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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang=en>
<head><meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<title>CSS Text Level 3</title>
<link href=default.css rel=stylesheet type="text/css">
<style type="text/css">
.data, .proptable {
margin: 1em auto;
border-collapse: collapse;
border: solid #005A9B;
}
.data caption {
width: 100%;
text-align: center;
}
.data td, .data th,
.proptable td, .proptable th {
border: thin solid;
padding: 0.2em;
tex
8D6D
t-align: center;
}
.data thead th[scope="row"],
.proptable thead th[scope="row"] {
text-align: right;
background: #A4C8E2;
color: inherit;
}
.data thead,
.proptable thead {
background: #EEEEEE;
color: inherit;
}
.data tbody th:first-child,
.proptable tbody th:first-child {
text-align: right;
background: #EEEEEE;
color: inherit;
}
.data thead,
.data tbody,
.data tfoot,
.data colgroup {
border: solid;
}
table.propdef {
table-layout: auto;
}
.propdef th {
font-style: italic;
font-weight: normal;
text-align: left;
width: 3em;
}
dt dfn code {
font-size: inherit;
}
</style>
<style type="text/css">
.egbidiwsaA,.egbidiwsbB,.egbidiwsaB,.egbidiwsbC
{ white-space:pre;font-size:80%;font-family:monospace; vertical-align:2px; margin:1px }
.egbidiwsaA { background:lime;padding:2px; }
.egbidiwsbB { border:2px solid blue }
.egbidiwsaB { background:yellow;border:2px dotted white }
.egbidiwsbC { border:2px dotted red }
.char { border: 1px dotted gray; }
.quarter { font-size: 25%; }
tt[lang="ja"] { font-family: "MS Gothic", "Osaka", monospace }
</style>
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
type="text/css">
<body>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1>CSS Text Level 3</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 8 May 2011</h2>
<dl>
<dt>This version:
<dd><a href="http://dev.w3.org/csswg/css3-text/Overview.html">$Date:
2011/05/08 10:15:05 $ (CVS $Revision$)</a> <!--
<dd><a href="http://www.w3.org/TR/2011/WD-css3-text-20110508/">http://www.w3.org/TR/2011/WD-css3-text-20110508/</a></dd>
-->
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css3-text/">http://www.w3.org/TR/css3-text/</a>
<dt>Previous version:
<dd><a
href="http://www.w3.org/TR/2011/WD-css3-text-20110215/">http://www.w3.org/TR/2011/WD-css3-text-20110215/</a>
<dt>Editors:
<dd><a href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>
(Invited Expert)
<dd><a href="mailto:kojiishi@gluesoft.co.jp">Koji Ishii</a> (Invited
Expert)
<dd><a href="mailto:murakami@antenna.co.jp">Shinyu Murakami</a> (<a
href="http://www.antenna.co.jp/">Antenna House</a>)
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2011 <a
href="http://www.w3.org/"><acronym title="World Wide Web
Consortium">W3C</acronym></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute
of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym
title="European Research Consortium for Informatics and
Mathematics">ERCIM</acronym></a>, <a
href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p>This CSS3 module defines properties for text manipulation and specifies
their processing model. It covers line breaking, justification and
alignment, white space handling, text decoration and text transformation.
<h2 class="no-num no-toc" id=status>Status of This Document</h2>
<p><em>This section describes the status of this document at the time of
its publication. Other documents may supersede this document. A list of
current W3C publications and the latest revision of this technical report
can be found in the <a href="http://www.w3.org/TR/">W3C technical reports
index at http://www.w3.org/TR/.</a></em>
<p>Publication as a Working Draft does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite this
document as other than work in progress.
<p>This CSS module has been produced as a combined effort of the <a
href="http://www.w3.org/International/Activity">W3C Internationalization
Activity</a>, and the <a href="http://www.w3.org/Style/Activity">Style
Activity</a> and is maintained by th
7E53
e <a
href="http://www.w3.org/Style/CSS/members">CSS Working Group</a>. It also
includes contributions made by participants in the <a
href="http://www.w3.org/Style/XSL/Group/">XSL Working Group</a> (<a
href="http://cgi.w3.org/MemberAccess/AccessRequest">members only</a>).
