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

[Richard Stallman]

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  > Type "C-x 8 RET COMBINING", press TAB, then filter out of the
  > candidates those which pertain to Cyrillic, Greek, and other specific
  > scripts, leaving just Latin and those which don't belong to specific
  > scripts.

Amazing!

I see that it is possible to compute automatically the alist I proposed,
from these names.  A program can look at each of these
COMBINING names, delete `COMBINING ', and look up the rest as a
character name.  No need to make the correspondence alist by hand.

However, some of those COMBINING forms have no non-COMBINING counterpart.
For instance, there is COMBINING ZIGZAG ABOVE, but no ZIGZAG ABOVE.

How do you represent an uncombined zigzag-above in Unicode?
Put it after SPACE as a combination?

  > Your proposal is to have separate rules to produce the equivalent of
  > each diacritic, so you will never see "o?'", only its components
  > separately.

Yes.  On a terminal that can't display that letter, I'd like Emacs to
display it as a trigraph of one letter and two diacritics.

They should be non-combining diacritics, so that display won't try
to combine them.

  > My point is that there isn't a mechanical way of producing "o/" from
  > ø, because Unicode decompositions don't support that.

It wouldn't be very hard to add a list of extra decompositions that
are not known to Unicode itself.

  > > You have told me this several times, and I believe you.  But how does
  > > it relate to the case I am talking about?  I don't see a relationship.

  > As I said, that remark was for other people, those who will read my
  > email on GUI displays.

It is good to know that we don't have a misunderstanding about that point.




-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)