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[CSS21] invalid at-keywords in declaration blocks (issue-71)

From: Bert Bos <bert@w3.org>
Date: Mon, 29 Mar 2010 10:00:54 -0700
Message-ID: <4BB0DCC6.6050703@w3.org>
To: W3C style mailing list <www-style@w3.org>
Re: http://wiki.csswg.org/spec/css2.1#issue-71

I previously suggested not changing any text in CSS 2.1, because the
rule for "malformed declarations" already defined how to deal with
unexpected at-keywords occurring in declaration blocks (viz., by
ignoring the declaration in which they occurred). But on looking at
the minutes of the decision again, I saw that the problem wasn't that
the handling was undefined, but that it was defined twice, and the
second rule, specific to invalid at-keywords, says to ignore just the
at-keyword and what follows it, which is not what we want.

It seems the rule about invalid at-keywords was only  meant to
apply to unknown at-keywords at the start of at-rules, but it fails to
say so. Thus the solution is to add that. I suggest the following:

Insert the phrase

    at the start of an at-rule

in the bullet "Invalid at-keywords" as follows:

    User agents must ignore an invalid at-keyword <ins>at the start of
    an at-rule</ins> together with everything following it[...]


I also looked at what Opera, Prince, Firefox, IE and Safari do: inside
declaration blocks they indeed apply the rule for malformed
declarations and not the one for unknown at-keywords, so their
programmers apparently interpreted the rules as I did.

Amaya and the CSS Validator don't apply the rule about unknown
at-keywords either, but seem to drop the whole rule set, not just the
declaration.



Bert
-- 
  Bert Bos                                ( W 3 C ) http://www.w3.org/
  http://www.w3.org/people/bos                               W3C/ERCIM
  bert@w3.org                             2004 Rt des Lucioles / BP 93
  +33 (0)4 92 38 76 92            06902 Sophia Antipolis Cedex, France
Received on Monday, 29 March 2010 17:01:33 GMT

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