<p>This document was produced by a group operating under the <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
2004 W3C Patent Policy</a>. W3C maintains a <a
href="http://www.w3.org/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the W3C Patent Policy</a>.
<p><strong>Feedback on this draft should be posted to the (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a
href="mailto:www-style@w3.org">www-style@w3.org</a></strong> (see <a
href="http://www.w3.org/Mail/Request">instructions</a>) <strong>with
<kbd>[css3-text]</kbd> in the subject line.</strong> You are strongly
encouraged to complain if you see something stupid in this draft. The
editors will do their best to respond to all feedback.
<p><strong>If you have implemented properties from the <a
href="http://www.w3.org/TR/2003/CR-css3-text-20030514/">May 2003 CSS3 Text
CR</a></strong> <em>please</em> let us know so we can take that into
account as we redraft the spec. You can post to <a
href="http://lists.w3.org/Archives/Public/www-style/">www-style</a>
(public), post to the <a
href="http://lists.w3.org/Archives/Member/w3c-css-wg/">CSS WG mailing
list</a> (<a
href="http://cgi.w3.org/MemberAccess/AccessRequest">Member-restricted</a>),
or <a href="http://fantasai.inkedblade.net/contact">email fantasai
directly</a> (personal).
<p>The following features are at risk and may be cut from the spec during
its CR period if there are no (correct) implementations:
<ul>
<li>the ‘<a href="#hanging-punctuation0"><code
class=property>hanging-punctuation</code></a>’ property
<li>the ‘<code class=css>all</code>’ value of the ‘<a
href="#hyphens0"><code class=property>hyphens</code></a>’ property
<li>the percentage values of ‘<a href="#letter-spacing0"><code
class=property>letter-spacing</code></a>’ and ‘<a
href="#word-spacing0"><code class=property>word-spacing</code></a>’
<li>the ‘<code class=css>hyphenate-limit-*</code>’ properties
<li>the ‘<a href="#hyphenate-resource"><code
class=property>hyphenate-resource</code></a>’ property / ‘<a
href="#hyphenate-resource"><code
class=css>@hyphenate-resource</code></a>’ at-rule
<li>the ‘<a href="#text-outline0"><code
class=property>text-outline</code></a>’ property
<li>the ‘<a href="#text-spacing"><code
class=property>text-spacing</code></a>’ property
<li>the ‘<a href="#text-decoration-skip0"><code
class=property>text-decoration-skip</code></a>’ property /
‘<code class=css>ink</code>’ value
<li>the ‘<a href="#text-emphasis-skip0"><code
class=property>text-emphasis-skip</code></a>’ property
<li><span class=issue>audit draft and add more here</span>
</ul>
<h2 class="no-num no-toc" id=contents>Table of Contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#intro"><span class=secno>1. </span> Introduction</a>
<li><a href="#conformance"><span class=secno>2. </span> Conformance</a>
<ul class=toc>
<li><a href="#partial-impl"><span class=secno>2.1. </span> Partial and
Experimental Implementations</a>
</ul>
<li><a href="#transforming"><span class=secno>3. </span> Transforming
Text</a>
<ul class=toc>
<li><a href="#text-transform"><span class=secno>3.1. </span>
Transforming Text: the ‘<code
class=property>text-transform</code>’ property</a>
</ul>
<li><a href="#white-space-processing"><span class=secno>4. </span> White
Space Processing</a>
<ul class=toc>
<li><a href="#white-space-collapsing"><span class=secno>4.1. </span>
