The Use of Z

During 1990 and 1991 we carried out a survey of Z users in the UK; in this paper we present the results. Z is being used by a wide variety of companies for many different applications. Many institutions use Z because they choose to, rather than because it is mandated by a defence or security related client. Half of the participants in the survey were first-time users of Z; with a little training and some expert guidance they were soon able to produce Z specifications. Nearly all the institutions who have used Z intend to do so again; those who don’t plan to use a formal method more appropriate to their needs. We did not uncover many really large projects using Z, but most of those which we did survey are of a reasonable size. Over half the projects surveyed are using tools, with the majority of them employing type checking support. Tools use grows with the size of the project, although several large specifications have been produced without the use of tools. Not many people are proving their specifications, nor stating desirable theorems or proof obligations. However, many people expressed an interest in this with the unavailability of appropriate tool support being given as a reason for not attempting proof.