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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html dir=ltr lang=en>
<head profile="http://www.w3.org/2006/03/hcard"><meta content="IE=edge"
http-equiv=X-UA-Compatible>
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<title>CSS regions Module</title>
<link href="http://dev.w3.org/csswg/default.css" rel=stylesheet
type="text/css">
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=Stylesheet
type="text/css">
<link href=alternate-spec-style.css id=st rel=stylesheet title="additional
spec styles" type="text/css">
<script src=style-toggle.js type="text/javascript">
</script>
<!-- <script src='http://test.csswg.org/harness/annotate.js#CSS3-REGIONS_DEV' type=
'text/javascript'> -->
<body>
<div class=head id=div-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--></p>
<h1 id=css-regions-module>CSS regions Module</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 23 August 2011</h2>
<dl>
<dt>This version:
<dd><a
href="http://www.w3.org/TR/2011/ED-css3-regions-20110823/">http://www.w3.org/csswg/css3-regions</a>
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css3-regions">http://www.w3.org/csswg/css3-regions</a>
<dt>Previous version:
<dd>none
<dt>Editors:
<dd class=vcard><span class=fn>Vincent Hardy</span>, <span
class=org>Adobe Systems, Inc.</span>, <span
class=email>vhardy@adobe.com</span>
<dd class=vcard><span class=fn>Alex Mogilevsky</span>, <span
class=org>Microsoft</span>, <span
class=email>alexmog@microsoft.com</span>
<dt>Authors and Former Editors:
<dd class=vcard><span class=fn>Stephen Zilles</span>, <span
class=org>Adobe Systems, Inc.</span>, <span
class=email>szilles@adobe.com</span>
<dd class=vcard><span class=fn>Alexandru Chiculita</span>, <span
class=org>Adobe Systems, Inc.</span>, <span
class=email>achicu@adobe.com</span>
<dd class=vcard><span class=fn>Andrei Bucur</span>, <span class=org>Adobe
Systems, Inc.</span>, <span class=email>abucur@adobe.com</span>
<dd class=vcard><span class=fn>Mihnea Ovidenie</span>, <span
class=org>Adobe Systems, Inc.</span>, <span
class=email>mihnea@adobe.com</span>
<dd class=vcard><span class=fn>Peter Sorotokin</span>, <span
class=org>Adobe Systems, Inc.</span>, <span
class=email>psorotok@adobe.com</span>
<dd class=vcard><span class=fn>Virgil Palanciuc</span>, <span
class=org>Adobe Systems, Inc.</span>, <span
class=email>virgilp@adobe.com</span>
<dd class=vcard><span class=fn>Arno Gourdol</span>, <span class=org>Adobe
Systems, Inc.</span>, <span class=email>agourdol@adobe.com</span>
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2011 <a
href="http://www.w3.org/"><acronym title="World Wide Web
Consortium">W3C</acronym></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute
of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym
title="European Research Consortium for Informatics and
Mathematics">ERCIM</acronym></a>, <a
href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p><strong>CHANGES IN PROGRESS, NOT READY FOR REVIEW</strong>
<p>The CSS regions module allows content to flow across multiple areas
called regions. The regions do not necessarily follow the document order.
The CSS regions module provides an advanced content flow mechanism, which
can be combined with positioning schemes as defined by other CSS modules
such as the Multi-Column Module <a href="#CSS3COL"
rel=biblioentry>[CSS3COL]<!--{{CSS3COL}}--></a> or the Grid Layout Module
<a href="#CSS3-GRID-LAYOUT"
rel=biblioentry>[CSS3-GRID-LAYOUT]<!--{{CSS3-GRID-LAYOUT}}--></a> to
position the regions where content flows.
<h2 class="no-num no-toc" id=status-of-this-document>Status of this
document</h2>
<!--begin-status-->
<p>This is a public copy of the editors' draft. It is provided for
discussion only and may change at any moment. Its publication here does
not imply endorsement of its contents by W3C. Don't cite this document
other than as 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=%5Bcss3-regions%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
“css3-regions” in the subject, preferably like this:
“[<!---->css3-regions<!---->] <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/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="/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>
<!--end-status-->
<h2 class="no-num no-toc" id=table-of-contents>Table of contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#introduction"><span class=secno>1. </span>Introduction</a>
<ul class=toc>
<li><a href="#named-flows-and-regions"><span class=secno>1.1.
