Maybe I could include the headers on character set in the RFC-MNEM,
if we can agree on something. It should not be a lot of words.
I would be happy with just having it in the Subject field and other
fields that is free text. That should be simple and allow anything.
RFC-MNEM is basically a 7-bit standard, but is carefully worded
so that if agreed between the two parties, other character sets
can be employed. This agreement can be either a firm agreement
or an agreement arranged by a new SMTP protocol negotiation
or other agreement; how to agree it is simply unspecified.
I would then chose something like the following wording:
Header-Text-Charset: charset
This header defines the charset for what is defined as <text> fields in
RFC 822. It follows the same guideline as for the Content-Charset
header defined elsewhere in this specification.
If not present, the header <text> fields are encoded in the same
charset as the body.
Header-Text-Mnemonic-Intro: decimal
This header defines the Mnemonic intro character in decimal to encode
what is defined as <text> fields in RFC 822.
It follows the same guideline as for the Content-Mnemonic-Intro
header defined elsewhere in this specification.
If not present, the the mnemonic intro character for header <text>
fields are the same as for the body, if any.
Keld