White Space Collapsing: the ‘<code
class=property>bikeshedding</code>’ property</a>
<li><a href="#tab-size"><span class=secno>4.2. </span> Tab Character
Size: the ‘<code class=property>tab-size</code>’
property</a>
<li><a href="#white-space-rules"><span class=secno>4.3. </span> The
White Space Processing Rules</a>
<ul class=toc>
<li><a href="#egbidiwscollapse"><span class=secno>4.3.1. </span>
Example of bidirectionality with white space collapsing</a>
<li><a href="#line-break-transform"><span class=secno>4.3.2. <
23C
;/span>
Line Feed Transformation Rules</a>
<li><a href="#white-space-summary"><span class=secno>4.3.3. </span>
Informative Summary of White Space Collapsing Effects</a>
</ul>
<li><a href="#white-space"><span class=secno>4.4. </span> White Space
and Text Wrapping Shorthand: the ‘<code
class=property>white-space</code>’ property</a>
</ul>
<li><a href="#line-breaking"><span class=secno>5. </span> Line Breaking
and Word Boundaries</a>
<ul class=toc>
<li><a href="#line-break"><span class=secno>5.1. </span> Line Breaking
Strictness: the ‘<code class=property>line-break</code>’
property</a>
<li><a href="#word-break"><span class=secno>5.2. </span> Word Breaking
Rules: the ‘<code class=property>word-break</code>’
property</a>
</ul>
<li><a href="#hyphenation"><span class=secno>6. </span>Hyphenation</a>
<ul class=toc>
<li><a href="#hyphens"><span class=secno>6.1. </span>Hyphenation
Control: the ‘<code class=property>hyphens</code>’
property</a>
<li><a href="#hyphenate-character"><span class=secno>6.2. </span>
Hyphens: the ‘<code
class=property>hyphenate-character</code>’ property</a>
<li><a href="#hyphenate-size-limits"><span class=secno>6.3. </span>
Hyphenation Size Limit: the ‘<code
class=property>hyphenate-limit-zone</code>’ property</a>
<li><a href="#hyphenate-char-limits"><span class=secno>6.4. </span>
Hyphenation Character Limits: the ‘<code
class=property>hyphenate-limit-word</code>’ property</a>
<li><a href="#hyphenate-line-limits"><span class=secno>6.5. </span>
Hyphenation Line Limits: the ‘<code
class=property>hyphenate-limit-lines</code>’ and ‘<code
class=property>hyphenate-limit-last</code>’ properties</a>
<li><a href="#hyphenation-resource"><span class=secno>6.6. </span>
Hyphenation Resources</a>
<ul class=toc>
<li><a href="#at-hyphenate-resource"><span class=secno>6.6.1.
</span>The ‘<code class=css>@hyphenate-resource</code>’
rule </a>
<li><a href="#the-hyphenate-resource"><span class=secno>6.6.2.
</span>The ‘<code
class=property>hyphenate-resource</code>’ property</a>
</ul>
</ul>
<li><a href="#wrapping"><span class=secno>7. </span> Text Wrapping</a>
<ul class=toc>
<li><a href="#text-wrap"><span class=secno>7.1. </span> Text Wrap
Settings: the ‘<code class=property>text-wrap</code>’
property</a>
<ul class=toc>
<li><a href="#example-avoid"><span class=secno>7.1.1. </span>Example
of using ‘<code class=css>text-wrap: avoid</code>’ in
presenting a footer</a>
</ul>
<li><a href="#word-wrap"><span class=secno>7.2. </span> Emergency
Wrapping: the ‘<code class=property>word-wrap</code>’
property</a>
</ul>
<li><a href="#justification"><span class=secno>8. </span> Alignment and
Justification</a>
<ul class=toc>
<li><a href="#text-align"><span class=secno>8.1. </span> Text Alignment:
the ‘<code class=property>text-align</code>’ property</a>
<ul class=toc>
<li><a href="#character-alignment"><span class=secno>8.1.1.
