RFC 5322, "Internet Message Format", October 2008Source of RFC: IETF - NON WORKING GROUP
Area Assignment: app
Errata ID: 3088
Reported By: Michael Redwine
Date Reported: 2012-01-11
Rejected by: Pete Resnick
Date Rejected: 2012-02-20
Section 3.3 says:
date-time = [ day-of-week "," ] date time [CFWS]
It should say:
date-time = [ day-of-week "," ] date time [comment]
If using the [CFWS] at the end of the original text, by the rules of CFWS, the next line could contain only FWS after the CRLF, which would violate the requirement found in 3.2.2, which reads: "...where CFWS occurs in this specification, it MUST NOT be inserted in such a way that any line of a folded header field is made up entirely of WSP characters and nothing else."
CFWS allows there to be multiple comments, including comments that go on to the second line, which is perfectly OK.