>What would be the MIME charset parameter for a document that used
>more than one charset?
It's not clear to me what you mean by "use more than one charset." An
SGML document has exactly one document character set. A MIME text body
part has exactly one charset (be it the implicit default or an
explicit charset parameter).
Some character encodings (e.g. iso2022) allow a kind of "mode
switching" where the mapping of bytes to characters changes via escape
codes. In that case, the character repertoire of the document
character set contains _all_ the characters that can be encoded in any
mode. But it's still just one big character set, as far as SGML is
concerned or one big character encoding, as far as MIME is concerned.
I think.
Dan