bug#1726: 23.0.60; end-of-sentence and non-breaking space

[Stefan Monnier]

>     This raw-byte char is what used to be called an eight-bit-control (or
>     eight-bit-graphic depending on the actual value) char.

>     I.e. "\xa0" is treated as a string that contains the \xa0 byte (i.e. an
>     eight-bit-* (aka raw-byte) char) rather than the \xa0 char (a latin-1
>     non-breaking space).

> 1. Is that the right thing for \xa0 in a string to mean?
> Or should it mean the character with code xa0?

> 2. I find it hard to think about that question since I don't see any
> documentation explaining how this ought to work.  That documentation
> is essential.

Good point.  Especially because I think this changed from Emacs-20 to
Emacs-21, and I think it also changed now from Emacs-22 to Emacs-23.

IIUC if you want the character with code #xa0, then using \u00a0 would
seem like the most unambiguous option (I notice that "\ua0" gives
a weird error "Non-hex digit used for Unicode escape").

Not sure what \NNN or \xMM should do.


        Stefan