Recommendation ITU-T G.8273/Y.1368 is a framework Recommendation for phase and time clocks for devices used in synchronizing network equipment that operate in the network architecture defined in Recommendations ITU-T G.8271, ITU-T G.8275 and the ITU-T G.8271.x series of Recommendations. Amendment 1 to Recommendation ITU-T G.8273/Y.1368 (03/2018) provides the following updates: -Updates References -Adds Appendix IV -Editorial changes in Annex B and minor edits throughout the document