1.1 --- a/css3-conditional/Overview.src.html Tue Nov 13 14:21:28 2012 -0800
1.2 +++ b/css3-conditional/Overview.src.html Tue Nov 13 14:58:23 2012 -0800
1.3 @@ -370,35 +370,13 @@
1.4 ;
1.5
1.6 <dfn>supports_condition</dfn>
1.7 - : NOT S* general_enclosed |
1.8 - general_enclosed ( ( AND | OR ) S* general_enclosed )*
1.9 -
1.10 -<dfn>general_enclosed</dfn>
1.11 - : ( FUNCTION | '(' ) any+ ')' S*
1.12 -</pre>
1.13 -
1.14 -<p>
1.15 - The <code>any</code> token is taken from <a href="http://www.w3.org/TR/CSS21/syndata.html">CSS 2.1 Syntax and Basic Data Types</a>.
1.16 -
1.17 -<p>
1.18 - The above grammar is purposely very loose for forwards-compatibility reasons.
1.19 - Any ''@supports'' rule that does not parse according to the grammar above is invalid.
1.20 - Style sheets <strong>must not</strong> use such a rule and processors <strong>must</strong> ignore such a rule.
1.21 -
1.22 -<p>
1.23 - The actual processing model of ''@supports'' is predicated on a more restricted grammar,
1.24 - composed of functions or parenthesized declarations,
1.25 - combined together with logical combinators,
1.26 - as defined by the following productions:
1.27 -
1.28 -<pre><dfn>supports_condition</dfn>
1.29 : supports_negation | supports_conjunction | supports_disjunction |
1.30 supports_condition_in_parens
1.31 ;
1.32
1.33 <dfn>supports_condition_in_parens</dfn>
1.34 : ( '(' S* supports_condition ')' S* ) | supports_declaration_condition |
1.35 - supports_function
1.36 + general_enclosed
1.37 ;
1.38
1.39 <dfn>supports_negation</dfn>
1.40 @@ -414,20 +392,29 @@
1.41 ;
1.42
1.43 <dfn>supports_declaration_condition</dfn>
1.44 - : '(' S* core_declaration ')' S*
1.45 + : '(' S* declaration ')' S*
1.46 ;
1.47
1.48 -<dfn>supports_function</dfn>
1.49 - : FUNCTION S* [any|unused]* ')'
1.50 - ;</pre>
1.51 +<dfn>general_enclosed</dfn>
1.52 + : ( FUNCTION | '(' ) (any|unused)* ')' S*
1.53 +</pre>
1.54
1.55 -<p>in which <code>core_declaration</code> is the production
1.56 -<code>declaration</code> in the core syntax of CSS defined in <a
1.57 +<p>in which <code>declaration</code>, <code>any</code>, and
1.58 +<code>unused</code> are the productions in the core syntax of CSS
1.59 +defined in <a
1.60 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization">section
1.61 4.1.1 (Tokenization)</a> of [[!CSS21]],
1.62 and the <code>AND</code> and <code>NOT</code> tokens are defined in
1.63 the Media Queries specification [[!MEDIAQ]].</p>
1.64
1.65 +<p>
1.66 + The above grammar is purposely very loose for forwards-compatibility reasons,
1.67 + since the <code>general_enclosed</code> production
1.68 + allows for substantial future extensibility.
1.69 + Any ''@supports'' rule that does not parse according to the grammar above is invalid.
1.70 + Style sheets <strong>must not</strong> use such a rule and
1.71 + processors <strong>must</strong> ignore such a rule (including all of its contents).
1.72 +
1.73 <p>Each of these grammar terms is associated with a boolean result, as
1.74 follows:</p>
1.75 <dl>
1.76 @@ -468,19 +455,19 @@
1.77 within the parentheses.
1.78 </dd>
1.79
1.80 -<dt>supports_function</dt>
1.81 +<dt>general_enclosed</dt>
1.82 <dd>
1.83 The result is always false.
1.84 - <span class="note">Note that future levels may define functions that can evaluate to true.</span>
1.85 + Additionally, style sheets <strong>must not</strong>
1.86 + write ''@supports'' rules
1.87 + that match this grammar production.
1.88 + (In other words, this production exists only for future extensibility,
1.89 + and is not part of the description of a valid style sheet
1.90 + in this level of the specification.)
1.91 + <span class="note">Note that future levels may define functions
1.92 + or other parenthesized expressions that can evaluate to true.</span>
1.93 </dd>
1.94
1.95 -<dt>anything else</dt>
1.96 -<dd>
1.97 - If a parenthesized expression does not match the result of one of the grammar productions above,
1.98 - it must not be treated as invalid,
1.99 - but rather simply be false for the purpose of support conditions.
1.100 -</dl>
1.101 -
1.102 <p>The condition of the '@supports' rule is the result of the
1.103 <code>supports_condition</code> term that is a child of the
1.104 <code>supports_rule</code> term.</p>
