This read-create object holds the specified ATM address of the Broadcast and Unknown Server on the interface, and the description warns that setting it reinitializes the BUS and drops all clients connected to it; if left unspecified at row creation, the BUS chooses a value itself and registers with the switch. Because changing this value forcibly reinitializes the BUS and drops every LEC client currently connected, this is not a setting to tweak on a live, in-service emulated LAN without expecting an outage, it's really meant to be set, or left blank for auto-assignment, at initial provisioning time. Changing this on a BUS already serving 40 active LEC clients would immediately disconnect all 40 of them as the BUS reinitializes and re-registers its address with the switch.