Huang, R., Wu, Q., Asaeda, H., and G. Zorn, "RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG-2 Transport Stream (TS) Program Specific Information (PSI) Independent Decodability Statistics Metrics Reporting", RFC 6990, DOI 10.17487/RFC6990, August 2013, <https://www.rfc-editor.org/info/rfc6990>.