</span>Named flows and regions</a>
<li><a href="#region-styling"><span class=secno>1.2. </span>Regions
styling</a>
</ul>
<li><a href="#css-regions-concepts"><span class=secno>2. </span>CSS
regions concepts</a>
<ul class=toc>
<li><a href="#regions"><span class=secno>2.1. </span>Regions</a>
<li><a href="#named-flow"><span class=secno>2.2. </span>Named flow</a>
<li><a href="#regions-flow-breaking-rules"><span class=secno>2.3.
</span>Regions flow breaking rules</a>
<li><a href="#relation-to-document-events"><span class=secno>2.4.
</span>Relation to document events</a>
</ul>
<li><a href="#properties-and-rules"><span class=secno>3. </span>Properties
and rules</a>
<ul class=toc>
<li><a href="#the-flow-into-property"><span class=secno>3.1. </span>The
‘<code class=property>flow-into</code>’ property</a>
<li><a href="#the-content-property"><span class=secno>3.2. </span>The
‘<code class=property>content</code>’ property</a>
<li><a href="#the-region-order-property"><span class=secno>3.3.
</span>The ‘<code class=property>region-order</code>’
property</a>
<li><a href="#region-flow-break"><span class=secno>3.4. </span>Region
flow break properties: ‘<code
class=property>break-before</code>’, ‘<code
class=property>break-after</code>’, ‘<code
class=property>break-inside</code>’</a>
<li><a href="#the-region-overflow-property"><span class=secno>3.5.
</span>The region-overflow property</a>
<li><a href="#the-at-region-style-rule"><span class=secno>3.6.
</span>The @region rule</a>
</ul>
<li><a href="#pseudo_elements"><span class=secno>4.
</span>Pseudo-elements</a>
<ul class=toc>
<li><a href="#region-markers-processing-model"><span class=secno>4.1.
</span>Region markers processing model</a>
<li><a href="#the-region-before-and-region-after-pseudo-elements"><span
class=secno>4.2. </span>The ::region-before and ::region-after
pseudo-elements</a>
</ul>
<li><a href="#cssom_view_and_css_regions"><span class=secno>5.
</span>CSSOM view and CSS regions</a>
<ul class=toc>
<li><a href="#the-namedflow-interface"><span class=secno>5.1. </span>The
NamedFlow interface</a>
<li><a href="#extension-to-the-element-interface"><span class=secno>5.2.
</span>Extension to the Element interface</a>
<li><a href="#region-flow-layout-events"><span class=secno>5.3.
</span>Region flow layout events</a>
</ul>
<li><a href="#relation-to-other-specifications"><span class=secno>6.
</span>Relation to other specifications</a>
<li><a href="#conformance"><span class=secno>7. </span>Conformance</a>
<li><a href="#changes"><span class=secno>8. </span>Changes</a>
<ul class=toc>
<li><a href="#changes_from_June_09_2011"><span class=secno>8.1.
</span>Changes from June 09<sup>th</sup> 2011 version</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=introduction><span class=secno>1. </span>Introduction</h2>
<p><em>This section is non-normative.</em>
<p>Capturing the complex layouts of a typical magazine, newspaper, or
textbook requires capabilities beyond those available in existing CSS
modules. This is the purpose of the CSS regions module.
<p>
<p>The CSS regions module can be seen as an extension of the concept of
multi-column elements. With CSS Multi-column layout <a href="#CSS3COL"
rel=biblioentry>[CSS3COL]<!--{{CSS3COL}}--></a>, columns share the same
dimensions and define column boxes organized in rows. Content flows from
one column to the next.
<p>
<p>The multi-column model is an example of flowing content from one area to
another, where the areas are the multi-column element's column boxes and
the flow is made of the multi-column element's children.
<p>
<p>However, for more complex layouts, content needs to flow from one area
of the page to the next without limitation of the areas' sizes and
positions. These arbitrary areas are the target of specific content flows.
