Using box structures with the Z notation

The box structure method (BSM) provides a framework that can be used to introduce formality into the requirements specification stage of software development. A method of requirements specification is presented which integrates the Z notation with BSM. The requirements specification is confined to the top level black box specification and the corresponding top level state box specification. The authors describe criteria for good requirements specification and explain advantages of the integrated method for achieving them. Summary introductions are given to both BSM and Z followed by an examination of the relationship between the two methods. They explain the integrated method and illustrate it using a simple birthday reminder system. Finally, they discuss issues that have emerged from the use of this method and indicate areas for future research.<>