 One corollary of this generalization is that if A and B have two distinct binary common causes C and D, we would expect each of \(CD, C\overline{D}, \overline{C}D, \overline{CD}\) to screen off A and B, but would not expect C and D to screen off A and B. For example, even if we condition on the common cause C, we would expect A and B to be correlated because of the further common cause D.