css-ruby/Overview.src.html@dbc00077efcc
css-ruby/Overview.src.html
Fri, 13 Sep 2013 15:24:38 -0700
- author
- fantasai <fantasai.cvs@inkedblade.net>
- date
- Fri, 13 Sep 2013 15:24:38 -0700
- changeset 9177
- dbc00077efcc
- parent 9174
- d0cb61f45f33
- child 13469
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[css-ruby] Remove issue text that's not particularly helpful...
1 <!DOCTYPE html>
2 <!--
4 Issues:
5 bidi
6 box layout/sizing
7 clean up inter-character vs. parallel layout requirements
9 Redo all examples with consistent font. (M+ 2p?)
11 -->
12 <html lang="en">
13 <head>
14 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
15 <title>CSS Ruby Module Level 1</title>
16 <link rel=contents href="#contents">
17 <link rel=index href="#index">
18 <link rel="stylesheet" type="text/css" href="../default.css">
19 <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
20 <link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS].css">
21 </head>
23 <body class="h-entry">
25 <div class="head">
26 <!--logo-->
28 <h1 class="p-name">CSS Ruby Module Level 1</h1>
30 <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>
31 <dl>
32 <dt>This version:
33 <dd><a class="u-url" href="[VERSION]">[VERSION]</a>
35 <dt>Latest version:
36 <dd><a href="http://www.w3.org/TR/[SHORTNAME]/">http://www.w3.org/TR/css3-ruby/</a>
38 <dt>Editor's draft:
39 <dd><a href="http://dev.w3.org/csswg/[SHORTNAME]/">http://dev.w3.org/csswg/[SHORTNAME]/</a>
40 (<a href="https://dvcs.w3.org/hg/csswg/log/tip/[SHORTNAME]/Overview.src.html">change log</a>)
42 <dt>Previous version:
43 <dd><a href="http://www.w3.org/TR/2011/WD-css3-ruby-20110630/">
44 http://www.w3.org/TR/2011/WD-css3-ruby-20110630/</a>
46 <dt>Issue Tracking:</dt>
47 <dd><a rel="issues" href="http://www.w3.org/Style/CSS/Tracker/products/FIXME">http://www.w3.org/Style/CSS/Tracker/products/FIXME</a>
49 <dt>Feedback:</dt>
50 <dd><a href="mailto:www-style@w3.org?subject=%5BSHORTNAME%5D%20feedback"
51 >www-style@w3.org</a>
52 with subject line “<kbd>[[SHORTNAME]]
53 <var>… message topic …</var></kbd>”
54 (<a rel="discussion" href="http://lists.w3.org/Archives/Public/www-style/"
55 >archives</a>)
57 <dt>Editors:
58 <dd class="p-author h-card vcard">
59 <a class="p-name fn u-url url" rel="author"
60 href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>,
61 <a class="p-org org h-org" href="http://www.mozilla.org/">Mozilla</a>
62 <dd class="p-author h-card vcard">
63 <a class="p-name fn u-url url" rel="author"
64 href="mailto:koji.a.ishii@mail.rakuten.com">Koji Ishii</a>,
65 <span class="p-org org">Rakuten, Inc.</span>
66 <dd class="p-author h-card vcard">
67 <a class="p-name fn u-url url" rel="author"
68 href="mailto:ishida@w3.org">Richard Ishida</a>,
69 <span class="p-org org">W3C</span>
71 <dt>Former editors:
72 <dd>Michel Suignard, Microsoft
73 <dd>Marcin Sawicki, Microsoft
74 </dl>
76 <!--copyright-->
78 <hr title="Separator for header">
79 </div>
81 <h2 class="no-num no-toc" id="abstract">Abstract</h2>
83 <p>
84 <span class="p-summary">
85 “Ruby” are short runs of text alongside the base text,
86 typically used in East Asian documents to indicate pronunciation
87 or to provide a short annotation.
88 This module describes the rendering model and formatting controls
89 related to displaying ruby annotations in CSS.
90 </span>
92 <a href="http://www.w3.org/TR/CSS/">CSS</a> is a language for describing
93 the rendering of structured documents (such as HTML and XML) on screen, on
94 paper, in speech, etc.
96 <h2 class="no-num no-toc" id="status">Status of this document</h2>
98 <!--status-->
100 <p>The following features are at risk: …
102 <h2 class="no-num no-toc" id="contents">
103 Table of Contents</h2>
105 <!--toc-->
107 <h2 id="intro">
108 Introduction</h2>
110 <p><em>This section is not normative.</em>
112 <h3 id="placement">
113 Module interactions</h3>
115 <p>This module extends the inline box model of CSS Level 2 [[!CSS21]]
116 to support ruby.
118 <p>None of the properties in this module apply to the <code>::first-line</code> or
119 <code>::first-letter</code> pseudo-elements.
121 <h3 id="values">
122 Values</h3>
124 <p>This specification follows the
125 <a href="http://www.w3.org/TR/CSS21/about.html#property-defs">CSS property
126 definition conventions</a> from [[!CSS21]]. Value types not defined in
127 this specification are defined in CSS Level 2 Revision 1 [[!CSS21]].
128 Other CSS modules may expand the definitions of these value types: for
129 example [[CSS3VAL]], when combined with this module, expands the
130 definition of the <var><length></var> value type as used in this specification.</p>
132 <p>In addition to the property-specific values listed in their definitions,
133 all properties defined in this specification also accept the
134 <a href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>
135 keyword as their property value. For readability it has not been repeated
136 explicitly.
138 <h3 id="diagram-conventions">
139 Diagram conventions</h3>
141 <p>Many typographical conventions in East Asian typography depend
142 on whether the character rendered is wide (CJK) or narrow (non-CJK).
143 There are a number of illustrations in this document
144 for which the following legend is used:
146 <dl>
147 <dt><img alt="Symbolic wide-cell glyph representation" width="39" height="39" src="images/fullwidth.gif">
148 <dd>Wide-cell glyph (e.g. Han) that is the <var>n</var>th character in the text run.
149 They are typically sized to 50% when used as annotations.
150 <dt><img alt="Symbolic narrow-cell glyph representation" width="19" height="39" src="images/halfwidth.gif">
151 <dd>Narrow-cell glyph (e.g. Roman) which is the <var>n</var>th glyph in the text run.
152 </dl>
154 <p>The orientation which the above symbols assume in the diagrams
155 corresponds to the orientation that the glyphs they represent
156 are intended to assume when rendered by the user agent.
157 Spacing between these characters in the diagrams is incidental,
158 unless intentionally changed to make a point.
160 <h3 id="ruby-def">
161 What is ruby?</h3>
163 <p><dfn>Ruby</dfn> is the commonly-used name for a run of text
164 that appears alongside another run of text (referred to as the “base”)
165 and serves as an annotation or a pronunciation guide associated with that run of text.
167 <p>The following figures show two examples of Ruby,
168 a simple case and one with more complicated structure.
170 <div class="example">
171 <p>In this first example, a single annotation is used to annotate the base text.
172 <div class="figure">
173 <p><img src="images/licence.png"
174 alt="Example of ruby applied on top of a Japanese expression">
175 <p class="caption">Example of ruby used in Japanese (simple case)
176 </div>
177 <p>In Japanese typography, this case is sometimes called
178 <i lang="ja">taigo</i> ruby or group-ruby (per-word ruby),
179 because the annotation as a whole is associated
180 with multi-character word (as a whole).
181 </div>
183 <div class="example">
184 <p>In this second example,
185 two levels of annotations are attached to a base sequence:
186 the hiragana characters on top refer to the pronunciation of each of the base kanji characters,
187 while the words “Keio” and “University” on the bottom are annotations describing the English translation.
188 <div class="figure">
189 <p><img src="images/ruby-univ.gif"
190 alt="Example showing complex ruby with annotation text over and under the base characters">
191 <p class="caption">Complex ruby with annotation text over and under the base characters
192 </div>
193 <p>
194 <p>Notice that to allow correct association between the hiragana characters and
195 their corresponding Kanji base characters,
196 the spacing between these Kanji characters is adjusted.
197 (This happens around the fourth Kanji character in the figure above.)
198 To avoid variable spacing between the Kanji characters in the example above
199 the hiragana annotations can be styled as a <i>collapsed annotation</i>,
200 which will look more like the group-ruby example earlier.
201 However because the base-annotation pairings are recorded in the ruby structure,
202 if the text breaks across lines, the annotation characters will stay
203 correctly paired with their respective base characters.
204 </div>
206 <p><i>Ruby</i> formatting as used in Japanese is described in JIS X-4051 [[JIS4051]] (in Japanese)
207 and in Requirements for Japanese Text Layout [[JLREQ]] (in English and Japanese)].
208 In HTML, ruby structure and markup to represent it is described
209 in the Ruby Markup Extension specification.
210 This module describes the CSS rendering model
211 and formatting controls relevant to ruby layout of such markup.
213 <h2 id="ruby-model">
214 Ruby Formatting Model</h2>
216 <p>The CSS ruby model is based on
217 the <a href="http://darobin.github.io/html-ruby/">HTML Ruby Markup Extension</a>
218 and <a href="http://www.w3.org/TR/ruby/">XHTML Ruby Annotation Recommendation</a> [[RUBY]].
