  Use case driven development methodologies put use cases at the center of the
software development process. However, in order to support automated
development and analysis, use cases need to be appropriately formalized. This
will also help guarantee consistency between requirements specifications and
the developed solutions. Formal methods tend to suffer from take up issues, as
they are usually hard to accept by industry. In this context, it is relevant
not only to produce languages and approaches to support formalization, but also
to perform their validation. In previous works we have developed an approach to
formalize use cases resorting to ontologies. In this paper we present the
validation of one such approach. Through a three stage study, we evaluate the
acceptance of the language and supporting tool. The first stage focusses on the
acceptance of the process and language, the second on the support the tool
provides to the process, and finally the third one on the tool's usability
aspects. Results show test subjects found the approach feasible and useful and
the tool easy to use.
