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[css2] New CONVENTIONS, new scripts correspond, new lists.src, worked on files
--HG-- extra : convert_revision : svn%3A73dc7c4b-06e6-40f3-b4f7-9ed1dbc14bfc/trunk%4032
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‎css2/Attic/conform.src‎

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<!DOCTYPE HTML SYSTEM "http://www.w3.org/TR/WD-html40/sgml/HTML4.dtd">
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<html lang="en">
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<!-- $Id: conform.src,v 1.3 1997-08-05 17:31:02 ijacobs Exp $ -->
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<!-- $Id: conform.src,v 1.4 1997-08-11 23:53:15 ian Exp $ -->
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<HEAD>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<TITLE>CSS2 Conformance</TITLE>
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</HEAD>
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<BODY>
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<H1 align="center">CSS2 Conformance</H1>
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<!-- Core conformance? All CSS1 stuff is *required* for conformance
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in CSS2 -->
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<P><em> This section only defines conformance to CSS2. There will be other
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levels of CSS in the future that may require a UA to implement a
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different set of features in order to conform.</em>
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<P> A User Agent that uses CSS2 <strong>to display</strong> documents
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conforms to the CSS2 specification if it:
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<UL>
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<LI> attempts to fetch all referenced style sheets and parse them
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according to this specification
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<LI> sorts the declarations according to the <a
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href="./cascade.html#cascade-order">cascade order</a>.
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<LI> implements the CSS2 functionality within the <a
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href="#presentation-constraints">constraints of the presentation
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medium</a> (see explanation below).
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<LI> implements all of CSS1, not just the core sections.
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</UL>
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<P> A User Agent that <strong>outputs</strong> CSS2 style sheets
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conforms to the CSS2 specification if it:
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<UL>
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<LI>
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outputs valid CSS2 style sheets
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</UL>
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<P> A User Agent that uses CSS2 to display documents <EM>and</EM>
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outputs CSS2 style sheets conforms to the CSS2 specification if it
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meets both sets of conformance requirements.
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A UA does not have to implement all the functionality of CSS2: it can
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conform to CSS2 by implementing the <a
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href="convent.html#definitions">core functionality</a>.
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<P> This specification also recommends, but doesn't require, that a
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UA:
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<UL>
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<LI> allows the reader to specify personal style sheets
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<LI> allows individual style sheets to be turned on and off
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</UL>
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<P> The above conformance rules describe only functionality, not user
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interface.
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<H2><a name="presentation-constraints">Conformance constraints due to presentation medium</a></H2>
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<P> Examples of constraints of the presentation medium are: limited
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resources (fonts, color) and limited resolution (so margins may not be
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accurate). In these cases, the UA should approximate the style sheet
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values. Also, different user interface paradigms may have their own
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constraints: a VR browser may rescale the document based on its
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"distance" from the user.
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<P> UAs may offer readers additional choices on presentation. For
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example, the UA may provide options for readers with visual
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impairments or may provide the choice to disable blinking.
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<P> Note that CSS2 does not specify all aspects of formatting, e.g.,
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the UA is free to select a letter-spacing algorithm.
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<H2><A NAME="forward-compatible-parsing">Forward-compatible parsing</A></H2>
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<em>See <a href="grammar.html">Appendix B</a> for the grammar of CSS2</em>
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<P> To ensure that UAs supporting just CSS2 will be able to parse style
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sheets containing higher level features, this section defines what the
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UA must do when it encounters certain constructs that are not valid in
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CSS2
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<UL>
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<LI> a declaration with an unknown property is ignored. For
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example, if the style sheet is
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<PRE> H1 { color: red; rotation: 70deg }
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</PRE>
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<P> the UA will treat this as if the style sheet had been
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<PRE> H1 { color: red; }
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</PRE>
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<LI> illegal values, <EM>or values with illegal parts</EM>, are
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treated as if the declaration weren't there at all:
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<PRE>
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IMG { float: left } /* CSS2 */
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IMG { float: left top } /* "top" is not a value of 'float' */
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IMG { background: "red" } /* keywords cannot be quoted in CSS2 */
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IMG { border-width: 3 } /* a unit must be specified for length values */
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</PRE>
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<P> In the above example, a CSS2 parser would honor the first rule and
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ignore the rest, as if the style sheet had been:
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<PRE>
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IMG { float: left }
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IMG { }
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IMG { }
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IMG { }
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</PRE>
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<P> A UA conforming to a future CSS specification may accept one or
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more of the other rules as well.
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<LI> an invalid at-keyword is ignored together with everything
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following it, up to and including the next semicolon (;) or brace pair
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({...}), whichever comes first. For example, assume the style sheet
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reads:
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<PRE>
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@three-dee {
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@background-lighting {
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azimuth: 30deg;
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elevation: 190deg;
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}
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H1 { color: red }
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}
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H1 {color: blue}
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</PRE>
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<P> The '@three-dee' is illegal according to CSS2. Therefore, the
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whole at-rule (up to, and including, the third right curly brace) is
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ignored. The CSS2 UA skips it, effectively reducing the style sheet
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to:
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<PRE>
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H1 {color: blue}
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</PRE>
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/UL>
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<H3>Statements</H3>
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<P> A CSS style sheet, for any version of CSS, consists of a list of
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<span class="index-inst" title="statements"><em>statements</em></span>.
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There are two kinds of statements: <span class="index-inst"
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title="at-rules|@-rules"><em>at-rules</em></span> and <span
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class="index-inst" title="rule sets"><em>rule sets</em> </span>. There
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may be whitespace (spaces, tabs, newlines) around the statements.
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<H3>At-rules</H3>
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<P> At-rules start with an <DFN>at-keyword</DFN>, which is an
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identifier with an '@' at the start (for example, '@import', '@page',
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etc.). An identifier consists of letters, digits, dashes and escaped
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characters (defined below).
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<P> An at-rule consists of everything up to and including the next
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semicolon (;) or the next block (defined shortly), whichever comes
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first. A CSS2 UA that encounters an at-rule that starts with an
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at-keyword other than '@import' ignores the whole of the at-rule and
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continue parsing after it. It also ignores any at-rule that starts
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with '@import' if it doesn't occur at the top of the style sheet,
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i.e., if it occurs after any rules (even ignored rules).
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<div class="example"><P>
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Here is an example. Assume a CSS2 parser encounters this style sheet:
