[NNTP] CAPABILITIES problem!

[Clive D.W. Feather]

Scott Hollenbeck said:
>>>>> Possible solutions:
>>>>> (1) Relax the 12 character limit to something longer (where did it come
>>>>> from anyway?).
>>>>> (2) Relax the requirement for the label to be a keyword.
>>>>> (3) Change the keyword to something shorter, like SERVER_INFO.

> Agreed.  All I would add to Ned's note is that I'd like to see a proposal
> confirmed by the WG before I agree with the change.  Ned's suggestion to
> bump the limit seems like the least intrusive document change, but I don't
> know what the impact would be on implementations.

Okay, here's some strawmen.

Option (1):

The term "keyword" is used for four things:
- command names
- command second word names (notably LIST)
- the argument to CAPABILITIES
- capability labels

The relevant wording is:

| A "keyword" MUST consist only of US-ASCII letters, digits, and the
| characters dot (".") and dash ("-"), and MUST begin with a letter.
| Keywords MUST be at least three characters and MUST NOT exceed 12
| characters.

and the syntax:

|   keyword = ALPHA 2*11(ALPHA / DIGIT / "." / "-")

We can change or remove either or both limits. For example:

  A "keyword" MUST consist only of US-ASCII letters, digits, and the
  characters dot (".") and dash ("-"), and MUST begin with a letter.
  Keywords MUST be at least three characters and MUST NOT exceed 16
  characters.

    keyword = ALPHA 2*15(ALPHA / DIGIT / "." / "-")

or:

  A "keyword" MUST consist only of US-ASCII letters, digits, and the
  characters dot (".") and dash ("-"), and MUST begin with a letter.
  Keywords MUST be at least two characters.

    keyword = ALPHA 1*(ALPHA / DIGIT / "." / "-")

No other wording changes would be needed. I don't know what the
implications are of changing the minimum or maximum command length. There
is no such limit in RFC 977 and I don't know where it came from.


Option (2):

The current wording is:

| The capability label, which is a keyword indicating the capability. 

| IANA is requested to maintain a registry of NNTP capability labels.
| All capability labels in the registry MUST be keywords and MUST NOT
| begin with X.

and the syntax:

|  capability-label = keyword

There are two sub-options:
(2A): remove the length restriction
(2B): remove all restrictions, except that it must begin with a letter
      other than X.

Option (2A):

New wording:

  The capability label, which is a token indicating the capability. 
  The label must be a keyword except that it can be longer than 12
  characters.

  IANA is requested to maintain a registry of NNTP capability labels.
  All capability labels in the registry MUST be keywords (except that
  they can be longer than 12 characters) and MUST NOT begin with X.

and the syntax:

   capability-label = ALPHA 2*(ALPHA / DIGIT / "." / "-")

Alternative wording, with no minimum length either:

  The capability label, which is a token indicating the capability. 
  It MUST consist only of US-ASCII letters, digits, and the characters
  dot (".") and dash ("-"), and MUST begin with a letter.

  IANA is requested to maintain a registry of NNTP capability labels.
  All capability labels in the registry MUST consist only of US-ASCII
  letters, digits, and the characters dot (".") and dash ("-"), and MUST
  begin with a letter other than X.

   capability-label = ALPHA *(ALPHA / DIGIT / "." / "-")

Option (2B):

New wording:

  The capability label, which is a token indicating the capability. 
  It MUST begin with a letter.

  IANA is requested to maintain a registry of NNTP capability labels.
  All capability labels in the registry MUST begin with a letter other
  than X.

   capability-label = ALPHA *P-CHAR


Option (3):

Change "IMPLEMENTATION" to "SERVER-INFO" wherever it occurs. Reorder the
table of predefined capabilities. In the syntax, change
"implementation-capability" to "server-info-capability" and reorder lists
as appropriate.

-- 
Clive D.W. Feather  | Work:  <clive at demon.net>   | Tel:    +44 20 8495 6138
Internet Expert     | Home:  <clive at davros.org>  | Fax:    +44 870 051 9937
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