None events are unspecified events, also called ‘blank’ events.
A process can have at most one none start event (besides other types of start events).
A none start event is where the process instance or a subprocess starts when the process or the subprocess is activated.
A process or subprocess can have multiple none end events. When a none end event is entered then the current execution path ends. If the process instance or subprocess has no more active execution paths then it is completed.
If an activity has no outgoing sequence flow then it behaves the same as it would be connected to a none end event. When the activity is completed then the current execution path ends.
A none start event:
A none end event: