This read-write attribute specifies the action taken on packets from a given learned MAC address entry - learned, processor, upstream, or reject - noting that entries the STU itself learned automatically become read-only. It gives an admin fine-grained control to block a specific device's traffic without disturbing the STU's normal auto-learning behavior for everything else. For example, to stop an unauthorized device identified in the learned-MAC table from reaching the network, an operator would set that entry's stuEtherMacType to reject.