Definition (RBox). A role box (RBox) R is a role hierarchy, a finite collection of generalized role inclusion axioms of the form RS, role equivalence axioms in the form RS, complex role inclusions of the form R1R2S, and role disjointness declarations of the form Dis(R, S), where R and S are roles, and transitivity axioms of the form R+R, where R+ is a set of transitive roles.