http://www.rfc-editor.org/rfc/rfc4566.txt
RFC 4566: SDP: Session Description Protocol, M. Handley, V. Jacobson, C. Perkins2006-07-01T23:00:00-00:00This memo defines the Session Description Protocol (SDP). SDP is intended for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. [STANDARDS-TRACK]