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Re: questions and comments about the Warning header

From: Jeffrey Mogul <mogul@pa.dec.com>
Date: Thu, 06 Jun 96 15:33:57 MDT
Message-Id: <9606062233.AA21094@acetes.pa.dec.com>
To: Anselm Baird-Smith <abaird@w3.org>
Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com, jg@w3.org
    The comment first: is there any reasons why the 'Warning' header is
    not stated in any of the {general,request,reply,entity}-headers
    (resp. sections 4.5, 5.3, 6.2 and 7.1). I think it's the only missing
    from the above lists (as far as I can tell), and I was wondering if
    there was some purpose behind this ?

Probably an oversight.  It looks like it should be a response-header
(section 6.2).
    
    The question: reading section 14.45 (and particularly the BNF), it is
    unclear to me that I am allowed to fold multiple Warning headers
    together (despite the text in section 2.2: "HTTP/1.1 headers can be
    folded onto multiple lines if the continuation line begins with a
    space or horizontal tab"). 
    
First of all, I think the folding rule in 2.2 applies to the
representation of a single header, not to the combination of
two different ones.

You probably should have quoted this from section 4.2:

    It MUST be
    possible to combine the multiple header fields into one "field-name:
    field-value" pair, without changing the semantics of the message, by
    appending each subsequent field-value to the first, each separated by a
    comma.

This suggests that the BNF for Warning is indeed subtly wrong.  It
now is

       Warning    = "Warning" ":" warn-code SP warn-agent SP warn-text
       warn-code  = 2DIGIT
       warn-agent = ( host [ ":" port ] ) | pseudonym
                       ; the name or pseudonym of the server adding
                       ; the Warning header, for use in debugging
       warn-text  = quoted-string

and I guess it should be

       Warning    = "Warning" ":" 1#warning-value
       warning-value = warn-code SP warn-agent SP warn-text
       warn-code  = 2DIGIT
       warn-agent = ( host [ ":" port ] ) | pseudonym
                       ; the name or pseudonym of the server adding
                       ; the Warning header, for use in debugging
       warn-text  = quoted-string

-Jeff
Received on Thursday, 6 June 1996 15:50:13 EDT

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