Subject: [Sipping] Question on Accept-Language grammar

From: "Szilagyi, Mike" <[email-masked]>
Date: Wed, 6 May 2009 15:29:51 -0400

What does it mean if the header is present but with an empty language value?

          Accept-Language:

In RFC3261, the Accept-Language section defines the headers meaning with a language value present and its meaning when the header is not present.

20.3 Accept-Language

   The Accept-Language header field is used in requests to indicate the
   preferred languages for reason phrases, session descriptions, or
   status responses carried as message bodies in the response.  If no
   Accept-Language header field is present, the server SHOULD assume all
   languages are acceptable to the client.

   The Accept-Language header field follows the syntax defined in
   [H14.4].  The rules for ordering the languages based on the "q"
   parameter apply to SIP as well.

   Example:

      Accept-Language: da, en-gb;q=0.8, en;q=0.7

The grammar for Accept-Language shows the language value as optional:

      Accept-Language  =  "Accept-Language" HCOLON
                              [ language *(COMMA language) ]

Regards,
Mike