</span>Details on Character-based Alignment in a Table Column</a>
</ul>
<li><a href="#text-align-last"><span class=secno>8.2. </span> Last Line
Alignment: the ‘<code
class=property>text-align-last</code>’ property</a>
<li><a href="#text-justify"><span class=secno>8.3. </span> Justification
Method: the ‘<code class=property>text-justify</code>’
property</a>
</ul>
<li><a href="#spacing"><span class=secno>9. </span> Spacing</a>
<ul class=toc>
<li><a href="#word-spacing"><span class=secno>9.1. </span> Word Spacing:
the ‘<code class=property>word-spacing</code>’ property</a>
<li><a href="#letter-spacing"><span class=secno>9.2. </span> Tracking:
the ‘<code class=property>letter-spacing</code>’
property</a>
<li><a href="#text-spacing-prop"><span class=secno>9.3. </span>
Character Class Spacing: the ‘<code
class=property>text-spacing</code>’ property</a>
<ul class=toc>
<li><a href="#fullwidth-collapsing"><span class=secno>9.3.1. </span>
Fullwidth Punctuation Collapsing</a>
<li><a href="#text-spacing-classes"><span class=secno>9.3.2. </span>
Text Spacing Character Classes</a>
</ul>
</ul>
<li><a href="#edge-effects"><span class=secno>10. </span> Edge Effects</a>
<ul class=toc>
<li><a href="#text-indent"><span class=secno>10.1. </span> First Line
Indentation: the ‘<code class=property>text-indent</code>’
property</a>
<li><a href="#hanging-punctuation"><span class=secno>10.2. </span>
Hanging Punctuation: the ‘<code
class=property>hanging-punctuation</code>’ property</a>
</ul>
<li><a href="#decoration"><span class=secno>11. </span> Text
Decoration</a>
<ul class=toc>
<li><a href="#line-decoration"><span class=secno>11.1. </span> Line
Decoration: Underline, Overline, and Strike-Through</a>
<ul class=toc>
<li><a href="#text-decoration-line"><span class=secno>11.1.1. </span>
Text Decoration Lines: the ‘<code
class=property>text-decoration-line</code>’ property</a>
<li><a href="#text-decoration-color"><span class=secno>11.1.2. </span>
Text Decoration Color: the ‘<code
class=property>text-decoration-color</code>’ property</a>
<li><a href="#text-decoration-style"><span class=secno>11.1.3. </span>
Text Decoration Style: the ‘<code
class=property>text-decoration-style</code>’ property</a>
<li><a href="#text-decoration"><span class=secno>11.1.4. </span> Text
Decoration Shorthand: the ‘<code
class=property>text-decoration</code>’ property</a>
<li><a href="#text-decoration-skip"><span class=secno>11.1.5. </span>
Text Decoration Line Continuity: the ‘<code
class=property>text-decoration-skip</code>’ property</a>
<li><a href="#text-underline-position"><span class=secno>11.1.6.
</span> Text Underline Position: the ‘<code
class=property>text-underline-position</code>’ property</a>
</ul>
<li><a href="#emphasis-marks"><span class=secno>11.2. </span> Emphasis
Marks</a>
<ul class=toc>
<li><a href="#text-emphasis-style"><span class=secno>11.2.1. </span>
Emphasis Mark Style: the ‘<code
class=property>text-emphasis-style</code>’ property</a>
<li><a href="#text-emphasis-color"><span class=secno>11.2.2. </span>
Emphasis Mark Color: the ‘<code
class=property>text-emphasis-color</code>’ property</a>
<li><a href="#text-emphasis"><span class=secno>11.2.3. </span>
Emphasis Mark Shorthand: the ‘<code
class=property>text-emphasis</code>’ property</a>
<li><a href="#text-emphasis-position"><span class=secno>11.2.4.
