An event (OT_EVT) that is not a boundary event (not linked to an activity with a can trigger connection (CT_BPMN_CAN_TRIGGER)) must be placed in a BPMN collaboration diagram (BPMN 2.0) in an object of type Lane (OT_BPMN_LANE with a symbol ST_BPMN_LANE_1).
This restriction does not apply in a model of the BPMN process diagram (BPMN 2.0) type.