1. A method of representing model-operative patterns, comprising: specifying, as a pattern codification for a particular pattern, structural features of the particular pattern and behavioral features of the pattern, wherein: the structural features identify at least one pattern role and at least one relationship involving the at least one pattern role; and the behavioral features identify how to use the structural features in constraining structural features of other composited patterns from which the particular pattern is composed or, when the particular pattern is not composed of other composited patterns, an operation to invoke for implementing the particular pattern.