User-Agent header (was: [PATCH] New function to send a mail to the recipient at point)

["Stephen J. Turnbull" <turnbull@sk.tsukuba.ac.jp>]

Reiner Steib writes:
 > On Sun, Feb 24 2008, Leo wrote:
 > 
 > > On 2008-02-24 09:05 +0000, Reiner Steib wrote:
 > >> [BTW, your User-Agent header is not confirming to RFC 2616 or the
 > >> usefor drafts.]

Of course it's conforming to RFC 2616; RFC 2616 defines HTTP headers,
not mail headers.  The drafts may define the same format (including by
reference to RFC 2616), but that's not the same as RFC 2616
conformance.

In particular, the "usefor drafts" may impose additional syntactic
restrictions or permit extensions (both unlikely) or add semantic
interpretations.  (In a trivial sense they do the latter two by
extending use of the header to mail.)

 > > How to test if it is conforming to RFC2616?

token           = 1*<any CHAR except CTLs or separators>
product         = token ["/" product-version]
product-version = token
User-Agent      = "User-Agent" ":" 1*( product | comment )

 > > ,----[ C-h v gnus-user-agent RET ]
 > > | gnus-user-agent is a variable defined in `gnus.el'.
 > > | Its value is 
 > > | "Gnus/5.130000 Emacs/23.0.60 (20080222) Fedora 8 (gnu/linux)"
 > 
 > IIRC, "Fedora 8" isn't allowed.  Probably "Fedora/8 (Fedora 8,
 > gnu/linux)" is correct.

The field value above is conformant to the RFC, although it doesn't
have the expected semantics.  It makes "Fedora" and "8" separate
products, where you would expect Fedora to be a product and 8 to be a
version.  (Consider "9" as a product token.)

I think the suggested change is simply to change the space in "Fedora
8" to a slash:

    "Gnus/5.130000 Emacs/23.0.60 (20080222) Fedora/8 (gnu/linux)"