W3C

CSS3 Ruby Module

W3C Candidate Recommendation 14 May 2003

This version:
http://www.w3.org/TR/2003/CR-css3-ruby-20030514
Latest version:
http://www.w3.org/TR/css3-ruby
Previous version:
http://www.w3.org/TR/2002/WD-css3-ruby-20021024
Editor:
Michel Suignard (Microsoft)
Contributors:
Marcin Sawicki (former editor) (Microsoft)
Michel Suignard (Microsoft)

Abstract

"Ruby" are short runs of text alongside the base text, typically used in East Asian documents to indicate pronunciation or to provide a short annotation. This document proposes a set of CSS properties associated with the 'Ruby' elements. They can be used in combination with the Ruby elements of HTML [RUBY].

Status of This Document

This specification is one of the "modules" for the upcoming CSS level 3 (CSS3) specification. It has been developed by the CSS Working Group which is part of the Style activity (see summary). It contains features to be included in CSS level 3.

This is a Candidate Recommendation, which means W3C believes the specification is ready to be implemented.

All persons are encouraged to review and implement this specification and send comments to the (archived) public mailing list www-style (see instructions). W3C Members can also send comments directly to the CSS Working Group.

For this specification to become a W3C Recommendation, the following criteria must be met:

  1. There must be at least two interoperable implementations for every feature in the specification.

    For the purposes of this criterion, we define the following terms:

    feature
    a section or subsection in the specification
    interoperable
    passing the respective test case(s) in the test suite, or, if the implementation is not a web browser, an equivalent test. Every relevant test in the test suite should have an equivalent test created if such a user agent (UA) is to be used to claim interoperability. In addition if such a UA is to be used to claim interoperability, then there must one or more additional UAs which can also pass those equivalent tests in the same way for the purpose of interoperability. The equivalent tests must be made publically available for the purposes of peer review.
    implementation
    a user agent which:
    1. implements the feature.
    2. is available (i.e. publicly downloadable or available through some other public point of sale mechanism). This is the "show me" requirement.
    3. is shipping (i.e. development, private or unofficial versions are insufficient).
    4. is not experimental (i.e. is intended for a wide audience and could be used on a daily basis.)
  2. A minimum of six months of the CR period must have elapsed. This is to ensure that enough time is given for any remaining major errors to be caught.

The comments that the CSS WG received on the last working draft, together with responses and resulting changes are listed in the disposition of comments.

Patent disclosures relevant to CSS may be found on the Working Group's public patent disclosure page.

To find the latest version of this specification, please follow the "Latest version" link above, or visit the list of W3C Technical Reports.

Contents


1. Dependencies on other modules

This CSS3 module depends on the following other CSS3 modules:

2. Introduction

2.1 Document conventions

There is a number of illustrations in this document for which the following legend is used:

Symbolic wide-cell glyph representation - wide-cell glyph (e.g. Han) which is the n-th character in the text run, they may also appear as half size boxes when used as annotations.
Symbolic narrow-cell glyph representation - narrow-cell glyph (e.g. Roman) which is the n-th glyph in the text run.

Many typographical properties in East Asian typography depend on the fact that a character is typically rendered as either a wide or narrow character. All characters described by the Unicode Standard [UNICODE] can be categorized by a width property. This is covered by the Unicode Standard Annex [UAX#11].

The orientation which the above symbols assume in the diagrams corresponds to the orientation that the glyphs they represent are intended to assume when rendered by the user agent. Spacing between these characters in the diagrams is usually symbolic, unless intentionally changed to make a point.

Finally, in this document, requirements are expressed using the key words "MUST", "MUST NOT", "REQUIRED", "SHALL" and "SHALL NOT". Recommendations are expressed using the key words "SHOULD", "SHOULD NOT" and "RECOMMENDED". "MAY" and "OPTIONAL" are used to indicate optional features or behavior. These keywords are used in accordance with [RFC 2119]. For legibility these keywords are used in lowercase form.

