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Re: Results of CSS case-sensitivity discussion at TPAC

From: John Daggett <jdaggett@mozilla.com>
Date: Thu, 13 Dec 2012 22:34:17 -0800 (PST)
To: WWW International <www-international@w3.org>
Message-ID: <820913634.6216139.1355466857900.JavaMail.root@mozilla.com>
Addison Phillips wrote:

> Tab Atkins wrote:
> > What was the result of the discussion about CSS identifiers and
> > case-sensitivity? If possible, can you point me to the minutes as
> > well?
> Our minutes are here:
>    http://www.w3.org/2012/11/02-i18n-minutes.html#item02
> The result of the discussion was that CSS should require full
> Unicode case folding without special cases (by which we mean
> "SpecialCasing.txt" in the Unicode Character Database, which
> includes languages such as Turkish and Latvian).
> Richard was actioned with writing up a detailed response, but
> hopefully the above is a clear summary. Let me know if you would
> like to discuss.

Norbert Lindenberg wrote:

> No, by "special cases" we meant the "T" cases in the CaseFolding.txt
> file of the UCD. SpecialCasing.txt defines special cases for
> upper/lower/title case. One case that's special in SpecialCasing and
> not so special in CaseFolding is ß.
> Expressed positively, CSS should use the mappings labeled C and F in
> CaseFolding.txt.

If what is being suggested here is simply "use C + F case mappings in
CaseFolding.txt", this isn't sufficient enough to define a case
matching algorithm that implementations can use.  In the minutes is a
discussion of situations better handled by what some are describing as
"full" Unicode case mapping but I think the details of the actual
algorithm to be used are being glossed over.  In particular, I think
two important questions need to be answered *after* an exact algorithm
for case insensitive matching has been laid out:

1. Does it make sense for CSS to be using one set of matching rules
   and other parts of the web platform to be using something else?

2. Is the complexity of the algorithm and the associated testing
   overhead justified by the importance of the problems it solves?

I think Anne's response [1] is related to both these questions but
it's hard to evaluate these questions because the exact algorithm
that's being proposed hasn't been described in detail.


John Daggett

[1] http://lists.w3.org/Archives/Public/www-international/2012OctDec/0109.html
Received on Friday, 14 December 2012 06:34:48 UTC

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