John Klensin wrote:
First thing we do is to get real serious, network-wide agreement about
what character set(s) we are going to support in the target network and
what we want to treat as "our" "network plaintext". We write reversible
mapping rules between MIME-registered characters sets of significant
interest into that/those character set(s) and get agreement about them.
Then we decide what we are going to do with any characters that happen
to be left over from the mappings and standardize that ritual. If we
end up with more than one EBCDIC, we figure out how to tell sites
without our network about which one is used in a particular message, but
we use a mechanism that treats Content-type as inviolate. Maybe a
EBDCIC-page header.
I would expect the above agreements might be very hard to get in a
network context that hasn't been able to agree on how to map 7bit ASCII,
but that isn't a MIME problem.
Much of this is done in RFC1345: definition of a number of charsets,
including many EBCDICs, reversible mapping rules and fallback notation.
Keld