[whatwg] Unicode mappings for ⟨ and ⟩

Øistein E. Andersen html5 at xn--istein-9xa.com
Sun Jul 1 14:40:34 PDT 2007

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  “〈”  and “〉” (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.

Øistein E. Andersen

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