VTCG, chapter 12 (Types), page 203

     Constrained Genericity rule

     Let `C' be a constrained generic class. A  Class_type
     `CT' having `C' as base class is valid if and only if
     `CT'  satisfies  the  Unconstrained  Genericity  rule
     (VTUG,  page  201)  and,   in   addition,   for   any
     Formal_generic parameter `G' in  the  declaration  of 
     `C'   having  a   constraint,  then  if  `D'  is  the
     Class_type listed  in  the  constraint and `T',  with
     base class `BT', is the Type corresponding to  `G' in
     the Actual_generics list of `CT':

        3 `T' conforms to the  type  obtained from `D'  by
          substituting any  occurence of a formal  generic
          parameter  of  `C' by  the  corresponding actual
          parameter.

        4 If the constraint for `G' has a Generic_creators
          part, the `C' version of every procedure of `BT'
          listed (as per rule VTCC, page 201) in that part
          is declared in `BT' as a creation procedure.