Subject: Unicode, ISO-2022, and 7-bit merged GB/Big5

From: Stephen G Simpson <[email-masked]>
Date: Tue, 26 Apr 1994 09:26:54 -0400

I wrote:
 > > The question is, how can internationalized software provide
 > > mixed-language capability?  Unicode and ISO-2022 are two good answers
 > > to that question, which GB and Big5 don't address at all.

Ross Paterson wrote:
 > And the next question is, which of these should we prefer?

Both Unicode and ISO-2022 provide good answers to the problem of
mixed-language capability in internationalized software.  In the past
Ross has been a strong advocate of Unicode, but now he seems to be
reconsidering and thinking that ISO-2022 may not be such a bad idea.

ISO-2022 is a "conservative" approach.  Unicode is a "radical"
approach.  Someone once said that a conservative is a radical who has
been mugged.

Here are some relevant considerations.

1. The ISO-2022 idea is to incorporate existing character sets
(Big5 Chinese, GB Chinese, JIS Japanese, ISO-8859-* European, ...) by
using escape sequences to switch between the character sets.  The
advantage is that the existing character sets are preserved.  The
disadvantage is that there are at least three different ways to
represent the Chinese character Da4 ("large"), namely the GB way, the
Big5 way, and the JIS way.

2.  The Unicode idea is to merge existing character sets into one
character set.  The advantage is that there will be only one
representation of Da4, which makes it easier to do searches etc.  The
disadvantage is that the mappings of existing character sets (Big5,
GB, JIS etc) into the unified character set are not linear, rather
they are given by tables.

3.  Theoretically, Unicode is a 16-bit standard, i.e. every character
is represented by 2 bytes.  In practice, software may end up
representing characters internally by anywhere from 1 to 3 bytes.
ISO-2022 does not try to claim that all characters will be represented
by the same number of bytes.

4.  In theory, Unicode is supposed to consist of one unified character
set.  In practice, Unicode implementations may patch together fonts
from various individual character sets.  ISO-2022 is more open about
this patching process.

5.  Both ISO-2022 and Unicode are just now coming into widespread use.
Plan 9 and Microsoft Windows NT use Unicode.  Multilingual Emacs
(Mule) and Multilingual Mosaic (Mosaic-L10N) use variants of ISO-2022.

My own view is that Unicode is a much better idea, but ISO-2022 may be
expedient in the short run.

As for 7-bit merged GB/Big5, my HZ+S proposal and Ya-Gui's unreleased
HZ-2 proposal are ISO-2022 style solutions.  Shann seems to be
proposing a Unicode-style solution.  Nothing is set in stone, so let's
keep our minds open.

-- Steve

---

From: Stephen G Simpson <[email-masked]>
Date: Tue, 26 Apr 1994 09:26:54 -0400

-- Steve