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RE: [CSS21][css3-namespace][css3-page][css3-selectors][css3-content] Unicode Normalization

From: Martin Duerst <duerst@it.aoyama.ac.jp>
Date: Sat, 31 Jan 2009 16:27:07 +0900
Message-Id: <>
To: "Richard Ishida" <ishida@w3.org>, "'fantasai'" <fantasai.lists@inkedblade.net>, <public-i18n-core@w3.org>, <www-style@w3.org>
Cc: "'Lachlan Hunt'" <lachlan.hunt@lachy.id.au>

At 00:19 09/01/31, Richard Ishida wrote:
>I think that the fact that some user agents may normalise and others not is 
>likely to produce problems in the following cases:
>1. in situations where someone has specifically relied on the fact that 
>although the two names are canonically equivalent in Unicode he/she has 
>specifically designed the CSS so that different combinations of base and 
>combining characters produce different effects.
>2. someone develops their code and tests only in user agents that normalise 
>away incompatible 'spellings' that other user agents don't.
>I expect case 1 is vanishingly rare.

I agree.

>Remember that these strings are 
>canonically equivalent in Unicode - they say exactly the same thing, it's 
>just as if the accent is changed. In fact, we may be doing people a favour 
>here in terms of disabling security issues.  On the other hand, we stand to 
>clarify and alleviate problems for a lot of people who have done this by mistake.

I'm not sure I understand. If it's vanishingly rare, there can't
be a lot of people who have done this by mistake.

>Case 2 can be alleviated by wider testing and as more user agents implement 
>normalisation. I think that wide testing is something that is normally 
>needed anyway, and applies to other features too.

I'm not sure how that "alleviation" would work. Currently, testing on
a single browser will reveal these problems immediately (of course,
cross-browser testing is still required for a lot of other issues,
but shouldn't we be happy that at least here there's one where it's
not needed?). Even if browsers that normalize are deployed at something
like 90%, this will still mean that testing with different browsers
is needed, and that the problem will have to be fixed.

>Adding a requirement to 
>a spec for normalization will help to get more user agents implementing 

"More" isn't good enough. And from what I see from browser implementers
on this point doesn't look like it will happen soon.

>Not doing so will just postpone the issue.

It will hopefully contribute to the issue being sorted out at the
right point, namely the input side.

>(I would note 
>that there was a reference to normalization in the selectors spec 
>previously that was taken out due to an editorial question.)

What point did you want to make by mentioning this?

Regards,   Martin.

#-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
#-#-#  http://www.sw.it.aoyama.ac.jp       mailto:duerst@it.aoyama.ac.jp     
Received on Sunday, 1 February 2009 08:33:13 UTC

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