RFC Editor Note
Change the 3rd sentence in the 3 para of Section 1:
OLD:
In this respect, the basic intent of the
application/multipart-core media type is like that of multipart/mixed
(Section 5.1.3 of [RFC2046]).
NEW:
In this respect, the basic intent of the
application/multipart-core media type is like that of multipart/mixed
(Section 5.1.3 of [RFC2046]), however the semantics is relaxed to
allow for both ordered and unordered collections of media types (*).
ADD after the 3rd para:
(*) Historical Note: Experience with multipart/mixed in email has shown that recipients
that care about order of included body parts will process them
in the order they are listed inside multipart/mixed and recipients
that don't care about the order will ignore it anyway. The media type
multipart/parallel that was intended for unordered collections didn't deploy.