This read-only Counter64 counts frames — not bytes — received on this PM instance that the switch accepted. Pairing it with the accepted-bytes counter on the same instance lets an admin derive the average accepted frame size, which flags whether the link is carrying many small control/voice frames or fewer large bulk-data frames; because it is drawn from the grand-total statistics bin for this PM instance, it aggregates across the whole PM instance rather than any single rotating window, so it's the number to cite for a service's overall lifetime performance rather than its behavior in one interval. On a 10 Gbps aggregation trunk carrying multiple EVCs, this might read 37,500,000 frames over the current statistics window, which an admin would cross-check against the matching byte counter to see if average frame size looks normal for that service.