From: Peter Kirk (firstname.lastname@example.org)
Date: Sat Apr 24 2004 - 16:50:03 EDT
On 24/04/2004 11:22, Ernest Cline wrote:
>As someone who has put a lot of thought into variation selectors, let me
>point out something. In the case of B M1 M2 VS what would the variation
>selector indicating as being varied if such a thing were to be allowed?
>Since variation selectors are combining marks, then just like any other
>combining marks they should be viewed as being applied to the entire
>combining sequence up to that point, and hence should be viewed as
>indicating a variant of B M1 M2, and not of just the preceding mark.
>Any other treatment complicates things too much.
I always assumed that VS's are intended to apply to just the immediately
preceding character, and not to a whole combining character sequence. In
my opinion, "Any other treatment complicates things too much." But
perhaps there are others who can tell us what the UTC intended for this.
>Thus in the case of the vowel marks, one could add a series of variation
>sequences with one for each base character that the variant vowel
>mark would be used with. If this causes too many other problems, ...
It would indeed if someone considers that every such combining sequence
has to be enumerated and defined individually. But if one simply says
that every combining sequence containing e.g. the sequence <QAMATS, VS1>
is legal and represents use of the variant qamats glyph, then there is
>...then adding a new mark for the vowel variant instead of trying to adapt
>variation selectors to the task would seem to be the best solution.
There are good reasons for applying VSs to certain characters rather
than defining new characters. If these reasons apply to certain
combining characters as well as to base characters, there is a good
reason to adjust the definitions of VSs to allow VSs to apply to
combining characters. Perhaps there is a good reason to define VSs
especially for combining marks with non-zero combining classes. But
there is no reason to abandon the principle of VSs.
-- Peter Kirk email@example.com (personal) firstname.lastname@example.org (work) http://www.qaya.org/
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