grammar and the individual grammars of each
1501 feature defined in this module.
1503 <p>A renderer is conformant to CSS Ruby Module
1504 if, in addition to interpreting the style sheet as defined by the
1505 appropriate specifications, it supports all the features defined
1506 by CSS Ruby Module by parsing them correctly
1507 and rendering the document accordingly. However, the inability of a
1508 UA to correctly render a document due to limitations of the device
1509 does not make the UA non-conformant. (For example, a UA is not
1510 required to render color on a monochrome monitor.)
1512 <p>An authoring tool is conformant to CSS Ruby Module
1513 if it writes style sheets that are syntactically correct according to the
1514 generic CSS grammar and the individual grammars of each feature in
1515 this module, and meet all other conformance requirements of style sheets
1516 as described in this module.
1518 <h3 id="partial">
1519 Partial implementations</h3>
1521 <p>So that authors can exploit the forward-compatible parsing rules to
1522 assign fallback values, CSS renderers <strong>must</strong>
1523 treat as invalid (and <a href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore
1524 as appropriate</a>) any at-rules, properties, property values, keywords,
1525 and other syntactic constructs for which they have no usable level of
1526 support. In particular, user agents <strong>must not</strong> selectively
1527 ignore unsupported component values and honor supported values in a single
1528 multi-value property declaration: if any value is considered invalid
1529 (as unsupported values must be), CSS requires that the entire declaration
1530 be ignored.</p>
1532 <h3 id="experimental">
1533 Experimental implementations</h3>
1535 <p>To avoid clashes with future CSS features, the CSS2.1 specification
1536 reserves a <a href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
1537 syntax</a> for proprietary and experimental extensions to CSS.
1539 <p>Prior to a specification reaching the Candidate Recommendation stage
1540 in the W3C process, all implementations of a CSS feature are considered
1541 experimental. The CSS Working Group recommends that implementations
1542 use a vendor-prefixed syntax for such features, including those in
1543 W3C Working Drafts. This avoids incompatibilities with future changes
1544 in the draft.
1545 </p>
1547 <h3 id="testing">
1548 Non-experimental implementations</h3>
1550 <p>Once a specification reaches the Candidate Recommendation stage,
1551 non-experimental implementations are possible, and implementors should
1552 release an unprefixed implementation of any CR-level feature they
1553 can demonstrate to be correctly implemented according to spec.
1555 <p>To establish and maintain the interoperability of CSS across
1556 implementations, the CSS Working Group requests that non-experimental
1557 CSS renderers submit an implementation report (and, if necessary, the
1558 testcases used for that implementation report) to the W3C before
1559 releasing an unprefixed implementation of any CSS features. Testcases
1560 submitted to W3C are subject to review and correction by the CSS
1561 Working Group.
1563 <p>Further information on submitting testcases and implementation reports
1564 can be found from on the CSS Working Group's website at
1565 <a href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
1566 Questions should be directed to the
1567 <a href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
1568 mailing list.
1570 <h2 class=no-num id="acknowledgments">
1571 Acknowledgments</h2>
1573 <p>This specification would not have been possible without the help from:</p>
1575 <p>Stephen Deach, Martin Dürst, Hideki Hiura(<span lang="ja">樋浦 秀樹</span>), Masayasu Ishikawa(<span lang="ja">石川
1576 雅康</span>), Chris
1577 Pratley, Takao Suzuki(<span lang="ja">鈴木 孝雄</span>), Frank Yung-Fong Tang, Chris Thrasher, Masafumi Yabe<span lang="ja">家辺
1578 勝文</span>), Steve Zilles.</p>
1580 <h2 class="no-num" id="changes">
1581 Changes</h2>
1583 <p>The following major changes have been made since the previous Working Draft:
1584 <dl>
1585 <dt>Remove 'ruby-span' and mentions of <code>rbspan</code>.
1586 <dd>
1587 Explicit spanning is not used in HTML ruby in favor of implicit spanning.
1588 This can't handle some pathological double-sided spanning cases,
1589 but there seems to be no requirement for these at the moment.
