An event subprocess is a specialized subprocess that is used within a process or a subprocess. Unlike a standard subprocess which uses the flow of its parent process as a trigger, an event subprocess is not part of the normal flow of its parent process, there is no incoming and outgoing sequence flow. An event subprocess has a start event with a trigger. Each time the start event is triggered while the parent process is active, then the event subprocess will start.

The symbols of an event subprocess are shown below. If the event subprocess is collapsed, its start event is used as a marker in the upper left corner of the symbol. The software will render this marker.

There is a Boolean ARIS attribute type Event subprocess representing the BPMN attribute triggeredByEvent (see table under Subprocess type: Subprocess). This attribute type is read-only and used by the software.