A new IETF Internet Draft "provides a framework for communicating information elements (a.k.a. metadata) in a consistent manner between applications and the network to provide better visibility of application flows, thereby enabling differentiated treatment of those flows. These information elements can be conveyed using various signaling protocols, including PCP, RSVP, and STUN".
Authors are: Toerless Eckert, Reinaldo Penno, Amine Choukir and Charles Eckel [pictured] - all from Cisco.
See "A Framework for Signaling Flow Characteristics between Applications and the Network" - here.