Every notification jaque sends is one of these kinds. This page is the catalogue: what fires each one, what silences it, what it does to the escalation ladder, what PagerDuty and incident.io do with it, and what a Nagios notification script sees in $NOTIFICATIONTYPE$.

Kind Fires when Silenced by Ladder PagerDuty / incident.io $NOTIFICATIONTYPE$
PROBLEM a hard problem persists, repeating every renotify_interval downtime, acknowledgement, unreachable parent, outside the period, disabled_kinds counts toward threshold, escalates trigger / firing PROBLEM
STATUS_CHANGE a hard problem changes status; not throttled downtime, acknowledgement, unreachable parent, outside the period, disabled_kinds counts toward threshold, escalates trigger / firing PROBLEM
RECOVERY a hard problem ends downtime, outside the period, disabled_kinds resets resolve / resolved RECOVERY
FLAPPING_START flapping starts downtime, outside the period, disabled_kinds untouched not posted FLAPPINGSTART
FLAPPING_STOP flapping stops downtime, outside the period, disabled_kinds untouched not posted FLAPPINGSTOP
ACKNOWLEDGEMENT an acknowledgement asks for it (the notify flag) outside the period, disabled_kinds untouched acknowledge / nothing ACKNOWLEDGEMENT
DOWNTIME_START a window starts outside the period, disabled_kinds untouched not posted DOWNTIMESTART
DOWNTIME_END a window ends outside the period, disabled_kinds untouched not posted DOWNTIMEEND
DOWNTIME_CANCELLED a window is cancelled while in effect outside the period, disabled_kinds untouched not posted DOWNTIMECANCELLED
CUSTOM an operator sends one by hand downtime, outside the period, disabled_kinds untouched not posted CUSTOM