This Counter32 counts inbound frames on this virtual circuit that were dropped either because of format errors or because the VC itself was inactive at the time. An admin watches this to catch a circuit that is silently losing traffic, which might otherwise only show up as application-level timeouts. For example, a VC with a rising csFrCircuitDiscards count while csFrCircuitState still reads active would prompt the admin to check for malformed frames rather than assume the circuit is simply down.