Re: Merging combining classes, was: New contribution N2676

From: John Cowan (
Date: Tue Oct 28 2003 - 15:35:19 CST

jim scripsit:

> Unicode encodes U+1E20 and U+1E21 as combinations of lower and uppercase
> _g_ with macron. The forms have canonical decomposition to _g_ or _G_
> followed by U+0304. This seems to rule out being able to consider a bar
> above and a bar below as variants of the same character within Unicode.

True. But that doesn't mean that the glyph that a particular font uses for
the sequence <g, COMBINING MACRON BELOW> can't have the bar above the g.
This is a pure rendering question.

> IPA specifications also indicate that U+0325 COMBINING RING BELOW and
> some other diacritics normally placed beneath a character may instead be
> displayed above a character for typographical reasons.

So a smart IPA-specific font could render <g, U+0325> with the ring above.

> But Unicode specifications currently say nothing about the possibility
> of moving under-diacritics to an over-character position for
> typographical reasons except for combination of _g_ and cedilla.

Nothing needs to be said, because glyphs are not normative.

> Perhaps we need instead special search folding between upper position
> and lower position diacritics that are otherwise identical in form,
> e.g. between U+0304 (COMBINING MACRON) and U+0331 (COMBINING MACRON
> BELOW) and so forth for any diacritics where an upper form and a lower
> form may have the same meaning.

That also can be done as a collation tailoring.

Principles.  You can't say A is         John Cowan <>
made of B or vice versa.  All mass
is interaction.  --Richard Feynman

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