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<!DOCTYPE html public '-//W3C//DTD HTML 4.01//EN' 'http://www.w3.org/TR/html4/strict.dtd'>
<html lang="en">
<head profile="http://www.w3.org/2006/03/hcard">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>CSS Fragmentation Controls Module Level 3</title>
<link rel="stylesheet" type="text/css" href="default.css" />
<link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS].css" />
</head>
<body>
<div class="head">
<!--logo-->
<h1 id="css-fragmentation-module">CSS Fragmentation Controls Module Level 3</h1>
<h2 class="no-num no-toc">[LONGSTATUS] [DATE]</h2>
<dl>
<dt>This version:</dt>
<dd><a href="[VERSION]">http://www.w3.org/csswg/css3-breaks/</a></dd>
<dt>Latest version:</dt>
<dd><a href="http://www.w3.org/TR/[SHORTNAME]/">http://www.w3.org/csswg/[SHORTNAME]/</a></dd>
<dt>Previous version:</dt>
<dd>None</dd>
<dt>Editors:</dt>
<dd class="vcard"><span class="fn">Rossen Atanassov</span>, <span class="org"><a class="fn org url" href="http://www.microsoft.com/">Microsoft Corporation</a></span>, <span class="email">ratan@microsoft.com</span></dd>
<dd class="vcard"><span class="fn"><a class="fn" href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a></span>, <span class="org"><a class="fn org url" href="http://www.mozilla.com/">Mozilla Corporation</a></span></dd>
</dl>
<!--copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id="abstract">Abstract</h2>
<p>
This module describes the fragmentation model that partitions a flow into pages.
It builds on the Page model module and introduces and defines the fragmentation
model. It adds functionality for pagination, breaking variable fragment size and
orientation, widows and orphans.
</p>
<h2 class="no-num no-toc" id="status">Status of this document</h2>
<!--status-->
<!--<p>The following features are at risk: …</p>-->
<h2 class="no-num no-toc" id="contents">Table of contents</h2>
<!--toc-->
<h2 id="intro">Introduction</h2>
<p><em>This section is not normative.</em></p>
<p>
Paged media (e.g., paper, transparencies, photo album pages, pages displayed on
computer screens as printed output simulations) differ from <a href="/TR/CSS2/media.html#continuous-media-group">
continuous media</a> in that the content of the document is split into one or
more discrete static display surfaces. To handle pages, CSS3 Paged Media describes
how:
</p>
<ul>
<li><a href="#page-breaks">page breaks</a> are created and avoided;</li>
<li>the page properties such as size, orientation, margins, border, and padding are specified;</li>
<li>headers and footers are established within the page margins;</li>
<li>content such as page counters are placed in the headers and footers; and</li>
<li>orphans and widows can be controlled.</li>
</ul>
<p>
This module defines a <a href="#page-model">page model</a> that specifies how a
document is formatted within a rectangular area, called the <a href="#page-box-page-rule">
page box</a>, that has finite width and height.
</p>
<p>
Although CSS3 does not specify how user agents transfer page boxes to sheets, it
does include certain mechanisms for telling user agents about the intended page
sheet <a href="#page-size">size and orientation</a>. In the general case, CSS3 assumes
that one page box will be transferred to one surface of similar size.</p>
<p>
All properties defined in this specification also accept the <a href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">
inherit</a> keyword as their value, but for readability it has not been listed
explicitly.
</p>
<h3 id="placement">Module Interactions</h3>
<p>This module replaces and extends the pagination controls defined in
[[CSS21]] <a href="http://www.w3.org/TR/CSS21/page.html#page-breaks">section 13.3</a>
and in [[CSS3PAGE]].</p>
<!-- End section "Modules Interactions" -->
<h3 id="values">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 [[!CSS21]]. Value types not defined
in this specification are defined in CSS Level 2 Revision 1 [[!CSS21]]. Other CSS
modules may expand the definitions of these value types: for example [[CSS3COLOR]],
when combined with this module, expands the definition of the <color> value
type as used in this specification.</p>
<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/CSS21/cascade.html#value-def-inherit">
inherit</a> keyword as their property value. For readability it has not been
repeated explicitly.
