Locale with shift state

[Paul Eggert]

On 05/24/2017 08:27 AM, Florian Weimer wrote:
> Do we have a locale with a multi-byte character set which has shift
> state (beyond a truncated multi-byte conversion)?  We support such
> charsets in iconv, but I can't find a locale which uses them.

I doubt whether we have any such locales.

> Would such a locale even be POSIX-compatible?

It depends what you mean by "POSIX-compatible". Locking-shift encodings 
cannot be defined by POSIX-compatible character set description files, 
and POSIX does not require support for such encodings. See:

http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap06.html#tag_06_04

Although a POSIX implementation could provide extensions to the 
character set description format and/or a builtin locale that supports 
such locking-shift encodings, I don't know of any practical POSIX 
implementation that does so. I vaguely recall hearing of attempts to 
build such systems many years ago for ISO-2022-JP, and that they didn't 
work.