On May 26, 2011, at 22:56, Andrew Thompson wrote:
> I believe this stems from a period in history when the unicode group believed
> that they'd be able to fit all practical scripts into 65536 code points.
> Which meant you could get away with all kinds of assumptions like 16 bit
> types and UCS-2.
>
> As it became clear that wasn't going to be enough code points the additional
> planes were defined and ucs2 fell out of favor being replaced by UTF16 which
> can model the higher planes.
That would explain the parting of the ways between "code unit" and "code
point", but not really the distinction between "code point" and "[Unicode]
character". My memory of the days when Unicode first started to get a foothold
(the early 90s IIRC) is very hazy, but I think there were actually two things
going on:
-- The belief, exactly as you describe, that 65536 was enough.
-- A vagueness (or perhaps a deliberate lack of definition) about what should
be called a "character".
This seems to have been resolved now, and we have this hierarchy, at least in
Unicode/Apple terms:
code unit -> code point -> character -> grapheme -> (whatever the
grouping is called upon which transformations like upper and lower case are
performed)
It's not ultimately so hard, just a bit perilous for the unwary. That's the
reason I've been going on about this ad nauseam. If we shine some light on it,
we may help demystify it.
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