[NNTP] Article Numbers Becoming Invalid (RFC 3977)

[Julien ÉLIE]

Hi Clive,

>> 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)?
>
> Here, "invalid" is a special value for CAN. CAN is set to "invalid" at the
> start of the session and when selectsing an empty newsgroup (but is not
> altered following an unsuccessful GROUP).
>
> So you get a 420 if you do NEXT/LAST before GROUP, or in an empty group.
> You get 421 when NEXT reaches the end of the numbers. Look at the last two
> examples for NEXT.

If we do NEXT/LAST before GROUP, isn't it 412?

RFC 3977:

   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.  If the currently
   selected newsgroup is invalid, a 412 response MUST be returned.

   Example of an attempt to retrieve an article without having selected
   a group (via the GROUP command) first:

      [Assumes currently selected newsgroup is invalid.]
      [C] NEXT
      [S] 412 no newsgroup selected



Maybe the text should be amended to say that 420 is when the current article
number is invalid and the selected newsgroup is valid.  Otherwise, there is
a discrepancy.

-- 
Julien ÉLIE

« Les amis de la vérité sont ceux qui la cherchent,
  et non ceux qui se vantent de l'avoir trouvée. » (Condorcet)