Re: Can watermarking Unicode text using invisible differences sneak through Emacs, or can Emacs detect it?

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Cc: psainty@orcon.net.nz, luangruo@yahoo.com,
>       kevin.legouguec@gmail.com, emacs-devel@gnu.org
> Date: Tue, 15 Feb 2022 23:14:25 -0500
> 
>   > No, for replacements for the cdr part of the likes of
> 
>   >              (?\ẵ "a(?")
> 
>   > You said that you didn't like (? as the equivalent of the two
>   > diacritics ̆̃, so I suggested that you propose alternative equivalents
>   > which you'd like better.
> 
> That is the question I answered -- in full generality.
> Instead of sending you a very long list of replacements,
> I sent simple general rules to handle ALL characters
> that have the form LETTER + DIACRITIC, and ALL characters
> that have the form LETTER + DIACRITIC1 + DIACRITIC2.
> 
> The character you just cited is LATIN SMALL LETTER A WITH BREVE AND TILDE.
> The rule is
> 
>     For each character whose name has the form
> 
>       latin (small|capital) letter \1 with \2 and \3
> 
>     if the terminal can't display that, but it can display \1 with \2,
>     it should display
> 
>       LATIN (SMALL|CAPITAL) LETTER \1 WITH \2
> 
>     followed by the graphical form of \3.
> 
>     Otherwise, it should display
> 
>       \1 followed by the graphical form of \2 followed by the graphical form 
> of \3.

I understand the general rule, but I hoped you had specific
suggestions for those \2 and \3 placeholders.

It now sounds like you actually suggest to display the diacritic in
its non-combining variety, as I understand from this example:

> Following this rule, Emacs would display ă~, if the terminal can handle that,
> otherwise a˘~ .

But in that case, it goes against the spirit of this feature, which
expresses non-ASCII characters with equivalent strings composed of
ASCII characters.  Since ˘ is non-ASCII, chances are that the terminal
which cannot display ă will be unable to display ˘ as well.