[NNTP] LIST EXTENSIONS and an NNTPv2 capability

[Clive D.W. Feather]

Ken Murchison said:
> Hmm, I just noticed that NNTPv2 isn't a valid extension label per the 
> latest grammar since extension-label is defined to be 3*12UPPER.  We'll 
> either have to come up with a new label or relax the grammar.  Since I 
> originally suggested NNTPv2, I'm in favor or relaxing the grammar and 
> perhaps making extension-label 3*12A-CHAR.  Is there a reason why this 
> wasn't done in the first place?

Nobody seems to know why we made it upper-only rather than case
insensitive, and it's a strange anomaly. I'd be very happy for us to fix
it.

However, we do have an implicit assumption elsewhere (see the 401 response
code) that dashes don't occur in extension labels. This can be worked
around, though.

At present a command name is not restricted in any way (other than no
spaces). I wonder if it would be a good idea to limit both extension labels
and command names to some smaller character set (say alphanumeric plus dot
and dash)? Do we want to forbid commands like "401" or "!@%)$&:#". Or, even
worse, names with quotes? Whatever we decide, I think that we should use
the same rule for extension labels and command names.

-- 
Clive D.W. Feather  | Work:  <clive at demon.net>   | Tel:    +44 20 8495 6138
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