Traditionally, when field acquisition parameters are chosen, an underlying consideration is the ability to process and image the data to be recorded. For the choice of the length of the receiver spread, a limiting factor is the root-mean-square (rms) restriction: for reflections from the depth of interest, one need not record data for which the propagation angle is so large that it cannot safely be included in an rms velocity analysis. This restriction has led to various criteria for the determination of the largest useful offset which can be recorded. For example, the farthest offset should be less than the depth of interest. Recent advances in analysis of wide-angle arrivals compel us to re-evaluate such criteria.