Re: ISO10646-1 XLFD registration

From: Kenneth Whistler (
Date: Mon Apr 03 2000 - 13:17:53 EDT

Markus wrote:

> The question of what to do with other planes came up and there are
> various options, including but not limited to
> - finally doing the urgently needed fundamental revision of the X11 font
> architecture, which should provide for
> o 31-bit character set

You may want to also consider the *21*-bit option now. WG2 has just
approved the proposal to remove the user planes and user groups from
10646 past Plane 16. That means there will be *no* assigned characters
past U-0010FFFF, and that UTF-16, UTF-8, and UCS-4 (=UTF-32) will all
have the same code ranges and be completely interoperable. This closes
the last main architectural mismatch between 10646 and the Unicode Standard.

This approval still needs to be ballotted in the next amendment for
10646 Part 1, but while not a foregone conclusion, its approval seems
quite likely to me.

What this means is that for the foreseeable future (50 - 100 years?),
10646 characters will be constrained to 20.1 bits (round up to 21).

> o proper separation between characters and glyphs
> o ligature support
> o combining character support
> o efficient subset support
> o etc.
> - use ISO 10646-2, -3, -4, etc. (decimal) to refer to plane 01, 02, 03, etc.
> - use ISO 10646-01, -02, etc. (hexadecimal) instead.
> Since there is no published ISO 10646-2 or plane 1 at the moment, I
> still think it is best that we defer the question until the problem
> actually materializes in the form of a published plane 1 (which I guess
> will take a few more years).

WG2 also just approved the Disposition of Comments for the CD for 10646-2
(Part 2), and that document is due to be submitted to start FCD ballotting
in May. The Disposition of Comments on the FCD ballot should be complete
in September, which means the FDIS should be issued in November. For all
intents and purposes, early implementations can count on the FDIS text,
since technical changes are not allowed at that point.

In any case, this is not "a few more years" away -- publication of Part 2
(with a couple thousand characters on Plane 1, more than 40,000 more
Han characters on Plane 2, plus Plane 14 language tags) is approximately
one year out at this point.

> There are far more urgent issues with X11
> fonts to be solved in plane 0, especially with regard to the Indic
> scripts, combining accents, and the memory efficient handling of sparse
> 16-bit fonts.

Well, yes, I agree those are urgent issues. ;-)


> Markus

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