VGCP, chapter 18 (Creating objects), page 285

     Creation_clause rule

     A Creation_clause appearing in the Creators part of a
     class  `C'  is  valid if and only if it satisfies the
     following four conditions:

        1 `C' is effective.

        2 For  every identifier `fname'  in  the  clause's
          Feature_list,  `fname' is  the  final name  of a
          procedure of `C'.

        3 For  every identifier `fname'  in  the  clause's
          Feature_list,  `fname' appears  only once in the
          Feature_list.

        4 If `C' is expanded, the version of the procedure
          `default_create' (inherited from ANY)  is listed
          in Feature_list.