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<!DOCTYPE html><html lang=en><head>
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<title>CSS Counter Styles Level 3</title>
<link href=../default.css rel=stylesheet type=text/css>
<link href=../csslogo.ico rel="shortcut icon" type=image/x-icon>
<link href=https://www.w3.org/StyleSheets/TR/W3C-CR rel=stylesheet type=text/css>
<style>
pre.stylesheet { white-space: pre-wrap; }
code.inline { display: inline-block; }
</style>
</head>
<body class=h-entry>
<div class=head>
<p data-fill-with=logo><a class=logo href=http://www.w3.org/>
<img alt=W3C height=48 src=https://www.w3.org/Icons/w3c_home width=72>
</a>
</p>
<h1 class="p-name no-ref" id=title>CSS Counter Styles Level 3</h1>
<h2 class="no-num no-toc no-ref heading settled" id=subtitle><span class=content>W3C Candidate Recommendation,
<time class=dt-updated datetime=2014-12-18>18 December 2014</time></span></h2>
<div data-fill-with=spec-metadata><dl><dt>This version:<dd><a class=u-url href=http://www.w3.org/TR/2014/CR-css-counter-styles-3-20141218/>http://www.w3.org/TR/2014/CR-css-counter-styles-3-20141218/</a><dt>Latest version:<dd><a href=http://www.w3.org/TR/css-counter-styles-3/>http://www.w3.org/TR/css-counter-styles-3/</a><dt>Editor's Draft:<dd><a href=http://dev.w3.org/csswg/css-counter-styles/>http://dev.w3.org/csswg/css-counter-styles/</a><dt>Previous Versions:<dd><a href=http://www.w3.org/TR/2014/WD-css-counter-styles-3-20140826/ rel=previous>http://www.w3.org/TR/2014/WD-css-counter-styles-3-20140826/</a><dd><a href=http://www.w3.org/TR/2013/WD-css-counter-styles-3-20130718/ rel=previous>http://www.w3.org/TR/2013/WD-css-counter-styles-3-20130718/</a><dd><a href=http://www.w3.org/TR/2013/WD-css-counter-styles-3-20130221/ rel=previous>http://www.w3.org/TR/2013/WD-css-counter-styles-3-20130221/</a><dd><a href=http://www.w3.org/TR/2012/WD-css-counter-styles-3-20121009/ rel=previous>http://www.w3.org/TR/2012/WD-css-counter-styles-3-20121009/</a><dt>Feedback:<dd><span><a href="mailto:www-style@w3.org?subject=%5Bcss-counter-styles%5D%20feedback">www-style@w3.org</a> with subject line “<kbd>[css-counter-styles] <var>… message topic …</var></kbd>” (<a href=http://lists.w3.org/Archives/Public/www-style/ rel=discussion>archives</a>)</span><dt>Issue Tracking:<dd><a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=CSS&component=Counter%20Styles&resolution=---">Bugzilla</a><dt class=editor>Editor:<dd class=editor><div class="p-author h-card vcard"><a class="p-name fn u-url url" href=http://xanthir.com/contact/>Tab Atkins Jr.</a> (<span class="p-org org">Google</span>)</div></dl></div>
<div data-fill-with=warning></div>
<p class=copyright data-fill-with=copyright><a href=http://www.w3.org/Consortium/Legal/ipr-notice#Copyright>Copyright</a> © 2014 <a href=http://www.w3.org/><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a href=http://www.csail.mit.edu/><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>, <a href=http://www.ercim.eu/><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href=http://www.keio.ac.jp/>Keio</a>, <a href=http://ev.buaa.edu.cn/>Beihang</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>
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc no-ref heading settled" id=abstract><span class=content>Abstract</span></h2>
<div class=p-summary data-fill-with=abstract><p>This module introduces the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule, which allows authors to define their own custom counter styles for use with CSS list-marker and generated-content counters <a data-biblio-type=informative data-link-type=biblio href=#biblio-css3list title=CSS3LIST>[CSS3LIST]</a>. It also predefines a set of common counter styles, including the ones present in CSS2 and CSS2.1.</p>
<a href=http://www.w3.org/TR/CSS/>CSS</a> is a language for describing the rendering of structured documents
(such as HTML and XML)
on screen, on paper, in speech, etc.</div>
<h2 class="no-num no-toc no-ref heading settled" id=status><span class=content>Status of this document</span></h2>
<div data-fill-with=status><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>
The (<a href=http://lists.w3.org/Archives/Public/www-style/>archived</a>)
public mailing list <a href="mailto:www-style@w3.org?Subject=%5Bcss-counter-styles%5D%20PUT%20SUBJECT%20HERE">www-style@w3.org</a>
(see <a href=http://www.w3.org/Mail/Request>instructions</a>)
is preferred for discussion of this specification.
When sending e-mail,
please put the text “css-counter-styles” in the subject,
preferably like this:
“[css-counter-styles] <em>…summary of comment…</em>”
<p>
This document was produced by the <a href=/Style/CSS/members>CSS Working Group</a>
(part of the <a href=/Style/>Style Activity</a>).
<p>
This document was produced by a group operating under
the <a href=/Consortium/Patent-Policy-20040205/>5 February 2004 W3C Patent Policy</a>.
W3C maintains a <a href=/2004/01/pp-impl/32061/sta
7DDD
tus 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=/Consortium/Patent-Policy-20040205/#def-essential>Essential Claim(s)</a>
must disclose the information in accordance with <a href=/Consortium/Patent-Policy-20040205/#sec-Disclosure>section 6 of the W3C Patent Policy</a>.
<p>
This document is governed by the <a href=http://www.w3.org/2014/Process-20140801/>1 August 2014 W3C Process Document</a>.
<p>
For changes since the last draft,
see the <a href=#changes>Changes</a> section.
</div>
<div data-fill-with=at-risk></div>
<h2 class="no-num no-toc no-ref heading settled" id=contents><span class=content>Table of Contents</span></h2>
<div data-fill-with=table-of-contents role=navigation><ul class=toc role=directory><li><a href=#intro><span class=secno>1</span> <span class=content>
Introduction</span></a><li><a href=#counter-styles><span class=secno>2</span> <span class=content>
Counter Styles</span></a><li><a href=#the-counter-style-rule><span class=secno>3</span> <span class=content>
Defining Custom Counter Styles: the <span class=css data-link-type=maybe title=@counter-style>@counter-style</span> rule</span></a><ul class=toc><li><a href=#counter-style-system><span class=secno>3.1</span> <span class=content>
Counter algorithms: the <span class=property data-link-type=propdesc title=system>system</span> descriptor</span></a><ul class=toc><li><a href=#cyclic-system><span class=secno>3.1.1</span> <span class=content>
Cycling Symbols: the <span class=css data-link-type=maybe title=cyclic>cyclic</span> system</span></a><li><a href=#fixed-system><span class=secno>3.1.2</span> <span class=content>
Exhaustible Symbols: the <span class=css data-link-type=maybe title=fixed>fixed</span> system</span></a><li><a href=#symbolic-system><span class=secno>3.1.3</span> <span class=content>
Repeating Symbols: the <span class=css data-link-type=maybe title=symbolic>symbolic</span> system</span></a><li><a href=#alphabetic-system><span class=secno>3.1.4</span> <span class=content>
Bijective Numerals: the <span class=css data-link-type=maybe title=alphabetic>alphabetic</span> system</span></a><li><a href=#numeric-system><span class=secno>3.1.5</span> <span class=content>
Positional Numerals: the <span class=css data-link-type=maybe title=numeric>numeric</span> system</span></a><li><a href=#additive-system><span class=secno>3.1.6</span> <span class=content>
Accumulating Numerals: the <span class=css data-link-type=maybe title=additive>additive</span> system</span></a><li><a href=#extends-system><span class=secno>3.1.7</span> <span class=content>
Building from Existing Counter Styles: the <span class=css data-link-type=maybe title=extends>extends</span> system
<span></span></span></a></ul><li><a href=#counter-style-negative><span class=secno>3.2</span> <span class=content>
Formatting negative values: the <span class=property data-link-type=propdesc title=negative>negative</span> descriptor</span></a><li><a href=#counter-style-prefix><span class=secno>3.3</span> <span class=content>
Symbols before the marker: the <span class=property data-link-type=propdesc title=prefix>prefix</span> descriptor</span></a><li><a href=#counter-style-suffix><span class=secno>3.4</span> <span class=content>
Symbols after the marker: the <span class=property data-link-type=propdesc title=suffix>suffix</span> descriptor</span></a><li><a href=#counter-style-range><span class=secno>3.5</span> <span class=content>
Limiting the counter scope: the <span class=property data-link-type=propdesc title=range>range</span> descriptor</span></a><li><a href=#counter-style-pad><span class=secno>3.6</span> <span class=content>
Zero-Padding and Constant-Width Representations: the <span class=property data-link-type=propdesc title=pad>pad</span> descriptor</span></a><li><a href=#counter-style-fallback><span class=secno>3.7</span> <span class=content>
Defining fallback: the <span class=property data-link-type=propdesc title=fallback>fallback</span> descriptor</span></a><li><a href=#counter-style-symbols><span class=secno>3.8</span> <span class=content>
