  Several time-independent methods have been devised for measuring the phase
gamma of the Cabibbo-Kobayashi-Maskawa unitarity triangle. It is shown that
such measurements generally suffer from discrete ambiguity which is at least
8-fold, not 4-fold as commonly stated. This has serious experimental
implications, which are explored in methods involving B->DK decays. The
measurement sensitivity and new physics discovery potential are estimated using
a full Monte Carlo detector simulation with realistic background estimates.
