From: Kent Karlsson (kentk@cs.chalmers.se)
Date: Thu Aug 07 2003 - 16:53:04 EDT
> > > > Canonical reordering is scoped to stop at combining class = 0.
> > >
> > > (I know it is. But I confess I'm not sure why.)
> >
> > Because God, er...., um... Mark Davis created it that way. ;-)
>
> Eeh, not really the answer I expected. This particular behaviour makes
> (marginal!) sense for *enclosing* (and that means something
Clarification: marginal since:
. There seems to be little point in putting
some kind of diacritic outside of an enclosing mark.
. Trying to put a diacritic outside of a double diacritic
is promptly considered to be inside of the double
diacritic (see fig. 3-2 in TUS 3.0 & 4.0). I don't think there
would have been any loss in doing the same for
diacritic marks with enclosing marks.
It may also be doubtful to use combining class 0 for Indic
vowels. E.g. is there any point in distinguishing <consonant,
nukta, dep. vowel> and <consonant, dep. vowel, nukta>?
Or in distinguishing <consonant, anusvara, dep. vowel> and
<consonant, dep. vowel, anusvara>? (Recall that Indic syllables
often go through quite a lot of shaping, including far reaching
glyph moves, unspecified by Unicode itself.) This can be
mitigated by defined a "syllable syntax", for the benefit of
those of us who don't find that obvious. Ok, the position of
nuktas is nearly given, since there are precomposed characters
with nukta. Not obvious how it interacts with conjunct formation
though. Maybe there is sense in distinguishing the examples
above (if so, why?).
As I've mentioned, assigning class 0 to invisible combining
characters, I find to be a major mistake. Can't be changed now,
but should be mitigated somehow.
/kent k
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