Rationale for U+10FFFF?

From: Harald Tveit Alvestrand (Harald@Alvestrand.no)
Date: Sun Mar 05 2000 - 06:58:58 EST

the current trend in UNICODE/ISO 10646 seems to be to limit the number of
planes to 17 (U+0 to U+10FFFF).
Can someone tell me the rationale for not deprecating plane 16, and leave us
with the much more rational U+0 to U+FFFFF?
Or even allocating the whole bit, and making it U+0 to U+1FFFFF?

To me, this seems on a par with the ISO session layer that mandated
sequence number ranges of 0 to 99999 (0x1869F - a 17-bit number) -
something that will cause readers for tens of years to come to shake their
heads and say "these guys didn't know what they were doing"; checks for
legality now need a range compare, not just an AND operation. Similar for
UTF-8 encoders/decoders; this extra plane will haunt implementations for
years to come.

It may not matter much in real CPU time, but to me, it is an offense to the
aesthetics of the representation.


                   Harald A

Harald Tveit Alvestrand, EDB Maxware, Norway

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