I think there is a reasonable compromise available:
Until such time as a mechanism for the specification of character
sets other than US-ASCII is established, the follow rule applies
to the character set of message headers:
Message headers MUST be in US-ASCII, with the exception of the
text of a Subject: or Comment: header. The text of a Subject:
or Comment: header is unparsed in its entire content, and MAY
be in an alternate character set provided that that alternate
character set otherwise follows the characteristics of US-ASCII
(that is, merely assigning different glyphs in the 0x21 - 0x7E
space, 7-bit, no conflicting use of 0x0C and 0x0A, etc.)
This is essentially the status quo, and one in which Western Europeans have an
obvious vested interest. There is no way that software can determine which
character set is intended, so a rule forbidding the practice would be
unenforcable anyway.
We are not proposing beating up on you Europeans, just that we in the US have
a vested interest in the status quo that needs preservation as well. Unlike
8-bit transport, allowing the compromise above doesn't impact our status quo
at all.
Another status quo matter is that it is good form for the Subject line of a
message to be readable in a US-ASCII context (which implies romanization for
non-Roman character sets such as Japanese) and possibly in the English
language followed by a tag indicating the language and character set of the
actual contents of the message. This is especially important for messages
with an international distribution. For example, we suggest subjects such as:
Subject: new mail design (in Swedish)
Subject: Urusei Yatsura EVENT in Budoukan!! (in Japanese/kanji)
in preferance to native language/character set subjects that can otherwise
create confusion.
This however is merely `good form' and should not be presented as any kind of
requirement (particularly the part about using English). There is no reason
why a domestic Swedish message with no foreign distribution should have to
abide by it.
-- Mark --