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<!DOCTYPE html>
<html lang=en>
<head>
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<title>CSS Display Module Level 3</title>
<!--
<link href="http://purl.org/dc/terms/" rel="schema.dcterms">
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<meta content="CSS Display Module Level 3" name=dcterms.title>
<meta content=text name=dcterms.type>
<meta content=2012-10-19 name=dcterms.issued>
<meta content="http://dev.w3.org/csswg/cssN-FIXME/" name=dcterms.creator>
<meta content=W3C name=dcterms.publisher>
<meta content="http://www.w3.org/TR/2012/ED-cssN-FIXME-20121019/"
name=dcterms.identifier>
<link href="#contents" rel=contents>
<link href="#index" rel=index>
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}
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content: "FIXME(";
color: black;
}
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content: ")";
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</style>
<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 Display Module Level 3</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 19 October
2012</h2>
<dl>
<dt>This version:
<dd><a class=replaceme
href="http://www.w3.org/TR/2012/ED-cssN-FIXME-20121019/">http://www.w3.org/TR/2012/ED-cssN-FIXME-20121019/</a>
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/cssN-FIXME/">http://www.w3.org/TR/cssN-FIXME/</a>
<dt>Editor's draft:
<dd><a
href="http://dev.w3.org/csswg/cssN-FIXME/">http://dev.w3.org/csswg/cssN-FIXME/</a>
<dt>Previous version:
<dd><a href="http://www.w3.org/PreviousVersionURI">
http://www.w3.org/PreviousVersionURI</a>
<dt>Issue Tracking:
<dd><a
href="http://www.w3.org/Style/CSS/Tracker/products/FIXME">http://www.w3.org/Style/CSS/Tracker/products/FIXME</a>
<dt>Feedback:</dt>
<dd><a href="mailto:www-style@w3.org?subject=%5B[css-display]%5D%20feedback"
>www-style@w3.org</a>
with subject line “<kbd>[css-display]
<var>… message topic …</var></kbd>”
(<a rel="discussion" href="http://lists.w3.org/Archives/Public/www-style/"
>archives</a>)
<dt>Editors:
<dd class="h-card vcard"> <a class="p-name fn u-url url"
href="http://www.xanthir.com/" rel=author>Tab Atkins Jr.</a> (<span
class="p-org org">Google, Inc.</span>), <span
class="u-email email">jackalmage@gmail.com</span>
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2012 <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>), 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 module contains the features of CSS relating to the ‘<a
href="#display"><code class=property>display</code></a>’ property. <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.
<h2 class="no-num no-toc" id=status>Status of this document</h2>
<p> This is currently a personal draft, not yet approved by the CSSWG to be
an Editor's Draft. (Ignore the branding on the side and heading, which are
artifacts of the spec generation process.) <!--//status-->
<p>The following features are at risk: …
<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>
<ul class=toc>
<li><a href="#placement"><span class=secno>1.1. </span> Module
interactions</a>
<li><a href="#values"><span class=secno>1.2. </span> Values</a>
</ul>
<li><a href="#the-display-properties"><span class=secno>2. </span> The
Display Properties</a>
<ul class=toc>
<li><a href="#the-display-inside"><span class=secno>2.1. </span> Setting
the layout mode: the ‘<code class=property>display-inside</code>’
property</a>
<li><a href="#the-display-outside"><span class=secno>2.2. </span>
Interacting with the layout mode: the ‘<code
class=property>display-outside</code>’ property</a>
<li><a href="#the-display-box"><span class=secno>2.3. </span>
Controlling box generation: the ‘<code
class=property>display-box</code>’ property</a>
<li><a href="#the-display-extras"><span class=secno>2.4. </span>
Additional stuff: the ‘<code class=property>display-extras</code>’
property</a>
<li><a href="#the-display"><span class=secno>2.5. </span> The ‘<code
class=property>display</code>’ shorthand property</a>
</ul>
<li><a href="#conformance"><span class=secno>3. </span> Conformance</a>
<ul class=toc>
<li><a href="#conventions"><span class=secno>3.1. </span> Document
conventions</a>
<li><a href="#conformance-classes"><span class=secno>3.2. </span>
Conformance classes</a>
<li><a href="#partial"><span class=secno>3.3. </span> Partial
implementations</a>
<li><a href="#experimental"><span class=secno>3.4. </span> Experimental
implementations</a>
<li><a href="#testing"><span class=secno>3.5. </span> Non-experimental
implementations</a>
<li><a href="#cr-exit-criteria"><span class=secno>3.6. </span> CR exit
criteria</a>
</ul>
<li class=no-num><a href="#acknowledgments"> Acknowledgments</a>
<li class=no-num><a href="#references"> References</a>
<ul class=toc>
<li class=no-num><a href="#normative-references"> Normative
references</a>
<li class=no-num><a href="#other-references"> Other references</a>
</ul>
<li class=no-num><a href="#index"> Index</a>
<li class=no-num><a href="#property-index"> Property index</a>
</ul>
<!--end-toc-->
<h2 id=intro><span class=secno>1. </span> Introduction</h2>
<p><em>This section is not normative.</em>
<p> <var class=replaceme>Provide background, motivation, etc.</var>
<h3 id=placement><span class=secno>1.1. </span> Module interactions</h3>
<p class=replaceme> Explain, normatively, how this module affects the
definition of CSS.
