From: John Hudson (john@tiro.ca)
Date: Fri Jun 16 2006 - 22:13:58 CDT
Kent Karlsson wrote:
> I think that all these changes of subscript to adscript *by the font*
> is a bad idea. Such changes should be done at the character level,
> not the glyph level.
> (And, if I understood right, uppercasing a lowercase (Greek) letter with
> subscript iota, should really be the corresponding uppercase letter
> with a *subscript* iota, except in not-so-common circumstances.)
No, this is not correct. The Unicode 4.0 and later code charts for the Greek Extended
block definitely have this right: the correct form of e.g. U+1F08 (uppercase Alpha with
psili breathing mark) plus U+0345 the combining subscript iota is with an adscript iota.
[Okay, so the actual form shown in the code charts isn't very good, because the adscript
iota is normally identical to the regular iota, but the idea is correct: it certainly
isn't a subscript iota.]
All of the instances of uppercase Greek character plus subscript iota which are part of
the standard polytonic system are encoded in Unicode as precomposed diacritics. These are
very much the 'common circumstances'. It is the not-so-common circumstances or fallback
circumstances that I was suggesting should be handled at the glyph level. These is the
kind of question we deal with in fonts all the time: 'How should this sequence of
characters be rendered?' and in the case of sequences that are outside the orthographic
norms of a writing system one has to take an intuitive approach. In this case we have a
typographic rule for subscript iota following those uppercase letters that it normally
follows -- i.e. that it properly takes an adscript form --, so the question is whether to
apply this same rule, via font lookups, when it follows other uppercase Greek letters. As
I say, this constitutes fallback circumstances, since such sequences are outside the
bounds of the orthography. My inclination is to say, yes, this rule should apply in those
circumstances, not least because if Unicode had not separately encoded these diacritics we
would need to handle all complex shaping for Greek in the font lookups as we do, for
instance, for smallcaps.
John Hudson
-- Tiro Typeworks www.tiro.com Vancouver, BC john@tiro.ca I am not yet so lost in lexicography, as to forget that words are the daughters of earth, and that things are the sons of heaven. - Samuel Johnson
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