Specifies the event that occurred. This value must be one of the event constants.
Identifies the kind of object that generated the event. This value is one of the predefined object identifiers or a custom object ID value.
Identifies whether the event was generated by an object or a child element of the object. If this value is CHILDID_SELF, the event was generated by the object itself. If not, this value is the child ID of the element that generated the event.