The mathematical concepts and notational conventions we know of as Z were first proposed around 1981. Its origins were in line with the objectives of the PRG - to establish a mathematical basis for program ming concepts and to verify the work by case studies with industry. Hence among early Z users some were from academic circles, with interests in the mathematical basis of programming; others came from industry and were involved with pilot projects and case studies linked with the Programming Research Group. Four years ago we had the first Z User Meeting, a fairly modest affair with...