<p> This module replaces and extends the <var class=replaceme>SUMMARIZE
HERE</var> features defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> sections <var
class=replaceme>W.X and Y.Z</var>.
<p> None of the properties in this module apply to the
<code>::first-line</code> or <code>::first-letter</code> pseudo-elements.
<h3 id=values><span class=secno>1.2. </span> Values</h3>
<p>This specification follows the <a
href="http://www.w3.org/TR/CSS21/about.html#property-defs">CSS property
definition conventions</a> from <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>. Value types not defined in
this specification are defined in CSS Level 2 Revision 1 <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>. Other CSS
modules may expand the definitions of these value types: for example <a
href="#CSS3COLOR" rel=biblioentry>[CSS3COLOR]<!--{{CSS3COLOR}}--></a>,
when combined with this module, expands the definition of the
<color> value type as used in this specification.
<p>In addition to the property-specific values listed in their definitions,
all properties defined in this specification also accept the <a
href="http://www.w3.org/TR/css3-values/#common-keywords">CSS-wide
keywords</a> as their property value. For readability it has not been
repeated explicitly.
<h2 id=the-display-properties><span class=secno>2. </span> The Display
Properties</h2>
<p> The ‘<a href="#display"><code class=property>display</code></a>’
shorthand and its associated family of properties control the layout mode
of elements (how the element determines the sizes and positions of itself
and its descendants), and what boxes they and their descendants generate.
<h3 id=the-display-inside><span class=secno>2.1. </span> Setting the layout
mode: the ‘<a href="#display-inside"><code
class=property>display-inside</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=display-inside>display-inside</dfn>
<tr>
<th>Value:
<td>auto | block | table | flex | grid
<tr>
<th>Initial:
<td>auto
<tr>
<th>Applies To:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Computed Value:
<td>a keyword
</table>
<dl>
<dt><dfn id="display-inside:auto">auto</dfn>
<dd> If the element's computed ‘<a href="#display-outside"><code
class=property>display-outside</code></a>’ value is ‘<a
href="#display-outside:inline-level"><code
class=css>inline-level</code></a>’, the element is an <i>inline
element</i>, and lays out its contents using inline layout. <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> If the
element's computed ‘<a href="#display-outside"><code
class=property>display-outside</code></a>’ value is ‘<a
href="#display-outside:table-row-group"><code
class=css>table-row-group</code></a>’, ‘<a
href="#display-outside:table-header-group"><code
class=css>table-header-group</code></a>’, ‘<a
href="#display-outside:table-footer-group"><code
class=css>table-footer-group</code></a>’, ‘<a
href="#display-outside:table-row"><code
class=css>table-row</code></a>’, ‘<a
href="#display-outside:table-column-group"><code
class=css>table-column-group</code></a>’, or ‘<a
href="#display-outside:table-column"><code
class=css>table-column</code></a>’, this elements acts as normal for
its given ‘<a href="#display-outside"><code
class=property>display-outside</code></a>’ value. Otherwise, this value
computes to ‘<a href="#display:block"><code
class=css>block</code></a>’.
