Objects in information systems usually have a very long lifespan. Therefore, it often happens that during the life of an object external requirements are changing, e.g. changes of laws. Such changes often require the object to adopt another behavior. In consequence, it is necessary to get a grasp of dynamically changing object behavior. Unfortunately, not all possible changes can in general be taken into account in advance at specification time. Hence, current object specification approaches cannot deal with this problem. Flexible extensions of object specification are needed to capture such situations.