In this document these areas are called regions, and the content flows are
called named flows. Regions are based on the rectangular geometry of the
CSS box model. Elements in a named flow are taken out of the normal visual
formatting and rendered in a chain of regions.
<h3 id=named-flows-and-regions><span class=secno>1.1. </span>Named flows
and regions</h3>
<p>Consider the layout illustrated in figure 1.
<div class=figure> <img alt="multiple chained regions which should receive
content from a flow" src="images/regions-intro.svg" width=400>
<p class=caption>Layout requiring sophisticated content flow</p>
</div>
<p>The designer's intent is to position an image in region ‘<code
class=property>A</code>’ and to flow an article's text from region
‘<code class=css>1</code>’, to region ‘<code
class=css>2</code>’, ‘<code class=css>3</code>’ and
‘<code class=css>4</code>’.
<p>The following code snippet shows the content to flow between the regions
1, 2, 3 and 4.
<pre>
<div <em>id="article"</em>>
<h1>Introduction</h1>
<p>This is an example ...</p>
<h1>More Details</h1>
<p>This illustrates ...</p>
<p>Then, the example ...</p>
<p>Finally, this ...</p>
</div>
</pre>
<p>CSS layout facilities can position and size regions as needed. However,
there is no existing mechanism to associate the content with the regions
so that content flows as intended. Figure 2 shows an example of the
intended visual rendering of the content.
<div class=figure> <img alt="Sample rendering showing a single thread of
text flowing through a chain of regions"
src="images/regions-intro-rendering.png" width=450>
<p class=caption>Sample rendering for desired layout</p>
</div>
<p>Since the CSS regions module is independent of the layout of regions and
the mechanism used to create them, the following assumes there is a CSS
selector for the regions and, for the purpose of the example, the
selectors for regions 1, 2, 3 and 4 show as ‘<code
class=css><region1_sel></code>’, ‘<code
class=css><region2_sel></code>’, ‘<code
class=css><region3_sel></code>’ and ‘<code
class=css><region4_sel></code>’ respectively.
<div class=example>
<pre>
<style>
#article {
<strong>flow-into: article_flow;</strong>
}
<region1_sel>, <region2_sel>,
<region3_sel>, <region4_sel> {
<strong>content: flow-from(article_flow);</strong>
}
</style>
</pre>
</div>
<p>The ‘<code class=css>article_flow</code>’ value on the
‘<a href="#flow-into"><code
class=property>flow-into</code></a>’ property directs the
‘<code class=css>#article</code>’ element to the ‘<code
class=css>article_flow</code>’ named flow. Setting the regions'
content property to ‘<code
class=css>flow-from(article_flow)</code>’ associates these regions
with the named flow: the flow is ‘<code
class=css>poured</code>’ into the desired regions.
<h3 id=region-styling><span class=secno>1.2. </span>Regions styling</h3>
<p>Region styling allows content to be styled depending on the region it
flows into. It is a form of context-based styling, similar to <a
href="#CSSMEDIAQUERIES">Media Queries</a> <a href="#MEDIAQ"
rel=biblioentry>[MEDIAQ]<!--{{MEDIAQ}}--></a> which enable or disable
selectors depending on the rendering context. With region styling,
additional selectors may apply depending on the region into which content
flows.
<p>In our example, the designer wants to make text flowing into region 1
larger, bold and dark blue. In addition, <code
class=html><h1></code> headers should be run-ins and crimson.
<p>This design can be expressed with region styling as shown below.
<div class=example>
<pre>
<style>
/*
* Default article styling.
*/
#article {
color:#777;
text-align: justify;
}
#article h1 {
border-left: 1px solid #777;
padding-left: 2ex;
}
/*
* Additional styling to apply to content when it falls into
* region1
*/
<strong>@region <region1_sel> {</strong>
#article::region-lines {
font-weight: bold;
color: #0C3D5F;
font-size: larger;
}
#article h1 {
color: crimson;
display: run-in;
border: none;
padding: 0px;
}
<strong>}</strong>
</style>
</pre>
</div>
<p>The ‘<code class=css>@region</code>’ rule for region 1
limits its selectors to content flowing into region 1. The following
figure shows how the rendering changes if we do not increase the font size
nor make it bold for content flowing into region 1. As more content can be
fitted, more content is subject to the contextual selectors, resulting in
more dark blue text into region 1.
