http://www.ietf.org/rfc/rfc1939.txt
http://www.ietf.org/rfc/rfc2045.txt
http://www.ietf.org/rfc/rfc2109.txt
http://www.ietf.org/rfc/rfc2387.txt
http://www.ietf.org/rfc/rfc2518.txt
http://www.ietf.org/rfc/rfc2616.txt
http://www.ietf.org/rfc/rfc2822.txt
http://www.ietf.org/rfc/rfc2965.txt
http://www.ietf.org/rfc/rfc822.txt
