Re: new coding system (was: Re: prettify symbols question)

[Eli Zaretskii]

> From: "Alfred M. Szmidt" <ams@gnu.org>
> Cc: emacs-devel@gnu.org
> Date: Sat, 14 Nov 2020 10:29:15 -0500
> 
>    Is this the encoding on Unix systems?  If so, maybe try without
>    mapping characters below ASCII 128, I'm not sure this is supported in
>    an ASCII-compatible encoding.
> 
> I am not sure I understand.  On unix #o0 maps to the MIDDLE DOT, #o1
> to DOWNWARDS ARROW, etc.

If the low codes aren't identical to ASCII, then I think
ascii-compatible should be nil, and I think the relevant example to
follow is that of EBCDIC.  I'd suggest to construct a map file by
hand, using EBCDIC maps as example, and see if that works.

If it doesn't work, we might need to bring Kenichi Handa on board of
the discussion.

> As I understood it, the charmap/charset is a mapping from UCS-4
> Unicode to whatever is on the target?

Not UCS-4, but Unicode codepoints (which is the same thing in
practice, but just so we get our terminology right.)