  We define spatial CPD-semigroup and construct their Powers sum. We construct
the Powers sum for general spatial CP-semigroups. In both cases, we show that
the product system of that Powers sum is the product of the spatial product
systems of its factors. We show that on the domain of intersection, pointwise
bounded CPD-semigroups on the one side and Schur CP-semigroups on the other,
the constructions coincide. This summarizes all known results about Powers sums
and generalizes them considerably.
