This book constitutes the refereed proceedings of the First International Conference of B and Z Users, ZB 2000, held in York, UK in August/September 2000.
The 25 revised full papers presented together with four invited contributions were carefully reviewed and selected for inclusion in the book. The book documents the recent advances for the Z formal specification notion and for the B method; the full scope, ranging from foundational and theoretical issues to advanced applications, tools, and case studies, is covered.

Formal methods have been established as the rigorous engineering methodology for the system development. Applying formal methods to a large and complex system development often requires the modelling of different aspects of such a system. For instance, complex systems (such as integrated avionics systems, engine control software) can involve functional and timing requirements that must be eventually implemented as executing code on a communicating distributed topology. This book contains the papers presented at the First International Workshop on Integrated Formal Methods, held at the University of York in June 1999. The conference provided a forum for the discussion of theoretical aspects of combing behavioural and state-based formalisms and practical solutions to the industrial problems of this approach.