  Phases of elements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, as obtained
using decays of $B$ mesons to $\pi^+ \pi^-$, $\pi^\pm K^\mp$, and $\pi^+ K^0$
or $\pi^- \overline{K}^0$, are shown to have a class of discrete ambiguities.
In most cases these can be eliminated using other information on CKM phases.
