This read-only counter tracks input PDUs discarded because the destination NSAP address in the CLNP header was not valid for receipt at this entity, including addresses the entity simply does not understand. On an end system specifically, this counter effectively measures how many PDUs arrived whose destination NSAP was not local to that host, which would be unusual traffic for a non-forwarding device to receive at all. For example, an end system seeing this counter climb unexpectedly might indicate a misconfigured neighboring router is sending it transit traffic that it, as an end system, has no business receiving.