</span> Emphasis Mark Position: the ‘<code
class=property>text-emphasis-position</code>’ property</a>
<li><a href="#text-emphasis-skip"><span class=secno>11.2.5. </span>
Emphasis Mark Skip: the ‘<code
class=property>text-emphasis-skip</code>’ property</a>
</ul>
<li><a href="#text-shadow"><span class=secno>11.3. </span> Text Shadows:
the ‘<code class=property>text-shadow</code>’ property</a>
<li><a href="#text-outline"><span class=secno>11.4. </span> Text
Outlines: the ‘<code class=property>text-outline</code>’
property</a>
</ul>
<li class=no-num><a href="#changes">Changes</a>
<ul class=toc>
<li class=no-num><a href="#recent-changes"> Changes from the February
2011 CSS3 Text <abbr title="Working Draft">WD</abbr></a>
</ul>
<li class=no-num><a href="#acknowledgements"> Appendix A:
Acknowledgements</a>
<li class=no-num><a href="#appendix-b-references">Appendix B:
References</a>
<ul class=toc>
<li class=no-num><a href="#normative-ref">Normative references</a>
<li class=no-num><a href="#informative-ref">Informative references</a>
</ul>
<li class=no-num><a href="#traditions">Appendix C: Cultural
Correlations</a>
<li class=no-num><a href="#default-stylesheet">Appendix D: Default UA
Stylesheet</a>
<li class=no-num><a href="#script-groups">Appendix E: Scripts and
Spacing</a>
<li class=no-num><a href="#appendix-f-full-property-index">Appendix F:
Full Property Index</a>
<li class=no-num><a href="#index">Appendix I: Index</a>
</ul>
<!--end-toc-->
<h2 id=intro><span class=secno>1. </span> Introduction</h2>
<p>[document here]
<p class=issue>This draft describes features that are specific to certain
scripts. There is an ongoing discussion about where these features belong:
in existing CSS properties, in new CSS properties, or perhaps in other
specifications.
<p id=grapheme-cluster>A <dfn id=grapheme-cluster0>grapheme cluster</dfn>
is what a language user considers to be a character or a basic unit of the
script. The term is described in detail in the Unicode Technical Report:
Text Boundaries <a href="#UAX29"
rel=biblioentry>[UAX29]<!--{{!UAX29}}--></a>. This specification uses the
<em>extended grapheme cluster</em> definition in <a href="#UAX29"
rel=biblioentry>[UAX29]<!--{{!UAX29}}--></a> (not the <em>legacy grapheme
cluster</em> definition). The UA may further tailor the definition as
allowed by Unicode.
<h2 id=conformance><span class=secno>2. </span> Conformance</h2>
<p>Conformance requirements are expressed with a combination of descriptive
assertions and RFC 2119 terminology. The key words “MUST”, “MUST
NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
“SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
normative parts of this document are to be interpreted as described in RFC
2119. However, for readability, these words do not appear in all uppercase
letters in this specification. All of the text of this specification is
normative except sections explicitly marked as non-normative, examples,
and notes. <a href="#RFC2119"
rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
<p>Examples in this specification are introduced with the words “for
example” or are set apart from the normative text with
<code>class="example"</code>, like this:
<div class=example>
<p>This is an example of an informative example.</p>
</div>
<p>Informative notes begin with the word “Note” and are set apart from
the normative text with <code>class="note"</code>, like this:
<p class=note>Note, this is an informative note.
<p>Conformance to CSS Text Level 3 is defined for three conformance
classes:
<dl>
<dt><dfn id=style-sheet title="style sheet!!as conformance class">style
sheet</dfn>
<dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
style sheet</a>.
<dt><dfn id=renderer>renderer</dfn>
<dd>A UA that interprets the semantics of a style sheet and renders
<span>documents</span> that use them.
<dt><dfn id=authoring-tool>authoring tool</dfn>
<dd>A UA that writes a style sheet.
</dl>
<p>A style sheet is conformant to CSS Text Level 3 if all of its
declarations that use properties defined in this module have values that
are valid according to the generic CSS grammar and the individual grammars
of each property as given in this module.
<p>A renderer is conformant to CSS Text Level 3 if, in addition to
interpreting the style sheet as defined by the appropriate specifications,
it supports all the properties defined by CSS Text Level 3 by parsing them
correctly and rendering the document accordingly. However, the inability
of a UA to correctly render a document due to limitations of the device
does not make the UA non-conformant. (For example, a UA is not required to
render color on a monochrome monitor.)
<p>An authoring tool is conformant to CSS Text Level 3 if it writes
syntactically correct style sheets, according to the generic CSS grammar
and the individual grammars of each property in this module.