219 In this model, a ruby structure consists of
220 one or more <dfn>ruby base</dfn> elements representing the base (annotated) text,
221 associated with one or more levels of <dfn>ruby annotation</dfn> elements representing the annotations.
222 The structure of ruby is similar to that of a table:
223 there are “rows” (the base text level, each annotation level)
224 and “columns” (each <i>ruby base</i> and its corresponding <i>ruby annotations</i>).
226 <p>Consecutive bases and annotations are grouped together into <dfn>ruby segments</dfn>.
227 Within a <i>ruby segment</i>, a <i>ruby annotation</i> may span multiple <i>ruby bases</i>.
229 <p class="note">In HTML, a single <code><ruby></code> element may contain multiple <i>ruby segments</i>.
230 (In the XHTML Ruby model, a single <code><ruby></code> element can only contain one <i>ruby segment</i>.)
232 <h3 id="ruby-display">
233 Ruby-specific 'display' property values</h3>
235 <p>For document languages (such as XML applications) that do not have pre-defined ruby elements,
236 authors must map document language elements to ruby elements;
237 this is done with the 'display' property.
239 <table class="propdef">
240 <tr>
241 <th>Name:
242 <td>display
243 <tr>
244 <th><a href="#values">New Values</a>:
245 <td>ruby | ruby-base | ruby-text | ruby-base-container | ruby-text-container
246 </table>
248 <p>The following new 'display' values assign ruby layout roles to an arbitrary element:
250 <dl>
251 <dt>''ruby''
252 <dd>Specifies that an element generates a <dfn title="ruby container | ruby container box">ruby container box</dfn>.
253 (Corresponds to HTML/XHTML <code><ruby></code> elements.)
254 <dt>''ruby-base''
255 <dd>Specifies that an element generates a <dfn title="ruby base box | ruby base">ruby base box</dfn>.
256 (Corresponds to HTML/XHTML <code><rb></code> elements.)
257 <dt>''ruby-text''
258 <dd>Specifies that an element generates a <dfn title="ruby annotation box | ruby annotation">ruby annotation box</dfn>.
259 (Corresponds to HTML/XHTML <code><rt></code> elements.)
260 <dt>''ruby-base-container''
261 <dd>Specifies that an element generates a <dfn title="ruby base container box | ruby base container">ruby base container box</dfn>.
262 (Corresponds to XHTML <code><rbc></code> elements; always implied in HTML.)
263 <dt>''ruby-text-container''
264 <dd>Specifies that an element generates a <dfn title="ruby annotation container box | ruby annotation container">ruby annotation container box</dfn>.
265 (Corresponds to HTML/XHTML <code><ruby></code> elements.)
266 </dl>
268 <h3 id="box-fixup">
269 Anonymous Ruby Box Generation</h3>
271 <p>The CSS model does not require that the document language
272 include elements that correspond to each of these components.
273 Missing parts of the structure are implied through the anonymous box generation rules
274 <a href="http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes">similar to those used to normalize tables</a>. [[!CSS21]]
276 <ol>
277 <li>Any in-flow block-level boxes directly contained by a
278 <i>ruby container</i>,
279 <i>ruby base container</i>,
280 <i>ruby annotation container</i>,
281 <i>ruby base box</i>,
282 or <i>ruby annotation box</i>
283 are forced to be inline-level boxes,
284 and their 'display' value computed accordingly.
285 For example,
286 the 'display' property of an in-flow element with ''display: block''
287 parented by an element with ''display: ruby-text''
288 computes to ''inline-block''.
289 This computation occurs after any intermediary anonymous-box fixup
290 (such as that required by internal table elements).
292 <li>Any consecutive sequence of <i>ruby bases</i> not parented by a <i>ruby base container</i>
293 is wrapped in an anonymous <i>ruby base container</i>.
294 Similarly, any consecutive sequence of <i>ruby annotations</i> not parented by a <i>ruby annotation container</i>
295 is wrapped in an anonymous <i>ruby annotation container</i>.
297 <li>Within each <i>ruby base container</i>,
298 each sequence of inline-level boxes is wrapped in an anonymous <i>ruby base box</i>.
299 Similarly, within each <i>ruby annotation container</i>,
300 each sequence of inline-level boxes is wrapped in an anonymous <i>ruby annotation box</i>.
302 <li>A sequence of <i>ruby base containers</i> and/or <i>ruby annotation containers</i>
303 not parented by a <i>ruby container</i>
304 is wrapped in an anonymous <i>ruby container</i>.
305 </ol>
307 <p>At this point, all ruby layout structures are properly parented,
308 and the UA can start to associate bases with their annotations.
310 <p class="note">
311 Note that the UA is not required to create any of these anonymous boxes in its internal structures,
312 as long as pairing and layout behaves as if they existed.
314 <h3 id="pairing">
315 Ruby Pairing and Annotation Levels</h3>
317 <p>Within a ruby structure,
318 each <i>ruby base</i> is associated with <i>ruby annotations</i>
319 and vice versa.
320 A <i>ruby base</i> can be associated with at most one <i>ruby annotation</i> per annotation level.
321 If there are multiple annotation levels, it can therefore be associated with multiple <i>ruby annotations</i>.
322 A <i>ruby annotation</i> is associated with one or more <i>ruby bases</i>;
323 annotations can span multiple bases.
325 <p><dfn>Annotation pairing</dfn> is the process of associating
326 <i>ruby annotations</i> with <i>ruby bases</i>.
328 <ol>
329 <li>
330 <p>First, the ruby structure is divided into <i>ruby segments</i>,
331 each consisting of a single <i>ruby base container</i>
332 followed by one or more <i>ruby annotation containers</i>.
333 If the first child of a <i>ruby container</i> is a <i>ruby annotation container</i>,
334 an anonymous, empty <i>ruby base container</i> is assumed to exist before it.
335 Similarly, if the <i>ruby container</i> contains consecutive <i>ruby base containers</i>,
336 anonymous, empty <i>ruby annotation containers</i> are assumed to exist between them.
337 The <i>ruby base container</i> in each segment is thus associated
338 with each of the <i>ruby annotation containers</i> in that segment.
340 <p>Each <i>ruby annotation containers</i> in a <i>ruby segment</i>
341 represents one <dfn title="annotation level | level">level</dfn> of annotation:
342 the first one represents the first level of annotation,
343 the second one represents the second level of annotation,
344 and so on.
346 <li>Within each <i>ruby segment</i>,
347 each <i>ruby base box</i> in the <i>ruby base container</i>
348 is paired with one <i>ruby annotation box</i>
349 from each <i>ruby annotation container</i> in its <i>ruby segment</i>.
350 If there are not enough <i>ruby annotations</i> in a <i>ruby annotation container</i>,
351 the last one is associated with any excess <i>ruby bases</i>.
352 (If there are not any in the <i>ruby annotation container</i>, an anonymous empty one is assumed to exist.)
353 If there are not enough <i>ruby bases</i>,
354 any remaining <i>ruby annotations</i> are assumed to be associated
355 with empty, anonymous bases inserted at the end of the <i>ruby base container</i>.
357 <p>If an implementation supports ruby markup with explicit spanning
358 (e.g. XHTML Complex Ruby Annotations),
359 it must adjust the pairing rules to pair spanning annotations to multiple bases
360 appropriately.
361 </ol>
363 <p>A this point, ruby “columns” are defined,
364 each represented by a single <i>ruby base</i>
365 and associated with one <i>ruby annotation</i> (possibly an empty, anonymous one)
366 from each <i>annotation level</i>.
368 <h4 id="nested-pairing">
369 Nested Ruby</h4>
371 <p>When <i>ruby containers</i> are nested,
372 pairing begins with the deepest <i>ruby container</i>,
373 then expands out,
374 treating each <i>ruby container</i> nested within another <i>ruby container</i>
375 essentially as a single <i>ruby base</i> in the outer <i>ruby container</i>,
376 and associating each <i>ruby annotation</i>
377 paired with the nested <i>ruby container</i>
378 as being associated with (spanning) all of its <i>ruby bases</i>.
380 <p>Using nested <i>ruby containers</i> thus allows the representation
381 of complex spanning relationships.
383 <p class="issue">This has to be Level 1 because HTML5 allows it, so we have to handle it. Yay HTML5.
385 <h3 id="autohide">
386 Autohiding Annotations</h3>
388 <p>If a <i>ruby annotation</i> has the exact same text content as its base,
389 it is <dfn title="hidden ruby annotation | hidden annotation">hidden</dfn>.
390 Hiding a <i>ruby annotation</i> does not affect annotation pairing
391 or the block-axis positioning of boxes in other <i>levels</i>.
392 However the <i>hidden annotation</i> is not visible,
393 and it has no impact on layout
394 other than to separate adjacent sequences of <i>ruby annotation boxes</i> within its level,
395 as if they belonged to separate segments
396 and the <i>hidden annotation</i>’s base were not a <i>ruby base</i> but an intervening inline.
398 <div class="example">
399 <p>This is to allow correct inlined display of annotations
400 for Japanese words that are a mix of kanji and hirangana.
