This Counter64 counts errored seconds at the physical TDM path layer underlying this pseudowire (the 'p' suffix marks it as the path-layer counterpart to the PW-layer Es counter). Because this is the cumulative TdmPwTotalStatistics counter for the pseudowire, tallied since the bin's own start time rather than being reset every short collection interval, Esp specifically isolates errors seen on the TDM interface hardware itself, so a rise here (independent of the PW-layer Es) points at the TDM side of the circuit rather than the packet network. For example, Esp rising in step with a known marginal TDM line card, while the PW-layer Es counter for the same pseudowire stays low, confirms the errors are physical-layer, not packet-network, in origin.