Marker characters: the <span class=property data-link-type=propdesc title=symbols>symbols</span> and <span class=property data-link-type=propdesc title=additive-symbols>additive-symbols</span> descriptors</span></a><li><a href=#counter-style-speak-as><span class=secno>3.9</span> <span class=content>
Speech Synthesis: the <span class=property data-link-type=propdesc title=speak-as>speak-as</span> descriptor</span></a></ul><li><a href=#symbols-function><span class=secno>4</span> <span class=content>
Defining Anonymous Counter Styles: the <span class=css data-link-type=maybe title=symbols()>symbols()</span> function</span></a><li><a href=#extending-css2><span class=secno>5</span> <span class=content>
Extending <span class=property data-link-type=propdesc title=list-style-type>list-style-type</span>, <span class=css data-link-type=maybe title=counter()>counter()</span>, and <span class=css data-link-type=maybe title=counters()>counters()</span></span></a><li><a href=#predefined-counters><span class=secno>6</span> <span class=content>
Simple Predefined Counter Styles</span></a><ul class=toc><li><a href=#simple-numeric><span class=secno>6.1</span> <span class=content>
Numeric: <span class=css data-link-type=maybe title=decimal>decimal</span>, <span class=css data-link-type=maybe title=decimal-leading-zero>decimal-leading-zero</span>, <span class=css data-link-type=maybe title=arabic-indic>arabic-indic</span>, <span class=css data-link-type=maybe title=armenian>armenian</span>, <span class=css data-link-type=maybe title=upper-armenian>upper-armenian</span>, <span class=css>lower-armenian</span>, <span class=css data-link-type=maybe title=bengali>bengali</span>, <span class=css data-link-type=maybe title=cambodian>cambodian</span>, <span class=css data-link-type=maybe title=khmer>khmer</span>, <span class=css data-link-type=maybe title=cjk-decimal>cjk-decimal</span>, <span class=css data-link-type=maybe title=devanagiri>devanagiri</span>, <span class=css data-link-type=maybe title=georgian>georgian</span>, <span class=css data-link-type=maybe title=gujarati>gujarati</span>, <span class=css data-link-type=maybe title=gurmukhi>gurmukhi</span>, <span class=css data-link-type=maybe title=hebrew>hebrew</span>, <span class=css data-link-type=maybe title=kannada>kannada</span>, <span class=css data-link-type=maybe title=lao>lao</span>, <span class=css data-link-type=maybe title=malayalam>malayalam</span>, <span class=css data-link-type=maybe title=mongolian>mongolian</span>, <span class=css data-link-type=maybe title=myanmar>myanmar</span>, <span class=css data-link-type=maybe title=oriya>oriya</span>, <span class=css data-link-type=maybe title=persian>persian</span>, <span class=css data-link-type=maybe title=lower-roman>lower-roman</span>, <span class=css data-link-type=maybe title=upper-roman>upper-roman</span>, <span class=css data-link-type=maybe title=telugu>telugu</span>, <span class=css data-link-type=maybe title=thai>thai</span>, <span class=css data-link-type=maybe title=tibetan>tibetan</span></span></a><li><a href=#simple-alphabetic><span class=secno>6.2</span> <span class=content>
Alphabetic: <span class=css data-link-type=maybe title=lower-alpha>lower-alpha</span>, <span class=css data-link-type=maybe title=lower-latin>lower-latin</span>, <span class=css data-link-type=maybe title=upper-alpha>upper-alpha</span>, <span class=css data-link-type=maybe title=upper-latin>upper-latin</span>, <span class=css data-link-type=maybe title=cjk-earthly-branch>cjk-earthly-branch</span>, <span class=css data-link-type=maybe title=cjk-heavenly-stem>cjk-heavenly-stem</span>, <span class=css data-link-type=maybe title=lower-greek>lower-greek</span>, <span class=css data-link-type=maybe title=hiragana>hiragana</span>, <span class=css data-link-type=maybe title=hiragana-iroha>hiragana-iroha</span>, <span class=css data-link-type=maybe title=katakana>katakana</span>, <span class=css data-link-type=maybe title=katakana-iroha>katakana-iroha</span></span></a><li><a href=#simple-symbolic><span class=secno>6.3</span> <span class=content>
Symbolic: <span class=css data-link-type=maybe title=disc>disc</span>, <span class=css data-link-type=maybe title=circle>circle</span>, <span class=css data-link-type=maybe title=square>square</span>, <span class=css data-link-type=maybe title=disclosure-open>disclosure-open</span>, <span class=css data-link-type=maybe title=disclosure-closed>disclosure-closed</span></span></a></ul><li><a href=#complex-predefined-counters><span class=secno>7</span> <span class=content>
Complex Predefined Counter Styles</span></a><ul class=toc><li><a href=#complex-cjk><span class=secno>7.1</span> <span class=content>
Longhand East Asian Counter Styles</span></a><ul class=toc><li><a href=#limited-japanese><span class=secno>7.1.1</span> <span class=content>
Japanese: <span class=css data-link-type=maybe title=japanese-informal>japanese-informal</span> and <span class=css data-link-type=maybe title=japanese-formal>japanese-formal</span></span></a><li><a href=#limited-korean><span class=secno>7.1.2</span> <span class=content>
Korean: <span class=css data-link-type=maybe title=korean-hangul-formal>korean-hangul-formal</span>, <span class=css data-link-type=maybe title=korean-hanja-informal>korean-hanja-informal</span>, and <span class=css data-link-type=maybe title=korean-hanja-formal>korean-hanja-formal</span></span></a><li><a href=#limited-chinese><span class=secno>7.1.3</span> <span class=content>
Chinese: <span class=css data-link-type=maybe title=simp-chinese-informal>simp-chinese-informal</span>, <span class=css data-link-type=maybe title=simp-chinese-formal>simp-chinese-formal</span>, <span class=css data-link-type=maybe title=trad-chinese-informal>trad-chinese-informal</span>, and <span class=css data-link-type=maybe title=trad-chinese-formal>trad-chinese-formal</span></span></a></ul><li><a href=#ethiopic-numeric-counter-style><span class=secno>7.2</span> <span class=content>
Ethiopic Numeric Counter Style: <span class=css data-link-type=maybe title=ethiopic-numeric>ethiopic-numeric</span></span></a></ul><li><a href=#additional-predefined><span class=secno>8</span> <span class=content>
Additional Predefined Counter Styles</span></a><li><a href=#apis><span class=secno>9</span> <span class=content>APIs</span></a><ul class=toc><li><a href=#extentions-to-cssrule-interface><span class=secno>9.1</span> <span class=content>
Extensions to the <code>CSSRule</code> interface</span></a><li><a href=#the-csscounterstylerule-interface><span class=secno>9.2</span> <span class=content>
The <code>CSSCounterStyleRule</code> interface</span></a></ul><li><a href=#ua-stylesheet><span class=secno>10</span> <span class=content>
Sample style sheet for HTML</span></a><li><a href=#changes><span class=secno></span> <span class=content>
Changes since the August 2014 Last CallWorking Draft</span></a><li><a href=#acknowledgments><span class=secno></span> <span class=content>
Acknowledgments</span></a><li><a href=#conformance><span class=secno></span> <span class=content>
Conformance</span></a><ul class=toc><li><a href=#conventions><span class=secno></span> <span class=content>
Document conventions</span></a><li><a href=#conformance-classes><span class=secno></span> <span class=content>
Conformance classes</span></a><li><a href=#partial><span class=secno></span> <span class=content>
Partial implementations</span></a><li><a href=#experimental><span class=secno></span> <span class=content>
Experimental implementations</span></a><li><a href=#testing><span class=secno></span> <span class=content>
Non-experimental implementations</span></a><li><a href=#cr-exit-criteria><span class=secno></span> <span class=content>
CR exit criteria</span></a></ul><li><a href=#references><span class=secno></span> <span class=content>References</span></a><ul class=toc><li><a href=#normative><span class=secno></span> <span class=content>Normative References</span></a><li><a href=#informative><span class=secno></span> <span class=content>Informative References</span></a></ul><li><a href=#index><span class=secno></span> <span class=content>Index</span></a><li><a href=#property-index><span class=secno></span> <span class=content>Property Index</span></a><ul class=toc><li><a href=#counter-style-descriptor-table><span class=secno></span> <span class=content><span data-link-type=at-rule>@counter-style</span> Descriptors</span></a></ul><li><a href=#idl-index><span class=secno></span> <span class=content>IDL Index</span></a></ul></div>
<main>
<h2 class="heading settled" data-level=1 id=intro><span class=secno>1. </span><span class=content>
Introduction</span><a class=self-link href=#intro></a></h2>
<p>CSS 1 defined a handful of useful counter styles based on the styles that HTML traditionally allowed on ordered and unordered lists.
