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RE: Errata on MathML (was: Re: UTC Agenda Item: Variation Selection Problem)

From: Kent Karlsson <kentk@md.chalmers.se>
Date: Tue, 2 Apr 2002 09:07:03 -0500 (EST)
To: "'Martin Duerst'" <duerst@w3.org>, <www-math@w3.org>
Cc: <unicore@unicode.org>, <ion@ams.org>, <bnb@ams.org>, <w3c-i18n-ig@w3.org>, <asmusf@ix.netcom.com>, <kenw@sybase.com>
Message-ID: <001c01c1da4f$877d1e40$8bc11081@chalmers95a69n>

> -----Original Message-----

> For background, the discussion started because there is a note
> in Unicode 3.2 that variant selectors cannot be used for
> decomposable characters, to avoid normalization problems,
> (see http://www.unicode.org/reports/tr28/#13_7_variation_selectors)
> but there are two cases where this is not respected, which
> lead to the following proposal:
> Especially in light of the fact that there is an already-encoded way
> to express the variation, the UTC should issue a corrigendum removing
> the variant sequences <2278, FE00> and <2279, FE00> and request that
> WG2 do the same in a corrigendum to 10646.

The list of 'variants' using a VS for MathML should be a **subset** of the
variants using a VS listed for Unicode (and 10646 at some point, I guess)
at any given time, excepting variants that are unrelated to math (and
excepting the two included by mistake in Unicode 3.2, even though they
are math related).  Other variants, like slanted negation stroke vs. vertical
negation stroke, can of course be listed for MathML, but use different
'negating' characters (0338 (slanted) vs. 20D2 (vertical)); please also
note the Unicode canonical decompostions for negated math symbols.

> >Incidentally, the MathML tables also make the nonsanctioned
> >extension of all character short identifiers to 5 digits
> >(defined neither by the Unicode Standard nor Clause 6.5 of
> >10646-1).
> I think the standard form is to use either four digits or
> six digits, is that correct?

No. But: 4 digits for code positions in the BMP, 5 digits for code
positions in plane 1-15, and 6 digits for code positions in plane 16.
(It's not formulated that way, but that is what it boils down to.)

		Kind regards
		/kent k
Received on Tuesday, 2 April 2002 10:56:20 UTC

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