2.2 What is ruby?

"Ruby" is the commonly used name for a run of text that appears in the immediate vicinity of another run of text, referred to as the "base", and serves as an annotation or a pronunciation guide associated with that run of text. Ruby, as used in Japanese, is described in JIS X-4051 [JIS4051]. The ruby structure and the XHTML markup to represent it is described in the Ruby Annotation [RUBY]. This section describes the CSS properties relevant to ruby. The following figures show two examples of Ruby.

Example of ruby applied on top of a Japanese expression

Figure 2.2.1: Example of ruby used in Japanese (simple case)

Example showing complex ruby with annotation text before and after 
the base characters

Figure 2.2.2: Complex ruby with annotation text before and after the base characters

In the first example, a single annotation is used to annotate the base sequence. In Japanese typography, this simple case is sometimes called  "taigo ruby" (per-word ruby).

In the second example, multiple annotations are attached to a base sequence, the hiragana characters on top refer to the pronunciation of each of the base Kanji characters (annotated in a monoruby fashion), while the words 'Keio' and 'University' on the bottom are annotations describing the English translation of respectively the first four and the last two Kanji characters of the base. To allow correct association between the hiragana characters and their corresponding Kanji base characters, the spacing between these Kanji characters may be adjusted (this happens to the fourth Kanji character in the figure 2.1.2 above).

Note: To avoid variable spacing between the Kanji characters in the example above the hiragana annotations can also be created as a simple annotation ruby.

The two examples correspond respectively to two types of ruby: a simple ruby using a simple ruby markup and a complex ruby using a complex ruby markup.

3. The CSS ruby model

3.1 Ruby specific 'display' property values

The CSS ruby model is based on the W3C Ruby Annotation Recommendation [RUBY], which is consistent with the XHTML Modularization Framework [XHTMLMOD]. The Recommendation specifies the ruby structure in a way to closely parallel the visual layout of the ruby element. In this model, a ruby consists of one or more base elements associated with one or more annotation elements.

The CSS model does not require that the document language include elements that correspond to each of these components. For document languages (such as XML applications) that do not have pre-defined ruby elements, authors must map document language elements to ruby elements; this is done with the 'display' property. The following 'display' values assign ruby semantics to an arbitrary element:

ruby (in XHTML: ruby)
Specifies that an element defines a ruby structure.
ruby-base (in XHTML: rb)
Specifies that an element defines a ruby base.
ruby-text (in XHTML: rt)
Specifies that an element defines a ruby text.
ruby-base-container (in XHTML: rbc)
Specifies that an element contains one or more ruby base.
ruby-text-container (in XHTML: rtc)
Specifies that an element contains one or more ruby text.

The rbspan attribute should also be used by XML applications to allow annotation spanning; but in addition, the 'ruby-span' property must be used by those applications to indicate to the user agent the number of ruby base elements to be spanned.

3.2 Ruby box model

In the following description, the elements specified by the Ruby Annotation [RUBY] are used to describe the box model. As mentioned earlier, a user agent can obtain the same results by using the Ruby specific 'display' property values.

For a user agent that supports the ruby markup, the ruby structure consists of three or more boxes. The outermost container is the ruby element itself. In the simple case, it is a container for two non-overlapping boxes: the ruby text box (rt element) and the ruby base box (rb element). The positioning of these two boxes relative to each other is controlled by the 'ruby-position' property.

Diagram of the ruby box model    consisting of two boxes, one on top of the other, enclosed within a third box representing the ruby element

Figure 3.2.1: Ruby box model (simple case)

In the case of complex ruby, the ruby element is a container for two or three non-overlapping boxes: one ruby base collection (rbc element), and one or two ruby text collections (rtc element). The rbc element is itself a container for one or several ruby base box (rb element), while each rtc element is a container for one or several ruby text box (rt element). The position of the rtc element in relation to the related rbc element is controlled by the 'ruby-position' property. The two following figures show examples of these complex ruby.

Diagram of a group ruby with a full ruby    text above and partial ruby text below

Figure 3.2.2: Ruby box model (complex ruby with an empty rt element after)

In the example above, the ruby text after (below) the ruby bases contains two rt elements with the first one being empty, the empty rt element corresponds to the first part of the ruby base collection (the first part is identified by the first rb element within the rbc element).