401 For example, the word <i>振り仮名</i> should be inlined as
402 <p class="figure">振り仮名(ふりがな)
403 <p>and therefore marked up as
404 <pre>
405 <!-- --><ruby>
406 <!-- --> <rb>振</rb><rb>り</rb><rb>仮</rb><rb>名</rb>
407 <!-- --> <rp>(</rp><rt>ふ</rt><rt>り</rt><rt>が</rt><rt>な</rt><rp>)</rp>
408 <!-- --><ruby></pre>
409 <p>However, when displayed as ruby, the “り” should be hidden
410 <div class="figure">
411 <p><img src="images/furigana-separate.png"
412 alt="Hiragana annotations for 振り仮名 appear, each above its base character.">
413 <p class="caption">Hiragana ruby for 振り仮名
414 </div>
415 </div>
417 <p class="note">
418 Future levels of CSS Ruby may add controls for this,
419 but in this level it is always forced.
421 <p>The content comparison for this auto-hiding behavior
422 takes place prior to white space collapsing
423 and ignores elements (considers only the <code>textContent</code> of the boxes).
424 <p 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.
426 <h3 id="white-space">
427 White Space</h3>
429 <p><i>Collapsible</i> white space within a ruby structure is discarded
430 <ul>
431 <li>at the beginning and end of a <i>ruby container</i>, <i>ruby annotation container</i>, or <i>ruby base container</i>,
432 <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,
433 <li>between a <i>ruby base container</i> and its following <i>ruby annotation container</i>,
434 <li>between <i>ruby annotation containers</i>.
435 </ul>
437 <p>Between <i>ruby segments</i>, between <i>ruby bases</i>, and between <i>ruby annotations</i>, however,
438 white space is not discarded.
440 <p>Where undiscarded white space is <i>collapsible</i>, it will collapse
441 following the standard <a href="http://www.w3.org/TR/css3-text/#white-space-rules">white space processing rules</a>. [[!CSS3TEXT]]
442 For <i>collapsible</i> white space between <i>ruby segments</i>, however,
443 the contextual text for determining collapsing behavior is given by the <i>ruby bases</i> on either side,
444 not the text on either side of the white space in the source document.
446 <div class="note">
447 <p>Note that the white space processing rules
448 cause a white space sequence containing a <i>segment break</i> (such as a line feed)
449 to <a href="http://www.w3.org/TR/css3-text/#line-break-transform">collapse to nothing</a> between CJK characters.
450 This means that CJK ruby can safely use white space for indentation of the ruby markup.
451 For example, the following markup will display without any spaces:
452 <pre>
453 <!-- --><ruby>
454 <!-- --> <rb>東</rb><rb>京</rb>
455 <!-- --> <rt>とう</rt><rt>きょう</rt>
456 <!-- --></ruby></pre>
457 <p>However, white space that does not contain a <i>segment break</i> does not collapse completely away,
458 so this markup will display with a space between the first and second ruby pairs:
459 <pre>
460 <!-- --><ruby>
461 <!-- --> <rb>東</rb> <rb>京</rb>
462 <!-- --> <rt>とう</rt> <rt>きょう</rt>
463 <!-- --></ruby></pre>
464 </div>
466 <p>Any preserved white space is then wrapped in an anonymous box belonging to
467 the <i>ruby base container</i> (if between <i>ruby bases</i>),
468 <i>ruby annotation container</i> (if between <i>ruby annotations</i>),
469 or <i>ruby container</i> (if between <i>ruby segments</i>).
470 In the latter case, the text is considered part of the <i>base level</i>.
471 Such anonynmous boxes do not take part in pairing.
472 They merely ensure separation between adjacent bases/annotations.
474 <p class="issue">Specify how these anonymous white space boxes impact layout.
476 <div class="example">
477 <p>These rules allow ruby to be used with space-separated scripts such as Latin.
478 For example,
479 <pre>
480 <!-- --><ruby>
481 <!-- --> <rb>W</rb><rb>W</rb><rb>W</rb>
482 <!-- --> <rt>World</rt> <rt>Wide</rt> <rt>Web</rt>
483 <!-- --></ruby></pre>
484 <p>They also ensure that annotated white space is preserved. For example,
485 <pre>
486 <!-- --><ruby>
487 <!-- --> <rb>Aerith</rb><rb> </rb><rb>Gainsboro</rb>
488 <!-- --> <rt>エアリス</rt><rt>・</rt><rt>ゲインズブール</rt>
489 <!-- --></ruby></pre>
490 </div>
492 <h3 id="ruby-layout">
493 Ruby layout</h3>
495 <p>When a ruby structure is laid out,
496 its base level is laid out on the line,
497 aligned according to its 'vertical-align' property
498 exactly as if its <i>bases</i> were a regular sequence of <i>inline</i> boxes.
499 Each <i>ruby base container</i> is sized and positioned
500 to contain exactly the full height of its <i>ruby bases</i>.
502 <p><i>Ruby annotations</i> associated with the base level
503 are then positioned with respect to their <i>ruby base boxes</i>
504 according to the applicable 'ruby-position' values.
505 <i>Ruby annotations</i> within a level (within a single <i>ruby container</i>)
506 are aligned to each other as if they were inline boxes
507 participating in the same inline formatting context.
508 Each <i>ruby annotation container</i> is sized and positioned
509 to contain exactly the full height of its <i>ruby annotations</i>.
511 <p>A ruby container (or fragment thereof)
512 measures as wide as the content of its widest level.
513 Similarly, <i>ruby base boxes</i> and <i>ruby annotation boxes</i>
514 within a ruby “column” have the measure of the widest content in that “column”.
515 In the case of spanning <i>annotations</i>
516 (whether actually spanning or pretending to span per 'ruby-collapse'),
517 the measures of the <i>ruby annotation box</i> and
518 the sum of its associated <i>ruby base boxes</i> must match.
520 <p>How the extra space is distributed
521 when ruby content is narrower than the measure of its box
522 is specified by the 'ruby-align' property.
524 <h4 id="inter-character-layout">
525 Inter-character ruby layout</h4>
527 <p>Inter-character annotations have special layout.
528 When 'ruby-position' indicates ''inter-character'' annotations,
529 the affected <i>annotation boxes</i>
530 are spliced into and measured as part of the layout of the base level.
531 The <i>ruby base container</i> must be sized to include both the <i>base boxes</i>
532 as well as the ''inter-character'' <i>annotation boxes</i>.
533 The affected <i>ruby annotation container</i> is similarly sized
534 so that its content box coincides with that of the <i>ruby base container</i>.
536 <p>For the purpose of laying out other levels of annotations,
537 an ''inter-character'' annotation effectively becomes part of its base.
538 <span class="issue">Or should it become a quasi-base between two bases?</span>
539 A spanning ''inter-character'' annotation is placed after
540 all the bases that it spans.
542 <h3 id="box-style">
543 Styling Ruby Boxes</h3>
545 <p>In most respects, ruby boxes can be styled similar to inline boxes.
546 However, the UA is not required to support
547 any of the box properties (borders, margins, padding),
548 any of the background properties or outline properties,
549 or any other property that illustrates the bounds of the box
550 on <i>ruby base container boxes</i>, <i>ruby annotation container boxes</i>,
551 or <a href="#nested-pairing">ruby-internal <i>ruby container boxes</i></a>.
552 The UA may implement these boxes simply as abstractions for inheritance
553 and control over the layout of their contents.
555 <h3 id="line-breaks">
556 Ruby box and line breaking</h3>
558 <p>When there is not enough space for an entire <i>ruby container</i> to fit on the line,
559 the ruby may be broken wherever all levels simultaneously allow a break.
560 Ruby most often breaks between base-annotation sets,
561 but if the line-breaking rules allow it, can also break within a <i>ruby base</i>
562 (and, in parallel, its associated <i>annotation boxes</i>).
564 <p>Whenever ruby breaks across lines, <i>ruby annotations</i> must stay
565 with their respective <i>bases</i>.
566 The line <em>must not</em> break between a <i>ruby base</i> and its <i>annotations</i>,
567 even in the case of ''inter-character'' <i>annotations</i>.
569 <div class="figure">
570 <img src="images/r-break-b.gif"
571 alt='Diagram showing the line breaking opportunity in a "Bopomofo" ruby'>
572 <p class="caption">''inter-character'' ruby line breaking opportunity
573 </div>
575 <h4 id="break-between">
576 Breaking between bases</h4>
578 <p>In typical cases, <i>ruby base boxes</i> and <i>ruby annotation boxes</i>
579 are styled to forbid internal line wrapping and do not contain forced breaks.
580 (See <a href="#default-stylesheet">Appendix A</a>.)
581 In such cases the <i>ruby container</i> can only break between adjacent <i>ruby bases</i>,
582 and only if no <i>ruby annotations</i> span those <i>ruby bases</i>.
584 <div class="figure">
585 <p><img src="images/r-break-a.gif"
586 alt="Diagram showing the line breaking opportunity in a complex ruby">
587 <p class="caption">Ruby line breaking opportunity
588 </div>
590 <p>Whether ruby can break between two adjacent <i>ruby bases</i>
591 is controlled by normal line-breaking rules for the base text,
592 exactly as if the <i>ruby bases</i> were adjacent <i>inline</i> boxes.
593 (The annotations are ignored when determining soft wrap opportunities for the base level.)
595 <div class="example">
596 <p>For example, if two adjacent ruby bases are “蝴” and “蝶”,
597 the line may break between them,
598 because lines are normally allowed to break between two Han characters.
