[dbaron revision history] Address some of Bjorn's comments. (date: 2003/07/29 04:40:46)

Author: dbaron

css3-syntax/Overview.src.html

@@ -30,7 +30,7 @@
 
 <h1>CSS3 module: Syntax</h1>
 
-<h2 class="no-num no-toc">W3C Working Draft, [DATE: 16 July 2003]</h2>
+<h2 class="no-num no-toc">W3C Working Draft, [DATE: 28 July 2003]</h2>
 <dl>
   <dt>This version:</dt>
     <dd><a
@@ -118,16 +118,16 @@ <h2>Introduction</h2>
 <p>This specification describes the basic syntax of CSS3 and the syntax
 conventions used in the property definitions spread through the CSS3
 modules.  The syntax of CSS3 has some error-handling requirements for
-forward-compatibility, but much of the error-handling behavior is
-user-agent dependent.</p>
+forward-compatibility, but much of the error-handling behavior depends
+on the user agent.</p>
 
 <h2>CSS style sheet representation</h2>
 
 <p>A CSS style sheet is a sequence of characters from the Universal
 Character Set (see [[!ISO10646]]). For transmission and storage, these
 characters must be <span class="index-def" title="character
 encoding">encoded</span> by a character encoding that supports the set
-of characters available in US-ASCII (e.g., ISO 8859-x, SHIFT JIS, etc.).
+of characters available in US-ASCII (e.g., ISO-8859-x, Shift_JIS, etc.).
 A <span id="BOM" class="index-inst">byte order mark (BOM)</span>, as described in
 section 2.7 of [[!UNICODE310]], that begins the sequence of characters
 should not be considered, for purposes of applying the grammar below, as
@@ -197,8 +197,15 @@ <h2>CSS style sheet representation</h2>
 EBCDIC.  This means that in general, the initial byte values of a
 style sheet enable a user agent to detect the encoding family reliably,
 which provides enough information to decode the @charset rule, which
-in turn determines the exact character encoding.
+in turn determines the exact character encoding.</p>
 
+<div class="issue">[Should this specification describe how to handle
+encoding errors?  Can a user agent ignore the <code>@charset</code> rule
+if it's wrong?  What if the user agent does not support the encoding
+used?  Should this specification describe how to handle a
+<code>@charset</code> rule that specifies a character encoding that is
+incompatible with the family of encodings used to decode the
+<code>@charset</code> rule (and BOM) itself?]</div>
 
 <!-- More examples of good encodings to use? -IJ -->
 
@@ -284,70 +291,73 @@ <h3 id="characters">Characters and case</h3>
 <p>  The following rules always hold:</p>
 
 <UL>
-    <LI> All CSS style sheets are <span class="index-inst" title="case
+    <li><p>All CSS style sheets are <span class="index-inst" title="case
     sensitivity">case-insensitive</span>, except for parts that are
     not under the control of CSS. For example, the case-sensitivity of
     values of the HTML attributes "id" and "class", of font names, and
     of URIs lies outside the scope of this specification. Note in
     particular that element names are case-insensitive in HTML, but
-    case-sensitive in XML.
+    case-sensitive in XML.</p></li>
 
-    <LI> In CSS3, <span class="index-def"
+    <li><p>In CSS3, <span class="index-def"
     title="identifier|identifier, definition of"><a
     name="value-def-identifier"><dfn>identifiers</dfn></a></span>
     (including element names, classes, and IDs in <a
     href="selector.html">selectors</a>) can contain only the
     characters [A-Za-z0-9] and ISO 10646 characters 161 and higher,
-    plus the hyphen (-); they cannot start with a hyphen or a
-    digit. They can also contain escaped characters and any ISO 10646
+    plus the hyphen (-) and the underscore (_); they cannot start with a
+    digit or a hyphen followed by a digit. They can also contain escaped
+    characters and any ISO 10646
     character as a numeric code (see next item).
-    <span class="example">For instance, the identifier "B&amp;W?" may
-    be written as "B\&amp;W\?" or "B\26 W\3F".</span>
-    <p>Note that Unicode is code-by-code equivalent to ISO 10646 (see
-    [[!UNICODE310]] and [[!ISO10646]]).
+    <span class="example">For instance, the identifier
+    "<code>B&amp;W?</code>" may
+    be written as "<code>B\&amp;W\?</code>" or "<code>B\26
+    W\3F</code>".</span>
+    (See [[!UNICODE310]] and [[!ISO10646]].)</p></li>
 
