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Possible issue: Accept-language priority based on language order

From: Harald Alvestrand <harald@alvestrand.no>
Date: Wed, 23 Nov 2011 16:41:36 +0100
Message-ID: <4ECD1430.30605@alvestrand.no>
To: ietf-http-wg@w3.org
I ran across this in a discussion, and went to check it up; it might 
need fixing.

At the moment, section 6.4 of draft-ietf-httpbis-p3-payload-17.txt says:

6.4.  Accept-Language

    The "Accept-Language" header field can be used by user agents to
    indicate the set of natural languages that are preferred in the
    response.  Language tags are defined in Section 2.4.

      Accept-Language =
                        1#( language-range [ OWS ";" OWS "q=" qvalue ] )
      language-range  =
<language-range, defined in [RFC4647], Section 2.1>

    Each language-range can be given an associated quality value which
    represents an estimate of the user's preference for the languages
    specified by that range.

Way back in ancient history, when I wrote RFC 3282, I inserted the 
following clarification:

    The syntax and semantics of language-range is defined in [TAGS].  The
    Accept-Language header may list several language-ranges in a comma-
    separated list, and each may include a quality value Q.  If no Q
    values are given, the language-ranges are given in priority order,
    with the leftmost language-range being the most preferred language;
    this is an extension to the HTTP/1.1 rules, but matches current
    practice.

    If Q values are given, refer to HTTP/1.1 [RFC 2616] for the details
    on how to evaluate it.

Now, it seems still to be fairly normal to give a sequence of 
language-ranges in this header without any q= values, and expect the 
result to be deterministic.

Should this clarification be inserted into the updated HTTP document?
(The status of RFC 3282 is, btw, DRAFT STANDARD according to the RFC 
Editor's list)

                Harald
Received on Wednesday, 23 November 2011 15:42:14 GMT

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