599 However, if 'word-break' is ''keep-all'', that line break is forbidden.
600 <pre><ruby>蝴<rt>hú</rt>蝶<rt>dié</rt></pre>
601 </div>
603 <p>Inter-base white space is significant for evaluating line break opportunities between <i>ruby bases</i>.
604 As with white space between inlines, it collapses when the line breaks there.
605 Similarly, annotation white space is also trimmed at a line break.
607 <div class="example">
608 <p>For example, given the following markup:
609 <pre><ruby><rb>one</rb> <rb>two</rb> <rt>1</rt> <rt>2</rt></ruby></pre>
610 <p>Due to the space, the line may break between “one” and “two“.
611 If the line breaks there, that space—and the space between “1” and “2”—disappears,
612 in accordance with standard CSS white space processing rules. [[CSS3TEXT]]
613 </div>
615 <h4 id="break-within">
616 Breaking within bases</h4>
618 <p>For longer base texts, it is sometimes appropriate to allow breaking within a base-annotation pair.
619 For example, if an English sentence is annotated with its Japanese translation,
620 allowing the text to wrap allows for reasonable line breaking behavior in the paragraph.
622 <p class="issue">
623 Insert scanned example so people don't think this is just the ramblings of an insane spec-writer.
625 <p>Line-breaking within a <i>ruby base</i> is only allowed if the 'white-space' property
626 of the <i>ruby base</i> and all its parallel <i>annotations</i> allow it,
627 and there exists a <i>soft wrap opportunity</i> <em>within</em> (i.e. not at the start or end)
628 the content of each base/annotation box.
629 Since there is no structural correspondance between fragments of content
630 within <i>ruby bases</i> and <i>annotations</i>,
631 the UA may break at any set of opportunities;
632 but it is recommended that the UA attempt to proportionally balance
633 the amount of content inside each fragment.
635 <p>There are no line breaking opportunities within ''inter-character'' <i>annotations</i>.
637 <p>Ruby alignment takes place within each fragment, after line-breaking.
639 <h3 id="ruby-bidi">
640 Bidi Reordering</h3>
642 <p class="issue">
643 Constraints:
644 Text within a ruby base must remain contiguous,
645 and bases belonging to a single annotation must remain contiguous.
646 Still figuring out exactly to enforce these limitations in a sensible manner.
648 <!--
650 <p>The Unicode bidirectional algorithm orders logically-stored text for visual presentation
651 when characters from scripts of opposing directionalities are mixed
652 within a single paragraph.
653 (See [[CSS3-WRITING-MODES]] for a more in-depth discussion of bidirectional text in CSS.)
654 Bidi reordering of ruby-annotation pairs is controlled by the ordering of the base text, as follows:
656 <h4 id="bidi-B">Proposal A</h4>
658 <p class="note">This proposal is simpler, but will require more frequent tagging of mixed-directionality content.
660 <p>To avoid the interference of the <i>annotations</i> in the ordering of base text,
661 all annotations are ignored for the purpose of resolving neutral characters in the base level.
663 <p>To preserve the correspondance of <i>ruby annotations</i>
664 to their respective <i>ruby bases</i>,
665 a few restrictions are imposed:
666 <ul>
667 <li>The contents of a <i>ruby base</i> or <i>ruby annotation</i> must remain contiguous.
668 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>.
669 <li>For the purpose of ordering <i>ruby bases</i> within a <i>ruby container</i>,
670 each <i>ruby base</i> is treated as a strong character of its specified 'direction'.
671 (<i>Ruby annotations</i> are positioned with respect to their <i>bases</i>,
672 so are affected by reordering, but do not themselves participate in reordering.)
673 <li>All <i>bases</i> spanned by a single <i>annotation</i> must remain contiguous.
674 To this end, the embedding level of all bases spanned by a spanning <i>annotation</i>
675 is increased by two prior to reordering.
676 </ul>
678 <h4 id="bidi-B">Proposal B</h4>
680 <p class="note">This preserves some aspects of implicit bidi.
681 For example, annotating each half of "first-second" would not cause the word to reverse itself to "second-first" within an opposite-order paragraph.
683 <p>To avoid the interference of the <i>annotations</i> in the ordering of the base text,
684 all annotations are ignored for the purpose of resolving neutral characters in the base text;
685 and the base text is resolved exactly as if each <i>ruby base</i> were
686 just a normal <i>inline box</i> embedded in the <i>ruby container</i>'s inline formatting context.
688 <p>Furthermore, to preserve the correspondance of <i>ruby annotations</i>
689 to their respective <i>ruby bases</i>,
690 a few restrictions are imposed:
691 <ul>
692 <li>The contents of a <i>ruby base</i> must remain contiguous.
693 <li>All <i>bases</i> spanned by a single <i>annotation</i> must remain contiguous.
694 </ul>
695 <p>To this end, the text of <i>ruby base</i> boxes that are not <i>bidi-isolated</i>
696 must have its embedding level increased by two;
697 and if an <i>annotation</i> spans more than one <i>ruby base</i>,
698 the spanned text's embedding level
699 (or the embedding level assigned to the isolation, if the <i>ruby base</i> is <i>bidi-isolated</i>)
700 is further increased by two.
702 -->
704 <h3 id="line-height">
705 Ruby box and line stacking</h3>
707 <p>The 'line-height' property controls spacing between lines in CSS.
708 When inline content on line is shorter than the 'line-height',
709 half-leading is added on either side of the content,
710 as specificed in <a href="http://www.w3.org/TR/CSS21/visudet.html#line-height">CSS2.1§10.8</a>. [[!CSS21]]
712 <p>In order to ensure consistent spacing of lines,
713 documents with ruby typically ensure that the 'line-height' is large enough
714 to accommodate ruby between lines of text.
715 Therefore, ordinarily, <i>ruby annotation containers</i> and <i>ruby annotation boxes</i>
716 do not contribute to the measured height of a line's inline contents;
717 any alignment (see 'vertical-align') and line-height calculations
718 are performed using only the <i>ruby base container</i>,
719 exactly as if it were a normal inline.
721 <p>However, if the 'line-height' specified on the <i>ruby container</i>
722 is less than the distance between
723 the top of the top <i>ruby annotation container</i>
724 and the bottom of the bottom <i>ruby annotation container</i>,
725 then additional leading is added
726 on the appropriate side of the <i>ruby base container</i>
727 such that if a block consisted of three lines
728 each containing ruby identical to this,
729 none of the <i>ruby containers</i> would overlap.
731 <p class="note">Note that this does not ensure that the <i>ruby annotations</i> remain within the line box.
732 It merely ensures that <em>if all lines had equal spacing</em>
733 and equivalent amounts and positioning of <i>ruby annotations</i>,
734 there would be enough room to avoid overlap.
736 <p>Authors should ensure appropriate 'line-height' and 'padding' to accommodate ruby,
737 and be particularly careful at the beginning or end of a block
738 and when a line contains inline-level content
739 (such as images, inline blocks, or elements shifted with 'vertical-align')
740 taller than the paragraph's default font size.
742 <div class="figure">
743 <p><img src="images/rlh-a.gif"
744 alt="The content of each line sits in the middle of its line height;
745 the additional space on each side is called half-leading.
746 Ruby fits between lines if it is smaller than twice the half-leading,
747 but this means that it occupies space belonging to the half-leading of the previous line.">
748 <p class="caption">Ruby annotations will often overflow the line;
749 authors should ensure content over/under a ruby-annotated line
750 is adequately spaced to leave room for the ruby.
751 </div>
753 <p class="note">More control over how ruby affects alignment and line layout
754 will be part of the CSS Line Layout Module Level 3.
755 Note, it is currently in the process of being rewritten;
756 the current drafts should not be relied upon.
758 <h2 id="ruby-props">
759 Ruby Properties</h2>
761 <p>The following properties are introduced to control ruby positioning and alignment.
763 <h3 id="rubypos">
764 Ruby positioning: the 'ruby-position' property</h3>
766 <table class="propdef">
767 <tr>
768 <th>Name:
769 <td><dfn>ruby-position</dfn>
770 <tr>
771 <th><a href="#values">Value</a>:
772 <td>[ over | under | inter-character ] && [ right | left ]
773 <tr>
774 <th>Initial:
775 <td>over right
776 <tr>
777 <th>Applies to:
778 <td>ruby annotation containers
779 <tr>
780 <th>Inherited:
781 <td>yes
782 <tr>
783 <th>Percentages:
784 <td>N/A
785 <tr>
786 <th>Media:
787 <td>visual
788 <tr>
789 <th>Computed value:
790 <td>specified value
791 <tr>
792 <th>Animatable:
793 <td>no
794 <tr>
795 <th>Canonical order:
796 <td><abbr title="follows order of property value definition">per grammar</abbr>
797 </table>
799 <p>This property controls position of the ruby text with respect to its base.
800 Values have the following meanings:
802 <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>
803 <dl>
804 <dt><dfn title="ruby-position:over">''over''</dfn>
805 <dd>The ruby text appears <i>over</i> the base in horizontal text.
