We propose an Executable Requirements Specification Language(EXERSL) to accurately express data flow diagrams which are widely used in systems analysis and design. A requirements specification written in EXERSL serves as an executable model for the diagrams. The oprational semantics of this specification language is defined using Vienna Definition Language(VDL). A semantic net processor used for maintaining the specification is also described.
The hierarchical characteristics of data flow diagrams is incorporated into the operational semantics of EXERSL, and a technique using a semantic net is applied to facilitated the maintenance of the requirements specification.
