[en] Several methods have been devised for measuring the weak phase γ using decays of the type B→DK. It is shown that these and other direct CP-violation measurements suffer from discrete ambiguity which is at least 8-fold. Combining two measurement methods helps reduce the ambiguity and the experimental error. The measurement sensitivity and new physics discovery potential are estimated using a full Monte Carlo detector simulation with realistic background estimates, giving particular consideration to ambiguities. copyright 1999 The American Physical Society