We present an approach for classifying and retrieving reusable software
based on exemplary descriptions of its functionality. The functionality of
reusable components is described by a set of tuples with each tuple
representing a characteristic input-output (or stimulus-response)
transformation of the component at hand. With careful choice of these
characteristic tuples, information equivalent to conventional formal
specifications is given, except that (re-)users not versed in formal
specification can provide such queries.

The concept just introduced depends on the discriminative potential of the
tuples provided and on the equivalence of behavior representations by the
librarian and by the (re-)user. The former can be assured by the librarians
professionalism, the latter by an adequate user-interface of the system
supporting a dialog, based on what the system has to offer rather than on
guesses about what the (re-)user is looking for.