Subject: bug#16007: admin/charsets/mule-charsets.el requires old Emacs version

From: [email-masked] (K. Handa)
Date: Wed, 25 Dec 2013 00:00:39 +0900

In article <[email-masked]>, Eli Zaretskii <[email-masked]> writes:

> Ping!
> Is the patch suggested below correct, please?

I'm sorry for being late.  It took time to recall why I
didn't specify the unify map for indian-is13194.

The story is a little bit complicated, but, in short, Emacs
22 was wrong in providing is13194->Unicode map in
ucs-tables.el.  That map maps indian-is13194 to Unicode
Devanagari area, but such a mapping is correct only for
Devanagari users.  For Telugu users, for instance, the
characters in indian-is13194 should be mapped to Unicode
Telugu area.  IS13194 is actually not a charset but an
encoding mechanism of all (ah, almost all) Indian scripts,
and it uses the sequence 0xE0 0x4? to switch scripts.

So, at the time of designing Unicode-base Emacs, I had
intended to solve this incorrect behavior of Emacs 22.  But,
while attacking many other problems, I forgot this issue.  :-(

For instance, iscii-to-ucs-region (IS13194 is called as
ISCII) of ind-util.el still has this comment:

  ;; only Devanagari is supported now.

I am still wondering how to solve this problem.  At least,
the docstring of indian-is13194 should state that the
current implementation of that charset is for Devanagari
users only if we suply the unify-map as your patch.

The better will be to provide a different unify map for
different lang. env.  But, as IS13194 is used very rarely
now, I'm not sure it's worth making such an effort.

Please give me some more time to decide what to do for the
next release.

---
Kenichi Handa
[email-masked]