+let compare_objs (v1,n1) (v2,n2) =
+ let b = compare_versions v1 v2 in
+ if b = 0 then compare_names n1 n2 else b
+
+let objs_union os1 os2 =
+ let error o = ET.EObjClash o in
+ list_union error compare_objs os1 os2
+
+let obj_of_role r =
+ let n = match r.ET.n with
+ | [] -> []
+ | (_,n):: _ -> n
+ in
+ r.ET.v, n
+
+let string_of_role r =
+ string_of_obj (obj_of_role r)
+
+let compare_roles r1 r2 =
+ compare_objs (obj_of_role r1) (obj_of_role r2)
+
+let roles_union rs1 rs2 =
+ let error r = ET.ERoleClash r in
+ list_union error compare_roles rs1 rs2
+