Scientic Decisions which Characterize VDM

Dedicated to the memory of Heinz-Peter Chladek Abstract. The formal description and development method known as VDM has been used extensively, its specication language is now an ISO standard, and it has influenced other specication languages. The origins of VDM are normally placed in language description or semantics but it is probably best known in the wider arena of formal methods for (general) program specication and design. This paper sets out a personal view of some of the key technical decisions which characterize the Vienna Development Method.