This field reports the number of packet discards on this PM instance, exposed here as cienaCesPmExtendedTxRxStatsBinInDiscards. On this Ciena CES port's PM data, these are packets this port discarded despite arriving with no error at all — typically a policy action like an ACL deny, ingress rate-limit, or a full queue — which is a different problem class from the CRC/alignment error counters on this same table; 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 healthy port would sit at 0 for discarded packets in this bin; even 0 is enough to warrant a look, since this class of counter isn't supposed to move under normal operation.