ietf-nntp HDR parameter proposal

[Russ Allbery]

Clive D W Feather <clive at demon.net> writes:

> I quite like the idea. Here's a possible way to both solve the Xref
> problem and make it extensible.

> The HDR extension can have zero or more parameters. Each parameter is a
> "header package name" indicating some set of headers and metadata items
> that are available through HDR.

>     BASE   the 7 items mentioned above
>     XREF   the Xref header

> (we could perhaps add:

>     BASEX  = BASE + XREF
> )

> Other package names may be defined in revisions to this specification or
> in other RFCs. Private package names may be defined, prefixed with "-"
> (e.g. "-INNUSUAL").

It would be lovely to be able to reserve X as an indication that the
package name is a private extension.  Perhaps we could reserve X- as the
prefix instead.  I don't really like using "-" to indicate a private
extension without the X in there, since it doesn't match what any other
protocol does to my knowledge.

BASEX seems kind of ugly.  Adding XREF as a package seems okay to me; I
don't have a very strong opinion about it.

> The package name "+" SHOULD be last on the list, and means that the
> server also provides other headers and metadata items, but not all (it's
> equivalent to a private package name specific to that server and with a
> meaning that can change without warning).

> I would lean towards saying that "HDR" with no parameters means "will
> accept any header name or metadata item it knows about". I'm assuming
> there's no backwards-compatibility issue here; if there is, then use
> "HDR *" for this case and make "HDR" equivalent to "HDR +".

I'd personally rather use ALL than * just because adding more punctuation
seems confusing to me.  ALL is a package just like any other.

For the "+" bit I don't feel as strongly between "+" and EXTRA or OTHER or
some such thing, but the punctuation does make me feel like we're making
the syntax more complicated without really needing to.  If we just define
some package name like "OTHER" meaning just what you define "+" to be
above and letting it occur anywhere on the HDR line, that would seem to
provide the same functionality to me and it "feels" less complicated.

-- 
Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>