While this was expanded slightly by CSS2.1,
it doesn’t address the needs of worldwide typography.</p>
<p>This module introduces the <a class=css data-link-type=maybe
1090E
href=#at-ruledef-counter-style>@counter-style</a> rule which allows CSS to address this in an open-ended manner,
by allowing the author to define their own counter styles.
These styles can then be used in the <a class=property data-link-type=propdesc href=http://www.w3.org/TR/css3-lists/#propdef-list-style-type>list-style-type</a> property
or in the <a class=css data-link-type=maybe href=http://www.w3.org/TR/css3-lists/#funcdef-counter>counter()</a> and <a class=css data-link-type=maybe href=http://www.w3.org/TR/css3-lists/#funcdef-counters>counters()</a> functions.
It also defines some additional predefined counter styles,
particularly ones which are common but complicated to represent with <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a>.</p>
<h2 class="heading settled" data-level=2 id=counter-styles><span class=secno>2. </span><span class=content>
Counter Styles</span><a class=self-link href=#counter-styles></a></h2>
<p>A <dfn data-dfn-type=dfn data-export="" id=counter-style>counter style<a class=self-link href=#counter-style></a></dfn> defines how to convert a counter value into a string.
Counter styles are composed of:</p>
<ul>
<li>
a name,
to identify the style
<li>
an algorithm,
which transforms integer counter values into a basic string representation
<li>
a negative sign,
which is prepended or appended to the representation of a negative counter value.
<li>
a prefix,
to prepend to the representation
<li>
a suffix
to append to the representation
<li>
a range,
which limits the values that a counter style handles
<li>
a spoken form,
which describes how to read out the counter style in a speech synthesizer
<li>
and a fallback style,
to render the representation with when the counter value is outside the counter style’s range
or the counter style otherwise can’t render the counter value
</ul>
<p>When asked to <dfn data-dfn-type=dfn data-export="" id=generate-a-counter title="generate a counter|generate a counter representation">generate a counter representation<a class=self-link href=#generate-a-counter></a></dfn>
using a particular counter style for a particular counter value,
follow these steps:</p>
<ol>
<li>
If the counter style is unknown,
exit this algorithm and instead <i>generate a counter representation</i>
using the <a class=css data-link-type=maybe href=#decimal>decimal</a> style and the same counter value.
<li>
If the counter value is outside the <a class=property data-link-type=propdesc href=#descdef-counter-style-range>range</a> of the counter style,
exit this algorithm and instead <i>generate a counter representation</i>
using the counter style’s fallback style and the same counter value.
<li>
Using the counter value and the counter algorithm for the counter style,
generate an <dfn data-dfn-type=dfn data-noexport="" id=initial-representation-for-the-counter-value>initial representation for the counter value<a class=self-link href=#initial-representation-for-the-counter-value></a></dfn>.
If the counter value is negative
and the counter style <i>uses a negative sign</i>,
instead generate an initial representation using the absolute value of the counter value.
<li>
Prepend symbols to the representation as specified in the <a class=property data-link-type=propdesc href=#descdef-counter-style-pad>pad</a> descriptor.
<li>
If the counter value is negative
and the counter style <i>uses a negative sign</i>,
wrap the representation in the counter style’s negative sign
as specified in the <a class=property data-link-type=propdesc href=#descdef-counter-style-negative>negative</a> descriptor.
<li>
Return the representation.
</ol>
<p class=note role=note>Note: the prefix and suffix don’t play a part in this algorithm.
This is intentional;
the prefix and suffix aren’t part of the string returned by the counter() or counters() functions.
Instead, the prefix and suffix are added by the algorithm that constructs the value of the <a class=css data-link-spec=css-ui-3 data-link-type=property href=http://www.w3.org/TR/css3-ui/#content>content</a> property
for the <a class=css data-link-type=maybe href=http://www.w3.org/TR/css3-lists/#selectordef-marker>::marker</a> pseudo-element.
This also implies that the prefix and suffix always come from the specified counter-style,
even if the actual representation is constructed by a fallback style.</p>
<p>Some values of <a class=property data-link-type=propdesc href=#descdef-counter-style-system>system</a> (<a class=css data-link-type=maybe href=#valdef-system-symbolic>symbolic</a>, <a class=css data-link-type=maybe href=#valdef-counter-style-system-additive>additive</a>)
and some descriptors (<a class=property data-link-type=propdesc href=#descdef-counter-style-pad>pad</a>)
can generate representations with size linear to an author-supplied number.
This can potentially be abused to generate excessively large representations
and consume undue amounts of the user’s memory or even hang their browser.
User agents must support representations at least 60 Unicode codepoints long,
but they may choose to instead use the fallback style for representations that would be longer than 60 codepoints.</p>
<h2 class="heading settled" data-level=3 id=the-counter-style-rule><span class=secno>3. </span><span class=content>
Defining Custom Counter Styles: the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule</span><a class=self-link href=#the-counter-style-rule></a></h2>
<p>The <dfn class=css data-dfn-type=at-rule data-export="" id=at-ruledef-counter-style>@counter-style<a class=self-link href=#at-ruledef-counter-style></a></dfn> rule allows authors to define a custom <i>counter style</i>.
The components of a <i>counter style</i> are specified by descriptors in the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule.
The algorithm is specified implicitly by a combination of the <span class=css>system</span>, <span class=css>symbols</span>, and <span class=css>additive-symbols</span> properties.</p>
<p>The general form of an <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is:</p>
<pre>@counter-style <a class=production data-link-type=type href=#typedef-counter-style-name><counter-style-name></a> { <a class=production data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-declaration-list><declaration-list></a> }</pre>
<p>where <dfn class=css data-dfn-type=type data-export="" id=typedef-counter-style-name><counter-style-name><a class=self-link href=#typedef-counter-style-name></a></dfn> is a <a class="production css" data-link-type=type href=http://www.w3.org/TR/css3-values/#identifier-value><custom-ident></a>.</p>
<p>If a counter style’s name is an <a data-link-type=dfn href=http://dev.w3.org/csswg/css-syntax-3/#ascii-case-insensitive>ASCII case-insensitive</a> match for "decimal" or "none",
the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is invalid.</p>
<p class=note role=note>Note: Note that <a class="production css" data-link-type=type href=http://www.w3.org/TR/css3-values/#identifier-value><custom-ident></a> also automatically excludes the <a data-link-spec=css-values data-link-type=dfn href=http://www.w3.org/TR/css3-values/#css-wide-keywords>CSS-wide keywords</a>.
In addition, some names, like <span class=css>inside</span>,
are valid as counter style names,
but conflict with the existing values of properties like <a class=property data-link-type=propdesc href=http://www.w3.org/TR/css3-lists/#propdef-list-style>list-style</a>,
and so won’t be usable there.</p>
<p>Counter style names are case-sensitive.
However, the names defined in this specification are ASCII lower-cased on parse
wherever they are used as counter styles, e.g.
in the <a class=property data-link-type=propdesc href=http://www.w3.org/TR/css3-lists/#propdef-list-style>list-style</a> set of properties,
in the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule,
and in the <a class=css data-link-type=maybe href=http://www.w3.org/TR/css3-lists/#funcdef-counter>counter()</a> functions.</p>
<p>Each <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule specifies a value for every counter-style descriptor,
either implicitly or explicitly.
