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[whatwg] Unicode mappings for ⟨ and ⟩

From: Řistein E. Andersen <html5@xn--istein-9xa.com>
Date: Sun, 01 Jul 2007 23:40:34 +0200
Message-ID: <E1I579m-000O0l-2U@node1-7.ouvaton.local>
L. David Baron wrote:
> What's wrong with these mappings, and why shouldn't they
> also be the mappings in HTML5?

The problem is that they are canonically equivalent to CJK characters.

http://www.unicode.org/reports/tr15/ describes Unicode
normalisation in general and mentions singleton decompositions
in particular.

http://unicode.org/reports/tr25/#_Toc25 highlights the problem
with the HTML 4.01 mappings:
> The left and right angle brackets at U+2329 and U+232A
> have long been canonically equivalent with the CJK
> punctuation characters  ?&#12296;?  and ?&#12297;? (U+3008 and U+3009).
> Canonical equivalence implies that the use of the latter
> code points is preferred and can be substituted at any time.
> As a consequence, not only 3008 and 3009 but also the
> characters 2329 and 232A are ?wide? characters. [...]
> Unicode 3.2 added two new mathematical angle bracket
> characters (U+27E8 and U+27E9) that are unequivocally
> intended for mathematical use.

?istein E. Andersen
Received on Sunday, 1 July 2007 14:40:34 UTC

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