6.4.3 TYPES OF MODEL BEHAVIOR
A model is created or destroyed under the terms of another model, a model which the created or destroyed model is not necessarily aware. As such, these actions are called meta-actions. A model needs to be created under some other type model.
Destruction is not necessarily a self-determined thing. Outside record- keeping may be necessary. For a model to be destroyed without deference to the system within which it resides, the destruction places unnecessary burden to the system. Although it may register itself for communication, other objects may think this object is still available and attempt to communicate with the destroyed object. This places the overhead of existence checking on each attempt at communication, which can be burdensome.
Meta-actions must be associated with models other than the object. While there is a interdependence between a model and its meta-model, the model is not necessarily aware of any associations with the meta-model.