RFC 1496 (rfc1496) - Page 2 of 5
Rules for downgrading messages from X
Alternative Format: Original Text Document
RFC 1496 HARPOON August 1993
It replaces chapter 6 of RFC-1328. The rest of RFC-1328 is NOT
obsoleted.
NOTE: A desireable side-effect of HARPOON is that a standardized
method for the identification and transmission of multimedia and
binary data (like spreadsheets) between X.400/84 UAs is achieved.
While this method is not compatible with current proprietary
approaches, we believe that it requires less invasive changes to
current UAs than other possible methods.
This memo updates RFC 1328. HARPOON is a pure name, and has no
meaning. Please send comments to the MIME-MHS mailing list
[email protected]>.
2. Basic approach
The approach is to imagine that the connection X.400(84)
SMTP(MIME) never happens. This, of course, is an illusion, but can be
a very useful illusion.
All mail will therefore go on one of the paths
X.400(84) -> X.400(88) -> SMTP(MIME)
SMTP(MIME) -> X.400(88) -> X.400(84)
when it goes between a MIME user and an X.400(84) user.
The approach at the interface between X.400(88) and X.400(84) is:
o Convert what you can
o Encapsulate what you have to
o Never drop a message
Of course, for X.400/88 body parts that are already defined in
X.400/84, no downgrading should be done. In particular, multi-body
messages should remain multi-body messages, IA5 messages including
IA5 messages encoded as Extended Body Parts) should remain IA5
messages, and G3Fax messages should remain G3Fax messages.
Alvestrand, Romaguera & Jordan