-    <LI> In CSS3, a backslash (\) character indicates three types of
+    <li><p>In CSS3, a backslash (\) character indicates three types of
     <span class="index-def" title="backslash escapes">
-    <a name="escaped-characters">character escapes</a></span>.
+    <a name="escaped-characters">character escapes</a></span>.</p>
 
     <p>First, inside a <a href="#strings">string</a>, a backslash
     followed by a newline is ignored (i.e., the string is deemed not
-    to contain either the backslash or the newline).
+    to contain either the backslash or the newline).</p>
 
     <p>Second, it cancels the meaning of special CSS characters.
         Any character (except a hexadecimal digit) can be escaped
         with a backslash to remove its special meaning.
         For example, <samp>"\""</samp> is a string consisting of one
         double quote. Style sheet preprocessors must not remove
        these backslashes from a style sheet since that would
-       change the style sheet's meaning.
+       change the style sheet's meaning.</p>
 
     <p>Third, backslash escapes allow authors to refer to characters
     they can't easily put in a style sheet. In this case, the backslash
     is followed by at most six hexadecimal digits (0..9A..F), which
     stand for the ISO 10646 ([[!ISO10646]]) character with
     that number. If a digit or letter follows the hexadecimal number,
     the end of the number needs to be made clear. There are two ways
-    to do that:
+    to do that:</p>
 
     <ol>
     <li>with a space (or other whitespace character): "\26 B" ("&amp;B").
         In this case, user agents should treat a "CR/LF" pair 
         (13/10) as a single
-        whitespace character.
-    <li>by providing exactly 6 hexadecimal digits: "\000026B" ("&amp;B")
+        whitespace character.</li>
+    <li>by providing exactly 6 hexadecimal digits: "\000026B" ("&amp;B")</li>
     </ol>
 
     <p>In fact, these two methods may be combined. Only one whitespace
     character is ignored after a hexadecimal escape. Note that this means
     that a "real" space after the escape sequence must itself either be
-    escaped or doubled.
+    escaped or doubled.</p>
+    </li>
 
-    <LI>Backslash escapes are always considered to be part of an <a
+    <li><p>Backslash escapes are always considered to be part of an <a
     href="#value-def-identifier">identifier</a> or a string (i.e.,
     "\7B" is not punctuation, even though "{" is, and "\32" is allowed
-    at the start of a class name, even though "2" is not).
-  </UL>
+    at the start of a class name, even though "2" is not).</p></li>
+  </ul>
 
 <h3 id="tokenization">Tokenization</h3>
 
@@ -383,7 +393,7 @@ <h3 id="tokenization">Tokenization</h3>
 <tr><td id="SUBTOK-string">string	<td>::=<td><code>'"' (<a href="#SUBTOK-stringchar">stringchar</a> | "'")* '"' | "'" (<a href="#SUBTOK-stringchar">stringchar</a> | '"')* "'"</code>
 <tr><td id="SUBTOK-stringchar">stringchar <td>::=<td><code><a href="#SUBTOK-urlchar">urlchar</a> | #x20 | '\' <a href="#SUBTOK-nl">nl</a></code>
 <tr><td id="SUBTOK-urlchar">urlchar <td>::=<td><code>[#x9#x21#x23-#x26#x27-#x7E] | <a href="#SUBTOK-nonascii">nonascii</a> | <a href="#SUBTOK-escape">escape</a></code>
-<tr><td id="SUBTOK-nl">nl	<td>::=<td><code>#xA | #xD #xA | #xA | #xC</code>
+<tr><td id="SUBTOK-nl">nl	<td>::=<td><code>#xA | #xD #xA | #xD | #xC</code>
 <tr><td id="SUBTOK-w">w	<td>::=<td><code><a href="#SUBTOK-wc">wc</a>*</code>
 <tr><td id="SUBTOK-wc">wc	<td>::=<td><code>#x9 | #xA | #xC | #xD | #x20</code>
 </table>
@@ -573,26 +583,20 @@ <h3 id="keywords">Keywords</h3>
 <pre>
 width: "auto";
 border: "none";
-font-family: "serif";
 background: "red";
 </pre>
 </div>
 