Diagram of a group ruby with a spanning    ruby text above and partial ruby text below

Figure 3.2.3: Ruby box model (complex ruby with a spanning ruby text element)

In the example above, the ruby text before (above) the ruby bases spans the whole ruby base collection. The ruby text after (below) the ruby bases still contain two rt elements, one of which is empty. The spanning behavior of rt text elements is controlled by the  rbspan attribute in a way similar to the colspan attribute used for table column.

Note: The visual description of the ruby elements does not refer necessarily to the logical orders of the elements

The width of the ruby box is by default determined by its widest child element, whose width in turn is determined by its content. The width of all direct children of the ruby element is the width of the widest children. In this respect, the ruby box is much like a two or three row table element, with the following exceptions:

If the ruby text is not allowed to overhang, then the ruby behaves like a traditional box, i.e. only its contents are rendered within its boundaries and adjacent elements do not cross the box boundary:

Diagram showing the ruby boxes interacting with adjacent text

Figure 3.2.4: Simple ruby whose text is not allowed to overhang adjacent text

However, if ruby text is allowed to overhang adjacent elements and it happens to be wider than its base, then the adjacent content is partially rendered within the area of the ruby base box, while the ruby text may be partially overlapping with the upper blank parts of the adjacent content:

Diagram showing the ruby boxes interacting with adjacent text

Figure 3.2.5: Simple ruby whose text is allowed to overhang adjacent text

The ruby text related to a ruby base can never overhang another ruby base.

The alignment of the contents of the base or the ruby text is not affected by the overhanging behavior. The alignment is achieved the same way regardless of the overhang behavior setting and it is computed before the space available for overlap is determined. It is controlled by the 'ruby-align' property.

The exact circumstances in which the ruby text will overhang other elements, and to what degree it will do so, will be controlled by the 'ruby-overhang' property.

This entire logic applies the same way in vertical ideographic layout, only the dimension in which it works in such a layout is vertical, instead of horizontal.

Note: Because the purpose of the XHTML rp element [RUBY] is to allow pre-existing user agents to parenthesize ruby text content, an XHTML user agent should use a styling rule for these elements that avoids rendering them such as  rp {display: none}.

3.3 Ruby box and line stacking

The interaction of the ruby box and line stacking is controlled by the 'line-stacking-ruby' property described in the CSS3 Line Module. That property takes two values: 'include-ruby' and 'exclude-ruby. Depending on the property value, the ruby box is considered or excluded for line stacking. Even if the ruby box is considered for line stacking, some values of the 'line-stacking-strategy' property (also described in the CSS3 Line module) can still create occurrences where a the ruby box will eventually be ignored (e.g. case where the 'line-stacking-strategy' value is 'block-line-height').

In the following figure, each line box is shown with leading space distributed before and after the two text segments ('Previous line' and 'Ruby base'); the dotted lines show the line box for each line. The 'line-stacking-ruby' property is set to 'exclude-ruby'. The achieved effect is that the ruby box does not affect the line to line spacing. It is however the responsibility of the style author to avoid 'bleeding' effects between the ruby text and the surrounding text of images.

Diagram showing the ruby text using 2 half leading

Figure 3.3.1: Excluded Ruby text

In the following figure, the line boxes have no extra leading space. The 'line-stacking-ruby' property is set to 'include-ruby' and the 'line-stacking-strategy' property is set to a value where inline boxes are considered for line stacking. In this case, the line box with the ruby text is affected and has its 'stack-height' increased by the amount necessary to fit the ruby text.

Diagram showing the ruby text expanding above base text

Figure 3.3.2: Ruby text increasing line height

This mechanism allows rendering of evenly spaced lines of text within a block-level element, whether a line contains ruby or not. The authors need only to set for the block-level element a line height value larger than the computed line-height of the largest ruby element within the block.

4. Ruby Properties

All properties, in addition to the noted values, take 'initial' and 'inherit'. These values are not repeated in each of the property value enumeration.

