This chapter considers "point models" of the vertical structure of currents, with particular reference to the case of combined wave and current flow. Theoretical models of vertical current structure have been developed extensively for the bottom boundary layers associated with steady currents, tidal currents, and gravity waves. The nature of the bottom boundary layer the seabed has been studied for many years by physical oceanographers and coastal engineers. Coastal engineers have tended to concentrate attention on the bottom boundary layers associated with surface waves, and on such phenomena as the stability of beaches and the scour around structures. In general, models of the combined wave and current bottom boundary layer have assumed the flow to be horizontally uniform, and have aimed to predict "at a point" the vertical distribution of properties such as the fluid velocity, shear stress, and turbulence intensity. Zero-Equation Models do not involve "transport equations" for turbulence quantities.