A Specification language. It expreSSeSblack box interface SpecificationS for large diStributed SyStemS with real-time conStraintS. It incorporateS conceptual modelS, inheritance and the event model. It iS a deScendant of MSG.84. ["An Introduction to the Specification Language Spec", V. BerzinS et al, IEEE Software 7(2):74-84 (Mar 1990)].