The Object Constraint Language (OCL) is not a programming language; it is a formal expression language used to express constraints and conditions on object-oriented models. The evaluation of an OCL expression always delivers a value. It does not change anything in the system model. As an expression language OCL is also neutral about implementation decisions. This means that the usage of OCL is not tied to any specific platform or programming language.

The OCL is a subset of the UML (Unified Modeling Language), which is mainly used for documentation. Based on the Syntropy object-oriented analysis and design method, the OCL was originally developed within IBM as a language for business modeling. One of the guidelines of the OCL was that an easy-to-use standard was needed to document constraints. It was incorporated into the UML 1.1 specification in 1997 and is considered the standard notation...