  The field of oscillation physics is about to make an enormous leap forward in
statistical precision: first through the MINOS experiment in the coming year,
and later through the NOvA and T2K experiments. Because of the relatively poor
understanding of neutrino interactions in the energy ranges of these
experiments, there are systematics that can arise in interpreting far detector
data that can be as large as or even larger than the expected statistical
uncertainties. We describe how these systematic errors arise, and how specific
measurements in a dedicated neutrino scattering experiment like MINERvA can
reduce the cross section systematic errors to well below the statistical
errors.