807 <div class="figure">
808 <p><img src="images/shinkansen-top.gif"
809 alt="Diagram of ruby glyph layout in horizontal mode with ruby text appearing above the base">
810 <p class="caption">Ruby over Japanese base text in horizontal layout
811 </div>
812 </dd>
814 <dt><dfn title="ruby-position:right">''right''</dfn>
815 <dd>The ruby text appears on the right side of the base in vertical text.
816 <div class="figure">
817 <p><img src="images/shinkansen-right.gif" width="33"
818 alt="Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the right of the base">
819 <p class="caption">Ruby to the right of Japanese base text in vertical layout
820 </div>
821 </dd>
823 <dt><dfn title="ruby-position:under">''under''</dfn>
824 <dd>The ruby text appears under the base in horizontal text.
825 This is a relatively rare setting used in ideographic East Asian writing systems,
826 most easily found in educational text.
828 <div class="figure">
829 <p><img src="images/shinkansen-bottom.gif"
830 alt="Diagram of ruby glyph layout in horizontal mode with ruby text appearing below the base">
831 <p class="caption">Ruby under Japanese base text in horizontal layout
832 </div>
833 </dd>
835 <dt><dfn title="ruby-position:left">''left''</dfn>
836 <dd>The ruby text appears on the left side of the base in vertical text.
838 <div class="figure">
839 <p><img src="images/shinkansen-left.gif"
840 alt="Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the left of the base">
841 <p class="caption">Ruby to the left of Japanese base text in vertical layout
842 </div>
843 </dd>
845 <dt><dfn title="ruby-position:inter-character">''inter-character''</dfn></dt>
846 <dd>
847 <p>The ruby text appears on the right of the base in horizontal text.
848 This value forces the 'writing-mode' of the <i>ruby annotation</i> to be vertical.
850 <p>This value is provided for the special case of traditional Chinese
851 as used especially in Taiwan:
852 ruby (made of <a href="#g-bopomofo">bopomofo</a> glyphs) in that context
853 appears vertically along the right side of the base glyph,
854 even when the layout of the base characters is horizontal:
856 <div class="figure">
857 <p><img src="images/bopomofo.gif"
858 alt="Example of Taiwanese-style ruby">
859 <p class="caption">“Bopomofo” ruby in traditional Chinese
860 (ruby text shown in blue for clarity) in horizontal layout
861 </div>
862 <p class="note">
863 Note that the user agent is responsible for ensuring the correct relative alignment and positioning of the glyphs,
864 including those corresponding to the tone marks, when displaying.
865 Tone marks are spacing characters that occur (in memory) at the end of the ruby text for each base character.
866 They are usually displayed in a separate column to the right of the bopomofo characters,
867 and the height of the tone mark depends on the number of characters in the syllable.
868 One tone mark, however, is placed above the bopomofo, not to the right of it.
869 <!-- See Taiwanese requirements doc for EPUB at http://epub-revision.googlecode.com/files/EGLS_TW_eng.ppt -->
870 </dd>
871 </dl>
873 <p>If multiple <i>ruby annotation containers</i> have the same 'ruby-position',
874 they stack along the block axis,
875 with lower levels of annotation closer to the base text.
877 <h3 id="collapsed-ruby">
878 Collapsed Ruby Annotations: the 'ruby-merge' property</h3>
880 <table class="propdef">
881 <tr>
882 <th>Name:
883 <td><dfn>ruby-merge</dfn>
884 <tr>
885 <th><a href="#values">Value</a>:
886 <td>separate | collapse | auto
887 <tr>
888 <th>Initial:
889 <td>separate
890 <tr>
891 <th>Applies to:
892 <td>ruby annotation containers
893 <tr>
894 <th>Inherited:
895 <td>yes
896 <tr>
897 <th>Percentages:
898 <td>N/A
899 <tr>
900 <th>Media:
901 <td>visual
902 <tr>
903 <th>Computed value:
904 <td>specified value
905 <tr>
906 <th>Animatable:
907 <td>no
908 <tr>
909 <th>Canonical order:
910 <td><abbr title="follows order of property value definition">per grammar</abbr>
911 </table>
913 <p>
914 This property controls how ruby annotation boxes should be rendered
915 when there are more than one in a ruby container box.
917 <p>Possible values:</p>
918 <dl>
919 <dt><dfn title="ruby-merge:separate">''separate''</dfn>
920 <dd>
921 <p>
922 Each ruby annotation box is rendered in the same column(s) as its corresponding base box(es).
923 This style is called “mono ruby” in [[JLREQ]].
925 <div class="example">
926 <p>For example, the following two markups render the same:
927 <pre><ruby>無<rt>む</ruby><ruby>常<rt>じょう</ruby></pre>
928 <p>and:
929 <pre><ruby style="ruby-merge:separate"><rb>無<rb>常<rt>む<rt>じょう</ruby></pre>
930 </div>
931 </dd>
933 <dt><dfn title="ruby-merge:collapse">''collapse''</dfn>
934 <dd>
935 <p>
936 All <i>ruby annotation boxes</i> within the same <i>ruby segment</i> on the same line are concatenated,
937 and laid out as if their contents belonged to a single <i>ruby annotation box</i>
938 spanning all their associated <i>ruby base boxes</i>.
939 This style renders similar to “group ruby” in [[JLREQ]],
940 except that <i>ruby annotations</i> are kept together with their respective <i>ruby bases</i> when breaking lines.
941 </p>
943 <div class="example">
944 <p>The following two markups render the same both characters fit on one line:
945 <pre><ruby>無常<rt>むじょう</ruby></pre>
946 <p>and:
947 <pre><ruby style="ruby-merge:collapse"><rb>無<rb>常<rt>む<rt>じょう</ruby></pre>
948 <p>However, the second one renders the same as ''ruby-position: separate''
949 when the two bases are split across lines.
950 </div>
951 </dd>
953 <dt><dfn title="ruby-merge:auto">''auto''</dfn></dt>
954 <dd>
955 <p>
956 The user agent may use any algorithm to determine how each ruby annotation box
957 is rendered to its corresponding base box,
958 with the intention that if all annotations fit over their respective bases,
959 the result is identical to “mono ruby”,
960 but if some annotations are wider than their bases
961 the space is shared in some way
962 to avoid forcing space between bases.
963 <div class="example">
964 <p>
965 One possible algorithm is described as “jukugo ruby” in [[JLREQ]].
966 <p>
967 Another, more simplified algorithm of “jukugo ruby” is
968 to render as ''separate'' if all ruby annotation boxes fit
969 within the advances of their corresponding base boxes,
970 and render as ''collapse'' otherwise.
971 </p>
972 </div>
973 </dd>
974 </dl>
976 <h3 id="ruby-align-property"><a id="rubyalign"></a>
977 Ruby Text Distribution: the 'ruby-align' property</h3>
979 <table class="propdef">
980 <tr>
981 <th>Name:
982 <td><dfn>ruby-align</dfn>
983 <tr>
984 <th><a href="#values">Value</a>:
985 <td>start | center | space-between | space-around
986 <tr>
987 <th>Initial:
988 <td>space-around
989 <tr>
990 <th>Applies to:
991 <td>ruby bases, ruby annotations, ruby base containers, ruby annotation containers
992 <tr>
993 <th>Inherited:
994 <td>yes
995 <tr>
996 <th>Percentages:
997 <td>N/A
998 <tr>
999 <th>Media:
1000 <td>visual
1001 <tr>
1002 <th>Computed value:
1003 <td>specified value (except for initial and inherit)
1004 </table>
1006 <p>This property specifies how text is distributed within the various ruby boxes
1007 when their contents do not exactly fill their respective boxes.
1008 Note that space distributed by 'ruby-align' is unrelated to, and independent of,
1009 any space distributed due to justification.
1011 <p>Values have the following meanings:
1012 <dl>
1013 <dt><dfn title="ruby-align:start">''start''</dfn></dt>
1014 <dd>The ruby content is aligned with the start edge of its box.
1015 <div class="figure">
1016 <p><img
1017 alt="Diagram of glyph layout in left aligned ruby when ruby text is shorter than base"
1018 width="145" height="91" src="images/ra-l.gif" /><img
1019 width="145" height="91"
1020 alt="Diagram of glyph layout in left aligned ruby when ruby text is longer than base"
1021 src="images/ra-l-rb.gif" />
1022 <p class="caption">''start'' ruby distribution
1023 </div>
1024 </dd>
1026 <dt><dfn title="ruby-align:center">''center''</dfn></dt>
1027 <dd>The ruby content is centered within its box.
1028 <div class="figure">
1029 <p><img width="145" height="91"
1030 alt="Diagram of glyph layout in center aligned ruby when ruby text is shorter than base"
1031 src="images/ra-c.gif" /><img width="145" height="91"
1032 alt="Diagram of glyph layout in center aligned ruby when ruby text is longer than base"
1033 src="images/ra-c-rb.gif" />
1034 <p class="caption">''center'' ruby distribution
1035 </div>
1036 </dd>
1038 <dt><dfn title="ruby-align:space-between">''space-between''</dfn></dt>
1039 <dd>
1040 <p>The ruby content expands as defined for normal text justification
1041 (as defined by 'text-justify'),
1042 except that if there are no <a href="http://www.w3.org/TR/css3-text/#expansion-opportunity"><i>expansion opportunities</i></a>
1043 the content is centered.
