1.    [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
    2.               Extensions (MIME) Part Two: Media Types", RFC 2046,
    3.               November 1996.
    5.    [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
    6.               Requirement Levels", BCP 14, RFC 2119, March 1997.
    8.    [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
    9.               Specifications: ABNF", STD 68, RFC 5234, January 2008.
    11.    [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
    12.               Protocol (HTTP/1.1): Message Syntax and Routing",
    13.               RFC 7230, June 2014.
    15.    [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
    16.               Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
    17.               June 2014.
    19.    [RFC7232]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
    20.               Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
    21.               June 2014.
    23.    [RFC7234]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
    24.               Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
    25.               RFC 7234, June 2014.
    27. 8.2.  Informative References
    29.    [BCP13]    Freed, N., Klensin, J., and T. Hansen, "Media Type
    30.               Specifications and Registration Procedures", BCP 13,
    31.               RFC 6838, January 2013.
    33.    [BCP90]    Klyne, G., Nottingham, M., and J. Mogul, "Registration
    34.               Procedures for Message Header Fields", BCP 90, RFC 3864,
    35.               September 2004.
    37.    [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
    38.               Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
    39.               Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
    41.    [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
    42.               IANA Considerations Section in RFCs", BCP 26, RFC 5226,
    43.               May 2008.