Regarding non-US-ASCII characters (punt):
Current [RFC 1521] grammar restricts parameter values (and
hence Content-Disposition filenames) to US-ASCII. We
recognize the great desirability of allowing arbitrary
character sets in filenames, but it is beyond the scope of
this document to define the necessary mechanisms. We expect
that the basic [RFC 1521] `value' specification will someday
be amended to allow use of non-US-ASCII characters, at which
time the same mechanism should be used in the Content-
Disposition filename parameter.
Hmmm. If 'value' is redefined for all of MIME, won't it break
existing MIME implementations and thus have a negative impact on the
installed base? It's one thing to define a new way of representing
arbitrary {octet,character}-strings in new parameters, something else
to make it retroactively apply to old ones.
Mind you, I'd *really* like to have MIME be consistent in the way it
treats parameters, but I would be surprised if we could justify a
retroactive change. (am I the only one who thinks this is shaky?)
(I suppose the RFC that redefines 'value' could include a caution to
not use the new syntax for awhile, at least not except for non-ASCII
strings.)
Still, it seems reasonable to put this for the Proposed Standard
version of Content-Disposition, as long as nobody intends to ship
product based on that version of the spec...but this feature is needed
so badly that I somehow suspect that people are going to want to do
exactly that...
Keith