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[css2] Shortened text on BOM, removed all hint at priority of BOM and
@charset, removed confusing explanation of BOM and when it may occur, added explicit mention of UTF-8. --HG-- extra : convert_revision : svn%3A73dc7c4b-06e6-40f3-b4f7-9ed1dbc14bfc/trunk%402226
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‎css2/syndata.src‎

Lines changed: 13 additions & 40 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
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"http://www.w3.org/TR/1998/REC-html40-19980424/loose.dtd">
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<html lang="en">
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<!-- $Id: syndata.src,v 2.98 2004-02-20 22:46:24 bbos Exp $ -->
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<!-- $Id: syndata.src,v 2.99 2004-02-23 11:14:24 bbos 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>Syntax and basic data types</title>
@@ -1177,7 +1177,7 @@ display declaration.
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Character Set (see [[ISO10646]]). For transmission and
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storage, these characters must be <span class="index-def"
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title="character encoding">encoded</span> by a character encoding that
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supports the set of characters available in US-ASCII (e.g., ISO
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supports the set of characters available in US-ASCII (e.g., UTF-8, ISO
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8859-x, SHIFT JIS, etc.). For a good introduction to character sets
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and character encodings, please consult the HTML 4.0
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specification ([[-HTML40]], chapter 5), See also the XML 1.0
@@ -1195,19 +1195,17 @@ encoding::default|default::character encoding">character
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encoding</span> (from highest priority to lowest):
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</p>
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<ol>
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<li>An HTTP "charset" parameter in a "Content-Type" field</li>
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<li><a
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href="#BOM">BOM</a></li>
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<li>The <span class="index-def" title="@charset">@charset</span>
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at-rule</li>
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<li>An HTTP "charset" parameter in a "Content-Type" field
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(or similar parameters in other protocols)</li>
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<li>BOM and/or @charset (see below)</li>
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<li><code>&lt;link charset=""&gt;</code> or other metadata from the linking mechanism (if any)</li>
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<li>character encoding of referring stylesheet or document (if any)</li>
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<li>UA-dependent mechanisms</li>
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<li>charset of referring stylesheet or document (if any)</li>
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<li>Assume UTF-8</li>
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</ol>
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<p>At most one @charset rule may appear in an external style sheet and
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it must appear at the very start of the style sheet, not preceded by any
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characters, except possibly a <a href="#BOM">"BOM" (see below)</a>.
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characters, except possibly a "BOM" (U+FEFF).
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Any other @charset rules must be ignored by the UA.
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</p>
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@@ -1219,40 +1217,15 @@ For example:
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<pre class="example">@charset "ISO-8859-1";</pre>
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<p>This specification does not specify what algorithm a UA must
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apply to derive the encoding from the BOM and the @charset. In
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particular, it does not specify the encoding to use if the BOM and the
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@charset conflict. This is expected to be defined in CSS3.</p>
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<p>This specification does not mandate which character encodings
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a user agent must support.
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</p>
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<p id="BOM">If an external style sheet has U+FEFF ("zero width
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non-breaking space") as the first character (i.e., even before any
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@charset rule), this character is interpreted as a so-called "Byte
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Order Mark" (BOM), as follows:
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</p>
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<ul>
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<li>If the style sheet is encoded as "UTF-16" [[RFC2781]] or "UTF-32"
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[[UNICODE]], the BOM determines the byte order (e.g. "big-endian" or
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"little-endian") as explained in the cited RFC.
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</li>
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<li>If the style sheet is encoded as anything else, the U+FEFF
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character is ignored.
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</li>
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</ul>
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<p>An external style sheet <em>should</em> start with a BOM if it is
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encoded as "UTF-16" or "UTF-32" and <em>should not</em> have a BOM in
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any other encodings.
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</p>
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<p class="note">Note that the BOM can only be ignored if it agrees
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with the encoding. E.g., if a style sheet encoded as "UTF-8" starts
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with 0xEF 0xBB 0xBF those three bytes are ignored, since they
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correctly encode the character U+FEFF in UTF-8. But if a style sheet
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encoded as "ISO-8859-1" starts with the two bytes 0xFE 0xFF (the BOM
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for big-endian UTF-16), the two bytes are simply interpreted as the
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two characters "&#254;" and "&#255;".
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</p>
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<p class="note">Note that reliance on the @charset construct
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theoretically poses a
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problem since there is no <em>a priori</em> information on how it is

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