<p>The ‘<code class=css>::region-lines</code>’ pseudo-element
is described later in this specification.
<div class=figure> <img alt="Illustrate how changing region styling affects
the flow of content." src="images/region-styling.png" width=450>
<p class=caption>Different rendering with a different region styling</p>
</div>
<h2 id=css-regions-concepts><span class=secno>2. </span>CSS regions
concepts</h2>
<p><em>This section is non-normative.</em>
<h3 id=regions><span class=secno>2.1. </span>Regions</h3>
<p class=index id=region title=region>A region is an element that generates
a <a href="http://www.w3.org/TR/CSS21/visuren.html#block-boxes">block
container box</a> and has an associated <em>named flow</em> (see the
‘<a href="#content-from"><code
class=property>content</code></a>’ property).
<p>A <span title=region>region</span>‘<code class=css>s intrinsic
width is zero.</code>
<div class="issue moved">
<p>See <a
href="http://wiki.csswg.org/spec/css3-regions#issue-2-auto-sizing-of-regions"></a></p>
.
<p>There was a recent discussion on intrinsic sizing of regions which <a
href="http://lists.w3.org/Archives/Public/www-style/2011Jun/0629.html">has
not been resolved</a></p>
.</div>
<h3 id=named-flow><span class=secno>2.2. </span>Named flow</h3>
<p>A <def name=named-flow>named flow</def> is the ordered sequence of
elements associated with a flow with a given identifier. Elements in a
named flow are ordered according to the document order.
<p>Elements are placed into a named flow with the ’flow-into'
property. The elements in a named flow are laid out in the chain of
regions that are associated with this named flow. The ‘<a
href="#region-order"><code class=property>region-order</code></a>’
property defines how <span title=region>regions</span> are organized in to
a <span title=region-chain>region chain</span>.
<p>Content from a named flow is broken up between regions according to the
regions flow breaking rules.</p>
<!--
<p>In the <a href="http://www.w3.org/TR/CSS21/visuren.html">CSS formatting
model</a>, elements and pseudo-elements can be in the <em>normal flow</em> or out of the
<em>(normal) flow</em>. Boxes generated by elements in the normal flow are
subject to their container box's normal layout scheme. Boxes generated by
elements out of the normal flow are subject to a different layout scheme.
For example, absolutely positioned elements are subject to absolute
positioning into their <a href=
"http://www.w3.org/TR/CSS21/visudet.html#containing-block-details">containing
block</a>. This can be described by saying that the absolutely positioned
elements are part of a special flow (called <span title=
"positioned-flow">positioned flow</span>) which is subject to a special
layout by its container box (i.e., its container box positions it into the
containing block's box).</p>
<p> </p>
<p>In both cases, there is a notion of flow containing a sequence of
elements and there is a notion of <a href=
"http://www.w3.org/Style/Group/css2-src/visuren.html#block-boxes">(block)
container box</a> into which the elements flow.</p>
<p> </p>
<p>The CSS regions module generalizes the concept of flow by adding the
concept of a <em>named flow</em>. This module lets authors explicitly place
elements into a <em>named flow</em>.</p>
<p> </p>
<p>With this model, all elements are moved to a flow as part of the visual
formatting. That flow may be the normal flow, a named flow or a positioned
flow, for example. A flow gets formatted visually when associated with one
or several elements' container box(es). When an flow is associated with
container boxes, the boxes generated by the flow's elements are laid out
according to the container box's layout scheme and the flow is subject to
the <a href='#flow-breaking-rules'>'flow breaking rules'</a> described
below.</p>
<p>A container's layout scheme is the strategy used by a container to
position the boxes generated by its children and itself. Examples are the
normal layout (block and inline formatting) ([[CSS21]]), table layout
([[CSS21]]), the multi-column layout ([[CSS3COL]]) or the grid layout
([[CSS3-GRID-LAYOUT]]).</p>
-->
<h3 id=regions-flow-breaking-rules><span class=secno>2.3. </span>Regions
flow breaking rules</h3>
<p>Breaking a named flow across multiple regions is similar to breaking a
document's content across multiple pages (see <a href="#CSS3PAGE"
rel=biblioentry>[CSS3PAGE]<!--{{CSS3PAGE}}--></a>) or a multi-column
element's content across column boxes (see <a href="#CSS3COL"
rel=biblioentry>[CSS3COL]<!--{{CSS3COL}}--></a>). One difference is that
page boxes are generated based on the available content whereas regions
are a predefined set of recipient boxes for the named flow content.
