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Re: comments on latest MIME drafts

1995-05-24 14:26:45
Keith Moore writes:

I'll also note that the MIME term "character set" is NOT the same
thing as the ISO term "coded character set".

What is the difference?
The RFC1345, where many MIME charsets are defined, follows ISO
terminology closely, and has the following definition of "charset":

   The ISO definition of the term "coded character set" is as follows:
   "A set of unambiguous rules that establishes a character set and the
   one-to-one relationship between the characters of the set and their
   coded representation." and this definition may be subject to
   different interpretations.

RFC 1345 is not a standards-track document, and is therefore
irrelevant to this discussion.  The RFC 1521 definition holds.

MIME does not require that there be a one-to-one relationship between
characters and their coded representation; it requires only that there
be a unique mapping *from* the coded representation of a sequence of
characters to those characters.

Yes, that is what we agreed. And that was also what was in the 
rest of the RFC1345 definition, which you deleted in your
representation above of my mail:

   This memo does not put further
   restrictions on the term of "coded character set" than the following:
   "A coded character set is a set of rules that unambiguously and
   completely determines which sequence of characters, if any, is
   represented by each possible sequence of n-bit bytes for a certain
   value of n." This implies that e.g. a coded character set extended
   with one or more other coded character sets by means of the extension
   techniques of ISO 2022 constitutes a coded character set in its own
   right.  In this memo the term "charset" is used to refer to the above
   interpretation of the ISO term "coded character set".

BTW, this is not *my* definition, but wordings that was done
by the group creating the RFC1345.