This field reports the number of received frames dropped on this PM instance, exposed here as cienaCesPmBasicTxRxHistoryBinRxDroppedFrames. On this Ciena CES port's PM data, this is the frame-count companion to RxDroppedBytes — frames outright discarded on ingress for exceeding this port's bandwidth profile, distinct from frames merely remarked yellow; and this lives in the basic bandwidth-profile-aware PM group's history bin — a closed-out interval whose own Duration and State tell you how long it ran and whether it closed cleanly, so the number is settled rather than still being written to. For example, a healthy port would sit at 0 for dropped frames in this bin; even 4 is enough to warrant a look, since this class of counter isn't supposed to move under normal operation.