6.3.3 MODELS AS TYPES

When a model serves as a modeling language, the configurations within that model are the only ones allowed in an instantiation of the modeling language. As shall be seen, the method of access to the values in the model are controlled as well. Essentially, models that define a modeling language are "types". Using a model as a type limits the choice of objects and links with which a design model instantiated under that type can be constructed.

For example, an "All_Patterns" modeling language contains objects representing all patterns conceivable. An instantiation in this language is the Stripe_Configs model, which select certain combinations of only stripes, as illustrated in Figure 73 (a). The model of Figure 73 (b) uses the previous Stripe_Configs model as its language. Only the configurations found in the Stripe_Configs are permissible within the Custom_Model model.

Figure 73 A Model and its Use as a Modeling Language