Garcia-Martin, M., Bormann, C., Ott, J., Price, R., and A. Roach, "The Session Initiation Protocol (SIP) and Session Description Protocol (SDP) Static Dictionary for Signaling Compression (SigComp)", RFC 3485, DOI 10.17487/RFC3485, February 2003, <https://www.rfc-editor.org/info/rfc3485>.