 between any two outputs of T-BC) This recommendation defines T-BC and T-TSC clocks into four classes based on their performance, known as Class A through D (in order of increasing accuracy). Class A and B clocks are appropriate to deploy together with SyncE (G.8262) or some equivalent TDM-based method. For Class C and D clocks, the values in the recommendation were developed based on simulations that assume it is be- ing deployed with eSyncE (G.8262.1). The importance of these classes of clocks will become apparent in the sections on deployment and time error budgeting. Obviously, the more accurately that a clock can transport time, the more clocks the time can pass through without exceeding the end-to-end budget limits. Similarly, the time error delivered to an application at the end of a chain of clocks can be minimized by utilizing clocks with a lower contribution to the overall time error. There are two versions of this recommendation consented in March and October 2020. Link to recommendation: https://handle.itu.int/11.1002/1000/14507 G.8273.3: Timing Characteristics of Telecom Transparent Clocks for Use with Full Timing Support from the Network ITU-T G.8273.3 defines the minimum requirements for telecom transparent clocks (T-TCs) when used to transport time and phase over a packet network with full timing support. From the scope of the recommendation: This Recommendation specifies minimum requirements for time and phase synchronization devices used in synchronizing network equipment. It supports time and/or phase syn- chronization distribution for packet-based networks. This Recommendation defines the minimum requirements for transparent clocks. These re- quirements apply under normal environmental conditions specified for the equipment. This recommendation includes the following main topics and appendixes: Physical layer frequency performance requirements. T-TC performance requirements. It includes parameters for maximum absolute time error noise generation (max|TE|, constant time error (cTE), filtered dy