<p><span title=region>Regions</span> are organized in to a <span
title=region-chain>region chain</span> (see the ‘<a
href="#region-order"><code class=property>region-order</code></a>’
property).
<p>Each region in turn consumes content from its associated <span
title=named-flow>named flow</span>. The named flow content is positioned
in the <dfn id=current-region title=current-region>current region</dfn>
until a natural or forced region break occurs, at which point the <a
href="#current-region" title=current-region>current region</a> becomes the
next one in the <span title=region-chain>region chain</span>. If there is
no more <span>region</span> in the region chain and there is still content
in the flow, the positioning of the remaining content is controlled by the
‘<a href="#region-overflow"><code
class=property>region-overflow</code></a>’ property on the last
<span>region</span> in the chain.</p>
<!--
<h3 id="the-visual-formatting-model-and-flows">The Visual Formatting Model
and Flows</h3>
<p>This section describes the flows to which elements formatted according
to the CSS <a href="http://www.w3.org/TR/CSS21/visuren.html">Visual
Formatting Model</a> and other layout modules (such as Multi-Column Layout
[[CSS3COL]]) belong to.</p>
<p>In particular, this section describes the 'generated flow' where
generated content of pseudo-elements is placed and several <dfn id=
"auto-flow" title="auto flows">'auto flows'</dfn> where children of content
elements are automatically placed.</p>
<h4 id="normal-flow">Normal flow</h4>
<p>In the CSS formatting model, elements are by default placed in the
<dfn id="normal-flow-def">normal flow</dfn> of their container. Also by
default, a container element gets its content from its <em>normal
flow</em>. This means that by default, a container element will visually
format its children elements and will be the only container associated with
its normal flow.</p>
<p>Note that floats and relatively positioned elements, in this model, are
part of the same flow of content and flow into the same container but are
positioned in different ways.</p>
<p>The <em>normal flow</em> is one of the <em>auto flows</em>.</p>
<h4 id="positioned-flow">Positioned flow</h4>
<p>An absolutely positioned element is placed into the <dfn title=
"positioned-flow">positioned flow</dfn> of its container. The container
positions this element into its <em>containing block</em>.</p>
<p>If a container has children in the <em>normal flow</em> and in the
<em>positioned flow</em>, it applies different positioning schemes to each
flow.</p>
<p>The <em>positioned flow</em> is one of the <em>auto flows</em>.</p>
<h4 id="column-flow">Column flow</h4>
<p>Children of the multi-column element are placed in the element's
<dfn id="column-flow-def">column flow</dfn>. The column boxes are then
implicitly associated with the element's 'column flow'. In this model,
multiple regions (column boxes) get their content from a single flow (the
element's 'column flow', which is the content of the element).</p>
<p>The <em>column flow</em> is one of the <em>auto flows</em>.</p>
<div class="issue">
Need to add a <dfn id="grid-cell-flow">grid cell flow</dfn> section.
</div>
<div class="issue">
Need to add examples for the different flow types.
</div>
<h4 id="generated-flow">Generated flow</h4>
<p>In the CSS formatting model, when the ''::before'' or ''::after''
pseudo-elements have their content property set to one of
''<string>'', ''<uri>'', ''<counter>'',
''attr(<identifier>)'', ''open-quote'', ''close-quote'',
''no-open-quote'' or ''no-close-quote'', they create a <dfn id=
"generated-flow-def">generated flow</dfn> which they format visually.</p>
-->
<h3 id=relation-to-document-events><span class=secno>2.4. </span>Relation
to document events</h3>
<p>The CSS regions module does not alter the normal processing of events in
the document tree. In particular, if an event occurs on an element that is
part of a named flow, the <a
href="http://www.w3.org/TR/DOM-Level-3-Events/#dom-event-architecture">event's
bubble and capture phases</a> happen following the document tree order.