1044 <div class="figure">
1045 <p><img width="145" height="91"
1046 alt="Diagram of glyph layout in distribute-letter aligned ruby when ruby text is shorter than base"
1047 src="images/ra-dl.gif" /><img width="145" height="91"
1048 alt="Diagram of glyph layout in distribute-letter aligned ruby when ruby text is longer than base"
1049 src="images/ra-dl-rb.gif" />
1050 <p class="caption">''space-between'' ruby distribution
1051 </div>
1052 </dd>
1054 <dt><dfn title="ruby-align:space-around">''space-around''</dfn></dt>
1055 <dd>
1056 <p>As for ''space-between''
1057 except that there exists an extra <a href="http://www.w3.org/TR/css3-text/#expansion-opportunity"><i>expansion opportunity</i></a>
1058 whose space is distributed half before and half after the ruby content.
1059 <div class="example">
1060 <p>Since a typical implementation will by default define <i>expansion opportunities</i>
1061 between every adjacent pair of CJK <i>characters</i>
1062 and not between adjacent pairs of Latin <i>characters</i>,
1063 this should result in the behavior recommended by [[JLREQ]]:
1064 for wide-cell ruby content to be distributed...
1065 <div class="figure">
1066 <p><img width="145" height="91"
1067 alt="Diagram of glyph layout in auto aligned ruby when ruby text is shorter than base"
1068 src="images/ra-ds.gif" /><img width="145" height="91"
1069 alt="Diagram of glyph layout in auto aligned ruby when ruby text is longer than base"
1070 src="images/ra-ds-rb.gif" />
1071 <p class="caption">Wide-cell text in ''space-around'' ruby distribution is spaced apart
1072 </div>
1073 <p>... and narrow-cell glyph ruby to be centered.
1074 <div class="figure">
1075 <p><img
1076 alt="Diagram of glyph layout in auto aligned ruby when halfwidth ruby text is shorter than base"
1077 width="145" height="91"
1078 src="images/ra-c-h.gif" /><img
1079 alt="Diagram of character layout in auto aligned ruby when ruby text is longer than narrow-width base"
1080 width="145" height="91"
1081 src="images/ra-c-rb-h.gif" />
1082 <p class="caption">Narrow-width ruby text in ''space-around'' ruby distribution is centered
1083 </div>
1084 </div>
1085 </dd>
1086 </dl>
1088 <p class="issue">Add a paragraph explaining how to distribute space in situations with spanning annotations.
1089 <!--
1090 <p>For a complex ruby with spanning elements, one additional consideration is
1091 required. If the spanning element spans multiple 'rows' (other rbc or rtc
1092 elements), and the ruby alignment requires space distribution among the
1093 'spanned' elements, a ratio must be determined among the 'columns' of spanned
1094 elements. This ratio is computed by taking into consideration the widest
1095 element within each column.</p>
1096 -->
1097 <h2 id="edge-effects">
1098 Edge Effects</h2>
1100 <h3 id="ruby-overhang">
1101 Overhanging Ruby</h3>
1103 <p>
1104 When <i>ruby annotation box</i> is longer than its corresponding <i>ruby base box</i>,
1105 the <i>ruby annotation box</i> may partially overhang adjacent boxes.
1106 </p>
1107 <p>
1108 This level of the specification does not define
1109 how much the overhang may be allowed, and under what conditions.
1110 </p>
1112 <p>If the ruby text is not allowed to overhang,
1113 then the ruby behaves like a traditional inline box,
1114 i.e. only its own contents are rendered within its boundaries
1115 and adjacent elements do not cross the box boundary:
1117 <div class="figure">
1118 <p><img src="images/ro-n.gif"
1119 alt="Diagram showing the ruby boxes interacting with adjacent text">
1120 <p class="caption">Simple ruby whose text is not allowed to overhang adjacent text
1121 </div>
1123 <p>However, if <i>ruby annotation</i> content is allowed to overhang adjacent elements
1124 and it happens to be wider than its base,
1125 then the adjacent content is partially rendered within the area of the <i>ruby container box</i>,
1126 while the <i>ruby annotation</i> may partially overlap the upper blank parts of the adjacent content:
1128 <div class="figure">
1129 <p><img src="images/ro-a.gif"
1130 alt="Diagram showing the ruby boxes interacting with adjacent text">
1131 <p class="caption">Simple ruby whose text is allowed to overhang adjacent text
1132 </div>
1134 <p>The <i>ruby annotations</i> related to a <i>ruby base</i>
1135 must never overhang another <i>ruby base</i>.
1137 <p>The alignment of the contents of the base or the ruby text
1138 is not affected by overhanging behavior.
1139 The alignment is achieved the same way regardless of the overhang behavior setting
1140 and it is computed before the space available for overlap is determined.
1141 It is controlled by the 'ruby-align' property.
1143 <p class="issue">
1144 I suspect overhanging interacts with alignment in some cases;
1145 might need to look into this later.
1147 <p>This entire logic applies the same way in vertical ideographic layout,
1148 only the dimension in which it works in such a layout is vertical,
1149 instead of horizontal.
1151 <div class="example">
1152 <p>
1153 The user agent may use [[JIS4051]] recommendation of
1154 using one ruby text character length as the maximum overhang length.
1155 Detailed rules for how ruby text can overhang adjacent characters for Japanese are described by [[JLREQ]].
1156 </p>
1157 </div>
1159 <h3 id="line-edge">
1160 Line-edge Alignment</h3>
1162 <p>
1163 When a <i>ruby annotation box</i> that is longer than its <i>ruby base</i>
1164 is at the start or end edge of a line,
1165 the user agent <em>may</em> force the side of the <i>ruby annotation</i> that touches the edge of the line
1166 to align to the corresponding edge of the base.
1167 This type of alignment is described by [[JLREQ]].
1168 </p>
1169 <p>
1170 This level of the specification does not provide a mechanism to control this behavior.
1171 </p>
1172 <div class="figure">
1173 <p><img src="images/ra-le-l.gif"
1174 alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is shorter than base">
1175 <img src="images/ra-le-r.gif"
1176 alt="Diagram of glyph layout in line-edge aligned ruby when ruby text is longer than base">
1177 <p class="caption">Line-edge alignment
1178 </div>
1180 <!--
1181 <h3 id="rubyover">
1182 Ruby overhanging: the 'ruby-overhang' property</h3>
1184 <table class="propdef">
1185 <tr>
1186 <th>Name:
1187 <td><dfn>ruby-overhang</dfn>
1188 <tr>
1189 <th>Value:
1190 <td>auto | start | end | none
1191 <tr>
1192 <th>Initial:
1193 <td>none
1194 <tr>
1195 <th>Applies to:
1196 <td>the parent of elements with display: ruby-text
1197 <tr>
1198 <th>Inherited:
1199 <td>yes
1200 <tr>
1201 <th>Percentages:
1202 <td>N/A
1203 <tr>
1204 <th>Media:
1205 <td>visual
1206 <tr>
1207 <th>Computed value:
1208 <td>specified value (except for initial and inherit)
1209 </table>
1211 <p>This property determines whether, and on which side, ruby text is allowed
1212 to partially overhang any adjacent text in addition to its own base, when the
1213 ruby text is wider than the ruby base. Note that ruby text is never allowed to
1214 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
1215 a maximum amount by which ruby text may overhang adjacent text. The user agent may use
1216 the [[JIS4051]] recommendation of using one ruby text character
1217 length as the maximum overhang length. Detailed rules for how ruby text can overhang adjacent characters for Japanese are described by [[JLREQ]].</p>
1219 <p>Possible values:</p>
1220 <dl>
1221 <dt><strong>auto</strong></dt>
1222 <dd>The ruby text can overhang text adjacent to the base on either side. [[JLREQ]] and [[JIS4051]] specify the categories of characters that
1223 ruby text can overhang. The user agent is free to follow those recommendations or specify its own classes of
1224 characters to overhang. This is the initial value.
1225 <div class="figure">
1226 <p><img class="example" width="177" height="91"
1227 alt="Diagram of glyph layout in overhanging ruby" src="images/ro-a.gif" /></p>
1228 <p><b>Figure 4.3.1</b>: Ruby overhanging adjacent text</p>
1229 </div>
1230 </dd>
1231 <dt><strong>start</strong></dt>
1232 <dd>The ruby text can only overhang the text that precedes it. That means, for
1233 example, that ruby cannot overhang text that is to the right of it in
1234 horizontal LTR layout, and it cannot overhang text that is below it in
1235 vertical-ideographic layout.
1236 <div class="figure">
1237 <p><img class="example" width="199" height="91"
1238 alt="Diagram of glyph layout when ruby overhangs the preceding glyphs only"
1239 src="images/ro-s.gif" /></p>
1240 <p><b>Figure 4.3.2</b>: Ruby overhanging preceding text only</p>
1241 </div>
1242 </dd>
1243 <dt><strong>end</strong></dt>
1244 <dd>The ruby text can only overhang the text that follows it. That means, for
1245 example, that ruby cannot overhang text that is to the left of it in
1246 horizontal LTR layout, and it cannot overhang text that is above it in
1247 vertical-ideographic layout.
