Unreachable states in model-oriented specifications

Formal specification methods are being used to improve the quality of written specifications and to eliminate errors at an early stage of software development. The detection of errors in a specification generally requires that the specification be compared against some loosely defined real-world concepts. A criterion for evaluating the quality of a model-oriented specifications is introduced and the problems associated with specifications which do not meet this criterion are explained. These problems are particularly troublesome when reusable software components are being specified or when a bottom-up implementation strategy is being used