VNCS, chapter 13 (Conformance), page 219

     A signature `t' = (<B1', ..., `Bn>, <S>) conforms  to
     a  signature `s' = (<A1', ..., `An>, <R>) if and only
     if it satisfies the following conditions:

        1 Each of the two sequence components of  `t'  has
          the same number of elements as the corresponding
          component of `s'.

        2 Every type `Ti' in  each  of  the  two  sequence
          components  of `t' conforms to the corresponding
          type  `Si' in  the  corresponding  component  of
          `s'.
