Xie, Q. and D. Pearce, "RTP Payload Formats for European Telecommunications Standards Institute (ETSI) European Standard ES 202 050, ES 202 211, and ES 202 212 Distributed Speech Recognition Encoding", RFC 4060, DOI 10.17487/RFC4060, May 2005, <https://www.rfc-editor.org/info/rfc4060>.