This field reports the number of bytes received per second on this PM instance, exposed here as cienaCesPmExtendedTxRxStatsBinRxBytesPerSec. On this Ciena CES port's PM data, this is a pre-computed rate gauge for the bin rather than a running total, letting you read this port's received-bandwidth directly without manually differencing two RxBytes polls and dividing by elapsed time yourself; 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, polling this field mid-bin and seeing 60,300,000 bytes/sec received tells you this port's live throughput right now, no extra math required.