<h3 id=partial-impl><span class=secno>2.1. </span> Partial and Experimental
Implementations</h3>
<p>UAs must treat as invalid any properties or values they do not support.
Experimental implementations of a feature should support only a
vendor-prefixed syntax for the property/value.
<h2 id=transforming><span class=secno>3. </span> Transforming Text</h2>
<h3 id=text-transform><span class=secno>3.1. </span> <a name=caps-prop></a>
Transforming Text: the ‘<a href="#text-transform0"><code
class=property>text-transform</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=text-transform0>text-transform</dfn>
<tr>
<th>Value:
<td>none | [ [ capitalize | uppercase | lowercase ] || fullwidth ||
fullsize-kana ]
<tr>
<th>Initial:
<td>none
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>yes
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
</table>
<p>This property transforms text for styling purposes. Values have the
following meanings:
<dl>
<dt><dfn id=none title="text-transform:none"><code>none</code></dfn>
<dd>No effects.
<dt><dfn id=capitalize
title="text-transform:capitalize"><code>capitalize</code></dfn>
<dd>Puts the first character of each word in titlecase; other characters
are unaffected.
<dt><dfn id=uppercase
title="text-transform:uppercase"><code>uppercase</code></dfn>
<dd>Puts all characters in uppercase.
<dt><dfn id=lowercase
title="text-transform:lowercase"><code>lowercase</code></dfn>
<dd>Puts all characters in lowercase.
<dt><dfn id=fullwidth
title="text-transform:fullwidth"><code>fullwidth</code></dfn>
<dd>Puts all characters in fullwidth form. If the character does not have
a corresponding fullwidth form, it is left as is. This value is typically
used to typeset Latin characters and digits like ideographic characters.
<dt><dfn id=fullsize-kana
title="text-transform:fullsize-kana"><code>fullsize-kana</code></dfn>
<dd>Converts all small Kana characters to normal Kana. This value is
typically used for ruby annotation text, where all small Kana should be
drawn as large Kana.
<p class=note>Authors using this for ruby text may also want to use
‘<code class=css>font-variant: ruby</code>’. <a
href="#CSS3FONT" rel=biblioentry>[CSS3FONT]<!--{{CSS3FONT}}--></a>
</dl>
<p>Although limited, the case mapping process has some language
dependencies. Some well known examples are Turkish and Greek. If the
content language is known then any such language-specific rules must be
used.
<p>The case mapping rules for the character repertoire specified by the
Unicode Standard can be found on the Unicode Consortium Web site. <a
href="#UNICODE" rel=biblioentry>[UNICODE]<!--{{!UNICODE}}--></a> Only
characters belonging to bicameral scripts are affected.
<p>The definition of "word" used for ‘<code
class=css>capitalize</code>’ is UA-dependent; <a href="#UAX29"
rel=biblioentry>[UAX29]<!--{{!UAX29}}--></a> is suggested (but not
required) for determining such word boundaries. Authors should not expect
‘<code class=css>capitalize</code>’ to follow
language-specific titlecasing conventions (such as skipping articles in
English).
<!-- www-style notes that UAX29 won't work for 'Tis and similar, so
the UA might want to use UAX29 to split into words, but skip forward
past any starting non-letters (as an example of why UAX29 is not ideal) -->
<p>The definition of fullwidth and halfwidth forms can be found on the
Unicode consortium web site at <a href="#UAX11"
rel=biblioentry>[UAX11]<!--{{!UAX11}}--></a>. The mapping to fullwidth
form is defined by <wide> tag of Character Decomposition Mapping in
<a href="#UAX44" rel=biblioentry>[UAX44]<!--{{!UAX44}}--></a>.
