From: glenn@wheat-chex.ai.mit.edu (Glenn A. Adams)
Newsgroups: comp.std.internat,soc.culture.turkish,soc.culture.nordic
Subject: Re: Latin unification in ISO 10646
Date: 10 Sep 92 14:18:05 GMT
Article-I.D.: life.27738
Followup-To: comp.std.internat
Organization: MIT Artificial Intelligence Laboratory


  In article <1992Sep9.163417.8803@corax.udac.uu.se> andersa@Riga.DoCS.UU.SE (Anders Andersson) writes:
  >In article <TT.92Sep9114439@tarzan.jyu.fi>, tt@tarzan.jyu.fi (Tapani Tarvainen) writes:
  >> In article <1992Sep8.160511.1976@corax.udac.uu.se> andersa@Riga.DoCS.UU.SE (Anders Andersson) writes:
  >> >The Turkish alphabet is different here (and more consistent, in my
  >> >opinion), as it has two different vowels 'i'; one with dot and the
  >> >other without (both letters of course appear in upper- and lowercase).
  >> >I'm afraid even ISO 10646 fails to support them properly...

I must disagree that 10646 "fails to support [the Turkish alphabet] properly."
10646 contains the following characters (UCS2 codes given):

0131 LATIN SMALL LETTER DOTLESS I
0049 LATIN CAPITAL LETTER I

0069 LATIN SMALL LETTER I (with a dot)
0130 LATIN CAPITAL LETTER I WITH DOT ABOVE

These *adequately* support representations of both European and Turkish
language texts.  The fact that one has to take language into account in
performing case conversion is not relevant.  The coding structure of
10646 does not represent case transformations nor does it represent
sorting order; an application (or system) must use table lookup to
perform these operations correctly, taking language into account as
necessary.  The efficiencies obtained by programmers using ASCII for
representing English text are simply not possible with a universal character
set.

Other examples of language (or regional) differences in case conversion:

LATIN SMALL LETTER SHARP S (ESS-ZED) -> "SS" or "SZ" in uppercase, the latter
				   	sometimes used in Austrian German

LATIN SMALL LETTER E ACUTE	     -> "CAPITAL E" or "CAPITAL E ACUTE",
					the former sometimes used in France

An ISO character set is simply a repertoire of characters, their mappings to
code points, and a list of unique names for those characters.  No semantics
regarding usage are specified for "graphic characters."  Other standards
are free to address semantics or particular usages of characters.

  >Latin and Cyrillic capital 'M' look the same, while the small forms
  >don't.

10646 encodes the elements of scripts, independent of their use by particular
languages.  Latin and Cyrillic, though both derived from the Greek alphabet
along with influences from Etruscan and Aramaic, are clearly distinct
scripts.  On the other hand, the Han script, as used in China, Japan, Korea,
and Vietnam, is clearly one script, though some innovations were introduced
in its different writing systems.

Since Cyrillic, Greek, and Latin are separate scripts, their elements are
encoded separately, even when they happen to have some overlap of form.

An even more important reason for their distinction in 10646 is because they
are distinct in ISO8859-5.  The prime directive, as it were, for 10646 was
to facilitate a 1-1 round-trip mapping between 10646 and existing character
sets.  This precludes any unification of the few similar Cyrillic, Greek,
and Latin characters.

Glenn Adams
Newsgroups: comp.std.internat,soc.culture.turkish,soc.culture.nordic