This read-only PerfCounter64 counts frames discarded because Elephant Flow rate limiting acted on this flow point, per its source description. It lets an administrator see when the device's large-flow detection mechanism actively shed frames from an oversized, sustained flow to protect fairness for other traffic sharing the flow point. For example, a large file-transfer session that suddenly gets throttled would show a corresponding rise in cmFlowPointHistoryEfFramesDiscarded during the transfer window.