We present work on a formal model for the composition of object-oriented modules, or hyperslices, which represent different perspectives on the system being built. With the model, we should be able to study existing approaches such as subject-oriented programming, as well as extend other object-oriented languages, such as the UML, to accommodate the use of hyperslices. We show here a sample of the specification language that accompanies the formal model, and a small example of its use.