<p class=issue>Should all characters be transformed, or only letters (i.e.
not symbols, punctuation, or white space)
<p>Text transformation happens after <a href="#white-space-rules">white
space processing</a>. (This only matters when ‘<code
class=css>fullwidth</code>’ transforms U+0020 space characters to
U+3000.) <span class=issue>This requirement may need to be relaxed during
CR, so mark at-risk.</span>
<div class=example>
<p>The following example converts the ASCII characters in abbreviations in
Japanese to their fullwidth variants so that they lay out and line break
like ideographs:
<pre>abbr:lang(ja) { text-transform: fullwidth; }</pre>
</div>
<h2 id=white-space-processing><span class=secno>4. </span> White Space
Processing</h2>
<p>The source text of a document often contains formatting that is not
relevant to the final rendering: for example, breaking the source into
segments (lines) for ease of editing or adding white space characters such
as tabs and spaces to indent the source code. CSS white space processing
allows the author to control interpretation of such formatting: to
preserve or collapse it away when rendering the document.
<p id=segment-normalization> In the document source, segments can be
delimited by carriage returns (U+000D), linefeeds (U+000A) or a
combination (U+000D U+000A), or by some other mechanism, such as the SGML
RECORD-START and RECORD-END tokens. If no segmentation rules are specified
for the document language, each line feed (U+000A), carriage return
(U+000D) and CRLF sequence (U+000D U+000A) in the text is considered a
segment break. (This default rule also applies to generated content.) In
CSS, each such segment break is treated as a single line feed character
(U+000A).
<p>White space processing in CSS interprets white space characters only for
rendering: it has no effect on the underlying document data.
<p class=note>Note that the document parser may have not only normalized
segment breaks, but also collapsed other space characters or otherwise
processed white space according to markup rules. Because CSS processing
occurs <em>after</em> the parsing stage, it is not possible to restore
these characters for styling. Therefore, some of the behavior specified
below can be affected by these limitations and may be user agent
dependent.
<p>Control characters (Unicode class Cc) other than tab (U+0009), line feed
(U+000A), space (U+0020), and the bidi formatting characters
(U+202<var>x</var>) should be rendered as invisible zero-width characters.
UAs may instead treat them as visible characters. (Note, however, that
this will usually result in them being rendered as missing glyphs.) <span
class=issue>What's the line-breaking behavior? Effects on joining? Can we
just copy the behavior of some zero-width Unicode character?</span>
<h3 id=white-space-collapsing><span class=secno>4.1. </span> White Space
Collapsing: the ‘<a href="#bikeshedding"><code
class=property>bikeshedding</code></a>’ property</h3>
<p class=issue>This section is still under discussion and may change in
future drafts.
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=bikeshedding>bikeshedding</dfn>
<tr>
<th>Value:
<td>collapse | discard | [ [preserve | preserve-breaks] && [ trim-inner
|| consume-before || consume-after ]
<tr>
<th>Initial:
<td>collapse
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>yes
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>specified value
</table>
<p class=issue>Need a property name
<p>This property declares whether and how <a
href="#white-space-processing">white space</a> inside the element is
collapsed. Values have the following meanings, which must be interpreted
according to the <a href="#white-space-rules">white space processing
rules</a>:
<dl>
<dt><dfn id=collapse0
title="white-space:collapse"><code>collapse</code></dfn>
<dd>This value directs user agents to collapse sequences of white space
into a single character (or <a href="#line-break-transform">in some
cases</a>, no character).
<dt><dfn id=preserve
title="white-space:preserve"><code>preserve</code></dfn>
<dd>This value prevents user agents from collapsing sequences of white
space. Line feeds are preserved as forced line breaks.
<dt><dfn id=preserve-breaks
title="white-space:preserve-breaks"><code>preserve-breaks</code></dfn>
<dd>This value collapses white space as for ‘<code
class=css>collapse</code>’, but preserves line feeds as forced line
breaks.
<dt><dfn id=discard title="white-space:discard"><code>discard</code></dfn>
<dd>This value directs user agents to "discard" all white space in the
element.
<dt><dfn id=trim-inner
title="white-space:trim-inner"><code>trim-inner</code></dfn>
<dd>For block containers this value directs UAs to discard all whitespace
at the beginning of the element up to and including the last line feed
before the first non-white-space character in the element as well as to
discard all white space at the end of the element starting with the first
line feed after the last non-white-space character in the element. For
inline elements this value directs UAs to discard all whitespace at the
beginning and end of the element. For other elements, this has no effect.