4.1 Ruby positioning: the 'ruby-position' property

Name:'ruby-position'
Value: before | after | right
Initial: before
Applies to: the parent of elements with display: ruby-text.
Inherited: yes
Percentages:  N/A
Media: visual
Computed value:   specified value (except for initial and inherit)

This property is used by the parent of elements with display: ruby-text to control the position of the ruby text with respect to its base. Such parents are typically either the ruby element itself (simple ruby) or the rtc element (complex ruby). This assures that all part of a rtc element will be displayed in the same position. Possible values:

before
The ruby text appears before the base. This is the most common setting used in ideographic East Asian writing systems. This is the initial value.

Diagram of ruby glyph layout in horizontal mode with ruby text appearing above the base

Figure 4.1.1: Top ruby in horizontal layout applied to Japanese text

If the base appears in a vertical-ideographic layout mode, the ruby appears on the right side of the base and is rendered in the same layout mode as the base (i.e. vertical-ideographic).

Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the right of the base

Figure 4.1.2: Top ruby in vertical ideographic layout applied to Japanese text

Note the special case of traditional Chinese as used especially in Taiwan: ruby (made of Bopomofo glyphs) in that context can appear along the right side of the base glyph, as if the text were in vertical layout, but the bases themselves are rendered on a horizontal line, since the actual layout is horizontal:

Example of Taiwanese-style ruby

Figure 4.1.3: "Bopomofo" ruby in traditional Chinese (ruby text shown in blue for clarity) in horizontal layout

In order to achieve that effect, vertical-ideographic layout should be set on each individual ruby. That can be accomplished with the following simple CSS rule:

ruby.bopomofo { writing-mode: tb-rl }

Note: The Bopomofo transcription is written in the normal way as part of the ruby text. The user agent is responsible for ensuring the correct relative alignment and positioning of the glyphs, including those corresponding to the tone marks, when displaying as vertical ruby.

after
The ruby text appears after the base. This is a relatively rare setting used in ideographic East Asian writing systems, most easily found in educational text.

Diagram of ruby glyph layout in horizontal mode with ruby text appearing below the base

Figure 4.1.4: Bottom ruby in horizontal layout applied to Japanese text

If the base appears in a vertical ideographic mode, the bottom ruby appears on the left side of the base and is rendered in the same layout mode as the base (i.e. vertical).

Diagram of ruby glyph layout in vertical mode with ruby text apearing vertically on the left of the base

Figure 4.1.5: Bottom ruby in vertical ideographic layout applied to Japanese text

right
The ruby text appears on the right of the base. Unlike 'before' and 'after', this value is not relative to the text flow direction.

If two rtc elements are set with the same ruby-position value, (for example both 'before'), the relative position of the two elements is undefined. This setting should not be used.

4.2 Ruby alignment: the 'ruby-align' property

Name:'ruby-align'
Value: auto | start | left | center | end | right | distribute-letter | distribute-space | line-edge
Initial: auto
Applies to: all elements and generated content
Inherited: yes
Percentages:  N/A
Media: visual
Computed value:   specified value (except for initial and inherit)

This property can be used on any element to control the text alignment of the ruby text and ruby base contents relative to each other. It applies to all the ruby's in the element. For simple ruby, the alignment is applied to the ruby child element whose content is shorter: either the rb element or the rt element [RUBY]. For complex ruby, the alignment is also applied to the ruby child elements whose content is shorter: either the rb element and/or one or two rt elements for each related ruby text and ruby base element within the rtc and rbc element.

Possible values:

auto
The user agent determines how the ruby contents are aligned. This is the initial value. The behavior recommended by [JIS4051] is for a wide-cell ruby is to be aligned in the 'distribute-space' mode:

Diagram of glyph layout in auto aligned ruby when ruby text is shorter than baseDiagram of glyph layout in auto aligned ruby when ruby text is longer than base

Figure 4.2.1: Wide-cell text in 'auto' ruby alignment is 'distribute-space' justified

The recommended behavior for a narrow-cell glyph ruby is to be aligned in the 'center' mode.

Diagram of glyph layout in auto aligned ruby when halfwidth ruby text is shorter than baseDiagram of character layout in auto aligned ruby when ruby text is longer than narrow-width base

Figure 4.2.2: Narrow-width ruby text in 'auto' ruby alignment is centered

start
left
The ruby text content is aligned with the start edge of the base.

