Recommendation ITU-T G.8260 provides the definitions, terminology and abbreviations used in Recommendations on frequency, phase and time synchronization in packet networks. It includes mathematical definitions for various synchronization stability and quality metrics for packet networks, and also provides background information on the nature of packet timing systems and the impairments created by packet networks. This revision provides the following updates: Edits to definitions 3.1.2, 3.1.16, 3.1.18, 3.1.19, 3.1.20, 3.1.26. New definition 3.1.30 UTC time signal source. New definition 3.1.31 compensation. New definition 3.1.32 constant temperature. New definition 3.1.33 transient response. New definition 3.1.34 congruent time and frequency. New definition 3.1.35 synchronization networks and systems resiliency. New acronym BIPM International Bureau of Weights and Measures (“Bureau International des Poids et Mesures”) New acronym TAI International Atomic Time (“Temps Atomique International”) Edits to clause 6.5. Edits to Appendix II Time scales.