Subject: Correct designaion of UTF-16 and UTF-32

From: Jacob Palme <[email-masked]>
Date: Tue, 4 Mar 2003 09:21:14 +0100

I have seen both UCS-16/UCS-32 and UTF-16/UTF-32 as
designations for the 16 bit Unicode and 32-bit ISO 10646
encodings. What is the correct designation?
-- 
Jacob Palme <[email-masked]> (Stockholm University and KTH)
for more info see URL: http://www.dsv.su.se/jpalme/

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From: Francois Yergeau <[email-masked]>
Date: Tue, 4 Mar 2003 09:35:26 -0500

Neither UCS-16 nor UCS-32 exist in Unicode, in ISO 10646 or in the IANA
registry.

UTF-16 and UTF-32 exist in all three.  Furthermore, the IANA registry (see
http://www.iana.org/assignments/character-sets) has UTF-16BE, UTF-16LE,
UTF-32BE and UTF-32LE labels to designate UTF-16 or UTF-32 with the
indicated byte sex.

> -----Message d'origine-----
> De : Jacob Palme [mailto:[email-masked]]
> Envoyé : 4 mars 2003 03:21
> À : [email-masked]
> Objet : Correct designaion of UTF-16 and UTF-32
> 
>

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From: Jacob Palme <[email-masked]>
Date: Sat, 15 Mar 2003 09:25:51 +0100

Here is a quote from RFC 2044:

    The Unicode Standard, version 1.1 [UNICODE], and ISO/IEC 10646-1:1993
    [ISO-10646] jointly define a 16 bit character set, UCS-2, which
    encompasses most of the world's writing systems.  ISO 10646 further
    defines a 31-bit character set, UCS-4, with currently no assignments
    outside of the region corresponding to UCS-2 (the Basic Multilingual
    Plane, BMP).  The UCS-2 and UCS-4 encodings, however, are hard to use
    in many current applications and protocols that assume 8 or even 7
    bit characters.  Even newer systems able to deal with 16 bit
    characters cannot process UCS-4 data. This situation has led to the
    development of so-called UCS transformation formats (UTF), each with
    different characteristics.

Is this text incorrect? Should one say UTF-32 instead of UCS-4, and
UTF-16 instead of UCS-2?

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From: Francois Yergeau <[email-masked]>
Date: Mon, 24 Mar 2003 10:35:21 -0500

Jacob Palme wrote:
> Is this text incorrect?

This text is pretty old (Oct 96) but still correct, except for the "with
currently no assignments outside of the region corresponding to UCS-2" bit
and the versions of the standards, which are not current anymore.  Hmmm and
saying "The [standards] jointly define a 16 bit character set" is certainly
criticizable.  This was changed to " ISO/IEC 10646-1 defines a multi-octet
character set..." in RFC 2279 (Jan 98) and again to "ISO/IEC 10646-1 defines
a large character set..." in the current draft of the replacement of RFC
2279.

> Should one say UTF-32 instead of UCS-4, and
> UTF-16 instead of UCS-2?

In what context?

-- 
François Yergeau