<dt><dfn id="display-inside:block">block</dfn>
<dd> The element lays out its contents using block layout. <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<dt><dfn id="display-inside:table">table</dfn>
<dd> The element lays out its contents using table layout. <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<dt><dfn id="display-inside:flex">flex</dfn>
<dd> The element lays out its contents using flex layout. <a
href="#CSS3-FLEXBOX"
rel=biblioentry>[CSS3-FLEXBOX]<!--{{!CSS3-FLEXBOX}}--></a>
<dt><dfn id="display-inside:grid">grid</dfn>
<dd> The element lays out its contents using grid layout. [[!CSS3-GRID]]
</dl>
<h3 id=the-display-outside><span class=secno>2.2. </span> Interacting with
the layout mode: the ‘<a href="#display-outside"><code
class=property>display-outside</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=display-outside>display-outside</dfn>
<tr>
<th>Value:
<td>block-level | inline-level | table-row-group | table-header-group |
table-footer-group | table-row | table-cell | table-column-group |
table-column | table-caption
<tr>
<th>Initial:
<td>inline-level
<tr>
<th>Applies To:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Computed Value:
<td>as specified
</table>
<dl>
<dt><dfn id="display-outside:block-level">block-level</dfn>
<dd> The element is <a
href="#display-outside:block-level"><i>block-level</i></a>, and
participates in a block formatting context. Other formatting contexts,
such as flex formatting contexts, may also work with <a
href="#display-outside:block-level"><i>block-level</i></a> elements. <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<dt><dfn id="display-outside:inline-level">inline-level</dfn>
<dd> The element is <a
href="#display-outside:inline-level"><i>inline-level</i></a>, and
participates in an inline formatting context. <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<dt><dfn id="display-outside:table-row-group">table-row-group</dfn>, <dfn
id="display-outside:table-header-group">table-header-group</dfn>, <dfn
id="display-outside:table-footer-group">table-footer-group</dfn>, <dfn
id="display-outside:table-row">table-row</dfn>, <dfn
id="display-outside:table-cell">table-cell</dfn>, <dfn
id="display-outside:table-column-group">table-column-group</dfn>, <dfn
id="display-outside:table-column">table-column</dfn>, <dfn
id="display-outside:table-caption">table-caption</dfn>
<dd> The element is an internal table element, and participates in a table
layout context. <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
</dl>
<p class=issue> Do we need special bits about some of the interactions with
‘<a href="#display-inside"><code
class=property>display-inside</code></a>’? For example, how ‘<code
class=css>display:inline-level block;</code>’ works? Or does that fall
out of what exists, and the definitions of Block Layout in 2.1? (...or a
new Block Layout spec, explaining all the 2.1 stuff more sanely?)
<p class=issue> Is <a
href="http://lists.w3.org/Archives/Public/www-style/2012Jul/0450.html">fantasai's
proposal for a run-in model</a> sane enough to include in this spec?
<h3 id=the-display-box><span class=secno>2.3. </span> Controlling box
generation: the ‘<a href="#display-box"><code
class=property>display-box</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=display-box>display-box</dfn>
<tr>
<th>Value:
<td>normal | none | contents
<tr>
<th>Initial:
<td>normal
<tr>
<th>Applies To:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Computed Value:
<td>as specified
</table>
<dl>
<dt><dfn id="display-box:normal">normal</dfn>
<dd> The element generates boxes as normal, per its other ‘<code
class=css>display-*</code>’ properties.
<dt><dfn id="display-box:none">none</dfn>
<dd> The element generates no boxes at all.
<dt><dfn id="display-box:contents">contents</dfn>
<dd> The element itself does not generate any boxes, but its children and
pseudo-elements still generate boxes as normal. For the purposes of box
generation and layout, the element must be treated as if it had been
replaced with its children and pseudo-elements in the document tree.
</dl>
<p class=issue> Is there a need for a value that suppresses box generation
for layout purposes, but still generates them for the purposes of
animations/counters/etc.?
<p class=issue> ‘<a href="#display-box:contents"><code
class=css>contents</code></a>’ currently only has an effect on box
generation and layout. Other things that care about the document tree are
unaffected, like counter scopes. Is this what we want?