Diagram of glyph layout in left aligned ruby when ruby text is shorter than baseDiagram of glyph layout in left aligned ruby when ruby text is longer than base

Figure 4.2.3: Start ruby alignment

center
The ruby text content is centered within the width of the base. If the length of the base is smaller than the length of the ruby text, then the base is centered within the width of the ruby text.

Diagram of glyph layout in center aligned ruby when ruby text is shorter than baseDiagram of glyph layout in center aligned ruby when ruby text is longer than base

Figure 4.2.4: Center ruby alignment

end
right
The ruby text content is aligned with the end edge of the base.

Diagram of glyph layout in right aligned ruby when ruby text is shorter than baseDiagram of glyph layout in right aligned ruby when ruby text is longer than base

Figure 4.2.5: End ruby alignment

distribute-letter
If the width of the ruby text is smaller than that of the base, then the ruby text contents are evenly distributed across the width of the base, with the first and last ruby text glyphs lining up with the corresponding first and last base glyphs. If the width of the ruby text is at least the width of the base, then the letters of the base are evenly distributed across the width of the ruby text.

Diagram of glyph layout in distribute-letter aligned ruby when ruby text is shorter than baseDiagram of glyph layout in distribute-letter aligned ruby when ruby text is longer than base

Figure 4.2.6: Distribute-letter ruby alignment

distribute-space
If the width of the ruby text is smaller than that of the base, then the ruby text contents are evenly distributed across the width of the base, with a certain amount of white space preceding the first and following the last character in the ruby text. That amount of white space is normally equal to half the amount of inter-character space of the ruby text. If the width of the ruby text is at least the width of the base, then the same type of space distribution applies to the base. In other words, if the base is shorter than the ruby text, the base is distribute-space aligned. This type of alignment is sometimes referred to as the "1:2:1" alignment [JIS4051].

Diagram of glyph layout in distribute-space aligned ruby when ruby text is shorter than baseDiagram of glyph layout in distribute-space aligned ruby when ruby text is longer than base

Figure 4.2.7: Distribute-space ruby alignment

line-edge
If the ruby text is not adjacent to a line edge, it is aligned as in 'auto'. If it is adjacent to a line edge, then it is still aligned as in auto, but the side of the ruby text that touches the end of the line is lined up with the corresponding edge of the base. This type of alignment is specified by [JIS4051]. This type of alignment is relevant only to the scenario where the ruby text is longer than the ruby base. In the other scenarios, this is just 'auto'.

Diagram of glyph layout in line-edge aligned ruby when ruby text is shorter than baseDiagram of glyph layout in line-edge aligned ruby when ruby text is longer than base

Figure 4.2.8: Line edge ruby alignment

For a complex ruby with spanning elements, one additional consideration is required. If the spanning element spans multiple 'rows' (other rbc or rtc elements), and the ruby alignment requires space distribution among the 'spanned' elements, a ratio must be determined among the 'columns' of spanned elements. This ratio is computed by taking into consideration the widest element within each column.

In the context of this property, the 'left' and 'right' values are synonymous with the 'start' and 'end' values respectively. I.e. their meaning is relative according to the text layout flow. Most of the other CSS properties interpret 'left' and 'right' on an 'absolute' term. See Appendix A of the CSS3 Text Module for further details.

4.3 Ruby overhanging: the 'ruby-overhang' property

Name:'ruby-overhang'
Value: auto | start | end | none
Initial: none
Applies to: the parent of elements with display: ruby-text
Inherited: yes
Percentages:  N/A
Media: visual
Computed value:   specified value (except for initial and inherit)

This property determines whether, and on which side, ruby text is allowed to partially overhang any adjacent text in addition to its own base, when the ruby text is wider than the ruby base. Note that ruby text is never allowed to overhang glyphs belonging to another ruby base. Also the user agent is free to assume a maximum amount by which ruby text may overhang adjacent text. The user agent may use the [JIS4051] recommendation of using one ruby text character length as the maximum overhang length.