Those not given explicit value in the rule take the initial value listed with each descriptor in this specification.
These descriptors apply solely within the context of the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule in which they are defined,
and do not apply to document language elements.
There is no notion of which elements the descriptors apply to or whether the values are inherited by child elements.
When a given descriptor occurs multiple times in a given <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule,
only the last specified value is used;
all prior values for that descriptor must be ignored.</p>
<p>Defining a <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> makes it available to the entire document in which it is included.
If multiple <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rules are defined with the same name,
only one wins,
according to standard cascade rules.
<a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rules cascade "atomically":
if one replaces another of the same name,
it replaces it <em>entirely</em>,
rather than just replacing the specific descriptors it specifies.</p>
<p class=note role=note>Note: Note that even the predefined counter styles can be overridden;
the UA stylesheet occurs before any other stylesheets,
so the predefined ones always lose in the cascade.</p>
<p>This at-rule conforms with the forward-compatible parsing requirement of CSS;
conformant parsers that don’t understand these rules will ignore them without error.
Any descriptors that are not recognized or implemented by a given user agent,
or whose value does not match the grammars given here or in a future version of this specification,
must be ignored in their entirety;
they do not make the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule invalid.</p>
<h3 class="heading settled" data-level=3.1 id=counter-style-system><span class=secno>3.1. </span><span class=content>
Counter algorithms: the <a class=property data-link-type=propdesc href=#descdef-counter-style-system>system</a> descriptor</span><a class=self-link href=#counter-style-system></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-system>system<a class=self-link href=#descdef-counter-style-system></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod>cyclic <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> numeric <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> alphabetic <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> symbolic <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> additive <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> <span class=nobr>[fixed <a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a><a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#mult-opt>?</a>]</span> <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> <span class=nobr>[ extends <a class="production css" data-link-type=type href=#typedef-counter-style-name><counter-style-name></a> ]</span><tr><th>Initial:<td>symbolic</table>
<p>The <a class=property data-link-type=propdesc href=#descdef-counter-style-system>system</a> descriptor specifies which algorithm will be used to construct
the counter’s representation based on the counter value. For example,
<a class=css data-link-type=maybe href=#valdef-counter-style-system-cyclic>cyclic</a> counter styles just cycle through their symbols repeatedly,
while <a class=css data-link-for=system data-link-type=value href=#valdef-counter-style-system-numeric>numeric</a> counter styles interpret their symbols as digits and
build their representation accordingly. The systems are defined as follows:</p>
<h4 class="heading settled" data-level=3.1.1 id=cyclic-system><span class=secno>3.1.1. </span><span class=content>
Cycling Symbols: the <a class=css data-link-type=maybe href=#valdef-counter-style-system-cyclic>cyclic</a> system</span><a class=self-link href=#cyclic-system></a></h4>
<p>The <dfn class=css data-dfn-for=@counter-style/system data-dfn-type=value data-export="" id=valdef-counter-style-system-cyclic>cyclic<a class=self-link href=#valdef-counter-style-system-cyclic></a></dfn> counter system cycles repeatedly through its provided symbols,
looping back to the beginning when it reaches the end of the list.
It can be used for simple bullets
(just provide a single <i>counter symbol</i>),
or for cycling through multiple symbols.
The first <i>counter symbol</i> is used as the representation of the value 1,
the second <i>counter symbol</i> (if it exists) is used as the representation of the value 2, etc.</p>
<p>If the system is <a class=css data-link-type=maybe href=#valdef-counter-style-system-cyclic>cyclic</a>,
the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> descriptor must contain at least one <i>counter symbol</i>,
or else the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is invalid.
This system is defined over all counter values.</p>
<div class=example>
A "triangle bullet" counter style can be defined as:
<pre>@counter-style <dfn data-dfn-type=dfn data-noexport="" id=triangle>triangle<a class=self-link href=#triangle></a></dfn> {
system: cyclic;
symbols: ‣;
suffix: " ";
}
</pre>
<p>It will then produce lists that look like:</p>
<pre>‣ One
‣ Two
‣ Three
</pre>
</div>
<p>If there are <var>N</var> <i>counter symbols</i>
and a representation is being constructed for the integer <var>value</var>,
the representation is the <i>counter symbol</i>
at index ( (<var>value</var>-1) mod <var>N</var>)
of the list of <i>counter symbols</i> (0-indexed).</p>
<h4 class="heading settled" data-level=3.1.2 id=fixed-system><span class=secno>3.1.2. </span><span class=content>
Exhaustible Symbols: the <a class=css data-link-type=maybe href=#valdef-counter-style-system-fixed>fixed</a> system</span><a class=self-link href=#fixed-system></a></h4>
<p>The <dfn class=css data-dfn-for=@counter-style/system data-dfn-type=value data-export="" id=valdef-counter-style-system-fixed>fixed<a class=self-link href=#valdef-counter-style-system-fixed></a></dfn> counter system runs through its list of counter symbols once,
then falls back.
It is useful for representing counter styles that only have a finite number of representations.
For example, Unicode defines several limited-length runs of special cha
2B2
racters meant for lists,
such as circled digits.</p>
<p>If the system is <a class=css data-link-type=maybe href=#valdef-counter-style-system-fixed>fixed</a>,
the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> descriptor must contain at least one <i>counter symbol</i>,
or else the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is invalid.
This system is defined over counter values in a finite range,
starting with the <i>first symbol value</i> and having a length equal to the length of the list of <i>counter symbols</i>.</p>
<p>When this system is specified,
it may optionally have an integer provided after it,
which sets the <dfn data-dfn-type=dfn data-export="" id=first-symbol-value>first symbol value<a class=self-link href=#first-symbol-value></a></dfn>.
If it is omitted, the <i>first symbol value</i> is 1.</p>
<div class=example>
A "box-corner" counter style can be defined as:
<pre>@counter-style <dfn data-dfn-type=dfn data-noexport="" id=box-corner>box-corner<a class=self-link href=#box-corner></a></dfn> {
system: fixed;
symbols: ◰ ◳ ◲ ◱;
suffix: ': ';
}
</pre>
<p>It will then produce lists that look like:</p>
<pre>◰: One
◳: Two
◲: Three
◱: Four
5: Five
6: Six
</pre>
</div>
<p>The first <i>counter symbol</i> is the representation for the <i>first symbol value</i>,
and subsequent counter values are represented by subsequent <i>counter symbols</i>.
Once the list of <i>counter symbols</i> is exhausted,
further values cannot be represented by this counter style,
and must instead be represented by the fallback counter style.</p>
<h4 class="heading settled" data-level=3.1.3 id=symbolic-system><span class=secno>3.1.3. </span><span class=content>
Repeating Symbols: the <a class=css data-link-type=maybe href=#valdef-system-symbolic>symbolic</a> system</span><a class=self-link href=#symbolic-system></a></h4>
<p>The <dfn class=css data-dfn-for=system data-dfn-type=value data-export="" id=valdef-system-symbolic>symbolic<a class=self-link href=#valdef-system-symbolic></a></dfn> counter system cycles repeatedly through its provided symbols,
doubling, tripling, etc. the symbols on each successive pass through the list.
For example, if the original symbols were "*" and "†",
then on the second pass they would instead be "**" and "††",
while on the third they would be "***"and "†††", etc.
It can be used for footnote-style markers,
and is also sometimes used for alphabetic-style lists for a slightly different presentation than what the <a class=css data-link-for=system data-link-type=value href=#valdef-counter-style-system-alphabetic>alphabetic</a> system presents.</p>
<p>If the system is <a class=css data-link-type=maybe href=#valdef-system-symbolic>symbolic</a>,
the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> descriptor must contain at least one <i>counter symbol</i>,
or else the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is invalid.
This system is defined only over strictly positive counter values.</p>
<div class=example>
An "footnote" counter style can be defined as:
<pre>@counter-style <dfn data-dfn-type=dfn data-noexport="" id=footnote>footnote<a class=self-link href=#footnote></a></dfn> {
system: symbolic;
symbols: '*' ⁑ † ‡;
suffix: " ";
}
</pre>
<p>It will then produce lists that look like:</p>
<pre>* One
⁑ Two
† Three
‡ Four
** Five
⁑⁑ Six
</pre>
</div>
<div class=example>
Some style guides mandate a list numbering that looks similar to <a class=css data-link-type=maybe href=#upper-alpha>upper-alpha</a>,
but repeats differently after the first 26 values,
instead going "AA", "BB", "CC", etc.
