Ned Freed writes:
Header-set has two advantages over multipart/foo. One, the "header" part
is known a priori to be optional, and readers that don't understand it know
that ignoring it is ok (unlike multipart/unknown-foo, which gets treated
like mixed).
Interesting notion. Are you sure that readers are justified in ignoring the
header parts in things they don't recognize?
One "problem" with this idea of skipping unknown parts is the
case of AppleDouble. Example: A user runs a MIME aware mailer,
which don't know what to do with this message:
multipart/header-set
application/applefile
image/gif
According to the header-set proposal, the first part is skipped and
the second is saved to a file and presented to the user.
IF the first part was not skipped, the user might have had the
opportunity to save the first part as well as the second part,
and by naming the files "%picture.gif" and "picture.gif" the user
is able to pick up the appledouble file with Fetch for example
or any other file transfer software which understands AppleDouble.
What I mean is that it is dangerous to "skip and throw away" some
parts that the mailer doesn't understand, but the user does.
So, what header-set helps the mailer with is to make some more
intelligent message to the user than multipart/whatever which
is treated as multipart/mixed.
Are your ideas that the first part in a header-set multipart
always can be skipped, or how should it be treated by the mailer?
paf