<h2 id=properties-and-rules><span class=secno>3. </span>Properties and
rules</h2>
<!-- Commented out following section because it was redundant with the introduction -->
<!--
<p>The main CSS regions module properties are the ‘flow-into’ and 'content'
properties. The ‘flow-into’ property may place an element into a specific named
flow. The ‘content’ property binds a region with a particular named flow. When multiple
regions are bound to the same flow, the 'region-order' property determines
the order in which content flows into the sequence of regions. This
sequences of regions is called a <dfn>region chain</dfn>.</p>
<p>The “break-*” properties control how content is broken into segments which are
then fitted in regions.</p>
<p>Styling that is unique to the region can be specified by ‘@region’ rules.</p>
-->
<h3 id=the-flow-into-property><span class=secno>3.1. </span>The ‘<a
href="#flow-into"><code class=property>flow-into</code></a>’
property</h3>
<p>The ‘flow-into’ property can place an element into a named flow.
Elements that belong to the same flow are laid out in the regions
associated with that flow.
<table class=propdef summary="flow property definition">
<tbody>
<tr>
<th>Name:
<td><dfn id=flow-into>flow-into</dfn>
<tr>
<th>Value:
<td><ident> | auto
<tr>
<th>Initial:
<td>auto
<tr>
<th>Applies to:
<td>any element
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
</table>
<dl>
<dt>auto
<dd>The element is not moved to a named flow and normal CSS processing
takes place.
<dt><a
href="http://www.w3.org/TR/2011/REC-CSS2-20110607/syndata.html#value-def-identifier"><ident></a>
<dd>The element is placed into the flow with the name ‘<code
class=css><ident></code>’. The element is said to have a <dfn
id=specified-flow>specified flow</dfn>. The values ‘<code
class=property>none</code>’, ‘<code
class=property>inherit</code>’, ‘<code
class=property>default</code>’ and ‘<code
class=property>initial</code>’ are invalid flow names.
</dl>
<p>A named flow needs to be associated with one or more regions for its
elements to be visually formatted. If no region is associated with a given
named flow, the elements in the named flow are not rendered: they do not
generate boxes and are not displayed.
<p>The children of an element with a specified flow may themselves have a
specified flow.
<p>If an element has a the same specified flow value as one of its
ancestors, it becomes a sibling of it's ancestor for the purpose of layout
in the regions laying out content content from that flow.
<p>The ‘<a href="#flow-into"><code
class=property>flow-into</code></a>’ property does not affect the
CSS cascade and inheritance for the elements on which it is specified. The
‘<a href="#flow-into"><code
class=property>flow-into</code></a>’ property affects the visual
formatting of elements placed into a named flow and of regions laying out
content from a named flow.
<p>The edges of the first region in a region chain associated with a named
flow establish the rectangle that is the initial containing block of the
named flow.
<p>Elements in a named flow are sequenced in document order.
<div class=note>
<p><em>This note is informative.</em></p>
<p>The ‘<a href="#flow-into"><code
class=property>flow-into</code></a>’ property moves an element into
the flow and the interplay with selectors should be considered carefully.</p>
<p>For example,</p>
<pre>table {flow-into: table-content}</pre>
<p>will move all tables in the ‘<code
class=property>table-content</code>’ named flow. However, the</p>
<pre>table * {flow-into: table-content}</pre>
<p>selector will move all the descendants of table elements in the
‘<code class=property>table-content</code>’ named flow. This
will make all the descendants of table elements siblings in the named
flow. Having the descendants become siblings in the named flow results in
a different processing (see the <a
href="http://www.w3.org/TR/2011/REC-CSS2-20110607/tables.html#anonymous-boxes">CSS
2.1‘<code class=css>s anonymous table objects</code></a>). This
note illustrates how authors must exercise caution when choosing a
particular selector for setting the ’flow-into' property to avoid
unintended results.</p>
</div>
<p> If the ‘flow-into’ property is specified on an <code
class=html><iframe></code>, an <code
class=html><object></code> or a <code
class=html><embed></code> element, the ‘display’ property is
computed to ‘none’ and the referenced document within the element is
used as the named flow. In the case of the <code
class=html><object></code> element if fallback occurs and the
fallback element has a referenced document then that document is used as
the named flow, otherwise the fallback element itself is added to the
named flow.
