ncE running, you cannot compare any result to the standardized values to determine the class of clock. Testing compli- ance to the recommendation requires following the rules on input signals. See section 7.1 of G.8273.2, which relates to noise generation, for detailed information on the various classes of T-BC/T-TSC. Tolerance to phase/time and frequency noise from the input (reference) signals: The tester applies a noise pattern to both the PTP message flow and the SyncE frequency signal while the engineer monitors the clock behavior. A pass result is when the DUT maintains its lock to the reference signal without switchover or moving into holdover. The PTP noise is a profile of PDV that is defined in G.8271.1 (it is an MTIE mask) and applied in either direction. This is effectively the same as the dTE network limit that would apply at the end of a chain of clocks. This makes sense, because the last clock in the chain, which receives the most dTE of all nodes, needs to be able to tolerate the maximum amount of dTE that the chain is permitted to accumulate. Simultaneously with the PTP noise, a frequency wander is applied to the SyncE input (see the noise tolerance test from the preceding section on the EEC/eEEC). According to the latest ver- sion of G.8273.2, the main difference between Class A/B and Class C compliance is that a Class C clock should meet the frequency wander tolerance from the enhanced G.8262.1 rather than the EEC specification in G.8262. Like the SyncE noise tolerance case, the behavior of the clock can also be monitored through QL values generated by the DUT (or clockClass as well). To pass, the clock should not signal any degradation in clock quality levels. Characteristics of the transfer of phase/time noise through the clock: This is a complicated set of tests to run, and many operators do not attempt them. G.8273.2 clause 7.3 defines several types of noise transfer, which are as follows: PTP to PTP and PTP to 1PPS transfer, which measures the transfer of phase/time error from the input to 