1590 (For implementations that support full complex XHTML Ruby,
1591 they can imply spanning from the markup the same magic way
1592 that we handle cell spanning from tables. It doesn't seem
1593 necessary to include controls this in Level 1.)
1595 <dt>Defer 'ruby-overhang' and ''ruby-align: line-end'' to Level 2.
1596 <dd>
1597 It's somewhat complicated, advanced feature.
1598 Proposal is to make this behavior UA-defined
1599 and provide some examples of acceptable options.
1601 <dt>Close issue requesting 'display: rp': use ''display: none''.
1602 <dd>
1603 The Internationalization WG added an issue requesting a display value for <rp> elements.
1604 They're supposed to be hidden when &tl;ruby> is displayed as ruby.
1605 But this is easily accomplished already with ''display: none''.
1607 <dt>Change 'ruby-position' values to match 'text-emphasis-position'.
1608 <dd>
1609 Other than ''inter-character'', which we need to keep,
1610 it makes more sense to align ruby positions with 'text-emphasis-position',
1611 which can correctly handle various combinations of horizontal/vertical preferences.
1613 <dt>Remove unused values of 'ruby-align'.
1614 <dd>
1615 ''left'', ''right'', and ''end'' are not needed.
1617 <dt>Replace ''auto'', ''distribute-letter'', and ''distribute-space'' from 'ruby-align' with ''space-between'' and ''space-around''.
1618 <dd>
1619 The ''auto'' value relied on inspecting content to determine behavior;
1620 this can be avoided by just using ''space-around'' with standard justification rules
1621 (which allow spacing between CJK but not between Latin).
1622 Replaced ''distribute-letter'' and ''distribute-space'' with
1623 ''space-between'' and ''space-around'' for consistency with distribution keywords
1624 in [[CSS3-FLEXBOX]] and [[CSS3-ALIGN]]
1625 and to avoid any links to the definition of ''text-justify: distribute''.
1627 <dt>Added 'ruby-merge' property to control jukugo rendering.
1628 <dd>
1629 This is a stylistic effect, not a structural one;
1630 the previous model assumed that it was structural and suggested handling it by changing markup. :(
1632 <dt>Remove ''inline'' from 'ruby-position'.
1633 <dd>
1634 This is do-able via ''display: inline'' on all the ruby-related elements,
1635 see <a href="#default-inline">Appendix A</a>
1637 <dt>Added <a href="#default-style">Default Style</a> rules
1638 <dd>
1639 As requested by Internationalization WG.
1641 <dt>Wrote anonymous box generation rules
1642 <dd>
1643 And defined pairing of bases and annotations.
1644 Should now handle all the crazy proposed permutations of HTML ruby markup.
1646 <dt>Defined layout of ruby
1647 <dd>
1648 Defined in detail space distribution, white space handling, line breaking, line stacking, etc.
1649 Open issue left for bidi.
1650 </dl>
1652 <h2 class=no-num id="references">
1653 References</h2>
1655 <h3 class="no-num" id="normative-references">
1656 Normative references</h3>
1657 <!--normative-->
1659 <h3 class="no-num" id="other-references">
1660 Other references</h3>
1661 <!--informative-->
1663 <h2 class="no-num" id="index">
1664 Index</h2>
1665 <!--index-->
1667 <h2 class="no-num" id="property-index">
1668 Property index</h2>
1669 <!-- properties -->
1671 </body>
1672 </html>
1673 <!-- Keep this comment at the end of the file
1674 Local variables:
1675 mode: sgml
1676 sgml-declaration:"~/SGML/HTML4.decl"
1677 sgml-default-doctype-name:"html"
1678 sgml-minimize-attributes:t
1679 sgml-nofill-elements:("pre" "style" "br")
1680 sgml-live-element-indicator:t
1681 sgml-omittag:nil
1682 sgml-shorttag:nil
1683 sgml-namecase-general:t
1684 sgml-general-insert-case:lower
1685 sgml-always-quote-attributes:t
1686 sgml-indent-step:nil
1687 sgml-indent-data:t
1688 sgml-parent-document:nil
1689 sgml-exposed-tags:nil
1690 sgml-local-catalogs:nil
1691 sgml-local-ecat-files:nil
1692 End:
1693 -->
