  Let A be a commutative noetherian ring, and \a an ideal in it. In this paper
we continue the study, begun in [PSY1], of the derived \a-adic completion and
the derived \a-torsion functors. Here are our results: (1) a structural
characterization of bounded above cohomologically complete complexes; (2) the
Cohomologically Complete Nakayama Theorem; and (3) a characterization of
cohomologically cofinite complexes.
