  Present and planned dark matter detection experiments search for WIMP-induced
nuclear recoils in poorly known background conditions. In this environment, the
maximum gap statistical method provides a way of setting more sensitive cross
section upper limits by incorporating known signal information. We give a
recipe for the numerical calculation of upper limits for planned directional
dark matter detection experiments, that will measure both recoil energy and
angle, based on the gaps between events in two-dimensional phase space.
