Definition (RBox). A role box (RBox) R is a role hierarchy, a finite collection of generalized role inclusion axioms of the form R ⊑ S, role equivalence axioms in the form R ≡ S, complex role inclusions of the form R1 ◦ R2 ⊑ S, 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.