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In article <BstGEq.7E7@immd4.informatik.uni-erlangen.de>,
mskuhn@immd4.informatik.uni-erlangen.de (Markus Kuhn) wrote:

> - How is ISO 10646 structured? Is it a 16 or a 32 bit character set?

32, although there is a 16-bit form that includes only those characters in
the so-called Basic Multilingual Plane.  Currently, 10646 contains no
characters outside of the BMP. 

> - What subsets are defined in ISO 10646?

I don't believe there are any subsets formally defined right now, although
there is provision for "the specification of subsets of coded graphic
characters for use in interchange, by originating devices and by receiving
devices."  

> - How does it relate with US-ASCII, ISO Latin 1 and Unicode?

10646 code points 0000 0000 through 0000 007F are identical to 7-bit ASCII.
10646 code points 0000 0000 through 0000 00FF are identical to Latin 1.
10646 code points 0000 0000 through 0000 FFFF (the BMP) are identical to
Unicode 1.1.  (Version 1.1 of Unicode will be issued later this year.)

The main differences between 10646 and Unicode are:

10646 is a 32-bit character set which can exist in a 16-bit form.  Unicode
is a 16-bit character set.  

Although the BMP of 10646 and Unicode are code-point identical right now,
Unicode specifies additional semantics and behavior for characters
(particularly visual behavior) which are not in 10646.

> - What's the standard's status today (DIS?)? When will it be published
>   officially?

10646 passed its final vote last month and WG2 met in Seoul to dispose of
various countries' comments.  At this point, the editor has to determine
exactly what changes need to be made to bring it into accordance with the
resolutions made during the Seoul meeting and some administrative details
have to be taken care of, but the voting process has ended.  The IS will
probably be published early next year.  It will be printed by AFII and so
should look really nice.  

> - What requirements are there for application programs (editors, etc.)
>   and libraries if they what to handle ISO 10646 files?

The single biggest bugaboo is the fact that 10646 characters include NUL
bytes in them.  Don't assume that a NUL byte terminates a string, and don't
treat 10646 text as a series of bytes.  C programmers will have to get used
to using types other than char to represent text.  

This particular problem will, perhaps, hit UNIX-based systems harder than
others but is not insuperable.  AT&T is working on one solution which uses
the transformation format specified in the DIS that makes it possible to
represent and manipulate 10646 as a series of bytes.  

> - Has anyone already written a short ISO 10646 FAQ list with answers?

I've seen one or two short summaries but I'm not sure right now where they
might be hiding.  

If you want detailed information on 10646 but don't want to wait until the
IS is issued, you may want to look into acquiring the Unicode Standard, v.
1.0.  It's available in two volumes from Addison-Wesley (ISBN's
0-201-56788-1 and 0-201-60845-6; $32.95 and $29.95 in the US).  This is, of
course, a specification for a different standard and so should be used
cautiously, but it will make it possible to become acquainted with some of
the main architectural features of 10646 and its repertoire while you're
waiting for your copy of the IS to show up.  

Unicode will also be holding an implementers workshop in Germany later this
year.  Contact the Unicode Consortium at unicode-inc@cairo.eng.sun.com for
more details.  Again, this is about Unicode and not 10646 but will almost
certainly include a discussion of the two standards and the relationship
between them.  

> - What else should a computer science student know about ISO 10646 
>   in the future?
> 

Why, everything, of course.  :-)


John H. Jenkins
John_Jenkins@taligent.com

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