> use the posix/c/sc2 model of abstract characters that has been the model in iso for many
> years and is also the model in the internet. no big deal. unicode is just a number of
> harsets , utf8, utf16 utf32 etc.
>
> keld
>

I've looked at POSIX and the only thing I could find is this:
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap06.html#tag_06_01

This means zero Unicode support.

As for C, C only has char16_t, char32_t, minimalistic literal support...
I'm not sure about standard library. That's about 2% of Unicode support.

I don't know what is sc2.

So, in total:
POSIX - 0% Unicode.
C - ~2% Unicode.

That's how far "abstract characters" get you.