Additional-Registered-Clauses = CFWS Atom FWS String
; Additional standard clauses may be
added in this
; location by future standards and
registration with
; IANA. SMTP servers SHOULD NOT use
unregistered
; names. See Section 8.
and then there is no information in Section 8 (IANA Considerations). Section 8 needs to be updated.
Section 4.4 in an ABNF comment:
Additional-Registered-Clauses = CFWS Atom FWS String ; Additional standard clauses may be added in this ; location by future standards and registration with ; IANA. SMTP servers SHOULD NOT use unregistered ; names. See Section 8.
and then there is no information in Section 8 (IANA Considerations). Section 8 needs to be updated.