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<PRE>
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@import "subs.css";
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H1 { color: blue }
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@import "list.css";
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</PRE>
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<P> The second '@import' is illegal according to CSS2. The CSS2 parser
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skips the whole at-rule, effectively reducing the style sheet to:
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<PRE>
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@import "subs.css";
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H1 {color: blue}
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</PRE>
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</div>
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<H3>Blocks</H3>
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<P> A <span class="index-inst"
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title="block"><em>block</em></span> starts with a left curly brace ({)
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and ends with the matching right curly brace (}). In between there may
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be any characters, except that parentheses (()), brackets ([]) and
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braces ({}) always occur in matching pairs and may be nested. Single
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(') and double quotes (") <!-- " --> also occur in matching pairs, and
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characters between them are parsed as a <span class="index-inst"
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title="string">string</span>. See the tokenizer in <a
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href="grammar.html">Appendix B</a> for the definition of a string.
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<div class="example"><P>
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Here is an example of a block. Note that the right brace between the quotes
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does not match the opening brace of the block, and that the second
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single quote is an escaped character, and thus doesn't match the
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opening quote:
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<PRE>
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{ causta: "}" + ({7} * '\'') }
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</PRE>
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</div>
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<H3>Rule sets</H3>
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<P> A rule set consists of a <span class="index-inst" title="selector
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string"><em>selector string</em></span> followed by a <span
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class="index-inst" title="declaration block"><em>declaration
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block</em></span>. The selector-string consists of everything up to
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(but not including) the first left curly brace ({). A ruleset that
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starts with a selector-string that is not valid CSS2 is skipped.
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<div class="example"><P>
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For example, assume a CSS2 parser encounters this style sheet:
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<PRE>
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H1 { color: blue }
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P[align], UL { color: red; font-size: large }
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P EM { font-weight: bold }
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</PRE>
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<P> The second line contains a selector-string that is illegal in
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CSS2. The CSS2 UA will skip the ruleset, reducing the style sheet to:
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<PRE>
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H1 { color: blue }
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P EM { font-weight: bold }
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</PRE>
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<P> A declaration-block starts with a left curly brace ({) and ends
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with the matching right curly brace (}). In between there is a list of
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zero or more <DFN>declarations,</DFN> separated by semicolons (;).
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<H3>Properties</H3>
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<P> A declaration consists of a <span class="index-inst"
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title="property"><em>property</em></span>, a colon (:) and a
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<DFN>value</DFN>. Around each of these there may be whitespace.
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A property is an identifier, as defined earlier. Any character may
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occur in the value, but parentheses (()), brackets ([]), braces ({}),
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single quotes (') and double quotes (")
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<!-- " -->
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must come in matching pairs. Parentheses, brackets, and braces may be
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nested. Inside the quotes, characters are parsed as a string.
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<P> To ensure that new properties and new values for existing
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properties can be added in the future, a UA must skip a declaration
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with an invalid property name or an invalid value. Every CSS2 property
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has its own syntactic and semantic restrictions on the values it
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accepts.
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<div class="example"><P>
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For example, assume a CSS2 parser encounters this style sheet:
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<PRE>
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H1 { color: red; font-style: 12pt }
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P { color: blue; font-vendor: any; font-variant: small-caps }
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EM EM { font-style: normal }
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</PRE>
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<P> The second declaration on the first line has an invalid value
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'12pt'. The second declaration on the second line contains an
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undefined property 'font-vendor'. The CSS2 parser will skip these
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declarations, reducing the style sheet to:
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<PRE>
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H1 { color: red; }
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P { color: blue; font-variant: small-caps }
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EM EM { font-style: normal }
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</PRE>
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</div>
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<H3>Comments</H3>
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<P> <span class="index-inst" title="comments">Comments </span>(see the
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section on <a href="./syndata.html#comments">comments</a> for details)
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can occur anywhere where whitespace can occur and are considered to be
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whitespace. CSS2 defines additional places where whitespace can occur
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(such as inside values) and comments are allowed there as well.
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<H3>Characters and case</H3>
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<P> The following rules always hold:
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<UL>
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<LI> All CSS style sheets are <span class="index-inst" title="case
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sensitivity">case-insensitive</span>, except for parts that are
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not under the control of CSS. For example, the case-sensitivity of
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the HTML attributes 'id' and 'class', of font names, and of URLs
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lies outside the scope of this specification.
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<LI> In CSS2, selectors (element names, classes and IDs) can
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contain only the characters A-Z, 0-9, and <a rel="biblioentry" href="./refs.html#ref-UNICODE">[UNICODE]</a> characters
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161-255, plus dash (-); they cannot start with a dash or a digit;
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they can also contain escaped characters and any Unicode character
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as a numeric code (see next item).
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<LI> the backslash followed by at most four hexadecimal digits
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(0..9A..F) stands for the <a rel="biblioentry" href="./refs.html#ref-UNICODE">[UNICODE]</a> character with that number.
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<LI> any character except a hexadecimal digit can be escaped to
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remove its special meaning, by putting a backslash in front,
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Example: "\"" is a string consisting of one double quote.
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<LI> the two preceding items define <span class="index-inst" title="backslash escapes"><EM>backslash-escapes</EM></span>. Backslash-escapes are always
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considered to be part of an identifier, except inside strings
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(i.e., "\7B" is not punctuation, even though "{" is, and "\32" is
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allowed at the start of a class name, even though "2" is not).
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</UL>
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<H2>CSS and HTML</H2>
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<P> CSS style sheets may be embedded in HTML documents, and to be able
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to hide style sheets from older UAs, it is convenient put the style
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sheets inside HTML comments. The HTML comment tokens "&lt;!--" and
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"--&gt;" may occur before, after, and in between the statements. They
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may have whitespace around them.
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<P> The "class" attribute of HTML allows more characters in a class
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name than the set allowed for selectors above. In CSS2, these
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characters have to be escaped or written as Unicode numbers:
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"B&amp;W?" can be written as "B\&amp;W\?" or "B\26W\3F",
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"&#186;&#191;&Aring;&Aacute;&#191;&Acirc;" (Greek: "kouros") has to be written as
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"\3BA\3BF\3C5\3C1\3BF\3C2". It is expected that in later versions of
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CSS, more characters can be entered directly.
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</BODY>
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</HTML>

