  Generalizing the quantifiers used to classify correlations in bipartite
systems, we define genuine total, quantum, and classical correlations in
multipartite systems. The measure we give is based on the use of relative
entropy to quantify the "distance" between two density matrices. Moreover, we
show that, for pure states of three qubits, both quantum and classical
bipartite correlations obey a ladder ordering law fixed by two-body mutual
informations, or, equivalently, by one-qubit entropies.
