Eli Zaretskii <eliz@gnu.org> writes:

> CHAR_CHARSET always returns 'ascii' for ASCII characters, while
> showing 'charset' for ASCII characters probably makes littles sense.
> Of course, that's only my guess, the default behavior wrt this is pure
> heuristics, so YMMV.
>
> We could mention this exception in the manual.

Yeah, I think we should.  Here's a new patch with updated manual and
tests.