If we go back to the 1341 standard of non-unique boundaries, those programs
that have already moved forward to the 1521 rules (or some interpretation of
those rules) will be broken again.
The restriction is present in 1521 and 1342, assuming you read them for
their clear meaning:
body-part := <"message" as defined in RFC 822,
with all header fields optional, and with the
specified delimiter not occurring anywhere in
the message body, either on a line by itself
or as a substring anywhere. Note that the
semantics of a part differ from the semantics
of a message, as described in the text.>
The "delimiter" here referred to is OBVIOUSLY "--boundary parameter", and
not the BNF product "delimiter" which includes CRLF, however unfortunate
the dual use of the word might be.
The terminology is messed up, the BNF adds a restriction not discussed by
the text, and the restriction is pointless.
However, the restriction is as *harmless* as it is pointless, so if it
makes somebody happy, fine. I'm not going to fight it.
Steve Dorner, Qualcomm Incorporated. "Oog make mission statement."