Re: Code pages and Unicode

On Wed, 24 Aug 2011 12:40:54 -0700
Ken Whistler <kenw_at_sybase.com> wrote:

> On 8/24/2011 10:48 AM, Richard Wordingham wrote:
>> if, say,
>> code points are squandered.
 
> Oh.
 
> Well, in that case, the correct action is to work to ensure that code
> points are not squandered.

Have there not already been several failures on that front? The BMP is
littered with concessions to the limitations of rendering systems -
precomposed characters, Hangul syllables and Arabic presentation forms
are the most significant. Hangul syllables being also a political
compromise does not instil confidence in the lines of defence. I don't
dispute that there have also been victories. Has Japanese
disunification been completely killed, or merely scotched?

> > I think, however, that<high><high><rare
> > BMP code><low> offers a legitimate extension mechanism

> One could argue about the description as "legitimate". It is clearly
> not conformant,

With what? It's obviously not UTF-16 as we know it, but a possibly new
type of code-unit sequence.

> and would require a decision about an architectural change to the
> standard.

Naturally. The standard says only 17 planes. However, apart from
UTF-16, the change to the *standard* would not be big. (Even so, a lot
of UTF-8 and UTF-32 code would have to be changed to accommodate the new
limit.)

> I see no chance of that happening for either the Unicode
> Standard or 10646.

It will only happen when the need becomes obvious, which may be never,
or may be 30 years hence. It's even conceivable that UTF-16 will
drop out of use.

> Here are the current stats for the forthcoming Unicode 6.1, counting
> *designated*
> code points (as opposed to assigned graphic characters).
 
> Plane 0: 63,207 / 65,536 = 96.45% full
> Plane 1: 7497 / 65,536 = 11.44% full
> Plane 2: 47,626 / 65,536 = 72.67% full (plane reserved for CJK
> ideographs)
> Plane 14: 339 / 65,536 = 0.52% full
> Plane 15: 65,536 / 65,536 = 100% full (PUA)
> Plane 16: 65,536 / 65,536 = 100% full (PUA)

I only see two planes that are actually full. Which are you counting
as the full non-PUA plane?

Richard.
Received on Wed Aug 24 2011 - 17:55:52 CDT