The alarm history table is a limited size table that contains recent alarms and alarm events. A number of events cause an entry to be added to the alarm history table: 'new' - a trap was sent and an alarm added to the alarm table 'changed' - an existing alarm was updated and a changed trap sent 'cleared' - an existing alarm was removed and a clear trap sent 'notification' - only a trap was sent 'mibcleared' - the entire MIB statistics were cleared 'usercleared' - a user requested a clear of the alarm history table Only a fixed maximum of alarm events are stored in this table at once and events are aged out of this table over time.