<dt><dfn id=consume-before
title="white-space:consume-before"><code>consume-before</code></dfn>
<dd>This value directs the UA to collapse all collapsible whitespace
immediately before the start of the element.
<dt><dfn id=consume-after
title="white-space:consume-after"><code>consume-after</code></dfn>
<dd>This value directs the UA to collapse all collapsible whitespace
immediately after the end of the element.
</dl>
<h3 id=tab-size><span class=secno>4.2. </span> Tab Character Size: the
‘<a href="#tab-size0"><code
class=property>tab-size</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=tab-size0>tab-size</dfn>
<tr>
<th>Value:
<td><integer>
<tr>
<th>Initial:
<td>8
<tr>
<th>Applies to:
<td>block containers
<tr>
<th>Inherited:
<td>yes
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>specified value
</table>
<p>This property determines the width of the tab character (U+0009), in
space characters (U+0020), when rendered. Negative integers are not
allowed.
<p class=issue>BradK suggests allowing <length> values. Someone else
suggested spaces be given a unit, e.g. ‘<code
class=css>8sp</code>’. This unit could also be used for ‘<a
href="#letter-spacing0"><code
class=property>letter-spacing</code></a>’ and ‘<a
href="#word-spacing0"><code class=property>word-spacing</code></a>’.
<h3 id=white-space-rules><span class=secno>4.3. </span> The White Space
Processing Rules</h3>
<p>White space processing affects only spaces (U+0020), tabs (U+0009), and
(<a href="#segment-normalization">post-normalization</a>) line feeds
(U+00A0).
<p>For each inline (including anonymous inlines) within an inline
formatting context, white space characters are handled as follows,
ignoring bidi formatting characters as if they were not there:
<ul>
<li id=collapse>
<p>If ‘<a href="#bikeshedding"><code
class=property>bikeshedding</code></a>’ is set to ‘<code
class=css>collapse</code>’ or ‘<code
class=css>preserve-breaks</code>’, white space characters are
considered <dfn id=collapsible>collapsible</dfn> and are processed by
performing the following steps:</p>
<ol>
<li>All spaces and tabs immediately preceding or following a line feed
character are removed.
<li>If ‘<a href="#bikeshedding"><code
class=property>bikeshedding</code></a>’ is not ‘<code
class=css>preserve-breaks</code>’, line feed characters are
transformed for rendering according to the <a
href="#line-break-transform">line feed transformation rules</a>.
<li>Every tab is converted to a space (U+0020).
<li>Any space immediately following another collapsible space
—even one outside the boundary of the inline—is removed.
However, if removing this space would eliminate a line breaking
opportunity in the text, that opportunity is still considered to exist.
<li>A collapsible space immediately preceding an element with
‘<code class=css>consume-before</code>’ is removed. Such
removed spaces do not indicate a line breaking opportunity in the text.
<li>Any collapsible spaces after the end of an element with ‘<code
class=css>consume-after</code>’ are removed. Such removed spaces
do not indicate a line breaking opportunity in the text.
</ol>
<li>
<p>If ‘<a href="#bikeshedding"><code
class=property>bikeshedding</code></a>’ is set to ‘<code
class=css>preserve</code>’, any sequence of spaces unbroken by an
element boundary is treated as a sequence of non-breaking spaces.
However, a line breaking opportunity exists at the end of the sequence.
<li>
<p>If ‘<a href="#bikeshedding"><code
class=property>bikeshedding</code></a>’ is set to ‘<code
class=css>discard</code>’, the first white space character in
every white space sequence is converted to a zero width non-joiner
(U+200C) and the rest of the sequence is removed.</p>
</ul>
<p>Then, the entire block is rendered. Inlines are laid out, taking bidi
reordering into account, and wrapping as specified by the ‘<a
href="#text-wrap0"><code class=property>text-wrap</code></a>’
property.