1248 <div class="figure">
1249 <p><img class="example" width="198" height="91"
1250 alt="Diagram of glyph layout when ruby overhangs the following characters only"
1251 src="images/ro-e.gif" /></p>
1252 <p><b>Figure 4.3.3</b>: Ruby overhanging following text only</p>
1253 </div>
1254 </dd>
1255 <dt><strong>none</strong></dt>
1256 <dd>The ruby text cannot overhang any text adjacent to its base, only its
1257 own base.
1259 <div class="figure">
1260 <p><img class="example" width="220" height="91"
1261 alt="Diagram of glyph layout in non-overhanging ruby"
1262 src="images/ro-n.gif" /></p>
1263 <p><b>Figure 4.3.4</b>: Ruby not allowed to overhang adjacent text</p>
1264 </div>
1265 </dd>
1266 </dl>
1268 <h3 id="rubyspan">
1269 Ruby annotation spanning: the 'ruby-span' property</h3>
1271 <table class="propdef">
1272 <tr>
1273 <th>Name:
1274 <td><dfn>ruby-span</dfn>
1275 <tr>
1276 <th>Value:
1277 <td>attr(x) | none
1278 <tr>
1279 <th>Initial:
1280 <td>none
1281 <tr>
1282 <th>Applies to:
1283 <td>elements with display: ruby-text
1284 <tr>
1285 <th>Inherited:
1286 <td>no
1287 <tr>
1288 <th>Percentages:
1289 <td>N/A
1290 <tr>
1291 <th>Media:
1292 <td>visual
1293 <tr>
1294 <th>Computed value:
1295 <td><number>
1296 </table>
1298 <p>This property controls the spanning behavior of annotation elements. </p>
1300 <p class="note"><span class="note-label">Note:</span> A XHTML user agent may also use the <samp>rbspan</samp>
1301 attribute to get the same effect.</p>
1303 <p>Possible values:</p>
1305 <dl>
1306 <dt><strong>attr(x)</strong></dt>
1307 <dd>The value of attribute 'x' as a string value. The string value is
1308 evaluated as a <number> to determine the number of ruby base elements to be
1309 spanned by the annotation element. If the <number> is '0', it is replaced by
1310 '1'.The <number> is the computed value. </dd>
1311 <dt>none</dt>
1312 <dd>No spanning. The computed value is '1'.</dd>
1313 </dl>
1315 <p>The following example shows an XML example using the 'display' property
1316 values associated with the 'ruby structure and the 'ruby-span' property</p>
1317 <pre class="xml">myruby { display: ruby; }
1318 myrbc { display: ruby-base-container; }
1319 myrb { display: ruby-base; }
1320 myrtc.before { display: ruby-text-container; ruby-position: before}
1321 myrtc.after { display: ruby-text-container; ruby-position: after}
1322 myrt { display: ruby-text; ruby-span: attr(rbspan); }
1323 ...
1324 <myruby>
1325 <myrbc>
1326 <myrb>10</myrb>
1327 <myrb>31</myrb>
1328 <myrb>2002</myrb>
1329 </myrbc>
1330 <myrtc class="before">
1331 <myrt>Month</myrt>
1332 <myrt>Day</myrt>
1333 <myrt>Year</myrt>
1334 </myrtc>
1335 <myrtc class="after">
1336 <myrt rbspan="3">Expiration Date</myrt>
1337 </myrtc>
1338 </myruby></pre>
1339 -->
1341 <h2 id="default-stylesheet" class="no-num">
1342 Appendix A: Default Style Sheet</h2>
1344 <p><em>This section is informative.</em>
1346 <h3 id="default-ua-ruby" class="no-num">
1347 <span class="secno">A.1</span> Supporting Ruby Layout</h3>
1349 <p>The following represents a default UA style sheet
1350 for rendering HTML and XHTML ruby markup as ruby layout:
1352 <pre>
1353 <!-- -->ruby { display: ruby; }
1354 <!-- -->rb { display: ruby-base; white-space: nowrap; }
1355 <!-- -->rt { display: ruby-text; white-space: nowrap; font-size: 50%; }
1356 <!-- -->rbc { display: ruby-base-container; }
1357 <!-- -->rtc { display: ruby-text-container; }
1358 <!-- -->ruby, rb, rt, rbc, rtc { unicode-bidi: isolate; }</pre>
1360 <p>Additional rules for UAs supporting the relevant features of [[CSS3-TEXT-DECOR]] and [[CSS3-FONTS]]:
1361 <pre>rt { font-variant-east-asian: ruby; text-emphasis: none; }</pre>
1363 <p class="note">Authors should not use the above rules;
1364 a UA that supports ruby layout should provide these by default.
1366 <h3 id="default-inline" class="no-num">
1367 <span class="secno">A.2</span> Inlining Ruby Annotations</h3>
1369 <p>The following represents a sample style sheet
1370 for rendering HTML and XHTML ruby markup as inline annotations:
1372 <pre>ruby, rb, rt, rbc, rtc, rp {
1373 <!-- --> display: inline; white-space: inherit;
1374 <!-- --> font-variant-east-asian: inherit; text-emphasis: inherit; }</pre>
1376 <h3 id="default-parens" class="no-num">
1377 <span class="secno">A.3</span> Generating Parentheses</h3>
1379 <p>Unfortunately, because Selectors cannot match against text nodes,
1380 it's not possible with CSS to express rules that will automatically and correctly
1381 add parentheses to unparenthesized ruby annotations in HTML.
1382 (This is because HTML ruby allows implying the <i>ruby base</i> from raw text, without a corresponding element.)
1383 However, these rules will handle cases where either <code><rb></code>
1384 or <code><rtc></code> is used rigorously.
1386 <pre>
1387 <!-- -->/* Parens around <rtc> */
1388 <!-- -->rtc::before { content: "("; }
1389 <!-- -->rtc::after { content: ")"; }
1391 <!-- -->/* Parens before first <rt> not inside <rtc> */
1392 <!-- -->rb + rt::before,
1393 <!-- -->rtc + rt::before { content: "("; }
1395 <!-- -->/* Parens after <rt> not inside <rtc> */
1396 <!-- -->rb ~ rt:last-child::after,
1397 <!-- -->rt + rb::before { content: ")"; }
1398 <!-- -->rt + rtc::before { content: ")("; }</pre>
1400 <h2 id="glossary">
1401 Glossary</h2>
1402 <dl>
1403 <dt><a id="g-bopomofo"><strong><span
1404 lang="zh">Bopomofo</span></strong></a></dt>
1405 <dd>37 characters and 4 tone markings used as phonetics in Chinese,
1406 especially standard Mandarin.</dd>
1407 <dt><a id="g-hanja"><strong><span
1408 lang="ko">Hanja</span></strong></a></dt>
1409 <dd>Subset of the Korean writing system that utilizes ideographic
1410 characters borrowed or adapted from the Chinese writing system. Also see
1411 <a href="#g-kanji"><span lang="ja">Kanji</span></a>.</dd>
1412 <dt><a id="g-hiragana"><strong><span
1413 lang="ja">Hiragana</span></strong></a></dt>
1414 <dd>Japanese syllabic script, or character of that script. Rounded and
1415 cursive in appearance. Subset of the Japanese writing system, used together
1416 with kanji and katakana. In recent times, mostly used to write Japanese
1417 words when kanji are not available or appropriate, and word endings and
1418 particles. Also see <a
1419 href="#g-katakana"><span lang="ja">Katakana</span></a>.</dd>
1420 <dt><a id="g-ideogram"><strong>Ideograph</strong></a></dt>
1421 <dd>A character that is used to represent an idea, word, or word component,
1422 in contrast to a character from an alphabetic or syllabic script. The most
1423 well-known ideographic script is used (with some variation) in East Asia
1424 (China, Japan, Korea,...).</dd>
1425 <dt><a id="g-kana"><strong><span lang="ja">Kana</span></strong></a></dt>
1426 <dd>Collective term for hiragana and katakana.</dd>
1427 <dt><a id="g-kanji"><strong>Kanji</strong></a></dt>
1428 <dd>Japanese term for ideographs; ideographs used in Japanese. Subset of the
1429 Japanese writing system, used together with hiragana and katakana. Also see <a
1430 href="#g-hanja"><span lang="ko">Hanja</span></a>.</dd>
1431 <dt><a id="g-katakana"><strong><span
1432 lang="ja">Katakana</span></strong></a></dt>
1433 <dd>Japanese syllabic script, or character of that script. Angular in
1434 appearance. Subset of the Japanese writing system, used together with
1435 kanji and hiragana. In recent times, mainly used to write foreign words. Also see <a
1436 href="#g-hiragana"><span lang="ja">Hiragana</span></a>.</dd>
1437 </dl>
1439 <h2 id="conformance">
1440 Conformance</h2>
1442 <h3 id="conventions">
1443 Document conventions</h3>
1445 <p>Conformance requirements are expressed with a combination of
1446 descriptive assertions and RFC 2119 terminology. The key words “MUST”,
1447 “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”,
1448 “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this
1449 document are to be interpreted as described in RFC 2119.
1450 However, for readability, these words do not appear in all uppercase
1451 letters in this specification.
