Some years back, Muir & Dellinger (1985), in an attempt to simplify the processing of multi-component seismic data, introduced a system of equations that unified ray and wave theory in an approximate manner. This allowed, for example, time/offset relations to be converted to dispersion relations which could then form the basis for anisotropic imaging schemes.
This paper removes one drawback from that scheme--the use of an anelliptic factor that had no counterpart in normal experience--and broadens it sufficiently that it could find application in the three geometries now in common use, surface-to-surface, borehole-to-surface, and borehole-to-borehole.