behavior as a MIME user agent would upon receipt of a multipart type.
   If an application receives an unrecognized multipart subtype, the
   application MUST treat it as being equivalent to "multipart/mixed".

     Note: The "multipart/form-data" type has been specifically defined
     for carrying form data suitable for processing via the POST request
     method, as described in RFC 1867 [15].







 
RFC 2068                        HTTP/1.1                    January 1997


3.8 Product Tokens

   Product tokens are used to allow communicating applications to
   identify themselves by software name and version. Most fields using
   product tokens also allow sub-products which form a significant part
   of the application to be listed, separated by whitespace. By
   convention, the products are listed in order of their significance
   for identifying the application.

          product         = token ["/" product-version]
          product-version = token

   Examples:

          User-Agent: CERN-LineMode/2.15 libwww/2.17b3
          Server: Apache/0.8.4

   Product tokens should be short and to the point -- use of them for
   advertising or other non-essential information is explicitly
   forbidden.  Although any token character may appear in a product-
   version, this token SHOULD only be used for a version identifier
   (i.e., successive versions of the same product SHOULD only differ in
   the product-version portion of the product value).

3.9 Quality Values

   HTTP content negotiation (section 12) uses short "floating point"
   numbers to indicate the relative importance ("weight") of various
   negotiable parameters. A weight is normalized to a real number in the
   range 0 through 1, where 0 is the minimum and 1 the maximum value.
   HTTP/1.1 applications MUST NOT generate more than three digits after
   the decimal point. User configuration of these values SHOULD also be
   limited in this fashion.

          qvalue         = ( "0" [ "." 0*3DIGIT ] )
                         | ( "1" [ "." 0*3("0") ] )

   "Quality values" is a misnomer, since these values merely represent
   relative degradation in desired quality.

3.10 Language Tags

   A language tag identifies a natural language spoken, written, or
   otherwise conveyed by human beings for communication of information
   to other human beings. Computer languages are explicitly excluded.
   HTTP uses language tags within the Accept-Language and Content-
   Language fields.





 
RFC 2068                        HTTP/1.1                    January 1997


   The syntax and registry of HTTP language tags is the same as that
   defined by RFC 1766 [1]. In summary, a language tag is composed of 1
   or more parts: A primary language tag and a possibly empty series of
   subtags:

           language-tag  = primary-tag *( "-" subtag )

           primary-tag   = 1*8ALPHA
           subtag        = 1*8ALPHA

   Whitespace is not allowed within the tag and all tags are case-
   insensitive. The name space of language tags is administered by the
   IANA. Example tags include:

          en, en-US, en-cockney, i-cherokee, x-pig-latin

   where any two-letter primary-tag is an ISO 639 language abbreviation
   and any two-letter initial subtag is an ISO 3166 country code. (The
   last three tags above are not registered tags; all but the last are
   examples of tags which could be registered in future.)

3.11 Entity Tags

   Entity tags are used for comparing two or more entities from the same
   requested resource. HTTP/1.1 uses entity tags in the ETag (section
   14.20), If-Match (section 14.25), If-None-Match (section 14.26), and