The OPC UA server's OpcUaServerAlarmDeviceExt processes the Acknowledge, Enable, and Disable commands. OpcUaServerAlarmDeviceExt is a child of each namespace component.  Each OPC UA server namespace has a frozen slot named AlarmExt. This extension is a type of OpcUaServerAlarmDeviceExt.  It keeps track of all of the alarmable points under this namespace.  When the extension receives an Acknowledge command for the OPC UA client, it attempts to locate the alarm record being acknowledged and acknowledges the alarm.  When the extension receives a Disable command, it disables the alarm from generating any more OPC UA events from the associated control point until it receives an Enable command.