Formal specification in Z as a design and documentation tool

A general specification language, Z, based on set theory and developed at Oxford University is presented. A major advantage of a formal notation is that it is precise and unambiguous and thus the formal notation always provides the definitive description in the case of any misunderstanding. A number of examples are discussed, including network services, window systems, and microprocessor instruction sets. This paper is split into two main parts. The first half deals with the nature of formal specification and why it should be used. Additionally, a brief introduction to Z and how it is used is also presented in general terms, without covering the notation itself. The second half of the paper deals with the experiment gained using Z for the design and documentation of network services and during some case studies of existing systems. Finally some conclusions are drawn about the advantages and disadvantages of using a formal approach