</p>
<h2 id="page-breaks">Page Breaks</h2>
<p>
The following sections explain page breaking in CSS3 paged media. Five properties
indicate where the user agent <em class="RFC2119">MAY</em> or <em class="RFC2119">SHOULD</em>
break pages, and on what page (left or right) the subsequent content <em class="RFC2119">
SHOULD</em> resume. Each page break ends layout in the current <a href="#page-box">page
box</a> and causes remaining pieces of the document tree to be laid out
in a new page box.
</p>
<p>
When a page break splits a box, the box's bottom margins, borders, and padding have
no visual effect where the split occurs; the box's background and left and right
margins, border, and padding extend to the bottom of the page, through an ensuing
blank page if one exists, and onto the top of the subsequent page.
</p>
<h3 id="pg-br-before-after">
Break before/after elements: <span class="property">'page-break-before'</span>,
<span class="property">'page-break-after'</span>, <span class="property">'page-break-inside'</span>
</h3>
<table class="propdef" summary="property definition">
<tr>
<th>Name:
<td><dfn id="page-break-before">page-break-before</dfn>
<tr>
<th>Value:
<td>auto | always | avoid | left | right
<tr>
<th>Initial:
<td>auto
<tr>
<th>Applies to:
<td>block-level elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>paged
<tr>
<th>Computed value:
<td>specified value
</table>
<table class="propdef" summary="property definition">
<tr>
<th>Name:
<td><dfn id="page-break-after">page-break-after</dfn>
<tr>
<th>Value:
<td>auto | always | avoid | left | right
<tr>
<th>Initial:
<td>auto
<tr>
<th>Applies to:
<td>block-level boxes, table row groups, table rows (but see prose)
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>paged
<tr>
<th>Computed value:
<td>specified value
</table>
<table class="propdef" summary="property definition">
<tr>
<th>Name:
<td><dfn id="page-break-inside">page-break-inside</dfn>
<tr>
<th>Value:
<td>auto | avoid
<tr>
<th>Initial:
<td>auto
<tr>
<th>Applies to:
<td>block-level boxes, table row groups, table rows, and table cells
(but see prose)
<tr>
<th>Inherited:
6082
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>paged
<tr>
<th>Computed value:
<td>specified value
</table>
<p>Values for these properties have the following meanings:</p>
<dl>
<dt>auto</dt>
<dd>Neither force nor forbid a page break before / after / inside the generated box.</dd>
<dt>always</dt>
<dd>Always force a page break before / after the generated box.</dd>
<dt>avoid</dt>
<dd>Avoid a page break before / after / inside the generated box.</dd>
<dt>left</dt>
<dd>
Force one or two page breaks before (after) the generated box so that the next page
is formatted as a left page.
</dd>
<dt>right</dt>
<dd>
Force one or two page breaks before (after) the generated box so that the next page
is formatted as a right page.
</dd>
</dl>
<p>
A potential page break location is typically under the influence of the parent element's
<span class="property">'page-break-inside'</span> property, the <span class="property">
'page-break-after'</span> property of the preceding element, and the <span class="property">
'page-break-before'</span> property of the following element. When these
properties have values other than <span class="css">'auto'</span>, the values <span
class="css">'always'</span>, <span class="css">'left'</span>, and <span class="css">
'right'</span> take precedence over <span class="css">'avoid'</span>. See
the section on <a href="#allowed-pg-brk">allowed page breaks</a> for the exact rules
on how these properties affect page breaks.
</p>
<p>
User Agents must apply these properties to block-level boxes and to table rows,
table row groups, and—in the case of 'page-break-inside'—table cells
of block-level tables in the normal flow of the root element. User agents should
also apply these properties to floated boxes whose containing block is in the normal
flow of the root element. User agents may also apply these properties to other boxes.
</p>
<h3 id="using-named-pages">Using named pages: 'page'</h3>
<table class="propdef" summary="property definition">
<tr>
<th>Name:
<td><dfn id="page">page</dfn>
<tr>
<th>Value:
<td>auto | <identifier>
<tr>
<th>Initial:
<td>auto
<tr>
<th>Applies to:
<td>block-level elements
<tr>
<th>Inherited:
<td>no (but see prose)
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>paged
<tr>
<th>Computed value:
<td>specified value
</table>
<p>
The <span class="property">'page'</span> property is used to specify a particular
type of page where an element <em class="RFC2119">SHOULD</em> be displayed.
