Parameterized modules, theories and views are the basic building blocks of parameterized programming [7, 27]. As in OBJ, a theory defines the interface of a parameterized module, that is, the structure and properties required of an actual parameter. The instantiation of the formal parameters of a parameterized module with actual parameter modules requires a view from the formal interface theory to the corresponding actual module. That is, views provide the interpretation of the actual parameters.