RFC 2387, "The MIME Multipart/Related Content-type", August 1998

Errata ID: 5048
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: Adrian Kennard
Date Reported: 2017-06-22
Held for Document Update by: Barry Leiba
Date Held: 2019-04-30

Section 3.4 says:

related-param   := [ ";" "start" "=" cid ]
                        [ ";" "start-info"  "="
                           ( cid-list / value ) ]
                        [ ";" "type"  "=" type "/" subtype ]
                        ; order independent

It should say:

Unsure of best way to express this, but this syntax does not seem
to allow for the values to be in quotes. e.g. type="text/html"
rather than type=text/html

Notes:

Basically, the examples all have quotes around the values, e.g. type="Application/X-FixedRecord" rather than type=Application/X-FixedRecord

It appears that Yahoo email cannot accept type=text/html as per "syntax" in 3.4, but will accept type="text/html" which is consistent with the examples

The examples in the RFC currently do not comply with the RFC.

----- Verifier Notes -----
I think the last sentence in the submitter's notes is the correct one: it's the examples that are wrong, not the ABNF -- the values are not intended to be in quotes. In any case, this needs to be dealt with in a revision of the document, so we're sure we get it right and consider what multiple implementations are doing.

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