X11R7.5 and C.UTF-8

[Thomas Dickey]

On Thu, 3 Dec 2009, Eric Blake wrote:

> Thomas Dickey <dickey <at> his.com> writes:
>
>>> This means that characters 0..127 have to be treated as ASCII, but
>
> No, it means that portable characters and control characters must be < 128.
> ASCII meets this characteristic, but so does EBCDIC, as well as UTF-8.  The C
> locale also implies that you can manipulate bytes >= 128 in the naive manner,
> so long as you don't care about characters embedded in those bytes.  And what
> do you know - ASCII, EBCDIC, and UTF-8 all meet this property, too.
>
>>> beyond that an implementation can do what it wants. And on Cygwin 1.7,
>>> plain "C" actually does imply UTF-8, which happily is
>>> backward-compatible with ASCII.
>>
>> That's an interpretation that so far hasn't been blessed by the standards
>> people.  Any discussion of this topic should mention that, as a caveat.
>
> Actually, the standards people HAVE spoken - and they agreed with our
> interpretation.  POSIX was INTENTIONALLY written with the intent that a UTF-8
> encoding is valid for the C locale, for the same reason that it was written
> that an EBCDIC encoding is valid for the C locale.  These emails from the
> Austin Group (the folks that write POSIX) are telling:
>
> https://www.opengroup.org/sophocles/show_mail.tpl?
> CALLER=show_archive.tpl&source=L&listname=austin-group-l&id=12982

This is basically your email on the matter.

> https://www.opengroup.org/sophocles/show_mail.tpl?
> CALLER=show_archive.tpl&source=L&listname=austin-group-l&id=13012
>
> But they also admitted that there is still more work needed in POSIX to make
> this intent clearly codified (for example, that control characters must be
> single bytes < 128).

But they have not actually agreed with you yet.

-- 
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net

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