<p> Any properties set on the <code class=html><iframe></code>/<code
class=html><object></code>/<code class=html><embed></code>
elements (including margin, border, padding, background) have no effect.
This redirection of content does not change representation of the elements
in the document tree, just as for any other source of named flow; in this
case the <code class=html><iframe></code> still provides security
checks for script in content (and sandbox if required). Events and CSS
cascading work the same way as in a documents hosted in regular <code
class=html><iframe></code>s.
<p> Region styling applies to content coming from <code
class=html><iframe></code>/<code
class=html><object></code>/<code class=html><embed></code>
sources the same way it applies to other flow content.
<p><br>
<p>The ‘<a href="#flow-into"><code
class=property>flow-into</code></a>’ does not apply to the <code
class=css>::first-line</code> and <code
class=css>::first-character</code>.
<p>The effect of ‘<a href="#flow-into"><code
class=property>flow-into</code></a>’ on generated content such as
<code class=css>::marker</code>, <code class=css>::before</code> and <code
class=css>::after</code> is undefined. This may change depending on
implementation feedback.
<h3 id=the-content-property><span class=secno>3.2. </span>The ‘<a
href="#content-from"><code class=property>content</code></a>’
property</h3>
<p>This specification extends the definition of the ‘<a
href="#content-from"><code class=property>content</code></a>’
property.
<table class=propdef summary="content property definition">
<tbody>
<tr>
<th>Name:
<td><dfn id=content-from>content</dfn>
<tr>
<th>Value:
<td>normal | none | flow-from(<ident>)| [ <string> |
<uri> | <counter> | attr(<identifier>) | open-quote |
close-quote | no-open-quote | no-close-quote ]+ | inherit
<tr>
<th>Initial:
<td>normal
<tr>
<th>Applies to:
<td>non-replaced block elements and the ::before and ::after
pseudo-elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
</table>
<dl>
<dt><a id=x9 name=x9><span class=index-inst id=none
title=none><strong>none</strong></span></a>
<dd>For ‘<code class=css>::before</code>’ and ‘<code
class=css>::after</code>’ pseudo-elements, the pseudo-element is
not generated. For other elements, the element will not get any content
for its visual formatting
<dt><strong>normal</strong>
<dd>Computes to ‘<code class=property>none</code>’ for the
‘<code class=css>::before</code>’ and ‘<code
class=css>::after</code>’ pseudo-elements. For other elements, the
element formats its children as defined by the CSS Visual Formatting
Model <a href="#CSS21" rel=biblioentry>[CSS21]<!--{{CSS21}}--></a>.
<dt><strong><string></strong>
<dd>Text content (see the section on <a
href="syndata.html#strings">strings</a>).
<dt><strong><uri></strong>
<dd>The value is a URI that designates an external resource (such as an
image). If the user agent cannot display the resource it must either
leave it out as if it were not specified or display some indication that
the resource cannot be displayed.
<dt><strong><counter></strong>
<dd><a href="syndata.html#counter">Counters</a> may be specified with two
different functions: ‘<code class=css>counter()</code>’ or
‘<code class=css>counters()</code>’. The former has two
forms: ‘<code class=css>counter(<var>name</var>)</code>’ or
‘<code class=css>counter(<var>name</var>,
<var>style</var>)</code>’. The generated text is the value of the
innermost counter of the given name in scope at this pseudo-element; it
is formatted in the indicated <a href="#counter-styles">style</a>
(‘<code class=property>decimal</code>’ by default). The
latter function also has two forms: ‘<code
class=css>counters(<var>name</var>, <var>string</var>)</code>’ or
‘<code class=css>counters(<var>name</var>, <var>string</var>,
<var>style</var>)</code>’. The generated text is the value of all
counters with the given name in scope at this pseudo-element, from
outermost to innermost separated by the specified string. The counters
are rendered in the indicated <a href="#counter-styles">style</a>
(‘<code class=property>decimal</code>’ by default). See the
section on <a href="#counters">automatic counters and numbering</a> for
more information. The name must not be ‘<code
class=property>none</code>’, ‘<code
class=property>inherit</code>’ or ‘<code
class=property>initial</code>’. Such a name causes the declaration
to be ignored.
