[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

RE: Mix encodings in a document?

• From: Jerome McDonough <jmcdonou@l...>
• To: "Gavin Thomas Nicol" <gtn@e...>, "Deke Smith" <deke@t...>, <xml-dev@i...>
• Date: Tue, 22 Sep 1998 11:28:23 -0700

At 01:23 PM 9/22/98 -0400, Gavin Thomas Nicol wrote:
>> And Unicode represents a character as a single 16 bit word, so bytes
>> do not represent characters (even in UTF-8, where a character encoding
>> may be one to four bytes).
>
>This is no longer true. 

I'll accept that (I haven't seen Unicode 2.1 yet), but which part is no
longer true?

>> ISO-10646-UCS-2 (the 2-octet Basic Multilingual Plane) is the
>> same as Unicode (which is a 16-bit chararacter encoding), so
>> that would be your "UTF-16." (I don't think that, technically,
>> the 16-bit encoding gets referred to as a UCS Transmission Format).
>
>This is not correct. UTF-16 has not (to the best of my knowledge)
>been registered yet. UTF-16 differs from UCS-2 in some ways, the most
>significant of which is that it allows surrogate pairs (two 16 bit
>codes that represent a single logical character code).
>

OK, I shouldn't answer e-mail before coffee.  But let me check
this with you to see if I've got the spec. right (and make sure
they didn't change this in 2.1 as well).  Under Unicode version 2.0,
what I should've said is:

	Unicode == ISO-10646-UCS-2 != UTF-16

as Unicode and 10646 in UCS-2 format should be identical, but UTF-16
differs from both of these in it allows the use of code surrogate
pairs to enable encoding the BMP and next 16 planes of UCS-4.  From
what I can see at Unicode's home page, it now looks like Unicode is
dropping UCS-2 character encoding and now only endorses UTF-8 and 
UTF-16, so that the situation now is:

	Unicode != ISO-10646-UCS-2

and Unicode sometimes does/sometimes does not equal UTF-16.  Is that
more or less the case at the moment?


Jerome McDonough -- jmcdonou@l...  |  (......)
Library Systems Office, 386 Doe, U.C. Berkeley     |  \ *  * /
Berkeley, CA 94720-6000    (510) 643-2058          |  \  <>  /
"Well, it looks easy enough...."                   |   \ -- /  SGNORMPF!!!
         -- From the Famous Last Words file        |    ||||

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i...
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/
To (un)subscribe, mailto:majordomo@i... the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo@i... the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa@i...)

• Follow-Ups:
  • Re: Mix encodings in a document?
    • From: John Cowan <cowan@l...>

• References:
  • RE: Mix encodings in a document?
    • From: Jerome McDonough <jmcdonou@l...>

• Prev by Date: Preference Files
• Next by Date: Re: Corba data -> XML
• Previous by thread: RE: Mix encodings in a document?
• Next by thread: Re: Mix encodings in a document?
• Index(es):
  • Date
  • Thread