I suggest a comma-separated list of subtypes if there is an alternative
in the header-set's first body part.
A bit of human-factors input...
I'm regularly using Eudora now, and I ruin my addresses periodically by
hitting the period instead of the comma between addresses. I'll bet I'm
not alone...
It would be nice if the standards could help reduce this kind of problem,
which I realize may be nontrivial. But when possible, having the standards
accept a period OR a comma, for example, would be nice from the
human-factors perspective. As contrasted to the dramatically different
meanings of those two characters in addresses.
And, yes, I also realize that if I weren't so lazy and would use a comma
PLUS a space when typing addresses, I'd have less trouble when I hit a
period! ;-)
Jim