This PerfCounter64 counts Frames Marked Yellow by a QoS Policer in the current bin, i.e. frames found to exceed the committed rate but still forwarded, marked for possible later discard under congestion. An admin watches live yellow-marked frame counts to see how much traffic is currently running above its committed rate but is still being let through, which is useful for anticipating downstream congestion-triggered drops. If f3FpQosPolicerStatsFMY climbs steadily through the bin on a customer's policer, the admin knows that customer is regularly exceeding their committed rate even though none of that traffic has been discarded yet.