This object indicates the information for the device MAC address changes. And the detailed information include: Operation Code + MAC address + Box ID + Port Number + Zero... Operation Code: 1, 2 and 3 1 means learned a new MAC address 2 means deleted an old MAC address. 3 means station movement. Box ID: The switch box ID, for standalone device, it always 1. Port Number: The port number learned or deleted for the box. Zero: Used to separate each message (Operate Code + MAC address + Box ID + Port Number).