What does the event mask mean?
When an event gets into the OpenNMS event subsystem, it typically contains only information specific to that occurence of the event. Other information for the event (severity, description, autoaction etc.) are picked up from the eventconf.xml. To pick up relevant information, the uei (Universal Event Identifier) is used by default. However, this does not work in some cases, like in the case of SNMP traps – traps get converted into events and are sent into the event subsystem – in order to facilitate picking up relevant information for the traps and other similar events, the event masks are used.
