Script of U+0951 .. U+0954

[Antoine LECA]

Hi folks,

I recently notice (I was off line for a while) the inclusion of the
Scripts.txt file in the Unicode Character Database. I find it very
interesting.
I noticed it is informative. However, there is a detail that makes
me quite unhappy: characters U+0951 .. U+0954 (the various accents
described in ISCII-88 to mark tones in some Vedic texts) are assigned
to the DEVANAGARI script.

These accents are the only usable at the moment for Vedic/Sanskrit
tone marking, and they do include the probably most interesting ones,
U+0951 and U+0952. However, these two accents are not specific to
Devanagari, and could be used without problem with the other scripts
that may be used to write Sanskrit/Vedic. So I believe they should be
moved to another place, for example the "INHERITED" pseudo-script.

Concerning U+0953 and U+0954 (grave and acute accents), the point is
that they are mostly used with... Latin characters (grave is svarita,
and acute is udatta.) In fact, I believe that it happens with them
the same "problem" than with U+0340 and U+0341, with the exception
that one may contemplate the placement of U+0953/U+0954 above the
middle of the diphtongues ai/au (I do not believe this is standard
usage, though.)
So again, I believe they can be moved to the "INHERITED" pseudo-script.


This issue is of relevance to the rendering engines. For example,
Microsoft's Uniscribe refuse to draw U+095x on top of any syllable
which is not Devanagari. I believe this behaviour is incorrect,
but the Script.txt file seems to assert MS position. If this is right,
(and so if I am wrong), then that means that we need a number of new
characters, for each script used to write Sanskrit/Vedic (including Latin).

Another position could be to say that the combining character from the U+03xx range could be used, and equating (in addition to the above)
U+0951 (DEV.STRESS SIGN UDATTA, in fact a svarita accent) with
U+030D (COMB.VERTICAL LINE ABOVE), and
U+0952 (DEV.STRESS SIGN ANUDATTA) with U+0331 (COMB.MACRON BELOW).
Note that this implies changes to the rendering engines as well.

I welcome comments and critisms, 'cause I am very far from being
omniscient on the subject.


Regards,
Antoine