[NNTP] Article Numbers Becoming Invalid (RFC 3977)

[Julien ÉLIE]

Hi Clive,

> Most of your questions have been answered, but the usual way to do this is:
>
>    GROUP a.group
>    ARTICLE
>
> The ARTICLE might give a 420 failure response - don't worry if it does.
> Then repeat the following pair of commands:
>
>    NEXT
>    ARTICLE
>
> until you get a 421 response from NEXT.

Interesting.  It is indeed how it is implemented in INN 2.5.2 (previous versions
were improperly returning 423 instead of 420):

GROUP fr.test
211 7303 3716 11692 fr.test
ARTICLE
420 No current article
NEXT
223 3723 <20071207020930.77430463 at lavignotte.invalid> Article retrieved; request text separately



Yet, I do not understand the following paragraph in RFC 3977:


6.1.3.  LAST

6.1.3.2.  Description

   If the currently selected newsgroup is valid, the current article
   number MUST be set to the previous article in that newsgroup (that
   is, the highest existing article number less than the current article
   number).  If successful, a response indicating the new current
   article number and the message-id of that article MUST be returned.

[...]

   If the current article number is already the first article of the
   newsgroup, a 422 response MUST be returned.  If the current article
   number is invalid, a 420 response MUST be returned.


6.1.4.  NEXT

6.1.4.2.  Description

   In all other aspects (apart, of course, from the lack of 422 response),
   this command is identical to the LAST command (Section 6.1.3).




Isn't there a contradiction between the fact that the current article
number MUST be set to the [next] article in the newsgroup (and therefore
returning 423) and the fact that the current article number is invalid
(and therefore returning 420)?

-- 
Julien ÉLIE

« Aliquis non debet esse iudex in propria causa,
  quia non potest esse iudex et pars. »