Interpreting the object constraint language

The Object Constraint Language (OCL), which forms part of the UML 1.1. set of modelling notations is a precise, textual language for expressing constraints that cannot be shown in the standard diagrammatic notation used in UML. A semantics for OCL lays the foundation for building CASE tools that support integrity checking of whole UML models, not just the component expressed using OCL. This paper provides a semantics for OCL, at the same time providing a semantics for classes, associations, attributes and states.