This can be achieved with the symbolic system:
<pre>@counter-style <dfn data-dfn-type=dfn data-noexport="" id=upper-alpha-legal>upper-alpha-legal<a class=self-link href=#upper-alpha-legal></a></dfn> {
system: symbolic;
symbols: A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z;
}
</pre>
<p>This style is identical to <a class=css data-link-type=maybe href=#upper-alpha>upper-alpha</a> through the first 27 values,
but they diverge after that, with <a class=css data-link-type=maybe href=#upper-alpha>upper-alpha</a> going "AB", "AC", "AD", etc.
Starting at the 53rd value, <a class=css data-link-type=maybe href=#upper-alpha>upper-alpha</a> goes "BA", "BB", "BC", etc.,
while this style jumps into triple digits with "AAA", "BBB", "CCC", etc.</p>
</div>
<p>To construct the representation, run the following algorithm:</p>
<p>Let <var>N</var> be the length of the list of <i>counter symbols</i>,
<var>value</var> initially be the counter value,
<var>S</var> initially be the empty string,
and <var>symbol(n)</var> be the nth <i>counter symbol</i> in the list of <i>counter symbols</i> (0-indexed).</p>
<ol>
<li>Let the <var>chosen symbol</var> be <code class=inline>symbol( (<var>value</var> - 1) mod <var>N</var>)</code>.
<li>Let the <var>representation length</var> be <code class=inline>ceil( <var>value</var> / <var>N</var> )</code>.
<li>Append the <var>chosen symbol</var> to <var>S</var> a number of times equal to the <var>representation length</var>.
</ol>
<p>Finally, return <var>S</var>.</p>
<h4 class="heading settled" data-level=3.1.4 id=alphabetic-system><span class=secno>3.1.4. </span><span class=content>
Bijective Numerals: the <a class=css data-link-type=maybe href=#valdef-counter-style-system-alphabetic>alphabetic</a> system</span><a class=self-link href=#alphabetic-system></a></h4>
<p>The <dfn class=css data-dfn-for=@counter-style/system data-dfn-type=value data-export="" id=valdef-counter-style-system-alphabetic>alphabetic<a class=self-link href=#valdef-counter-style-system-alphabetic></a></dfn> counter system interprets the list of <i>counter symbols</i> as digits to an <em>alphabetic</em> numbering system,
similar to the default <a class=css data-link-type=maybe href=#lower-alpha>lower-alpha</a> counter style,
which wraps from "a", "b", "c", to "aa", "ab", "ac".
Alphabetic numbering systems do not contain a digit representing 0;
so the first value when a new digit is added is composed solely of the first digit.
Alphabetic numbering systems are commonly used for lists,
and also appear in many spreadsheet programs to number columns.
The first <i>counter symbol</i> in the list is interpreted as the digit 1,
the second as the digit 2,
and so on.</p>
<p>If the system is <a class=css data-link-for=system data-link-type=value href=#valdef-counter-style-system-alphabetic>alphabetic</a>,
the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> descriptor must contain at least two <i>counter symbols</i>,
or else the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is invalid.
This system is defined only over strictly positive counter values.</p>
<div class=example>
A counter style using go stones can be defined as:
<pre>@counter-style <dfn data-dfn-type=dfn data-noexport="" id=go>go<a class=self-link href=#go></a></dfn> {
system: alphabetic;
symbols: url(white.svg) url(black.svg);
suffix: " ";
}
</pre>
<p>It will then produce lists that look like:</p>
<div class=alphabetic-example>
<span><img alt="" src=images/white.svg></span> One<br>
<span><img alt="" src=images/black.svg></span> Two<br>
<span><img alt="" src=images/white.svg><img alt="" src=images/white.svg></span> Three<br>
<span><img alt="" src=images/white.svg><img alt="" src=images/black.svg></span> Four<br>
<span><img alt="" src=images/black.svg><img alt="" src=images/white.svg></span> Five<br>
<span><img alt="" src=images/black.svg><img alt="" src=images/black.svg></span> Six<br>
<span><img alt="" src=images/white.svg><img alt="" src=images/white.svg><img alt="" src=images/white.svg></span> Seven
</div>
<p class=note role=note>Note: This example requires support for SVG images to display correctly.</p>
</div>
<p>If there are <var>N</var> <i>counter symbols</i>,
the representation is a base <var>N</var> alphabetic number using the <i>counter symbols</i> as digits.
To construct the representation, run the following algorithm:</p>
<p>Let <var>N</var> be the length of the list of <i>counter symbols</i>,
<var>value</var> initially be the counter value,
<var>S</var> initially be the empty string,
and <var>symbol(n)</var> be the nth <i>counter symbol</i> in the list of <i>counter symbols</i> (0-indexed).</p>
<p>While <var>value</var> is not equal to 0:</p>
<ol>
<li>Set <var>value</var> to <code><var>value</var> - 1</code>.
<li>Prepend <var>symbol( <var>value</var> mod <var>N</var> )</var>
to <var>S</var>.
<li>Set <var>value</var> to <code>floor( <var>value</var> / <var>N</var> )</code>.
</ol>
<p>Finally, return <var>S</var>.</p>
<h4 class="heading settled" data-level=3.1.5 id=numeric-system><span class=secno>3.1.5. </span><span class=content>
Positional Numerals: the <a class=css data-link-type=maybe href=#valdef-counter-style-system-numeric>numeric</a> system</span><a class=self-link href=#numeric-system></a></h4>
<p>The <dfn class=css data-dfn-for=@counter-style/system data-dfn-type=value data-export="" id=valdef-counter-style-system-numeric>numeric<a class=self-link href=#valdef-counter-style-system-numeric></a></dfn> counter system interprets the list of <i>counter symbols</i>
as digits to a "place-value" numbering system,
similar to the default <a class=css data-link-type=maybe href=#decimal>decimal</a> counter style.
The first <i>counter symbol</i> in the list is interpreted as the digit 0,
the second as the digit 1,
and so on.</p>
<p>If the system is <a class=css data-link-for=system data-link-type=value href=#valdef-counter-style-system-numeric>numeric</a>,
the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> descriptor must contain at least two <i>counter symbols</i>,
or else the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is invalid.
This system is defined over all counter values.</p>
<div class=example>
A "trinary" counter style can be defined as:
<pre>@counter-style <dfn data-dfn-type=dfn data-noexport="" id=trinary>trinary<a class=self-link href=#trinary></a></dfn> {
system: numeric;
symbols: '0' '1' '2';
}
</pre>
<p>It will then produce lists that look like:</p>
<pre>1. One
2. Two
10. Three
11. Four
12. Five
20. Six
</pre>
</div>
<p>If there are <var>N</var> <i>counter symbols</i>,
the representation is a base <var>N</var> number using the <i>counter symbols</i> as digits.
To construct the representation, run the following algorithm:</p>
<p>Let <var>N</var> be the length of the list of <i>counter symbols</i>,
<var>value</var> initially be the counter value,
<var>S</var> initially be the empty string,
and <var>symbol(n)</var> be the nth <i>counter symbol</i> in the list of <i>counter symbols</i> (0-indexed).</p>
<ol>
<li>If <var>value</var> is 0, append <var>symbol(0)</var> to
<var>S</var> and return <var>S</var>.
<li>While <var>value</var> is not equal to 0:
<ol>
<li>Prepend <var>symbol( <var>value</var> mod <var>N</var> )</var>
to <var>S</var>.
<li>Set <var>value</var> to <code>floor( <var>value</var> / <var>N</var> )</code>.
</ol>
<
7DEE
li>Return <var>S</var>.
</ol>
<h4 class="heading settled" data-level=3.1.6 id=additive-system><span class=secno>3.1.6. </span><span class=content>
Accumulating Numerals: the <a class=css data-link-type=maybe href=#valdef-counter-style-system-additive>additive</a> system</span><a class=self-link href=#additive-system></a></h4>
<p>The <dfn class=css data-dfn-for=@counter-style/system data-dfn-type=value data-export="" id=valdef-counter-style-system-additive>additive<a class=self-link href=#valdef-counter-style-system-additive></a></dfn> counter system is used to represent "sign-value" numbering systems,
which, rather than using reusing digits in different positions to change their value,
define additional digits with much larger values,
so that the value of the number can be obtained by adding all the digits together.
