[css-syntax] Further clarify the '@charset does nothing' text.

Author: tabatkins

css-syntax/Overview.html

@@ -54,7 +54,7 @@
 </p>
   <h1 class="p-name no-ref" id=title>CSS Syntax Module Level 3</h1>
   <h2 class="no-num no-toc no-ref heading settled heading" id=subtitle><span class=content>Editor’s Draft,
-    <span class=dt-updated><span class=value-title title=20140108>8 January 2014</span></span></span></h2>
+    <span class=dt-updated><span class=value-title title=20140115>15 January 2014</span></span></span></h2>
   <div data-fill-with=spec-metadata><dl><dt>This version:<dd><a class=u-url href=http://dev.w3.org/csswg/css-syntax/>http://dev.w3.org/csswg/css-syntax/</a><dt>Latest version:<dd><a href=http://www.w3.org/TR/css-syntax-3/>http://www.w3.org/TR/css-syntax-3/</a><dt>Editor’s Draft:<dd><a href=http://dev.w3.org/csswg/css-syntax/>http://dev.w3.org/csswg/css-syntax/</a><dt>Previous Versions:<dd><a href=http://www.w3.org/TR/2013/WD-css-syntax-3-20131105/ rel=previous>http://www.w3.org/TR/2013/WD-css-syntax-3-20131105/</a><dd><a href=http://www.w3.org/TR/2013/WD-css-syntax-3-20130919/ rel=previous>http://www.w3.org/TR/2013/WD-css-syntax-3-20130919/</a>
     <dt>Feedback:</dt>
         <dd><a href="mailto:www-style@w3.org?subject=%5Bcss-syntax%5D%20feedback">www-style@w3.org</a>
@@ -4499,17 +4499,29 @@ <h3 class="heading settled heading" data-level=8.2 id=charset-rule><span class=s
 <p>	The <a class=css data-link-type=maybe href=#at-ruledef-charset title=@charset>@charset</a> rule has <strong>no effect on a stylesheet</strong>.
 
 	<div class=note>
-		Note: This only applies to the <a data-link-type=dfn href=#at-rule title=at-rule>at-rule</a>
-		created by the algorithm to <a data-link-type=dfn href=#parse-a-stylesheet0 title="parse a stylesheet">parse a stylesheet</a>,
-		not to the ASCII <code>@charset "XXX";</code> byte sequence
-		that the algorithm to <a data-link-type=dfn href=#determine-the-fallback-encoding title="determine the fallback encoding">determine the fallback encoding</a>
-		looks for at the beginning of a stylesheet.
-
-<p>		While they look similar, they are not actually the same thing.
-		For example, a slightly different byte sequence
-		(more whitespace, single instead of double quotes, …)
-		will not be considered for the fallback encoding
-		but may still generate an <a class=css data-link-type=maybe href=#at-ruledef-charset title=@charset>@charset</a> rule that shows up in <a data-biblio-type=informative data-link-type=biblio href=#cssom title=cssom>[CSSOM]</a>.
+		Confused?
+		Note that the preceding paragraph is talking about the <a class=css data-link-type=maybe href=#at-ruledef-charset title=@charset>@charset</a> <strong><a data-link-type=dfn href=#at-rule title=at-rule>at-rule</a></strong>.
+		CSS looks for a byte sequence that looks like "@charset" at the beginning of the document
+		to receive encoding enformation.
+		This is thematically similar to other encoding sequences at the beginning of files,
+		like a byte-order mark (BOM) hinting at the type of Unicode encoding used,
+		a DOCTYPE in an HTML document,
+		or a magic string like "MANIFEST" at the start of an HTML manifest.
+
+<p>		This byte sequence happens to <em>look</em> like a normal CSS rule, however,
+		and for legacy reasons,
+		that rule is reflected as an <a data-link-type=dfn href=#at-rule title=at-rule>at-rule</a> in the CSS Object Model <a data-biblio-type=informative data-link-type=biblio href=#cssom title=cssom>[CSSOM]</a>.
+		However, <strong>that at-rule object does nothing</strong>;
+		modifying it has no effect on the stylesheet,
+		nor does creating a fresh one and inserting it into a stylesheet.
+
+<p>		Note that some syntax that qualifies as a valid <a class=css data-link-type=maybe href=#at-ruledef-charset title=@charset>@charset</a> <a data-link-type=dfn href=#at-rule title=at-rule>at-rule</a>
+		is <strong>not</strong> a valid encoding declaration.
+		For example, since its argument is a string,
+		it can be written with single quotes around it.
+		This will create a valid <a class=css data-link-type=maybe href=#at-ruledef-charset title=@charset>@charset</a> rule,
+		but it won’t be recognized by the encoding detection step,
+		as it’s not the exact byte sequence that the algorithm requires.
 	</div>
 
 

css-syntax/Overview.src.html

@@ -3025,17 +3025,29 @@ <h3 id='charset-rule'>
 	The ''@charset'' rule has <strong>no effect on a stylesheet</strong>.
 
 	<div class='note'>
-		Note: This only applies to the <a>at-rule</a>
-		created by the algorithm to <a>parse a stylesheet</a>,
-		not to the ASCII <code>@charset "XXX";</code> byte sequence
-		that the algorithm to <a>determine the fallback encoding</a>
-		looks for at the beginning of a stylesheet.
-
-		While they look similar, they are not actually the same thing.
-		For example, a slightly different byte sequence
-		(more whitespace, single instead of double quotes, …)
-		will not be considered for the fallback encoding
-		but may still generate an ''@charset'' rule that shows up in [[CSSOM]].
+		Confused?
+		Note that the preceding paragraph is talking about the ''@charset'' <strong><a>at-rule</a></strong>.
+		CSS looks for a byte sequence that looks like "@charset" at the beginning of the document
+		to receive encoding enformation.
+		This is thematically similar to other encoding sequences at the beginning of files,
+		like a byte-order mark (BOM) hinting at the type of Unicode encoding used,
+		a DOCTYPE in an HTML document,
+		or a magic string like "MANIFEST" at the start of an HTML manifest.
+
+		This byte sequence happens to <em>look</em> like a normal CSS rule, however,
+		and for legacy reasons,
+		that rule is reflected as an <a>at-rule</a> in the CSS Object Model [[CSSOM]].
+		However, <strong>that at-rule object does nothing</strong>;
+		modifying it has no effect on the stylesheet,
+		nor does creating a fresh one and inserting it into a stylesheet.
+
+		Note that some syntax that qualifies as a valid ''@charset'' <a>at-rule</a>
+		is <strong>not</strong> a valid encoding declaration.
+		For example, since its argument is a string,
+		it can be written with single quotes around it.
+		This will create a valid ''@charset'' rule,
+		but it won't be recognized by the encoding detection step,
+		as it's not the exact byte sequence that the algorithm requires.
 	</div>