csswg-drafts/css-module/Overview.src.html at 1675a906d8894e91968294002f5127898318e5e4 · w3c/csswg-drafts · GitHub

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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 TEMPLATE Module Level N</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>

<div class="head">
<!--logo-->

<h1>CSS <var class="issue">TEMPLATE</var> Module Level <var class="issue">N</var></h1>

<h2 class="no-num no-toc">[LONGSTATUS] [DATE]</h2>
<dl>
  <dt>This version:
    <dd><a href="[VERSION]">
    http://www.w3.org/TR/[YEAR]/[STATUS]-[SHORTNAME]-[CDATE]</a>

  <dt>Latest version:
    <dd><a href="http://www.w3.org/TR/css3-TEMPLATE">
    http://www.w3.org/TR/css<var class="issue">3</var>-<var class="issue">TEMPLATE</var></var></a>

  <dt>Previous version:
    <dd><a href="http://www.w3.org/PreviousVersionURI">
    http://www.w3.org/PreviousVersionURI</a>

  <dt>Editors:
    <dd class=vcard><span class=fn>[editor1 name]</span>,
      <span class=org>[affiliation (opt.)]</span>,
      <span class=email>[email address (opt.)]</span>
    <dd class=vcard><span class=fn>[editor2 name]</span>,
      <span class=org>[affiliation (opt.)]</span>,
      <span class=email>[email address (opt.)]</span>
</dl>

<!--copyright-->

<hr title="Separator for header">
</div>

<h2 class="no-num no-toc" id=abstract>Abstract</h2>

  <p>CSS is a language for describing the rendering of structured documents
  (such as HTML and XML) on screen, on paper,  in speech, etc. This module
  contains the features of CSS level&nbsp;3 relating to <var class="issue">DESCRIBE HERE</var>.
  It includes and extends the functionality of CSS level&nbsp;2 [[CSS21]],
  which builds on CSS level&nbsp;1 [[CSS1]].
  The main extensions compared to level&nbsp;2 are <var class="issue">SUMMARIZE HERE</var>.

<h2 class="no-num no-toc" id=status>Status of this document</h2>

<!--status-->

<p>The following features are at risk: &hellip;

<h2 class="no-num no-toc" id="contents">Table of contents</h2>

<!--toc-->

<h2>Introduction</h2>

<h3 id="context">Background</h3>

  <p><em>This section is not normative.</em>

  <p><var class="issue">Provide background, motivation, etc.</var></p>

<h3 id="placement">Module Interactions</h3>

  <p class="issue">Explain, normatively, how this module affects the definition of CSS.</p>

  <p>This module replaces and extends the <var class="issue">SUMMARIZE HERE</var>
  features defined in [[!CSS21]] sections <var class="issue">W.X and Y.Z</var>.

<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>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:

  <div class="example">
    <p>This is an example of an informative example.</p>
  </div>

  <p>Informative notes begin with the word “Note” and are set apart from the
  normative text with <code>class="note"</code>, like this:

  <p class="note">Note, this is an informative note.</p>

<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 &lt;color&gt; 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.

<h2>Sample section</h2>

  <p>Look at the mark-up in this section for examples. See the <a
  href="https://www.w3.org/Style/Group/css3-src/bin/README">documentation</a> for more precise instructions. The
  companion of this template shows the <a href="Overview.html">processed
  result</a>.</p>

  <p>To refer to HTML, use [[HTML40]] (note the double square brackets). To
  make a normative reference, insert a &ldquo;!&rdquo;, like this:
  [[!CSS3SYN]] The currently available
  <a href="https://www.w3.org/Style/Group/css3-src/biblio.ref">list of bibliographic data</a>
  can of course be extended.</p>

  <p>We write about a property such as 'display-model' like this and
  about a piece of CSS code like this: ''foo: bar''. Inline HTML and XML
  are similar, but use the CODE element: <code
  class=html>&lt;blockquote&gt;...&lt;/blockquote&gt;</code> and <code
  class=xml>&lt;r:xyz&gt;...&lt;/r:xyz&gt;</code>.

  <p class=note>Note that the property will automatically be linked to its
  definition.

  <p>To put <span class=index>terms</span> into the <span
  class=index-def>index</span>, there are many <span class=index
  title="variant">variants</span>, but hopefully the <span class=index
  title="simple|simpler|simplest">simplest</span> will be the most <span
  class=index title="frequency::common">common</span>. But a little more
  <span class=index title="work|resource::time spent">work</span> now
  will help many people for a long time.

