[NNTP] Wording for the "x" status in RFC 6048

Following a discussion with Alfred Hönes, who reported:

> The only place where I got stuck in RFC 6048 was in Section 3.1,
> in the 6th paragraph on page 17.  The RFC says:
> 
> |  A newsgroup with status "x" is a newsgroup with status "n", except
> |  that articles from peers are not accepted.  [...]
> 
> Given the definition from RFC 3977 that you quote slightly above,
> at the bottom of page 16,
> 
>     "n"  Posting is not permitted.
> 
> the "except that" does not make sense to me.
> 
> (In contrast, where the 7th paragraph says ...
> 
> |  A newsgroup with status "j" is a newsgroup with status "y", except
> |  that (1) local postings are not accepted, (2) articles received from
>     a peer that are crossposted to one or more valid groups are filed
>     only into those valid groups, and (3) articles received from a peer
>     that are not crossposted to any valid groups are not filed into any
>     newsgroup, but are still propagated to other peers, if appropriate.
> 
> ... "except that" makes perfect sense.)
> 
> Reading the subsequent explanations and examples, I conclude that
> the RFC 3977 status field values only affect local posting and
> are transparent to forwarding behavior.
>