[NNTP] LIST EXTENSIONS (again)

[Howard Swinehart]

From: "Russ Allbery" <rra at stanford.edu>
> Well, I'm dubious that anyone would want to produce a version of NNTP that
> was that completely incompatible so that the same sort of fallback that
> you'd use for Netscape Collabra wouldn't also work.
>
> I'm not completely opposed to the idea, but I'm very suspicious of it
> because other protocols haven't needed it.  If I had my druthers, we'd
> just copy IMAP and not worry too much about it.

How about if we use the NNTPVx tokens exactly as you described with one
additional note that tokens beginning with the 5 letters "NNTPV" are
reserved for indicating the protocol version.  This way clients can reliably
detect a NNTPV2 or higher protocol by checking for NNTPV*, they can detect
current broken servers by the lack of NNTPV* and they can detect future
incompatible versions by the lack of NNTPV2.  RFC977 servers are detected by
an error on LIST EXTENSIONS as before.