A Doppler tomogram maps the relative intensity of emission regions in a binary system, as a function of its velocity components. Keeping in mind that the maps do not display spatial distributions of these emission regions, the emission from an accretion disk and/or mass transfer stream should be located in a specific area of the velocity map. For example, a stable, Keplerian disk is expected to map into an annulus in the velocity map, which is centered on the gainer star (Horne 1991). Also, as displayed in Fig. 5.3, the trajectory of the mass transfer stream has a predicted free-fall and associated Keplerian trajectory on the Doppler map. Recall that two parcels of gas can have exactly the same Doppler coordinates on the tomogram. Therefore, attempts to determine the spatial location of the emitting regions is hampered by this coincidence. Nevertheless, interpretation of the resulting Doppler tomogram of KU Cygni, as calculated using the Fourier-filtered back-projection technique, can be accomplished. The following sections attempt to understand the Doppler map of the accretion disk of KU Cyg.