This counts instances where a PDU's source individual address failed the screening policy configured via lportSmdsIaScrnOp and lportSmdsIaScrnMap, meaning the sender is a known address but is not permitted to originate traffic per this port's closed-user-group rules. An admin treats a rising count here as either a legitimate need to update the allowed-source list, or as evidence of an address trying to send traffic it should not be authorized to send. For example, a customer who was recently added to a partner's approved sender list but whose address has not yet been added to lportSmdsIaScrnMap would show up incrementing this counter until the screen map is updated.