What a body part is

Ned,
in the light of the recent discussions about Location:, I think that
draft-ietf-822ext-mime-imb-03.txt needs one additional definition
in its chapter 4:

  4.x  Content header

  A header whose name starts with "content-".

This is required to satisfy the dangling reference from 4.4:

  4.4.  Body Part

  The term "body part", in this document, refers to CONTENT
  HEADERS and contents of either a message or one of the parts
  in the body of a multipart entity.  A body part has a header
  and a body, so it makes sense to speak about the body of a
  body part.

(my caps).

We might want to add another definition:

  4.x  Extra header

  A header that has no defined semantics.
  Examples include "x-fruit-of-the-day:" in a Message, or any header
  not starting with "content-" in a Body Part.

If this is the consensus of the group, it is best to state this explicitly.

                  Harald A