Object Constraint Language
(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 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.