  We consider the set of all matrices of the form $p_{ij}=tr[W(E_{i}\otimes
F_{j})]$ where $E_{i}$, $F_{j}$ are projections on a Hilbert space $H$, and $W$
is some state on $H\otimes H$. We derive the basic properties of this set,
compare it with the classical range of probability, and note how its properties
may be related to geometric measures of entanglement.