 
 <h3>Statements</h3>
 
-<p> A CSS style sheet, for any version of CSS, consists of a list of
+<p>A CSS style sheet, for any version of CSS, consists of a list of
 <span class="index-inst" title="statements"><em>statements</em></span>
 (see the grammar above).  There are two kinds of statements: <span
 class="index-inst" title="at-rules"><em>at-rules</em></span>
 and <span class="index-inst" title="rule sets"><em>rule
 sets.</em></span> There may be <a href="#whitespace">whitespace</a>
-around the statements.
-
-<p>In this specification, the expressions "immediately before" or
-"immediately after" mean with no intervening whitespace or comments.
-
-<!-- Should comments be defined as whitespace? -->
+around the statements.</p>
 
 <h3 id="at-rules" class="index-def" title="at-rules">At-rules</h3>
 
@@ -603,14 +607,10 @@ <h3 id="at-rules" class="index-def" title="at-rules">At-rules</h3>
 
 <p> An at-rule consists of everything up to and including the next
 semicolon (;) or the next <a href="#block">block,</a> whichever comes
-first. A CSS user agent that encounters an unrecognized at-rule must
-<span class="index-inst" title="ignore"><a href="#ignore">ignore</a></span>
-the whole of the at-rule and continue parsing after it.
-
-<p>CSS3 user agents must <span class="index-inst" title="ignore"><a
-href="#ignore">ignore</a></span> any <a
-href="#at-import">'@import'</a> rule that occurs inside a <a
-href="#block">block</a> or that doesn't precede all rule sets.
+first. A CSS user agent that encounters an unrecognized or misplaced
+at-rule must <span class="index-inst" title="ignore"><a
+href="#ignore">ignore</a></span> the whole of the at-rule and continue
+parsing after it.</p>
 
 <div class="illegal-example"><p>
 Assume, for example, that a CSS3 parser encounters this style sheet:
@@ -621,7 +621,9 @@ <h3 id="at-rules" class="index-def" title="at-rules">At-rules</h3>
 @import "list.css";
 </PRE>
 
-<p> The second '@import' is illegal according to CSS3. The CSS3 parser
+<p>The second '<code>@import</code>' is illegal according to CSS3 since
+'<code>@import</code>' rules must occur before all rules other than
+'<code>@charset</code>' rules.  The CSS3 parser
 <span class="index-inst" title="ignore"><a href="#ignore">ignores</a></span>
 the whole at-rule, effectively reducing the style sheet to:
 
@@ -1222,10 +1224,11 @@ <h3 id="at-import">Style sheets including other style sheets:
 
 <p>The <span class="index-def"
 title="@import"><dfn>'@import'</dfn></span> rule allows users to
-import style rules from other style sheets. Any @import rules must
-precede all rule sets in a style sheet. The '@import' keyword must be
-followed by the URI of the style sheet to include. A string is also
-allowed; it will be interpreted as if it had url(...) around it.</p>
+import style rules from other style sheets.  Any @import rules must
+follow all @charset rules and precede all other at-rules and rule sets
+in a style sheet.  The '@import' keyword must be followed by the URI of
+the style sheet to include. A string is also allowed; it will be
+interpreted as if it had url(...) around it.</p>
 
 <div class="example"><p> 
 The following lines are equivalent in meaning and illustrate both
@@ -1269,9 +1272,9 @@ <h2>Defining namespaces:  the <code>@namespace</code> rule</h2>
 for example the Selectors Module [[!SELECT]] or the Generated Content
 module [[CSS3GENCON]].
 Any @namespace rules
-must follow all @import and @charset rules and precede all other rule sets
-in a style sheet. This is to avoid any confusion or issues regarding the
-scope of the declared namespace.
+must follow all @import and @charset rules and precede all other
+at-rules and rule sets in a style sheet. This is to avoid any confusion
+or issues regarding the scope of the declared namespace.
 </p>
 
 <p>If the optional namespace prefix is omitted, then the namespace URI