This read-only string of up to 10 characters reports the state of the external acoustic alarm output that COMETMS drives to signal alarms outside the immediate unit, such as a siren or buzzer wired to the alarm-out contact. An administrator checks this to verify whether the device is actively signaling an alarm condition to site-wide audible equipment, distinct from the unit's own internal buzzer. For example, extAcc might read "ON" when a door-open alarm triggers the external siren connected to the cabinet's alarm-out relay.