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[css3-writing-modes] referring to Unicode

From: John Daggett <jdaggett@mozilla.com>
Date: Sun, 1 May 2011 18:57:52 -0700 (PDT)
To: www-style@w3.org
Cc: markdavis@google.com
Message-ID: <1130793579.182853.1304301472016.JavaMail.root@cm-mail03.mozilla.org>
>From the section entitled "Orienting Text: the ‘text-orientation’ property":
http://www.w3.org/TR/css3-writing-modes/#text-orientation

> The orientation of characters belonging to the Common, Inherited, and
> Unknown script categories may be UA- or font-dependent in vertical
> typographic modes. The Unicode East Asian Width property [UAX11] can
> be used to distinguish whether a character is typically be set upright
> or sideways in ‘vertical-right’: characters classified as fullwidth
> (F) or wide (W) are typically set upright (using vertical font
> settings), whereas characters classified as neutral (N), narrow (Na)
> or halfwidth (H) are typically set sideways (using horizontal font
> settings).

Since CSS specs are both explaining behavior and defining
implementation, referring to a Unicode technical note is fine for
referring to a deeper explanation of a concept but is *not* sufficient
for defining implementation behavior. Implementation behavior should
be defined in terms of the Unicode database [1] instead, by
referencing specific data fields in specific files, e.g. the
EastAsianWidth.txt file in your example here.  The technical notes
often don't always cover all the subtleties implicit in using this
data and that's something any definition of implementation behavior
needs to cover explicitly, otherwise you end up with untestable muddle.

Same thing for references in CSS3 Text 'text-transform', 'text-wrap',
these need to point to the specific data fields in the respective
Unicode data files and define specific behavior based on those data
fields.

Regards,

John Daggett

[1] Unicode database
http://www.unicode.org/Public/UNIDATA/
http://www.unicode.org/reports/tr44/
Received on Monday, 2 May 2011 01:58:20 GMT

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