  The paper discusses the concept of separation of quantum mechanical systems
in the algebraic approach. We review known theorems, then establish a link
between the C*-algebraic and the corresponding W*-algebraic concepts. A
characterization of separation in terms of Bell inequalities, due to Raggio
(1988), is given a C*-algebraic formulation. Finally, we comment on the
implications for the understanding of the Bell inequalities.