<h3 id=the-display-extras><span class=secno>2.4. </span> Additional stuff:
the ‘<a href="#display-extras"><code
class=property>display-extras</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=display-extras>display-extras</dfn>
<tr>
<th>Value:
<td>none | [ list-item ]
<tr>
<th>Initial:
<td>none
<tr>
<th>Applies To:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Computed Value:
<td>as specified
</table>
<dl>
<dt><dfn id="display-extras:list-item">list-item</dfn>
<dd> The element generates a <code>::marker</code> pseudo-element and is
considered a <a href="../css3-lists/#list-item">list item</a>.
</dl>
<h3 id=the-display><span class=secno>2.5. </span> The ‘<a
href="#display"><code class=property>display</code></a>’ shorthand
property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=display>display</dfn>
<tr>
<th>Value:
<td>inline | block | list-item | inline-list-item | inline-block | table
| inline-table | table-cell | table-caption | flex | inline-flex | grid
| inline-grid | none | [ <‘<a href="#display-inside"><code
class=property>display-inside</code></a>’> || <‘<a
href="#display-outside"><code
class=property>display-outside</code></a>’> || <‘<a
href="#display-box"><code class=property>display-box</code></a>’> ||
<‘<a href="#display-extras"><code
class=property>display-extras</code></a>’> ]
<tr>
<th>Initial:
<td>see individual properties
<tr>
<th>Applies To:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>see individual properties
<tr>
<th>Computed Value:
<td>see individual properties
<tr>
<th>Animatable:
<td>see individual properties
</table>
<p> The single-keyword values listed explicitly in the grammar above are
handled specially, for legacy reasons. All other single-keyword values,
and all other values in general, are handled as normal for shorthands.
<p class=issue> The general rule for new layout modes seems to be that
they're block-level by default. However, this conflicts with the default
value of ‘<a href="#display-outside"><code
class=property>display-outside</code></a>’, which is ‘<a
href="#display-outside:inline-level"><code
class=css>inline-level</code></a>’. What's the best way to address this?
Simplest answer is to just expand this list of special values as we go
along. Another possibility is to magic up the expansion in a different
way, so that if the value is just a ‘<a href="#display-inside"><code
class=property>display-inside</code></a>’ keyword, ‘<a
href="#display-outside"><code class=property>display-outside</code></a>’
defaults to ‘<a href="#display-outside:block-level"><code
class=css>block-level</code></a>’. If the latter is chosen, we could
remove several more of the special expansions below (all the ones that are
identical to a ‘<a href="#display-inside"><code
class=property>display-inside</code></a>’ value).
<p class=note> Several of the "special" expansions below are actually just
what the shorthand would expand to normally. They're included here for
clarity, as they're very familiar from long usage in CSS 2.1, before the
‘<a href="#display"><code class=property>display</code></a>’ property
became a shorthand.
<dl>
<dt><dfn id="display:inline">inline</dfn>
<dd> Expands identically to ‘<code class=css>inline-level
auto</code>’.
<dt><dfn id="display:block">block</dfn>
<dd> Expands identically to ‘<code class=css>block-level
block</code>’.
<dt><dfn id="display:list-item">list-item</dfn>
<dd> Expands identically to ‘<code class=css>block-level block
list-item</code>’.
<dt><dfn id="display:inline-list-item">inline-list-item</dfn>
<dd> Expands identically to ‘<code class=css>inline-level block
list-item</code>’.
<dt><dfn id="display:inline-block">inline-block</dfn>
<dd> Expands identically to ‘<code class=css>inline-level
block</code>’.
<dt><dfn id="display:table">table</dfn>
<dd> Expands identically to ‘<code class=css>block-level
table</code>’.
<dt><dfn id="display:inline-table">inline-table</dfn>
<dd> Expands identically to ‘<code class=css>inline-level
table</code>’.
<dt><dfn id="display:table-caption">table-caption</dfn>
<dd> Expands identically to ‘<code class=css>table-caption
block</code>’.
<dt><dfn id="display:table-cell">table-cell</dfn>
<dd> Expands identically to ‘<code class=css>table-cell block</code>’.
<dt><dfn id="display:flex">flex</dfn>
<dd> Expands identically to ‘<code class=css>block-level flex</code>’.
<dt><dfn id="display:inline-flex">inline-flex</dfn>
<dd> Expands identically to ‘<code class=css>inline-level
flex</code>’.
<dt><dfn id="display:grid">grid</dfn>
<dd> Expands identically to ‘<code class=css>block-level grid</code>’.