<dt><strong>open-quote</strong> and <strong>close-quote</strong>
<dd>These values are replaced by the appropriate string from the <a
class=noxref
href="http://www.w3.org/TR/CSS21/generate.html#propdef-quotes"><span
class=propinst-quotes><strong>‘<code
class=property>quotes</code>’</strong></span></a> property.
<dt><strong>no-open-quote</strong> and <strong>no-close-quote</strong>
<dd>Introduces no content, but increments (decrements) the level of
nesting for quotes.
<dt><strong>attr(X)</strong>
<dd>This function returns as a string the value of attribute X for the
subject of the selector. The string is not parsed by the CSS processor.
If the subject of the selector does not have an attribute X, an empty
string is returned. The case-sensitivity of attribute names depends on
the document language.
<dt><dfn id=flow-from-name>flow-from(<ident>)</dfn>
<dd>If the element is not a <a
href="http://www.w3.org/TR/CSS21/visuren.html#block-boxes">block
container box</a>, the value evaluates to ‘<code
class=property>normal</code>’. <br>
Otherwise, the element becomes a <span>region</span> and is ordered in a
<span>region chain</span> according to its document order and ‘<a
href="#region-order"><code class=property>region-order</code></a>’
property. The content from the flow with the <a
href="http://www.w3.org/TR/2011/REC-CSS2-20110607/syndata.html#value-def-identifier"><ident></a>
name will be <a href="#region-flow-break">broken into segments</a> and
visually formatted in the <a
href="http://www.w3.org/TR/CSS21/visuren.html#principal-box">principal
boxes</a> of the regions in the region chain. If there is no flow with
name <ident>, then the element does not format any content
visually. <br>
Likewise, if the element is part of the flow with name <ident>,
then the element does not format any content visually. <br>
This might be expanded in future versions of the specification to allow
other types of containers to receive flow content.
</dl>
<p>When the ‘<a href="#content-from"><code
class=property>content</code></a>’ property is set to a value other
than ‘<code class=property>normal</code>’, the element's
document children are not visually formatted unless they are directed to a
named flow referenced by one or more regions.
<div class=note>
<p><em>This note is informative.</em></p>
<p>The ‘<a href="#content-from"><code
class=property>content</code></a>’ property applies to block-level
elements and the ‘<code class=css>::before</code>’ and
‘<code class=css>::after</code>’ pseudo elements. User agents
may apply the content property to inline elements. The behavior is
undefined in that case, but is generally expected to be similar to that
of inline ‘<code class=css>::before</code>’ and ‘<code
class=css>::after</code>’ pseudo-elements.</p>
<p>In particular, note that the behavior of a ‘<code
class=css>::before</code>’ or ‘<code
class=css>::after</code>’ pseudo-element with a ‘<code
class=property>display</code>’ value that makes it an inline
element combined with a ‘<a href="#content-from"><code
class=property>content</code></a>’ value set to ‘<a
href="#flow-from-name"><code
class=css>flow-from(<ident>)</code></a>’ is undefined.</p>
</div>
<div class="issue resolved">
<p><a
href="http://lists.w3.org/Archives/Public/www-style/2011Aug/0069.html">Third
resolution on Regions at the Seattle Face to Face meeting, July 2011</a>
<p><strong>content: flow-from(<flow-name>) v.s. flow-from:
<flow-name></strong></p>
<p><a
href="http://lists.w3.org/Archives/Public/www-style/2011Jun/0413.html">WG
Conference Call, CSSWG Minutes and Resolutions 2011-06-15</a>.</p>
<p>See <a