On Event Timeout process starter

The On Event Timeout process starter specifies a process to execute
when a Wait For ... activity discards an incoming event due to a
timeout. A Wait For ... activity’s event timeout is specified by the
Event Timeout field on the Event tab of the activity.
The default behavior for an event timeout is to confirm and then discard the
event. You can override the default behavior by creating a process definition
using the On Event Timeout process starter.
You can specify an On Event Timeout process definition for a specific event source
(that is, a specific Wait For... activity). You can specify one or more On Event
Timeout process definitions for specific event sources, but you should not create
more than one process definition for the same event source. Once a Wait For...
activity experiences a timeout, that timeout can only apply to one On Event
Timeout process definition.
You can also specify that an On Event Timeout process definition applies to any
event source that experiences a timeout. If there is no On Event Timeout specified
for a particular event source, the process engine calls the On Event Timeout
process definition whose Any Event Source field is checked.