VMCN, chapter 11 (Repeated inheritance), page 189


        1  A  class  may  not  introduce   two   different
          features,  both deferred or both effective, with
          the same name.

        2 If a class introduces a feature  with  the  same
          name as a feature it inherits in effective form,
          it must rename the inherited version.

        3 If a class inherits two  features  as  effective
          from  different  parents  and they have the same
          name, the class must also (except under  sharing
          for  repeated inheritance) remove the name clash
          through renaming.