This is used in Roman numerals
and other numbering systems around the world.</p>
<p>If the system is <a class=css data-link-type=maybe href=#valdef-counter-style-system-additive>additive</a>,
the <a class=property data-link-type=propdesc href=#descdef-counter-style-additive-symbols>additive-symbols</a> descriptor must contain at least one <i>additive tuple</i>,
or else the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is invalid.
This system is nominally defined over all counter values
(see algorithm, below, for exact details).</p>
<div class=example>
A "dice" counter style can be defined as:
<pre>@counter-style <dfn data-dfn-type=dfn data-noexport="" id=dice>dice<a class=self-link href=#dice></a></dfn> {
system: additive;
additive-symbols: 6 ⚅, 5 ⚄, 4 ⚃, 3 ⚂, 2 ⚁, 1 ⚀;
suffix: " ";
}
</pre>
<p>It will then produce lists that look like:</p>
<pre> ⚀ One
⚁ Two
⚂ Three
...
⚅⚄ Eleven
⚅⚅ Twelve
⚅⚅⚀ Thirteen
</pre>
</div>
<p>To construct the representation, run this algorithm:</p>
<p>Let <var>value</var> initially be the counter value,
<var>S</var> initially be the empty string,
and <var>symbol list</var> initially be the list of <i>additive tuples</i>.</p>
<ol>
<li>If <var>value</var> is initially 0, and there is an <i>additive tuple</i> with a weight of 0, append that tuple’s <i>counter symbol</i> to S and return S.
<li>While <var>value</var> is greater than 0 and there are elements left in the <var>symbol list</var>:
<ol>
<li>Pop the first <i>additive tuple</i> from the <var>symbol list</var>.
This is the <dfn data-dfn-type=dfn data-noexport="" id=current-tuple>current tuple<a class=self-link href=#current-tuple></a></dfn>.
<li>Append the <i>current tuple</i>’s <i>counter symbol</i> to <var>S</var>
<code>floor( <var>value</var> / <var><i>current tuple</i>’s weight</var> )</code>
times (this may be 0).
<li>Decrement <var>value</var> by the <var><i>current tuple</i>’s</var> weight multiplied
by the number of times the <i>current tuple</i> was appended to <var>S</var>
in the previous step.
</ol>
<li>If the loop ended because <var>value</var> is 0, return S. Otherwise, the given counter value cannot be represented by this counter style, and must instead be represented by the fallback counter style.
</ol>
<p class=note role=note>Note: All of the predefined additive <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rules in this specification
produce representations for every value in their range,
but it’s possible to produce values for <span class=css>additive-symbols</span> that will fail to find a representation
with the algorithm defined above,
even though theoretically a representation could be found.
For example, if a <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> was defined with <a class=css data-link-type=propdesc href=#descdef-counter-style-additive-symbols title=additive-symbols>additive-symbols: 3 "a", 2 "b";</a>,
the algorithm defined above will fail to find a representation for a counter value of 4,
even though theoretically a "bb" representation would work.
While unfortunate, this is required to maintain the property that the algorithm runs in linear time
relative to the size of the counter value.</p>
<h4 class="heading settled" data-level=3.1.7 id=extends-system><span class=secno>3.1.7. </span><span class=content>
Building from Existing Counter Styles: the <a class=css data-link-type=maybe href=#valdef-counter-style-system-extends>extends</a> system
<span id=override-system></span></span><a class=self-link href=#extends-system></a></h4>
<p>The <dfn class=css data-dfn-for=@counter-style/system data-dfn-type=value data-export="" id=valdef-counter-style-system-extends>extends<a class=self-link href=#valdef-counter-style-system-extends></a></dfn> system allows an author to use the algorithm of another counter style,
but alter other aspects,
such as the negative sign or the suffix.
If a counter style uses the <a class=css data-link-type=maybe href=#valdef-counter-style-system-extends>extends</a> system,
any unspecified descriptors must be taken from the extended counter style specified,
rather than taking their initial values.</p>
<p>If a @counter-style uses the <a class=css data-link-type=maybe href=#valdef-counter-style-system-extends>extends</a> system,
it must not contain a <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> or <a class=property data-link-type=propdesc href=#descdef-counter-style-additive-symbols>additive-symbols</a> descriptor,
or else the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rule is invalid.</p>
<p>If the specified counter style name isn’t the name of any currently-defined counter style,
it must be treated as if it was extending the <a class=css data-link-type=maybe href=#decimal>decimal</a> counter style.
If one or more <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> rules form a cycle with their <a class=css data-link-type=maybe href=#valdef-counter-style-system-extends>extends</a> values,
all of the counter styles participating in the cycle
must be treated as if they were extending the <a class=css data-link-type=maybe href=#decimal>decimal</a> counter style instead.</p>
<div class=example>
For example, if you wanted a counter style that was identical to decimal,
but used a parenthesis rather than a period after it, like:
<pre>1) first item
2) second item
3) third item
</pre>
<p>Rather than writing up an entirely new counter style,
this can be done by just extending <a class=css data-link-type=maybe href=#decimal>decimal</a>:</p>
<pre>@counter-style decimal-paren {
system: extends decimal;
suffix: ") ";
}
</pre>
</div>
<h3 class="heading settled" data-level=3.2 id=counter-style-negative><span class=secno>3.2. </span><span class=content>
Formatting negative values: the <a class=property data-link-type=propdesc href=#descdef-counter-style-negative>negative</a> descriptor</span><a class=self-link href=#counter-style-negative></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-negative>negative<a class=self-link href=#descdef-counter-style-negative></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod><a class="production css" data-link-type=type href=#typedef-symbol><symbol></a> <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a><a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#mult-opt>?</a><tr><th>Initial:<td>"\2D" ("-" hyphen-minus)</table>
<p>The <a class=property data-link-type=propdesc href=#descdef-counter-style-negative>negative</a> descriptor defines how to alter the representation when
the counter value is negative.</p>
<p>The first <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a> in the value is prepended to the representation when the
counter value is negative. The second <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a>, if specified, is appended
to the representation when the counter value is negative.</p>
<div class=example>
For example, specifying <a class=css data-link-type=propdesc href=#descdef-counter-style-negative title=negative>negative: "(" ")";</a> will make negative
values be wrapped in parentheses, which is sometimes used in financial
contexts, like "(2) (1) 0 1 2 3...".
</div>
<p>Not all <a class=property data-link-type=propdesc href=#descdef-counter-style-system>system</a> values use a negative sign.
In particular, a counter style <dfn data-dfn-type=dfn data-export="" id=use-a-negative-sign title="use a negative sign|uses a negative sign">uses a negative sign<a class=self-link href=#use-a-negative-sign></a></dfn>
if its <a class=property data-link-type=propdesc href=#descdef-counter-style-system>system</a> value is
<a class=css data-link-type=maybe href=#valdef-system-symbolic>symbolic</a>,
<a class=css data-link-for=system data-link-type=maybe href=#valdef-counter-style-system-alphabetic>alphabetic</a>,
<a class=css data-link-for=system data-link-type=maybe href=#valdef-counter-style-system-numeric>numeric</a>,
<a class=css data-link-type=maybe href=#valdef-counter-style-system-additive>additive</a>,
or <a class=css data-link-type=maybe href=#valdef-counter-style-system-extends>extends</a> if the extended counter style itself <a data-link-type=dfn href=#use-a-negative-sign>uses a negative sign</a>.
If a counter style does not <a data-link-type=dfn href=#use-a-negative-sign>use a negative sign</a>,
it ignores the negative sign when <a data-link-type=dfn href=#generate-a-counter title="generate a counter representation">generating a counter representation</a>.</p>
<h3 class="heading settled" data-level=3.3 id=counter-style-prefix><span class=secno>3.3. </span><span class=content>
Symbols before the marker: the <a class=property data-link-type=propdesc href=#descdef-counter-style-prefix>prefix</a> descriptor</span><a class=self-link href=#counter-style-prefix></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-prefix>prefix<a class=self-link href=#descdef-counter-style-prefix></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod><a class="production css" data-link-type=type href=#typedef-symbol><symbol></a><tr><th>Initial:<td>"" (the empty string)</table>
<p>The <a class=property data-link-type=propdesc href=#descdef-counter-style-prefix>prefix</a> descriptor specifies a <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a> that is prepended to the
marker representation. Prefixes are only added by the algorithm for constructing
the default contents of the <a class=css data-link-type=maybe href=http://www.w3.org/TR/css3-lists/#selectordef-marker>::marker</a> pseudo-element; the prefix is not
added automatically when the counter() or counters() functions are used.
