This read-only Counter64 counts bytes received on this PM instance that the switch discarded outright, rather than forwarding or yellow-marking them. This is the counter an admin escalates on — sustained non-zero drops mean traffic on this flow point exceeded even the excess-rate allowance or hit a policy/resource limit, and whatever service rides this instance will show real loss; 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 EVC 212 (E-LAN) on a metro access ring, this might read 5,500,000 bytes over the current statistics window — a number an admin would divide by the bin length to sanity-check it against the port's 1,000,000,000-bps ceiling.