Possible values:

auto
The ruby text can overhang text adjacent to the base on either side. [JIS4051] specifies the categories of characters that ruby text can overhang. The user agent is free to follow the [JIS4051] recommendation or specify its own classes of characters to overhang. This is the initial value.

Diagram of glyph layout in overhanging ruby

Figure 4.3.1: Ruby overhanging adjacent text

start
The ruby text can overhang the text that precedes it. That means, for example, that ruby can overhang text that is to the left of it in horizontal LTR layout, or it can overhang text that is above it in vertical-ideographic layout.

Diagram of glyph layout when ruby overhangs the preceding glyphs only

Figure 4.3.2: Ruby overhanging preceding text only

end
The ruby text can overhang the text that follows it. That means, for example, that ruby can overhang text that is to the right of it in horizontal LTR layout, or it can overhang text that is below it in vertical-ideographic layout.

Diagram of glyph layout when ruby overhangs the following characters only

Figure 4.3.3: Ruby overhanging following text only

none
The ruby text cannot overhang any text adjacent to its base, only its own base.

Diagram of glyph layout in non-overhanging ruby

Figure 4.3.4: Ruby not allowed to overhang adjacent text

4.4 Ruby annotation spanning: the 'ruby-span' property

Name:'ruby-span'
Value: attr(x) | none
Initial: none
Applies to: elements with display: ruby-text
Inherited: no
Percentages:  N/A
Media: visual
Computed value:   <number>

This property controls the spanning behavior of annotation elements.

Note: A XHTML user agent may also use the rbspan attribute to get the same effect.

Possible values:

attr(x)
The value of attribute 'x' as a string value. The string value is evaluated as a <number> to determine the number of ruby base elements to be spanned by the annotation element. If the <number> is '0', it is replaced by '1'.The <number> is the computed value.
none
No spanning. The computed value is '1'.

The following example shows an XML example using the 'display' property values associated with the 'ruby structure and the 'ruby-span' property

myruby       { display: ruby-base; }
myrbc        { display: ruby-base-container; }
myrb         { display: ruby-base; }
myrtc.before { display: ruby-text-container; ruby-position: before}
myrtc.after  { display: ruby-text-container; ruby-position: after}
myrt         { display: ruby-text; ruby-span: attr(rbspan); }
...
<myruby>
  <myrbc>
    <myrb>10</myrb>
    <myrb>31</myrb>
    <myrb>2002</myrb>
  </myrbc>
  <myrtc class="before">
    <myrt>Month</myrt>
    <myrt>Day</myrt>
    <myrt>Year</myrt>
  </myrtc>
  <myrtc class="after">
    <myrt rbspan="3">Expiration Date</myrt>
  </myrtc>
</myruby>

5. Properties index

In addition to the specified values, all properties take the 'inherit' and 'initial' values.

Name Values Initial Applies to Inh. Percentages Media groups
'ruby-align' auto | start | left | center | end | right | distribute-letter | distribute-space | line-edge auto  all elements and generated content yes N/A  visual
'ruby-overhang' auto | start | end | none none the parent of elements with display: ruby-text yes  N/A visual
'ruby-position' before | after | right | inline see individual properties the parent of elements with display: ruby-text yes  N/A visual
'ruby-span' attr(x) | none none elements with display: ruby-text no N/A visual

6. Profiles

There are two modules defined by this chapter:

CSS3 Simple Ruby model

CSS3 Complex Ruby model.

They both contain all the properties specified by this CSS chapter, i.e. 'ruby-align', 'ruby-overhang', 'ruby-position' and 'ruby-span'. They differ by the required 'display' property values. The Simple Ruby model requires the values: 'ruby', 'ruby-base' and 'ruby-text'. The Complex Ruby model requires in addition the values: 'ruby-base-container' and 'ruby-text-container'.