<dt><dfn id="display:inline-grid">inline-grid</dfn>
<dd> Expands identically to ‘<code class=css>inline-level
grid</code>’.
<dt><dfn id="display:none">none</dfn>
<dd> Expands identically to ‘<code class=css>inline-level auto
none</code>’.
</dl>
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<h2 id=conformance><span class=secno>3. </span> Conformance</h2>
<h3 id=conventions><span class=secno>3.1. </span> Document conventions</h3>
<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.
<p>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.
</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.
<h3 id=conformance-classes><span class=secno>3.2. </span> Conformance
classes</h3>
<p>Conformance to <var class=replaceme>CSS TEMPLATE Module</var> 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 <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
that i
1E88
nterprets the semantics of a style sheet and renders documents that
use them.
<dt><dfn id=authoring-tool>authoring tool</dfn>
<dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
that writes a style sheet.
</dl>
<p>A style sheet is conformant to <var class=replaceme>CSS TEMPLATE
Module</var> if all of its statements that use syntax defined in this
module are valid according to the generic CSS grammar and the individual
grammars of each feature defined in this module.
<p>A renderer is conformant to <var class=replaceme>CSS TEMPLATE
Module</var> if, in addition to interpreting the style sheet as defined by
the appropriate specifications, it supports all the features defined by
<var class=replaceme>CSS TEMPLATE Module</var> 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 <var class=replaceme>CSS TEMPLATE
Module</var> if it writes style sheets that are syntactically correct
according to the generic CSS grammar and the individual grammars of each
feature in this module, and meet all other conformance requirements of
style sheets as described in this module.
<h3 id=partial><span class=secno>3.3. </span> Partial implementations</h3>
<p>So that authors can exploit the forward-compatible parsing rules to
assign fallback values, CSS renderers <strong>must</strong> treat as
invalid (and <a
href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
appropriate</a>) any at-rules, properties, property values, keywords, and
other syntactic constructs for which they have no usable level of support.
In particular, user agents <strong>must not</strong> selectively ignore
unsupported component values and honor supported values in a single
multi-value property declaration: if any value is considered invalid (as
unsupported values must be), CSS requires that the entire declaration be
ignored.
<h3 id=experimental><span class=secno>3.4. </span> Experimental
implementations</h3>
<p>To avoid clashes with future CSS features, the CSS2.1 specification
reserves a <a
href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
syntax</a> for proprietary and experimental extensions to CSS.
<p>Prior to a specification reaching the Candidate Recommendation stage in
the W3C process, all implementations of a CSS feature are considered
experimental. The CSS Working Group recommends that implementations use a
vendor-prefixed syntax for such features, including those in W3C Working
Drafts. This avoids incompatibilities with future changes in the draft.
<h3 id=testing><span class=secno>3.5. </span> Non-experimental
implementations</h3>
<p>Once a specification reaches the Candidate Recommendation stage,
non-experimental implementations are possible, and implementors should
release an unprefixed implementation of any CR-level feature they can
demonstrate to be correctly implemented according to spec.
<p>To establish and maintain the interoperability of CSS across
implementations, the CSS Working Group requests that non-experimental CSS
renderers submit an implementation report (and, if necessary, the
testcases used for that implementation report) to the W3C before releasing
an unprefixed implementation of any CSS features. Testcases submitted to
W3C are subject to review and correction by the CSS Working Group.
<p>Further information on submitting testcases and implementation reports
can be found from on the CSS Working Group's website at <a
href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
Questions should be directed to the <a
href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
mailing list.
<h3 id=cr-exit-criteria><span class=secno>3.6. </span> CR exit criteria</h3>
<p class=replaceme>Remove this section unless/until the module is in CR.</p>
<!-- This text was <a href="http://www.w3.org/Style/CSS/Tracker/actions/44"> decided on 2008-06-04.</a> -->
<p> For this specification to be advanced to Proposed Recommendation, there
must be at least two independent, interoperable implementations of each
feature. Each feature may be implemented by a different set of products,
there is no requirement that all features be implemented by a single
product. For the purposes of this criterion, we define the following
terms:
<dl>
<dt>independent
<dd>each implementation must be developed by a different party and cannot
share, reuse, or derive from code used by another qualifying
implementation. Sections of code that have no bearing on the
implementation of this specification are exempt from this requirement.
