Re: UTF-1?

From: Kenneth Whistler (
Date: Fri Jul 30 1999 - 19:01:24 EDT

Frank asked:

Annex G (informative) "UCS transformation format (UTF-1)" was removed
from ISO/IEC 10646-1:1993 by Amendment 4. (Or more exactly, the content
of Annex G was removed, while the header for Annex G was left as a placeholder.)

For ISO/IEC 10646-1:2000 (the "second edition" of 10646-1) any dead annex
letters have been recovered, so Annex G will be "Alphabetically sorted list
of character names" (what was Annex E in the first edition).

Registering the contents of the original Annex G (i.e., the description of
UTF-1) in the IR was just a way to retain information about UTF-1 in the
ISO framework, even though it had been removed from the standard.

It is moot whether the registration occurred before or after UTF-1 was
removed from 10646-1, but if you care, you can look up the date of the
registration of IR 178 in the ISO Register. UTF-1 would not have *officially*
been removed until the publication of Amendment 4 in 1996, the same year
that UTF-8 was published as Amendment 2.

And yes, UTF-1 should just be ignored and forgotten.


> ISO/IEC 10646-1 Amendment 4 says:
> Annex G:
> Delete the complete text of the annex, except for the heading Annex G.
> Below the heading Annex G insert the following text:
> "[This annex has been deleted, and its contents have been registered in the
> "ISO International Register of coded character sets to be used with escape
> sequences" as Registration no. 178 (revised).]"
> The ISO Register contains:
> Registration Number: 178
> Escape Sequence: ESC 2/5 4/2
> Name: UCS Transformation Format (UTF-1)
> Description: ... The above escape sequence identifies ... UTF-1.
> The Unicode Standard 2.0 says on p.C-2:
> 4. Removal of Annex G: UTF-1
> I'm confused. Was UTF-1 *moved* or *removed*? Were its contents registered
> before or after they were deleted?
> Anyway, I take that UTF-1 is simply a precursor to UTF-8, to be ignored and
> forgotten?
> - Frank

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