Prefixes come before any negative sign.</p>
<h3 class="heading settled" data-level=3.4 id=counter-style-suffix><span class=secno>3.4. </span><span class=content>
Symbols after the marker: the <a class=property data-link-type=propdesc href=#descdef-counter-style-suffix>suffix</a> descriptor</span><a class=self-link href=#counter-style-suffix></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-suffix>suffix<a class=self-link href=#descdef-counter-style-suffix></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod><a class="production css" data-link-type=type href=#typedef-symbol><symbol></a><tr><th>Initial:<td>"\2E\20" ("." full stop followed by a space)</table>
<p>The <a class=property data-link-type=propdesc href=#descdef-counter-style-suffix>suffix</a> descriptor specifies a <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a> that is appended to the
marker representation. Suffixes are only added by the algorithm for constructing
the default contents of the <a class=css data-link-type=maybe href=http://www.w3.org/TR/css3-lists/#selectordef-marker>::marker</a> pseudo-element; the suffix is not
added automatically when the counter() or counters() functions are used.
Suffixes are added to the representation after negative signs.</p>
<h3 class="heading settled" data-level=3.5 id=counter-style-range><span class=secno>3.5. </span><span class=content>
Limiting the counter scope: the <a class=property data-link-type=propdesc href=#descdef-counter-style-range>range</a> descriptor</span><a class=self-link href=#counter-style-range></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-range>range<a class=self-link href=#descdef-counter-style-range></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod>[ [ <a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a> <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> infinite ]<a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#mult-num title={A}>{2}</a> ]<a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#mult-comma>#</a> <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> auto<tr><th>Initial:<td>auto</table>
<p>The <a class=property data-link-type=propdesc href=#descdef-counter-style-range>range</a> descriptor defines the ranges over which the counter style is defined.
If a counter style is used to represent a counter value outside of its ranges,
the counter style instead drops down to its fallback counter style.</p>
<dl data-dfn-for=@counter-style/range>
<dt><dfn class=css data-dfn-for=@counter-style/range data-dfn-type=value data-export="" id=valdef-counter-style-range-auto>auto<a class=self-link href=#valdef-counter-style-range-auto></a></dfn>
<dd>
The range depends on the counter system:
<ul>
<li>
For <a class=css data-link-type=maybe href=#valdef-counter-style-system-cyclic>cyclic</a>, <a class=css data-link-for=system data-link-type=value href=#valdef-counter-style-system-numeric>numeric</a>, and <a class=css data-link-type=maybe href=#valdef-counter-style-system-fixed>fixed</a> systems,
the range is negative infinity to positive infinity.
<li>
For <a class=css data-link-for=system data-link-type=value href=#valdef-counter-style-system-alphabetic>alphabetic</a> and <a class=css data-link-type=maybe href=#valdef-system-symbolic>symbolic</a> systems,
the range is 1 to positive infinity.
<li>
For <a class=css data-link-type=maybe href=#valdef-counter-style-system-additive>additive</a> systems,
the range is 0 to positive infinity.
D3B
<li>
For <a class=css data-link-type=maybe href=#valdef-counter-style-system-extends>extends</a> systems,
the range is whatever <a class=css data-link-for=range data-link-type=maybe href=#valdef-counter-style-range-auto>auto</a> would produce for the extended system;
if extending a complex predefined style (<a data-section="" href=#complex-predefined-counters>§7
Complex Predefined Counter Styles</a>),
the range is the style’s defined range.
</ul>
<dt>[ [ <a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a> | infinite ]{2} ]#
<dd>
This defines a comma-separated list of ranges.
For each individual range,
the first value is the lower bound
and the second value is the upper bound.
This range is inclusive - it contains both the lower and upper bound numbers.
If <span class=css>infinite</span> is used as the first value in a range,
it represents negative infinity;
if used as the second value,
it represents positive infinity.
The range of the counter style is the union of all the ranges defined in the list.
<p>If the lower bound of any range is higher than the upper bound,
the entire descriptor is invalid and must be ignored.</p>
</dl>
<p>Implementations must support ranges with a lower bound of at least -2<sup>15</sup>
and an upper bound of at least 2<sup>15</sup>-1
(the range of a signed 2-byte int).
They may support higher ranges.
If any specified bound is outside of the implementation’s supported bounds,
it must be treated as the closest bound that the implementation does support.</p>
<h3 class="heading settled" data-level=3.6 id=counter-style-pad><span class=secno>3.6. </span><span class=content>
Zero-Padding and Constant-Width Representations: the <a class=property data-link-type=propdesc href=#descdef-counter-style-pad>pad</a> descriptor</span><a class=self-link href=#counter-style-pad></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-pad>pad<a class=self-link href=#descdef-counter-style-pad></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod><a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a> && <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a><tr><th>Initial:<td>0 ""</table>
<p>The <a class=property data-link-type=propdesc href=#descdef-counter-style-pad>pad</a> descriptor allows an author to specify a "fixed-width" counter style,
where representations shorter than the pad value are padded with a particular <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a>.
Representations larger than the specified pad value are constructed as normal.</p>
<dl>
<dt><a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a> && <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a>
<dd>
The <a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a> specifies a minimum length that all counter representations must reach.
<p>Let <var>difference</var> be the provided <a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a>
minus the number of <a data-link-type=dfn href=http://www.w3.org/TR/css-text-3/#grapheme-cluster0>grapheme clusters</a> in the <a data-link-type=dfn href=#initial-representation-for-the-counter-value>initial representation for the counter value</a>.
<span class=note role=note>(Note that, per the algorithm to <a data-link-type=dfn href=#generate-a-counter>generate a counter representation</a>,
this occurs before adding prefixes/suffixes/negatives.)</span>
If the counter value is negative
and the counter style <i>uses a negative sign</i>,
further reduce <var>difference</var>
by the number of <a data-link-type=dfn href=http://www.w3.org/TR/css-text-3/#grapheme-cluster0>grapheme clusters</a> in the counter style’s <a class=property data-link-type=propdesc href=#descdef-counter-style-negative>negative</a> descriptor’s <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a>(s).</p>
<p>If <var>difference</var> is greater than zero,
prepend <var>difference</var> copies of the specified <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a> to the representation.</p>
<p>The <a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a> must be non-negative.
A negative value is a syntax error.</p>
</dl>
<div class=example>
The most common example of "fixed-width" numbering is zero-padded decimal numbering.
If an author knows that the numbers used will be less than a thousand, for example,
it can be zero-padded with a simple <a class=css data-link-type=propdesc href=#descdef-counter-style-pad title=pad>pad: 3 "0";</a> descriptor,
ensuring that all of the representations are 3 digits wide.
<p>This will cause, for example,
1 to be represented as "001",
20 to be represented as "020",
300 to be represented as "300",
4000 to be represented as "4000",
and -5 to be represented as "-05".</p>
</div>
<p class=note role=note>Note: The <a class=property data-link-type=propdesc href=#descdef-counter-style-pad>pad</a> descriptor counts the number of <a data-link-type=dfn href=http://www.w3.org/TR/css-text-3/#grapheme-cluster0>grapheme clusters</a> in the representation,
but pads it with <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a>s.
If the specified <a class=property data-link-type=propdesc href=#descdef-counter-style-pad>pad</a> <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a> is multi-character,
this will likely not have the desired effect.
Unfortunately, there’s no way to use the number of <a data-link-type=dfn href=http://www.w3.org/TR/css-text-3/#grapheme-cluster0>grapheme clusters</a> in the <a class=property data-link-type=propdesc href=#descdef-counter-style-pad>pad</a> <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a>
without violating useful constraints.
