Z Base Standard, Verson 1.0

and incorporating many changes proposed and decided by the committee. Version 0.4 (9th December 1991): Substantially the same as Version 0.3, incorporating corrections to minor typographical errors. Version 0.5 (20th March 1992): Revision and extension of Version 0.4, with new introductory sections, an extensive revision of the deenition of expression, and many other corrections and improvements. Version 0.6 (21st October 1992): Major revision, in which sections containing the language description have been restructured and updated, and all other sections have been revised. The following new sections are included in this version: the Z Interchange Format and a Logic for Z. Version 1.0 (30th November 1992): A version prepared for distribution at the 7th Z User Meeting and subsequent general distribution, incorporating changes made by the Z Standards Review Committee. These include enhancements to the Language Description sections and the Annexe describing A deductive system for Z (previously called A logic for Z), also modiications to several other sections. This document may be reproduced provided copies are not sold for proot and provided this copyright notice and acknowledgement of the source of the material is included with each copy, together with the version number of the document from which it has been copied. Acknowledgement Preparation of this paper has been undertaken as part of the ZIP project. Contributors The Z notation and its mathematical foundations have been developed by many people. A selected list of papers tracing a history of Z development is included in the References at the end of this document (see page 201). In addition to the listed contributors to the mathematical foundations of Z, many programmers, systems designers and architects have provided support by using Z and giving feedback to the designers of the notation. A more complete acknowledgement of contributions to the development of Z will be included in a History of Z to be published separately. Development of the Z Base Standard as part of the ZIP project has beneeted from contributions and reviews by the Z Standards Review Committee. The following list includes members of the SRC and their alternates or deputies.