</p>
<div class="example">
<p>This example will put all tables on a right-hand side landscape page (named "rotated"):</p>
<pre>
@page rotated { size: landscape }
table { page: rotated; page-break-before: right }
</pre>
</div>
<p>
The <span class="property">'page'</span> property works as follows: If a block box
with inline content has a <span class="property">'page'</span> property that is
different from the preceding block box with inline content, then one or two page
breaks are inserted between them, and the boxes after the break are rendered on
a page box of the named type. See <a href="#forced-pg-brk">"Forced page breaks" below</a>.
</p>
<p>
The 'page' property does not inherit. However, if the 'page' value on an element
is ''auto'', then it is treated as having the same name as its nearest ancestor
with a non-auto value. When indicated on the root element, the effective name is
the empty string.
</p>
<p>
Because a previous version of this specification indicated that the 'page' property
is inherited, an implementation that inherits the 'page' property and treats ''auto''
as always naming the empty string remains conformant to CSS3 Paged Media. Therefore
authors should not explicitly specify the ''auto'' value on a descendant of an element
with a non-''auto'' 'page' value as the resulting behavior will be unpredictable.
</p>
<p>
Page names are case-sensitive identifiers. However the ''auto'' value, being a CSS
keyword, is <a href="http://www.w3.org/TR/CSS21/syndata.html#characters">case-insensitive</a>.
</p>
<div class="example">
<p>
In this example, the two tables are rendered on landscape pages (indeed, on the
same page, if they fit). The page type "narrow" is used for the <p> after
the second table, as the page properties for the table element are no longer in
effect:</p>
<pre>
@page narrow { size: 9cm 18cm }
@page rotated { size: landscape }
div { page: narrow }
table { page: rotated }
</pre>
with this document:
<pre>
<div>
<table>...</table>
<table>...</table>
<p>This text is rendered on a 'narrow' page</p>
</div>
</pre>
</div>
<h3 id="breaks-inside">Breaks inside elements: 'orphans', 'widows'</h3>
<table class="propdef" summary="property definition">
<tr>
<th>Name:</th>
<td><dfn id="orphans">orphans</dfn></td>
</tr>
<tr>
<th>Value:</th>
<td><integer></td>
</tr>
<tr>
<th>Initial:</th>
<td>2</td>
</tr>
<tr>
<th>Applies to:</th>
<td>block-level elements</td>
</tr>
<tr>
<th>Inherited:</th>
<td>yes</td>
</tr>
<tr>
<th>Percentages:</th>
<td>N/A</td>
</tr>
<tr>
<th>Media:</th>
<td>visual</td>
</tr>
<tr>
<th>Computed value:</th>
<td>specified value</td>
</tr>
</table>
<table class="propdef" summary="property definition">
<tr>
<th>Name:</th>
<td><dfn id="widows">widows</dfn></td>
</tr>
<tr>
<th>Value:</th>
<td><integer></td>
</tr>
<tr>
<th>Initial:</th>
<td>2</td>
</tr>
<tr>
<th>Applies to:</th>
<td>block-level elements</td>
</tr>
<tr>
<th>Inherited:</th>
<td>yes</td>
</tr>
<tr>
<th>Percentages:</th>
<td>N/A</td>
</tr>
<tr>
<th>Media:</th>
<td>visual</td>
</tr>
<tr>
<th>Computed value:</th>
<td>specified value</td>
</tr>
</table>
<p>
The <span class="property">'orphans'</span> property specifies the minimum number
of line boxes in a block element that <em class="RFC2119">MUST</em> be left at the
bottom of a page. The <span class="property">'widows'</span> property specifies
the minimum number of line boxes of a block element that <em class="RFC2119">MUST</em>
be left at the top of a page. Examples of how they are used to control page breaks
are given below.
</p>
<p>
Only positive integers are allowed as values of 'orphans' and 'widows'. Negative
values and zero are invalid must cause the declaration to be <a href="http://www.w3.org/TR/CSS21/conform.html#ignore">
ignored</a>.
</p>
<p>
If a block contains fewer lines than the value of 'widows' or 'orphans', the rule
simply becomes that all lines in the block must be kept together.
</p>
<h3 id="allowed-pg-brk">Allowed page breaks</h3>
<p>In the normal flow, page breaks <em class="RFC2119">may</em> occur at the following places:</p>
<ol>
<li id="brk-btw-blocks">
In the vertical margin between sibling block boxes (or rows
in a table). When an unforced page break occurs here, both the adjoining 'margin-top'
and 'margin-bottom' are set to zero.
