This field reports the number of single collision packets transmitted on the interface, exposed here as cienaCesPmExtendedTxRxStatsBinTxSingleCollPkts. On this Ciena CES port's PM data, a single collision followed by a successful retransmit is routine background noise on a shared or half-duplex segment, so this counter climbing steadily (without TxExCollPkts or TxLateCollPkts climbing alongside it) is generally benign; and this sits in the currently active extended Tx/Rx interval bin — its sibling StartTime/ClearTime fields mark exactly which window is being counted, so a change here reflects activity happening in the live collection interval, not something already filed away in history. For example, a link under light load might show a low but steady 25 single-collision frames for this bin; it's the rate of growth, not the presence of a nonzero number, that would flag a real problem.