ietf-nntp HDR parameter proposal

[Russ Allbery]

Charles Lindsey <chl at clw.cs.man.ac.uk> writes:
> Russ Allbery <rra at stanford.edu> writes:

>> I don't understand how a client could use this information.  From the
>> perspective of the client, this is exactly equivalent to the server
>> saying:

>>    HDR BASE EXTRA

> Depends how "EXTRA" is defined.

EXTRA says "we also include some other unspecified set of headers."

> The point is that many current implementations of XHDR return only what
> can be found in the overview, and there is no way to be sure what
> headers that covers (because OVERVIEW.FMT is not 100% guaranteed). So
> what I am proposing is exactly what they are getting at present.

I really don't understand what you're saying.  The sentences all make
sense individually, but the point is escaping me entirely.  Let me try
again:

The client has no idea what headers the server considers to be "found in
the overview."  That information may vary from message to message stored
on the server, and at best the client can only obtain a snapshot of what
is going into the overview for new articles at a particular point.

So how, exactly, is the statement "all headers found in overview can also
be retrieved by HDR" useful to the client?  What useful thing could the
client do with that information?  Why is that not semantically equivalent
to saying "some unspecified set of additional headers are also available
via HDR"?

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