ApplicationDocumentChanged Event

public event EventHandler<DocumentChangedEventArgs> DocumentChanged

Public Event DocumentChanged As EventHandler(Of DocumentChangedEventArgs)

public:
 event EventHandler<DocumentChangedEventArgs^>^ DocumentChanged {
	void add (EventHandler<DocumentChangedEventArgs^>^ value);
	void remove (EventHandler<DocumentChangedEventArgs^>^ value);
}

member DocumentChanged : IEvent<EventHandler<DocumentChangedEventArgs>,
    DocumentChangedEventArgs>

This event is raised whenever a Revit transaction is either committed, undone or redone. This is a readonly event, designed to allow you to keep external data in synch with the state of the Revit database. To update the Revit database in response to changes in elements, use the IUpdater framework.