system events

System events are generated, whenever the system state of an instance in an application changes. System events are the most common events, which refer to meta-states or the data, i.e. to information, which is not considered as attribute of an object. System events are events like birth and death, but also reading, updating or storing data. For more practical reasons, events like entering or leaving a collection are considered as system events, although those are in fact data attributes (membership states).