</li>
<li id="brk-btw-lines">Between line boxes inside a block box.</li>
<li id="brk-end-block">
Between the content edge of a block box and the outer edges of
its child content (margin edges of block-level children or line box edges for inline-level
children) <em>if</em> there is a (non-zero) gap between them.
</li>
</ol>
<p>These breaks are subject to the following rules:</p>
<ul>
<li>
<strong>Rule A:</strong> Breaking at <a href="#brk-btw-blocks">(1)</a> is allowed
only if the 'page-break-after' and 'page-break-before' properties of all the elements
generating boxes that meet at this margin allow it, which is when at least one of
them has the value <span class
6082
="css">'always'</span>, <span class="css">'left'</span>,
or <span class="css">'right'</span>, or when all of them are <span class="css">'auto'</span>.
</li>
<li>
<strong>Rule B:</strong> However, if all of them are <span class="css">'auto'</span>
and a common ancestor of all the elements has a <span class="property">'page-break-inside'</span>
value of <span class="css">'avoid'</span>, then breaking here is not allowed.
</li>
<li>
<strong>Rule C:</strong> Breaking at <a href="#brk-btw-lines">(2)</a> is allowed
only if the number of line boxes between the break and the start of the enclosing
block box is the value of 'orphans' or more, and the number of line boxes between
the break and the end of the box is the value of 'widows' or more.
</li>
<li>
<strong>Rule D:</strong> In addition, breaking at <a href="#brk-btw-blocks">(2)</a>
or <a href="#brk-end-block">(3)</a> is allowed only if the 'page-break-inside' property
of all ancestors is ''auto''.
</li>
</ul>
<p>
If the above doesn't provide enough break points to keep content from overflowing
the page boxes, then rules A, B and D are dropped in order to find additional breakpoints.
In this case the UA may use the 'avoid's that are in effect at those points to weigh
the appropriateness of the new breakpoints; however, this specification does not
suggest a precise algorithm.
</p>
<p>
If that still does not lead to sufficient break points, rule C is dropped as well,
to find still more break points.
</p>
<h3 id="forced-pg-brk">Forced page breaks</h3>
<p>
A page break <em class="RFC2119">MUST</em> occur at <a href="#brk-btw-blocks">(1)</a>
if, among the'page-break-after' and 'page-break-before' properties of all the elements
generating boxes that meet at this margin, there is at least one with the value
<span class="css">'always'</span>, <span class="css">'left'</span>, or <span class="css">
'right'</span>.
</p>
<p>
When multiple 'page-break-before' and/or 'page-break-after' properties with values
of "always", "left" or "right" apply at a margin, only one of them should generate
page breaks. That is, no content-empty pages are generated by page-break properties,
except for at most one content-empty page as may be required by 'right' and 'left'
values to position ensuing content on a right- or left-facing page.
</p>
<p>
A page break <em class="RFC2119">MUST</em> also occur at <a href="#brk-btw-blocks">(1)</a>
if the last line box above this margin and the first one below it do not have the
same value for 'page'.
</p>
<p>
When a forced page break occurs at <a href="#brk-btw-blocks">(1)</a>, the used values
of any adjoining 'margin-bottom' are set to zero.
</p>
<h3 id="best-pg-brk">"Best" page breaks</h3>
<p>
CSS3 does <em>not</em> define which of a set of allowed page breaks <em class="RFC2119">
MUST</em> be used; except as defined earlier in the section, CSS3 does not forbid
a user agent to break at every possible break point, or to not break at all. But
CSS3 does recommend that user agents observe the following guidelines (while recognizing
that they are sometimes contradictory):</p>
<ul>
<li>Break as few times as possible.</li>
<li>Make all pages that don't end with a forced break appear to have about the same height.</li>
<li>Avoid breaking inside a replaced element.</li>
</ul>
<div class="example">
<p>
Suppose, for example, that the style sheet contains <span class="css">'orphans : 4'</span>,
<span class="css">'widows : 2'</span>, and there are 20 lines (line boxes) available
at the bottom of the current page, and the next block in normal flow is considered
for placement:
</p>
<ul>
<li>
If the block contains 20 line boxes or fewer, it <em class="RFC2119">SHOULD</em>
be placed on the current page.
