bug#3526: 23.0.94; `list-character-sets' display

[Kenichi Handa <handa@m17n.org>]

In article <CF216C40E93948CE89C4D4BEC2702E86@us.oracle.com>, "Drew Adams" <drew.adams@oracle.com> writes:

> What is a "supplementary character set"? Why are such sets listed
> separately? What sets are in the first, non "supplementary" list. IOW,
> why two lists, and what is the difference?

A supplementary character set is a character set defined
with `:supplementary-p' flag.  The meaning of this flag is
(in the docstring of define-charset):

VALUE must be nil or t.  If the VALUE is t, the charset is
supplementary, which means it is used only as a parent or a
subset of some other charset, or it is provided just for backward
compatibility.

For instance, gb18030-2-byte, gb18030-4-byte-bmp,
gb18030-4-byte-ext-1, gb18030-4-byte-ext-2, and
gb18030-4-byte-smp are all supplementary character sets to
define gb18030 which is a superset of the above all.

arabic-1-column, arabic-2-column, arabic-digit are also
supplementary character sets that are provided for backward
compatiblity.

Priorities of supplementary character sets are always lower
than the other character set, so, for instance (char-charset
CHAR) never return a supplementary character set.

---
Kenichi Handa
handa@m17n.org