<dt>interoperable
<dd>passing the respective test case(s) in the official CSS test suite,
or, if the implementation is not a Web browser, an equivalent test. Every
relevant test in the test suite should have an equivalent test created if
such a user agent (UA) is to be used to claim interoperability. In
addition if such a UA is to be used to claim interoperability, then there
must one or more additional UAs which can also pass those equivalent
tests in the same way for the purpose of interoperability. The equivalent
tests must be made publicly available for the purposes of peer review.
<dt>implementation
<dd>a user agent which:
<ol class=inline>
<li>implements the specification.
<li>is available to the general public. The implementation may be a
shipping product or other publicly available version (i.e., beta
version, preview release, or “nightly build”). Non-shipping product
releases must have implemented the feature(s) for a period of at least
one month in order to demonstrate stability.
<li>is not experimental (i.e., a version specifically designed to pass
the test suite and is not intended for normal usage going forward).
</ol>
</dl>
<p>The specification will remain Candidate Recommendation for at least six
months.
<h2 class=no-num id=acknowledgments> Acknowledgments</h2>
<p><var class=replaceme>[acknowledgments]</var>
<h2 class=no-num id=references> References</h2>
<h3 class=no-num id=normative-references> Normative references</h3>
<!--begin-normative-->
<!-- Sorted by label -->
<dl class=bibliography>
<dt style="display: none"><!-- keeps the doc valid if the DL is empty -->
<!---->
<dt id=CSS21>[CSS21]
<dd>Bert Bos; et al. <a
href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
2011. W3C Recommendation. URL: <a
href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
</dd>
<!---->
<dt id=CSS3-FLEXBOX>[CSS3-FLEXBOX]
<dd>Tab Atkins Jr.; Elika J. Etemad; Alex Mogilevsky. <a
href="http://www.w3.org/TR/2012/WD-css3-flexbox-20120612/"><cite>CSS
Flexible Box Layout Module.</cite></a> 12 June 2012. W3C Working Draft.
(Work in progress.) URL: <a
href="http://www.w3.org/TR/2012/WD-css3-flexbox-20120612/">http://www.w3.org/TR/2012/WD-css3-flexbox-20120612/</a>
</dd>
<!---->
<dt id=RFC2119>[RFC2119]
<dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
RFC 2119. URL: <a
href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
</dd>
<!---->
</dl>
<!--end-normative-->
<h3 class=no-num id=other-references> Other references</h3>
<!--begin-informative-->
<!-- Sorted by label -->
<dl class=bibliography>
<dt style="display: none"><!-- keeps the doc valid if the DL is empty -->
<!---->
<dt id=CSS3COLOR>[CSS3COLOR]
<dd>Tantek Çelik; Chris Lilley; L. David Baron. <a
href="http://www.w3.org/TR/2011/REC-css3-color-20110607"><cite>CSS Color
Module Level 3.</cite></a> 7 June 2011. W3C Recommendation. URL: <a
href="http://www.w3.org/TR/2011/REC-css3-color-20110607">http://www.w3.org/TR/2011/REC-css3-color-20110607</a>
</dd>
<!---->
</dl>
<!--end-informative-->
<h2 class=no-num id=index> Index</h2>
<!--begin-index-->
<ul class=indexlist>
<li>authoring tool, <a href="#authoring-tool"
title="authoring tool"><strong>3.2.</strong></a>
<li>auto, <a href="#display-inside:auto"
title=auto><strong>2.1.</strong></a>
<li>block, <a href="#display-inside:block"
title=block><strong>2.1.</strong></a>, <a href="#display:block"
title=block><strong>2.5.</strong></a>
<li>block-level, <a href="#display-outside:block-level"
title=block-level><strong>2.2.</strong></a>
<li>contents, <a href="#display-box:contents"
title=contents><strong>2.3.</strong></a>
<li>display, <a href="#display" title=display><strong>2.5.</strong></a>
<li>display-box, <a href="#display-box"
title=display-box><strong>2.3.</strong></a>
<li>display-extras, <a href="#display-extras"
title=display-extras><strong>2.4.</strong></a>
<li>display-inside, <a href="#display-inside"
title=display-inside><strong>2.1.</strong></a>