Re: Combining Class of Thai Nonspacing_Marks

On Tue, 4 Apr 2017 09:39:57 +0700
"Gerriet M. Denkmann" <gerrietm_at_icloud.com> wrote:

> So the rule should be:
>
> A consonant may have zero or one tone/other marks and also zero or
> one top/bottom vowels. Exceptions:
> NIKHAHIT + tone mark (no top/bottom vowel)
> MAITAIKHU + tone mark (no top/bottom vowel)

This list is not exhaustive. The order of MAITAIKHU and tone mark is
significant - it should affect rendering. Formally, the Unicode
Standard makes the point that the order of vowel above and tone mark is
significant.

> The order of these has no semantical meaning.

This is true for the combination of a mark above and a mark below. For
marks below, contrasting orders may be prevented (to a first
approximation) by the chaos of the canonical combining classes.

> All top/bottom vowels should have Combining Class 103,
> other marks should have Combining Class x (with 103 < x < 107),
> tone marks should have Combining Class 107.
>
> Is anybody working on or is responsible for these things?

Unicode combining classes cannot be changed. All that can be done is
to enforce the order of characters in normalised text. Asmus Freytag
has been working on an extreme version of that that disallows minority
languages in certain parts of domain names, and there is some pressure
to start using dotted circles in rendering so as to punish
transgressors, counterbalanced by the feeling that one shouldn't be
suppressing minority languages. Marshall Phibun's jackboots are
getting some exercise.

There is some input checking, loosely based on WTT (Wing Thuk Thi).
This may be implemented in such a way as to support the prohibition of
minority languages.

Richard.
Received on Tue Apr 04 2017 - 02:56:39 CDT