Combining Class of Thai Nonspacing_Marks

[Gerriet M. Denkmann]

> On Mon, 3 Apr 2017 14:12:51 +0700
> "Gerriet M. Denkmann" <gerrietm at icloud.com> wrote:
> 
>> The Combining Class is used for normalisation of strings.
>> Normalisation of strings is important for filenames in filesystems.
>> 
>> As far as I know, a Thai consonant (Lo, Other_Letter) can have
>> several Nonspacing_Marks. This cluster of nonspacing marks can
>> contain at most one top/bottom vowel and at most one tone/other mark.
>> There is no syntactically meaning in the order of these nonspacing
>> marks.
> 
> You're confusing the modern Thai language with the Thai script.  It
> seems that the Lao-style usage of NIKHAHIT as a vowel is known from
> older Thai writing, and when used this way it could of course take a
> tone mark.  It also seems that the pressure to have both MAITAIKHU and
> a tone mark on a consonant has been accepted for at least one minority
> language.

I stand corrected. I do know nothing about other languages written with Thai characters.

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)
The order of these has no semantical meaning.

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?

Kind regards,

Gerriet.