Meaning of browser headers?

Discussion in 'HTML' started by joshbeall@gmail.com, Aug 4, 2006.

  1. Guest

    This isn't really an HTML question, but as HTTP is the protocol most
    often used to transport HTML, I thought some people here might have
    some insights. Furthermore I'm not sure where else to ask.

    Consider the following request headers (I used || to separate names and
    values):

    Accept||text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
    Accept-Charset||ISO-8859-1,utf-8;q=0.7,*;q=0.7
    Accept-Encoding||gzip,deflate
    Accept-Language||en-us,en;q=0.5

    I'm curious what the q=0.5 , q=0.7 and so forth indicate. Can someone
    enlighten me? Point me to a reference?

    -Josh
     
    , Aug 4, 2006
    #1
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  2. On 04/08/2006 18:16, wrote:

    [snip]

    > Accept||text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
    > Accept-Charset||ISO-8859-1,utf-8;q=0.7,*;q=0.7
    > Accept-Encoding||gzip,deflate
    > Accept-Language||en-us,en;q=0.5
    >
    > I'm curious what the q=0.5 , q=0.7 and so forth indicate.


    They are referred to as "quality values" though that's a misnomer. They
    indicate a relative weight, allowing the browser to specify which
    content type, language, etc. is preferred. This allows the server to
    choose the best possible representation (assuming there's more than one)
    during content negotiation.

    The values range from zero (0) to one (1), with at most three decimal
    places. A value of zero means that item - character encoding, language,
    whatever it may be - is not acceptable; the server should never return
    something matching it. If there is no explicitly associated quality
    value, it is assumed to be 1.0.

    > Can someone enlighten me? Point me to a reference?


    RFC 2616[1] (HTTP/1.1) is the definitive reference. Quality values are
    described in section 3.9 Quality Values. HTTP headers are listed within
    chapter 14 Header Field Definitions.

    Mike


    [1] RFC 2616 Hypertext Transfer Protocol -- HTTP/1.1
    <http://www.ietf.org/rfc/rfc2616.txt>
     
    Michael Winter, Aug 4, 2006
    #2
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