The LARCH family of formal specification languages and tools was originally developed in the USA. Its user community has now spread to Europe and several industrial trial firms are interested in using it in their system development programs. It differs from the other higher profile file languages such as Z and VDM in three respects: firstly, it was designed to specify programs rather than mathematical models and therefore addresses the complexities of real programs; secondly, it has been specifically developed as a practical tool for use in several major application domains; finally, it has a...