(resending after having subscribed to ietf-smtp)
Dear SMTP interested people,
As some may have seen I held a discuss in two parts. The second part was
unfortunately not discussed until last week at all with me. I would like
to get your input into this question.
My discuss was started due to there was a rule which wasn't a rule, i.e.
it didn't contain any elements. A clear syntax violation in ABNF. The
rule in the issue was "Standardized-tag", this can be seen in version 10
of the draft in section 4.1.3.
I have received a proposal from John Klensin that would make section
4.1.3 read as below. The change is in the rule for
General-address-literal and removal of Standardized-tag as a defined rule.
General-address-literal = <Standardized-tag> ":" 1*dcontent
; Standardized-tag MUST be specified in a
; standards-track RFC and registered with IANA
However, my personal objection against this resolution of the error is
that it leaves use with a undefined rule that is intended for future
extensions. I see this as a interoperability issue as any parser
implemented according to the rules in this document will have the
potential to fail on any future tag. If one could clarify what possible
syntax that the future tags could have then this would not be an issue.
I fully understand that the old implementation will still not understand
the content, however, by not having the parsing fail an implementation
can at least take the correct action. Thus I wonder why one can't
specify it like:
Standardized-tag = ehlo-keyword
Any rule that defines what combination of character are allowed in any
future tag would be fine as a solution to this issue from my perspective.
Is there a any problem with defining a rule for what characters is
allowed in future tag for identifying literal address formats that is
large enough to motivate living with the interoperability issue?
Cheers
Magnus Westerlund
IETF Transport Area Director & TSVWG Chair
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Multimedia Technologies, Ericsson Research EAB/TVM
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