(OCL) A formal specification language extension to UML. The Object Constraint Language is a precise text language that provides constraint and object query expressions on an object-oriented model that cannot otherwise be expressed by diagrammatic notation. OCL supplements UML by providing expressions that have neither the ambiguities of natural language nor the inherent difficulty of using complex mathematics. OCL is a descendent of Syntropy, a second-generation object-oriented analysis and design method. The OCL 1.4 definition specified a constraint language. In OCL 2.0, the definition has been extended to include general object query language definitions.