RE: [idn] Re: Fwd: Unicode letter ballot

["Kent Karlsson" <kentk@md.chalmers.se>]

> Yes, you are right.  I was thinking of when changes like the one
> proposed here applies to any character, that doesn't happen to be a
> compatibility character.

By "compatibility character" you seem to mean "character that has
a (compatibility or canonical) decomposition".  But there are also
other compatibility characters. Among them "characters that should
have had a canonical decomposition, but has no decomposition".

I'm thinking about what Soobok Lee wrote:

> If option A wins in the coming ballot, then I will push 
> forward "correct NFC's hangul
> jamo handling errors!" in Unicode 4.0, because NFC backward 
> compatibility promises would
> be regarded as being broken already in those cases of 5 CJK 
> characters. I think "backward
> compatiblity promise of NFC" is useful and neccesary but 
> proved to be premature at least 
> in current version 3.2.  It is proved that proofreading takes 
> much time.

The correction mentioned here involves characters that are such that 
they in Unicode 3.2 have no decompositions, while they had compatibility
decompositions in Unicode 2.0, but logically should have canonical
decompositions.  For those not familiar with Hangul (jamo) in Unicode,
these characters are those that stand for a sequence of two or three Hangul
letters. For instance HANGUL CHOSEONG NIEUN-KIYEOK ('nk') should have
a canonical decomposition into HANGUL CHOSEONG NIEUN ('n') followed by
HANGUL CHOSEONG KIYEOK ('k'); there is no distinction between these,
they both stand for 'nk' (in the lead part of a syllable), there is no
ligaturing difference of any kind, no font difference (in theory), nor
anything else that should be different between them, except for
representation. But it, and several others like it, has no decomposition
at all in Unicode 3.2.

This has been mentioned several times before, but ignored by this WG.
I'm drafting a "Unicode Technical Note" on Hangul decompositions.

		Kind regards
		/kent k