Glossary

Bopomofo
37 characters and 4 tone markings used as phonetics in Chinese, especially standard Mandarin.
Hanja
Subset of the Korean writing system that utilizes ideographic characters borrowed or adapted from the Chinese writing system. Also see Kanji.
Hiragana
Japanese syllabic script, or character of that script. Rounded and cursive in appearance. Subset of the Japanese writing system, used together with kanji and katakana. In recent times, mostly used to write Japanese words when kanji are not available or appropriate, and word endings and particles. Also see Katakana.
Ideograph
A character that is used to represent an idea, word, or word component, in contrast to a character from an alphabetic or syllabic script. The most well-known ideographic script is used (with some variation) in East Asia (China, Japan, Korea,...).
Kana
Collective term for hiragana and katakana.
Kanji
Japanese term for ideographs; ideographs used in Japanese. Subset of the Japanese writing system, used together with hiragana and katakana. Also see Hanja.
Katakana
Japanese syllabic script, or character of that script. Angular in appearance. Subset of the Japanese writing system,  used together with kanji and hiragana. In recent times, mainly used to write foreign words. Also see Hiragana.
Monoruby
In Japanese typography: Ruby associated with a single character of the base text.
Ruby
A run of text that appears in the vicinity of another run of text and serves as an annotation or a pronunciation guide for that text.

Acknowledgements

This specification would not have been possible without the help from:

Stephen Deach, Martin Dürst,  Hideki Hiura(樋浦 秀樹), Masayasu Ishikawa(石川 雅康), Chris Pratley, Takao Suzuki(鈴木 孝雄), Frank Yung-Fong Tang, Chris Thrasher, Masafumi Yabe家辺 勝文), Steve Zilles.


References

[CSS2]
Cascading Stylesheets, level 2 (CSS2) Specification, W3C Recommendation
Bert Bos, Håkon Wium Lie, Chris Lilley and Ian Jacobs, 12 May 1998
Available at: http://www.w3.org/TR/1998/REC-CSS2-19980512
[CSS3TEXT]
CSS3 module: Text (working draft)
Michel Suignard; 24 October 2002
Available at: http://www.w3.org/TR/2002/WD-css3-text-20021024
[HTML4]
HTML 4.01 Specification, W3C Recommendation
Dave Raggett, Arnaud Le Hors and Ian Jacobs, 18 December 1997, latest revised 24 December 1999
Available at: http://www.w3.org/TR/1999/REC-html401-19991224
[JIS4051]
Line composition rules for Japanese documents (日本語文書の行組版方法)
JIS X 4051-1995, Japanese Standards Association, 1995 (in Japanese)
[JIS4052]
"Exchange format for Japanese documents with composition markup" (日本語文書の組版指定交換形式)
JIS X 4052:2000, Japanese Standards Association, 2000 (in Japanese)
[RFC 2119]
Scott Bradner, Key words for use in RFCs to Indicate Requirement Levels, IETF RFC 2119.
(See http://www.ietf.org/rfc/rfc2119.txt.)
[RUBY]
Ruby Annotation, W3C Recommendation
Marcin Sawicki, Michel Suignard, Masayasu Ishikawa, Martin Dürst and Tex Texin, 31 May 2001,
Available at: http://www.w3.org/TR/2001/REC-ruby-20010531
[UNICODE]
The Unicode Consortium. Book version: The Unicode Standard: Version 3.0. Addison Wesley Longman. 2000. ISBN 0-201-61633-5. Online version: The Unicode Standard: Version 3.2.0, URL:
http://www.unicode.org/unicode/standard/versions/enumeratedversions.html#Unicode_3_2_0
For more information, consult the Unicode Consortium's home page at http://www.unicode.org/
[UAX#11]
Asmus Freytag. East Asian Width. 15 March 2002. Unicode Standard Annex #11. URL:
http://www.unicode.org/unicode/reports/tr11/tr11-10
[XSL]
Extensible Stylesheet Language (XSL) Version 1.0, W3C Recommendation
Sharon Adler, Stephen Deach, et al., 15 October 2001
Available at: http://www.w3.org/TR/2001/REC-xsl-20011015/
[XHTMLMOD]
Modularization of XHTML, W3C Recommendation
Murray Altheim, Shane McCarron, et al., 10 April 2001
Available at: http://www.w3.org/TR/2001/REC-xhtml-modularization-20010410/