From: erik(_at_)poel(_dot_)juice(_dot_)or(_dot_)jp (Erik M. van der Poel)
Subject: restrictions when defining charsets
Date: Thu, 21 Jan 93 15:24:36 +0900
As far as I remember the discussions at Santa Fe, the group wanted to
have its own definition of character set.
It was never spelled out in the minutes or anything like that, but
went something like:
A set of rules for the interpretation of an octet stream, such that:
- The interpretation of each byte cannot be questioned
- The number of representable characters is limited
- No further parameters need to be parsed to get the complete
identity of the character set
"Never spelled out in the minutes or anything like that"? Doesn't
seem like a good state of affairs to me. If the above is indeed the
intention, it should be spelled out in MIME itself, perhaps in the
part that shows you how to register a new charset.
I agree that the revised MIME needs a better definition of "charset".
(I suggest it be in the text that discusses text/* body parts.)
"interpretation of an octet stream" needs to be followed by something like
"for the display of character-based text"...though I'm sure better language
can be found. "interpretation of an octet stream", by itself, could mean
that e.g. Z-80 machine code is a potential charset.
I would interpret the first rule as "every symbol has a unique
interpretation"...where "symbol" is not necessarily a byte...this rules out
things like ISO 646, in which the meaning of some code points differs from
place to place.
Keith Moore