Subject: Re: Differences between RFC 2822 and Usefor

From: John Stanley <[email-masked]>
Date: Mon, 11 Apr 2005 10:33:50 -0700 (PDT)

"Charles Lindsey" <chl@xxxxxxxxxxxxxxxx>:

>                Differences between RFC 2822 and Usefor.
>		----------------------------------------

>2.11 A References header MUST be provided for followups (as opposed to 
>SHOULD be provided for replies in RFC 2822).

Would you care to explain where you are getting this difference? In
draft-ietf-usefor-usefor-03.txt, the References header is defined thusly:

>3.2.1  References

>   The References header is the same as that specified in Section 3.6.4
>   of [RFC2822] with the added restrictions detailed in Section 2.2 and
>   those listed below:

Section 2.2 does not say anything about specific headers (and nothing at
all about References), and the remaining part of 3.2.1 says nothing about
followups and MUST. RFC2822 says "SHOULD". 

There is no section 2.11 at all, much less one that creates a difference
between RFC2822 and USEFOR. So, it appears to me that the artificial
requirement for References has been removed from the draft, as would be 
proper based upon a strict reading of RFC2119 and when a MUST is 
appropriate. So be it. That's one way of solving the debate between
"followups MUST/non-followups MUST NOT" and "followups MUST/non-followups
MAY". Not the way I would have picked, but one that is certainly RFC2119
conforming. 

Of course, now that this change has been made, it will require a full
justification for putting back an extraneous (w.r.t. RFC2119) MUST
condition. There is no interoperability issue, nothing breaks when it
isn't there, so it will take some special arguments to justify replacing
it.

---

From: "Charles Lindsey" <[email-masked]>
Date: Tue, 12 Apr 2005 11:08:04 GMT

>draft-ietf-usefor-usefor-03.txt, the References header is defined thusly:

The "SHOULD" in question is in the first paragraph of section 3.6.4 of RFC
2822. In consequence of that SHOULD, many MUAs still regard providing a
References header as an "optional extra", with the consequence that
attempts to display threading in mailing lists (including this one)
usually succeed only in showing broken threads.

The "MUST" in question arises from the long held consensus in this Working
Group that the References header in News is NOT an "optional extra". And
you yourself have been at the forefront in upholding that consensus. There
is a disagreement as to how exactly that requirement should be expressed,
and as to how the wording should reflect the use of the References header
in the case of multipart FAQs and the like, but there is no disagreement
at all that it MUST be provided in cases where a poster follows up
(responds/replies/whatever) to an article from an earlier poster. That
clear requirement has been in all our drafts up to article-13.

>followups and MUST. RFC2822 says "SHOULD". 

The text regarding the References header in the new usefor-03 draft is
just plain WRONG.

Yes. the bit about section 2.2 covers the obligatory SP after the ':', as
required in all headers, and the "listed below" refers to the avoidance of
comments (MUST accept but do not generate yet). But the requirement for
the header to be present for followups has been omitted, and it needs to
be put back (modulo the relatively minor matter of the precise wording).

And there is also an error in the syntax of the References header, which
Frank Ellermann pointed out some while back, and which needs to be
corrected.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 Fax: +44 161 436 6133   Web: http://www.cs.man.ac.uk/~chl
Email: [email-masked]      Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K.
PGP: 2C15F1A9      Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5

---

From: Alexey Melnikov <[email-masked]>
Date: Tue, 12 Apr 2005 17:00:35 +0100

Charles Lindsey wrote:

>comments (MUST accept but do not generate yet).
>

>But the requirement for
No it is not, because this is not a USEFOR business to say anything 
about followups. Any given article doesn't become valid/invalid because 
of presence or lack of References. USEFOR doesn't deal with a thread of 
messages, this is a protocol issue.

>Frank Ellermann pointed out some while back, and which needs to be
This should be fixed or at least discussed.

---

From: "Charles Lindsey" <[email-masked]>
Date: Wed, 13 Apr 2005 15:59:00 GMT

>messages, this is a protocol issue.

Then why is RFC 2822 allowed to say that the References header SHOULD be
present in the corresponding email situation?

And why does the word "followup" occur 10 times in the Usefor draft?

And why does the Usefor draft contain the words

   None of the headers appearing in this section is required to appear
   in every article but some of them are required in certain types of
   article, such as followups.

And it says

Which clearly implies that we have signed up to everything in RFC 2822
Section 3.6.4 except as detailed otherwise, which means that we have
signed up to that "SHOULD", which we haven't.

Netnews departs from RFC 2822 in various ways, which we document. Changing
that "SHOULD" to a "MUST" is one of them (the identical SHOULD->MUST for
Message-ID is another, but I do not see any objection to saying that).
I understand that we intend to document these differences in an Appendix
to Usefor, but how can we document differences that we are not allowed to
describe?

---

From: Alexey Melnikov <[email-masked]>
Date: Sun, 17 Apr 2005 22:05:31 +0100

>present in the corresponding email situation?
Because RFC 2822 is very much like a combined USEFOR+USEPRO. All I am 
trying to say is that USEFOR is not the proper place to state any 
requirement that doesn't apply to all articles.

>And why does the word "followup" occur 10 times in the Usefor draft?
6 of them are used when defining different terms, 3 are used when 
describing Followup-to (naturally), 1 is used in the sentence you've 
quoted below.
IMHO, this is quite reasonable. I would like to avoid any use of the 
term in USEFOR, but this is just not practical.

>   article, such as followups.
Which is also followed by the following sentence:
          Further discussion of these requirements appears in [USEPRO] 
and [USEAGE].

This is a clear indication that USEPRO is a proper place to define any 
additional requirements.

>signed up to that "SHOULD", which we haven't.
You can add it to USEPRO to "Duties of a Followup Agent" as per above.

---

From: "Charles Lindsey" <[email-masked]>
Date: Wed, 20 Apr 2005 20:12:34 GMT

>          Further discussion of these requirements appears in [USEPRO] 

Which sentence should not be there IMHO.

>You can add it to USEPRO to "Duties of a Followup Agent" as per above.

Yes, that is possible. Indeed it is already there, but might need a little
more saying about it there, including pointing out the divergence from RFC
2822 and something about using it in non-followup situations such as
mulipart FAQs and message/partial.

Incidentally, Usefor also needs the semantics of this header explaining
(such as the significance attaching to the order in which the precursors
are listed), so maybe the mention of multipart FAQs and message/partial
could be slipped in there.