‎css2/DOC/CONVENTIONS‎

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* To mark up property instances:
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<span class="propinst-propname">'propname'</span>
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<span id="propinst-propname" class="propinst">'propname'</span>
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- Property instances will link to the definitions.
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MarkUp all value instances with:
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<span class="index-inst" title="value">
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<span class="value-inst-value">value</span>
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<span id="value-inst-value" class="value-inst">value</span>
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</span>
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The "value" in the text may be marked up (e.g., &lt;value&gt;)
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<!DOCTYPE HTML SYSTEM "http://www.w3.org/TR/WD-html40/sgml/HTML4.dtd">
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<html lang="en">
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<!-- $Id: CONVENTIONS,v 1.6 1997-08-06 18:23:44 ijacobs Exp $ -->
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<!-- $Id: CONVENTIONS,v 1.7 1997-08-12 00:11:28 ian Exp $ -->
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<HEAD>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<TITLE>CSS2 Specification</TITLE>

‎css2/DOC/FILES‎

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colors.src
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fonts.src
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text.src
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lists.src
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ui.src
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conform.src

‎css2/Makefile‎

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# Makefile to generate the CSS2 document based on its "source files"
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# Arnaud Le Hors - lehors@w3.org
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# $Id: Makefile,v 1.8 1997-08-07 08:04:07 ijacobs Exp $
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# $Id: Makefile,v 1.9 1997-08-11 23:49:32 ian Exp $
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ROOT = .
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colors.src\
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fonts.src\
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text.src\
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lists.src\
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ui.src\
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conform.src \
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refs.src
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colors.html\
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fonts.html\
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text.html\
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lists.html\
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ui.html\
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conform.html\
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refs.html

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