This chapter defines a framework based on Request for Comments (RFC) 5888 that obsoletes RFC 3388 to group media lines commonly known as “m” lines in the Session Description Protocol (SDP) for different purposes, such as expressing a particular relationship between two or more of them. This framework uses the “group” and “mid” SDP attributes, both of which are defined in RFC 5888 specification. Additionally, it specifies how to use the framework for two more important purposes: lip synchronization and for receiving a media flow consisting of several media streams on different transport addresses.