Amendment 1 to Recommendation ITU-T G.8263/Y.1363 (2012) adds clarification to several clauses and introduces Appendix IV "Variable temperature testing methodology".
ITU-T Y.1363 AMD 1-2013 history
2013ITU-T Y.1363 AMD 1-2013 Timing characteristics of packet-based equipment clocks Amendment 1 (Study Group 15)