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Re: [css3-fonts] font-feature-settings syntax

From: Kang-Hao (Kenny) Lu <kennyluck@csail.mit.edu>
Date: Fri, 20 Apr 2012 00:39:00 +0800
Message-ID: <4F903FA4.1070906@csail.mit.edu>
To: John Daggett <jdaggett@mozilla.com>
CC: WWW Style <www-style@w3.org>
(12/04/19 15:33), John Daggett wrote:
> I propose changing the wording above to:
>   The <string> is a case-sensitive OpenType feature tag. For it to
>   match an OpenType feature contained in a font, it must follow the
>   syntax rules for these tags. As specified in the OpenType
>   specification, feature tags contain four ASCII characters. Tag
>   strings longer or shorter than four characters, or containing
>   characters outside the U+20-7E codepoint range must be treated as
>   invalid.  User agents must not use a feature tag created by
>   truncating or padding the string to four characters.

If I understand this correctly, if there's any tag string in
'font-feature-settings' that violates this, the whole list is invalid,
right? Note that this sentence in the previous wording

  # Tag strings longer than four characters must be ignored

might be interpreted as "UA must ignore the invalid items in the list"
and hence inconsistent with how we parse values in other parts of CSS
(i.e. an invalid value makes the whole declaration invalid). The new
wording gives me less impression about this but I would still hope that
the paragraph is rephrased to say "the declaration is invalid" instead
of "the tag strings are invalid".

Received on Thursday, 19 April 2012 16:39:34 UTC

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