</li>
<li>
If the block contains 21 or 22 line boxes, the second part of the paragraph <em
class="RFC2119">MUST</em> not violate the <span class="property">'widows'</span>
constraint, and so the second part <em class="RFC2119">MUST</em&
8096
gt; contain at least
two line boxes; likewise the first part <em class="RFC2119">MUST</em> contain at
least four line boxes.
</li>
<li>
If the block contains 23 line boxes or more, the first part <em class="RFC2119">
SHOULD</em> contain 20 lines and the second part the remaining lines. (But if any
part of the block is placed on the current page, that part <em class="RFC2119">MUST</em>
contain at least four line boxes and the second part at least two line boxes.)
</li>
</ul>
<p>
Now suppose that <span class="property">'orphans'</span> is <span class="css">'10'</span>,
<span class="property">'widows'</span> is <span class="css">'20'</span>, and there
are 8 lines available at the bottom of the current page:
</p>
<ul>
<li>
If the block contains 8 lines or fewer, it <em class="RFC2119">SHOULD</em> be placed
on the current page.
</li>
<li>
If the block contains 9 lines or more, it <em class="RFC2119">MAY NOT</em> be split
(that would violate the orphan constraint), so it <em class="RFC2119">MUST</em>
move as a block to the next page.
</li>
</ul>
</div>
<!-- End section "Page Breaks" -->
<h2 id="conformance">Conformance</h2>
<h3 id="conventions">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>
<p>
All of the text of this specification is normative except sections explicitly marked
as non-normative, examples, and notes. [[!RFC2119]]
</p>
<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:
</p>
<div class="example">
<p>This is an example of an informative example.</p>
</div>
<p>
Informative notes begin with the word “Note” and are set apart from the normative
text with <code>class="note"</code>, like this:
</p>
<p class="note">Note, this is an informative note.</p>
<h3 id="conformance-classes">Conformance Classes</h3>
<p>Conformance to CSS Fragmentation is defined for three conformance classes:</p>
<dl>
<dt><dfn title="style sheet!!as conformance class">style sheet</dfn></dt>
<dd>
A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS style sheet</a>.</dd>
<dt><dfn>renderer</dfn></dt>
<dd>
A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a> that interprets
the semantics of a style sheet and renders documents that use them.</dd>
<dt><dfn id="authoring-tool">authoring tool</dfn></dt>
<dd>
A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a> that writes
a style sheet.</dd>
</dl>
<p>
A style sheet is conformant to CSS Fragmentation if all of its declarations
that use properties defined in this module have values that are valid according
to the generic CSS grammar and the individual grammars of each property as given
in this module.
</p>
<p>
A renderer is conformant to CSS Fragmentation if, in addition to interpreting
the style sheet as defined by the appropriate specifications, it supports all the
features defined by CSS Fragmentation 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>
<p>
An authoring tool is conformant to CSS Fragmentation 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.
</p>
<h3 id="partial">
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.
</p>
<h3 id="experimental">
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>
<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.
</p>
<h3 id="testing">
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>
<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>
<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.
</p>
<h3 id="cr-exit-criteria">
CR Exit Criteria</h3>
<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:
</p>
<dl>
<dt>independent </dt>
<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.</dd>
<dt>interoperable</dt>
<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.
</dd>
<dt>implementation</dt>
<dd>
a user agent which:
<ol class="inline">
<li>implements the specification.</li>
<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>
<li>is not experimental (i.e., a version specifically designed to pass the test suite
and is not intended for normal usage going forward).</li>
</ol>
</dd>
</dl>
<p>
The specification will remain Candidate Recommendation for at least six months.
</p>
<h2 class="no-num" id="acknowledgments">Acknowledgments</h2>
<p>
The editors would like to extend special thanks to
Michael Day,
and the former [[CSS3PAGE]] editors
Jim Bigelow (HP),
Melinda Grant (HP),
Håkon Wium Lie (Opera),
and
Jacob Refstrup (HP)
for their contributions to this specification.
</p>
<h2 class="no-num" id="references">References</h2>
<h3 class="no-num" id="normative-references">Normative references</h3>
<!--normative-->
<h3 class="no-num" id="other-references">Other references</h3>
<!--informative-->
<h2 class="no-num" id="index">Index</h2>
<!--index-->
<h2 class="no-num" id="property-index">Property index</h2>
<!-- properties -->
</body>
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