  The Dwarf Nova Oscillations observed in Cataclysmic Variable (CV) stars are
interpreted in the context of a Low Inertia Accretor model, in which accretion
on to an equatorial belt of the white dwarf primary causes the belt to vary its
angular velocity. The rapid deceleration phase is attributed to propellering.
Evidence that temporary expulsion rather than accretion of gas occurs during
this phase is obtained from the large drop in EUV flux.
  We show that the QPOs are most probably caused by a vertical thickening of
the disc, moving as a travelling wave near the inner edge of the disc. This
alternately obscures and `reflects' radiation from the central source, and is
visible even in quite low inclination systems. A possible excitation mechanism,
caused by winding up and reconnection of magnetic field lines, is proposed.
  We apply the model, deduced largely from VW Hyi observations, to re-interpret
observations of SS Cyg, OY Car, UX UMa, V2051 Oph, V436 Cen and WZ Sge. In the
last of these we demonstrate the existence of a 742 s period in the light
curve, arising from obscuration by the travelling wave, and hence show that the
two principal oscillations are a DNO and its reprocessed companion.
