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• No policy actions are performed for events with the property action_checked set to 1 or for events that are (already) acknowledged.
  The former can be controlled by custom parser rules, the latter is mostly affected by the configuration options opevents_auto_acknowledge and opevents_auto_acknowledge_up:
  With auto-acknowledge enabled, a stateful down event is automatically acknowledged when the corresponding up event arrives. In that case, the up event itself is also automatically acknowledged if and only if opevents_auto_acknowledge_up is set.
• If the configuration option opevents_no_action_on_flap is set to true in conf/opCommon.nmis, then no actions are performed on the down event that is involved in a flap event. , and the down event is acknowledged. This is the default behaviour.
• Policy action handling is delayed by state_flap_window seconds for all stateful events, so that state flaps can be detected before any actions are performed.
• Policy action handling is delayed for synthetic events, if the event creation rule sets the property delayedaction.

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