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Re: What Characters Are Allowed in IDs?

From: Tim Bagot <tsb-w3-style-0002@earth.li>
Date: Mon, 26 Feb 2001 09:24:50 +0000 (UTC)
To: <www-style@w3.org>
Message-ID: <Pine.LNX.4.30.0102260855330.560-100000@windle.hack>
At 2001-02-26T03:59-0000, Sean B. Palmer wrote:-

> Is a forwardslash "/" an allowed part of a CSS2 IDENT? For example:-
>      .a/bc { font-weight: bold; }
> or does it have to be escaped as in:-
>      .a\/bc { font-weight: bold; }

The relevant productions are:-

ident    {nmstart}{nmchar}*
nmstart  [a-zA-Z]|{nonascii}|{escape}
nmchar   [a-z0-9-]|{nonascii}|{escape}
nonascii [^\0-\177]
unicode  \\[0-9a-f]{1,6}[ \n\r\t\f]?
escape   {unicode}|\\[ -~\200-\4177777]

This suggests: that the first character of an IDENT must be an alphabetic
ASCII character, or a non-ASCII character, or escaped; that each
subsequent character must be an alphanumeric ASCII character (the
tokeniser is not case sensitive) or '-', or a non-ASCII character, or
escaped; that ASCII characters other than space, dash and tilde may not be
escaped simply by prepending a backslash - a Unicode escape must be used
instead; and that a *single* (unescaped) whitespace character following a
Unicode escape will be ignored.

Therefore, in the example above, the selector should be:-

.a\2F bc



The latter seems less likely to be misinterpreted by a broken parser.

Tim Bagot
Received on Monday, 26 February 2001 04:25:01 UTC

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