VTAT
     It is valid to use an anchored type `AT' of the form
     `like anchor' in a class `C' if and only if it satisfies
     the following conditions:

        1 `anchor' is either `Current' or the final name
          of a query of `C'.

        2 `anchor' is not a cyclic anchor.

        3 The deanchored form `UT' of `AT' is valid in
          `C'.

     The base class and base type of `AT' are those of `UT'.