1453 <p>All of the text of this specification is normative except sections
1454 explicitly marked as non-normative, examples, and notes. [[!RFC2119]]</p>
1456 <p>Examples in this specification are introduced with the words “for example”
1457 or are set apart from the normative text with <code>class="example"</code>,
1458 like this:
1460 <div class="example">
1461 <p>This is an example of an informative example.</p>
1462 </div>
1464 <p>Informative notes begin with the word “Note” and are set apart from the
1465 normative text with <code>class="note"</code>, like this:
1467 <p class="note">Note, this is an informative note.</p>
1469 <h3 id="conformance-classes">
1470 Conformance classes</h3>
1472 <p>Conformance to CSS Ruby Module
1473 is defined for three conformance classes:
1474 <dl>
1475 <dt><dfn title="style sheet!!as conformance class">style sheet</dfn>
1476 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
1477 style sheet</a>.
1478 <dt><dfn>renderer</dfn></dt>
1479 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
1480 that interprets the semantics of a style sheet and renders
1481 documents that use them.
1482 <dt><dfn id="authoring-tool">authoring tool</dfn></dt>
1483 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
1484 that writes a style sheet.
1485 </dl>
1487 <p>A style sheet is conformant to CSS Ruby Module
1488 if all of its statements that use syntax defined in this module are valid
1489 according to the generic CSS grammar and the individual grammars of each
1490 feature defined in this module.
1492 <p>A renderer is conformant to CSS Ruby Module
1493 if, in addition to interpreting the style sheet as defined by the
1494 appropriate specifications, it supports all the features defined
1495 by CSS Ruby Module by parsing them correctly
1496 and rendering the document accordingly. However, the inability of a
1497 UA to correctly render a document due to limitations of the device
1498 does not make the UA non-conformant. (For example, a UA is not
1499 required to render color on a monochrome monitor.)
1501 <p>An authoring tool is conformant to CSS Ruby Module
1502 if it writes style sheets that are syntactically correct according to the
1503 generic CSS grammar and the individual grammars of each feature in
1504 this module, and meet all other conformance requirements of style sheets
1505 as described in this module.
1507 <h3 id="partial">
1508 Partial implementations</h3>
1510 <p>So that authors can exploit the forward-compatible parsing rules to
1511 assign fallback values, CSS renderers <strong>must</strong>
1512 treat as invalid (and <a href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore
1513 as appropriate</a>) any at-rules, properties, property values, keywords,
1514 and other syntactic constructs for which they have no usable level of
1515 support. In particular, user agents <strong>must not</strong> selectively
1516 ignore unsupported component values and honor supported values in a single
1517 multi-value property declaration: if any value is considered invalid
1518 (as unsupported values must be), CSS requires that the entire declaration
1519 be ignored.</p>
1521 <h3 id="experimental">
1522 Experimental implementations</h3>
1524 <p>To avoid clashes with future CSS features, the CSS2.1 specification
1525 reserves a <a href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
1526 syntax</a> for proprietary and experimental extensions to CSS.
1528 <p>Prior to a specification reaching the Candidate Recommendation stage
1529 in the W3C process, all implementations of a CSS feature are considered
1530 experimental. The CSS Working Group recommends that implementations
1531 use a vendor-prefixed syntax for such features, including those in
1532 W3C Working Drafts. This avoids incompatibilities with future changes
1533 in the draft.
1534 </p>
1536 <h3 id="testing">
1537 Non-experimental implementations</h3>
1539 <p>Once a specification reaches the Candidate Recommendation stage,
1540 non-experimental implementations are possible, and implementors should
1541 release an unprefixed implementation of any CR-level feature they
1542 can demonstrate to be correctly implemented according to spec.
1544 <p>To establish and maintain the interoperability of CSS across
1545 implementations, the CSS Working Group requests that non-experimental
1546 CSS renderers submit an implementation report (and, if necessary, the
1547 testcases used for that implementation report) to the W3C before
1548 releasing an unprefixed implementation of any CSS features. Testcases
1549 submitted to W3C are subject to review and correction by the CSS
1550 Working Group.
1552 <p>Further information on submitting testcases and implementation reports
1553 can be found from on the CSS Working Group's website at
1554 <a href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
1555 Questions should be directed to the
1556 <a href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
1557 mailing list.
1559 <h2 class=no-num id="acknowledgments">
1560 Acknowledgments</h2>
1562 <p>This specification would not have been possible without the help from:</p>
1564 <p>Stephen Deach, Martin Dürst, Hideki Hiura(<span lang="ja">樋浦 秀樹</span>), Masayasu Ishikawa(<span lang="ja">石川
1565 雅康</span>), Chris
1566 Pratley, Takao Suzuki(<span lang="ja">鈴木 孝雄</span>), Frank Yung-Fong Tang, Chris Thrasher, Masafumi Yabe<span lang="ja">家辺
1567 勝文</span>), Steve Zilles.</p>
1569 <h2 class="no-num" id="changes">
1570 Changes</h2>
1572 <p>The following major changes have been made since the previous Working Draft:
1573 <dl>
1574 <dt>Remove 'ruby-span' and mentions of <code>rbspan</code>.
1575 <dd>
1576 Explicit spanning is not used in HTML ruby in favor of implicit spanning.
1577 This can't handle some pathological double-sided spanning cases,
1578 but there seems to be no requirement for these at the moment.
1579 (For implementations that support full complex XHTML Ruby,
1580 they can imply spanning from the markup the same magic way
1581 that we handle cell spanning from tables. It doesn't seem
1582 necessary to include controls this in Level 1.)
1584 <dt>Defer 'ruby-overhang' and ''ruby-align: line-end'' to Level 2.
1585 <dd>
1586 It's somewhat complicated, advanced feature.
1587 Proposal is to make this behavior UA-defined
1588 and provide some examples of acceptable options.
1590 <dt>Close issue requesting 'display: rp': use ''display: none''.
1591 <dd>
1592 The Internationalization WG added an issue requesting a display value for <rp> elements.
1593 They're supposed to be hidden when <ruby> is displayed as ruby.
1594 But this is easily accomplished already with ''display: none''.
1596 <dt>Change 'ruby-position' values to match 'text-emphasis-position'.
1597 <dd>
1598 Other than ''inter-character'', which we need to keep,
1599 it makes more sense to align ruby positions with 'text-emphasis-position',
1600 which can correctly handle various combinations of horizontal/vertical preferences.
1602 <dt>Remove unused values of 'ruby-align'.
1603 <dd>
1604 ''left'', ''right'', and ''end'' are not needed.
1606 <dt>Replace ''auto'', ''distribute-letter'', and ''distribute-space'' from 'ruby-align' with ''space-between'' and ''space-around''.
1607 <dd>
1608 The ''auto'' value relied on inspecting content to determine behavior;
1609 this can be avoided by just using ''space-around'' with standard justification rules
1610 (which allow spacing between CJK but not between Latin).
1611 Replaced ''distribute-letter'' and ''distribute-space'' with
1612 ''space-between'' and ''space-around'' for consistency with distribution keywords
1613 in [[CSS3-FLEXBOX]] and [[CSS3-ALIGN]]
1614 and to avoid any links to the definition of ''text-justify: distribute''.
1616 <dt>Added 'ruby-merge' property to control jukugo rendering.
1617 <dd>
1618 This is a stylistic effect, not a structural one;
1619 the previous model assumed that it was structural and suggested handling it by changing markup. :(
1621 <dt>Remove ''inline'' from 'ruby-position'.
1622 <dd>
1623 This is do-able via ''display: inline'' on all the ruby-related elements,
1624 see <a href="#default-inline">Appendix A</a>
1626 <dt>Added <a href="#default-style">Default Style</a> rules
1627 <dd>
1628 As requested by Internationalization WG.
1630 <dt>Wrote anonymous box generation rules
1631 <dd>
1632 And defined pairing of bases and annotations.
1633 Should now handle all the crazy proposed permutations of HTML ruby markup.
1635 <dt>Defined layout of ruby
1636 <dd>
1637 Defined in detail space distribution, white space handling, line breaking, line stacking, etc.
1638 Open issue left for bidi.
1639 </dl>
1641 <h2 class=no-num id="references">
1642 References</h2>
1644 <h3 class="no-num" id="normative-references">
1645 Normative references</h3>
1646 <!--normative-->
1648 <h3 class="no-num" id="other-references">
1649 Other references</h3>
1650 <!--informative-->
1652 <h2 class="no-num" id="index">
1653 Index</h2>
1654 <!--index-->
1656 <h2 class="no-num" id="property-index">
1657 Property index</h2>
1658 <!-- properties -->
1660 </body>
1661 </html>
1662 <!-- Keep this comment at the end of the file
1663 Local variables:
1664 mode: sgml
1665 sgml-declaration:"~/SGML/HTML4.decl"
1666 sgml-default-doctype-name:"html"
1667 sgml-minimize-attributes:t
1668 sgml-nofill-elements:("pre" "style" "br")
1669 sgml-live-element-indicator:t
1670 sgml-omittag:nil
1671 sgml-shorttag:nil
1672 sgml-namecase-general:t
1673 sgml-general-insert-case:lower
1674 sgml-always-quote-attributes:t
1675 sgml-indent-step:nil
1676 sgml-indent-data:t
1677 sgml-parent-document:nil
1678 sgml-exposed-tags:nil
1679 sgml-local-catalogs:nil
1680 sgml-local-ecat-files:nil
1681 End:
1682 -->