It is recommended that authors only specify <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a>s of a single <a data-link-type=dfn href=http://www.w3.org/TR/css-text-3/#grapheme-cluster0>grapheme cluster</a>
in the <a class=property data-link-type=propdesc href=#descdef-counter-style-pad>pad</a> descriptor.</p>
<h3 class="heading settled" data-level=3.7 id=counter-style-fallback><span class=secno>3.7. </span><span class=content>
Defining fallback: the <a class=property data-link-type=propdesc href=#descdef-counter-style-fallback>fallback</a> descriptor</span><a class=self-link href=#counter-style-fallback></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-fallback>fallback<a class=self-link href=#descdef-counter-style-fallback></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod><a class="production css" data-link-type=type href=#typedef-counter-style-name><counter-style-name></a><tr><th>Initial:<td>decimal</table>
<p>The <a class=property data-link-type=propdesc href=#descdef-counter-style-fallback>fallback</a> descriptor specifies a fallback counter style to be used
when the current counter style can’t create a representation for a given
counter value. For example, if a counter style defined with a range of 1-10
is asked to represent a counter value of 11, the counter value’s representation
is instead constructed with the fallback counter style (or possibly the
fallback style’s fallback style, if the fallback style can’t represent that
value, etc.).</p>
<p>If the value of the <a class=property data-link-type=propdesc href=#descdef-counter-style-fallback>fallback</a> descriptor isn’t the name of any
currently-defined counter style, the used value of the <a class=property data-link-type=propdesc href=#descdef-counter-style-fallback>fallback</a> descriptor
is <a class=css data-link-type=maybe href=#decimal>decimal</a> instead. Similarly, while following fallbacks to find
a counter style that can render the given counter value, if a loop in the
specified fallbacks is detected, the <a class=css data-link-type=maybe href=#decimal>decimal</a> style must be used instead.</p>
<p class=note role=note>Note that it is not necessarily an error to specify fallback
loops. For example, if an author desires a counter style with significantly
different representations for even and odd counter values, they may find it
easiest to define one style that can only represent odd values and one that
can only represent even values, and specify each as the fallback for the
other one. Though the fallback graph is circular, at no point do you encounter
a loop while following these fallbacks - every counter value is represented
by one or the other counter style.
<h3 class="heading settled" data-level=3.8 id=counter-style-symbols><span class=secno>3.8. </span><span class=content>
Marker characters: the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> and <a class=property data-link-type=propdesc href=#descdef-counter-style-additive-symbols>additive-symbols</a> descriptors</span><a class=self-link href=#counter-style-symbols></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-symbols>symbols<a class=self-link href=#descdef-counter-style-symbols></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod><a class="production css" data-link-type=type href=#typedef-symbol><symbol></a><a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#mult-one-plus>+</a><tr><th>Initial:<td>n/a</table>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-additive-symbols>additive-symbols<a class=self-link href=#descdef-counter-style-additive-symbols></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod>[ <a class="production css" data-link-type=type href=http://www.w3.org/TR/css-syntax-3/#typedef-integer><integer></a> && <a class="production css" data-link-type=type href=#typedef-symbol><symbol></a> ]<a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#mult-comma>#</a><tr><th>Initial:<td>n/a</table>
<pre class=prod><dfn data-dfn-type=type data-export="" id=typedef-symbol><symbol><a class=self-link href=#typedef-symbol></a></dfn> = <a class=production data-link-type=type href=http://www.w3.org/TR/css3-values/#string-value><string></a> <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> <a class=production data-link-type=type href=http://www.w3.org/TR/css3-images/#image-type><image></a> <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> <a class=production data-link-type=type href=http://www.w3.org/TR/mediaqueries-4/#typedef-ident><ident></a></pre>
<p>The <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> and <a class=property data-link-type=propdesc href=#descdef-counter-style-additive-symbols>additive-symbols</a> descriptors specify the symbols
used by the marker-construction algorithm specified by the <a class=property data-link-type=propdesc href=#descdef-counter-style-system>system</a> descriptor.
The <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> descriptor must be specified if the counter system is <a class=css data-link-type=maybe href=#valdef-counter-style-system-cyclic>cyclic</a>,
<a class=css data-link-for=system data-link-type=value href=#valdef-counter-style-system-numeric>numeric</a>, <a class=css data-link-for=system data-link-type=value href=#valdef-counter-style-system-alphabetic>alphabetic</a>, <a class=css data-link-type=maybe href=#valdef-system-symbolic>symbolic</a>, or <a class=css data-link-type=maybe href=#valdef-counter-style-system-fixed>fixed</a>, and the
<a class=property data-link-type=propdesc href=#descdef-counter-style-additive-symbols>additive-symbols</a> descriptor must be specified if the counter system is
<a class=css data-link-type=maybe href=#valdef-counter-style-system-additive>additive</a>; otherwise, the <a class=css data-link-type=maybe href=#at-ruledef-counter-style>@counter-style</a> is invalid and must be ignored.</p>
<p>Some counter systems specify that the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> descriptor must have at
least two entries. If the counter style’s system is such, and the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a>
descriptor has only a single entry, the counter style is invalid and must
be ignored.</p>
<p>Each entry in the <a class=property data-link-type=propdesc href=#descdef-counter-style-symbols>symbols</a> descriptor’s value defines a <dfn data-dfn-type=dfn data-export="" id=counter-symbol>counter symbol<a class=self-link href=#counter-symbol></a></dfn>,
which is interpreted differently based on the counter style’s system. Each
entry in the <a class=property data-link-type=propdesc href=#descdef-counter-style-additive-symbols>additive-symbols</a> descriptor’s value defines an <dfn data-dfn-type=dfn data-export="" id=additive-tuple>additive tuple<a class=self-link href=#additive-tuple></a></dfn>,
which consists of a <i>counter symbol</i> and a non-negative integer weight.
Each weight must be a non-negative integer, and the <i>additive tuples</i>
must be specified in order of descending weight; otherwise, the @counter-style
is invalid and must be ignored.</p>
<p><i>Counter symbols</i> may be strings, images, or identifiers,
and the three types can be mixed in a single descriptor.
Counter representations are constructed by concatenating counter symbols together.
Identifiers are rendered as strings containing the same characters.
Images are rendered as inline replaced elements.
The <a href=http://dev.w3.org/csswg/css3-images/#default-object-size>default object size</a> of an image <i>counter symbol</i> is a 1em by 1em square.</p>
<p class=note role=note>Note: If using identifiers rather than strings to define the symbols,
be aware of the syntax of identifiers.
In particular, ascii non-letters like "*" are not identifiers,
and so must be quoted in a string.
Hex escapes,
used in several of the counter styles defined in this specification,
"eat" the following space
(to allow a digit to follow a hex escape without ambiguity),
so two spaces must be put after a hex escape
to separate it from the following one,
or else they’ll be considered adjacent,
and part of the same identifier.</p>
<h3 class="heading settled" data-level=3.9 id=counter-style-speak-as><span class=secno>3.9. </span><span class=content>
Speech Synthesis: the <a class=property data-link-type=propdesc href=#descdef-counter-style-speak-as>speak-as</a> descriptor</span><a class=self-link href=#counter-style-speak-as></a></h3>
<table class="definition descdef" data-dfn-for=@counter-style><tr><th>Name:<td><dfn class=css data-dfn-for=@counter-style data-dfn-type=descriptor data-export="" id=descdef-counter-style-speak-as>speak-as<a class=self-link href=#descdef-counter-style-speak-as></a></dfn><tr><th>For:<td><a class=css data-link-type=at-rule href=#at-ruledef-counter-style>@counter-style</a><tr><th>Value:<td class=prod>auto <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> bullets <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> numbers <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> words <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> spell-out <a data-link-for="" data-link-type=grammar href=http://dev.w3.org/csswg/css-values-3/#comb-one>|</a> <a class="production css" data-link-type=type href=#typedef-counter-style-name><counter-style-name></a><tr><th>Initial:<td>auto</table>
<p>A counter style can be constructed with a meaning that is obvious visually,
but impossible to meaningfully represent via a speech synthesizer,
or possible but nonsensical when naively read out.
The <a class=property data-link-type=propdesc href=#descdef-counter-style-speak-as>speak-as</a> descriptor describes how to synthesize the spoken form of a counter formatted with the given counter style.
Values have the following meanings:</p>
<dl data-dfn-for=@counter-style/speak-as data-dfn-type=value>
<dt><dfn class=css data-dfn-for=@counter-style/speak-as data-dfn-type=value data-export="" id=valdef-counter-style-speak-as-auto>auto<a class=self-link href=#valdef-counter-style-speak-as-auto></a></dfn>
<dd>
You can’t perform that action at this time.