Re: Unicode 3.2 support (6)

[Bruno Haible <haible at ilog dot fr>]

Anthony Fok writes:

> One thing special about BIG5-HKSCS and HKSCS-2001 on GNU/Linux though:
> there are still quite a few important components (and HKSCS fonts)
> which do not yet fully support the HKSCS-2001 and ISO 10646-2:2001
> standards, specifically mappings beyond the BMP.  (XFree86, Qt, and
> most existing TrueType Big5-HKSCS fonts on the market, etc.) So, while
> mapping HKSCS-2001 to ISO 10646-2:2001 is definitely desirable, it is
> not time yet because the rest of the system is not ready. ... migration plan.
> 
> So, in the interim, please consider using the following scheme for the
> default BIG5-HKSCS charmap/converter:
> 
>     BIG5-HKSCS --> ISO 10646-1:2000 + PUA
> 
>     PUA + ISO 10646-1:2000 \___\  BIG5-HKSCS
>           ISO 10646-2:2001 /   /

This is not a migration plan. Real migration would be to convert like
this:

    BIG5-HKSCS --> ISO 10646-1:2000 + ISO 10646-2:2001

    PUA + ISO 10646-1:2000 \___\  BIG5-HKSCS
          ISO 10646-2:2001 /   /

> or perhaps make two versions of "BIG5-HKSCS" in glibc:
> say "BIG5-HKSCS-1999" which maps BIG5-HKSCS to ISO 10646-1:2000+PUA,

That sounds reasonable. I will provide a patch that adds
BIG5-HKSCS-1999 with the old semantics, for use by people who have not
upgraded their fonts to use the non-BMP planes.

> There is another intricacy with BIG5-HKSCS with unified characters,
> in big5cmp.txt.  If you like, please take a look at:
> 
> 	http://www.thizlinux.com/~anthony/hkscs/

I don't understand what this big5cmp.txt means for the converters. Can
you explain in more detail, please?

Bruno