  <p class=note>Note that you can add non-normative notes like this.

  <p>Of course, multi-paragraph notes are also possible: just enclose them in a
  DIV:

  <div class=note>
    <p>Note that this note is a multi-paragraph note.</p>
    <p>It doesn't <em>need</em> to have two paragraphs, but it could.</p>
  </div>

  <p>Displayed examples come in eight different types: CSS examples that need
  no separate paragraph of explanation are put in a simple PRE:

  <pre class=example>EM { font-style: italic }</pre>

  <p>CSS examples that need extra text need a DIV.</p>

  <div class=example>
  <p>The following example is the same as the previous one, but now it is
  explained:</p>
  <pre>EM { font-style: italic }</pre>
  </div>

  <p>Illegal CSS examples (examples of errors) are the same, but with class
  "illegal-example". Examples of HTML and XML code have class "html" and "xml"
  respectively, but are otherwise ditto.</p>

  <p>A formal definition of a property looks like this:</p>

<h3 id="the-display-model">Inner Display Model: the 'display-model' property</h3>

  <table class=propdef>
    <tr>
      <th>Name:
      <td><dfn>display-model</dfn>
    <tr>
      <th>Value:
      <td>inline-inside | block-inside | table | ruby | icon
    <tr>
      <th>Initial:
      <td>text
    <tr>
      <th>Applies to:
      <td>all elements
    <tr>
      <th>Inherited:
      <td>no
    <tr>
      <th>Percentages:
      <td>N/A
    <tr>
      <th>Media:
      <td>visual
    <tr>
      <th>Computed&nbsp;value:
      <td>specified value
  </table>

  <dl>
    <dt><dfn>''value-name''</dfn></dt>
      <dd>Define values using a DL
  </dl>

  <p><dfn>Cross-references</dfn> are created by enclosing a term or phrase in
  &lt;dfn&gt; (like the word <em>cross-references</em> earlier in this
  sentence). Then any element with the same content will automatically be
  linked. For example: <span>cross-references</span>.</p>

  <p>And a figure with a caption is done like this:

  <div class=figure>
  <p><img src="corner.png"
  alt="A table with a caption above it; both have margins and the margins between them are collapsed, as is normal for vertical margins.">

  <p class=caption>Just a random image. SVG would be nice, but maybe SVG
  isn't sufficiently easy to use yet. W3C prefers PNG over GIF (obviously,
  since PNG is a W3C Rec).
  </div>

  <p>Don't forget to write the longdesc.

  <p class=issue>An open issue or editorial remark is OK in a WD, but
  they should be resolved/removed before the document goes to
  &ldquo;CR&rdquo; (Candidate Recommendation). Use
  class=&ldquo;issue&rdquo;.

<h2 id="conformance">
Conformance</h2>

<h3 id="conformance-classes">
Conformance Classes</h3>

  <p>Conformance to <var class="issue">CSS TEMPLATE Module</var>
  is defined for three conformance classes:
  <dl>
    <dt><dfn 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>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.
    <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.
  </dl>

  <p>A style sheet is conformant to <var class="issue">CSS TEMPLATE Module</var>
  if all of its declarations that use properties defined in this module
  have values that are valid according to the generic CSS grammar and the
  individual grammars of each property as given in this module.

  <p>A renderer is conformant to <var class="issue">CSS TEMPLATE Module</var>
  if, in addition to interpreting the style sheet as defined by the
  appropriate specifications, it supports all the properties defined
  by <var class="issue">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="issue">CSS TEMPLATE Module</var>
  if it writes syntactically correct style sheets, according to the
  generic CSS grammar and the individual grammars of each property in
  this module.

<h3 id="partial">
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 CSS specifications
  reserve a <a href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
  syntax</a> for proprietary property and value extensions to CSS. The CSS
  Working Group recommends that experimental implementations of features in
  CSS Working Drafts also use vendor-prefixed property or value names. This
  avoids any incompatibilities with future changes in the draft. Once a
  specification reaches the Candidate Recommendation stage, implementors
  should implement the non-prefixed syntax for any feature they consider to
  be correctly implemented according to spec.</p>

<h3 id="cr-exit-criteria">
CR Exit Criteria</h3>

  <p class=issue>[Change or remove the following CR exit criteria if
  the spec is not a module, but, e.g., a Note or a profile. This text was <a
  href="http://www.w3.org/Style/CSS/Tracker/actions/44"> decided on 2008-06-04.</a>]</p>

  <p id=cr-exit-criteria>
  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="issue">[acknowledgments]</var></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>
</html>
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