  Mean field analysis of the effective interfacial Hamiltonian shows that with
increasing temperature the adsorption on a periodically corrugated substrate
can proceed in two steps: first, there is the filling transition in which the
depressions of the substrate become partially or completely filled; then there
is the wetting transition at which the substrate as a whole becomes covered
with a macroscopically thick wetting layer. The actual order and location of
both transitions are related to the wetting properties of the corresponding
planar substrate and to the form of corrugation. Certain morphological
properties of the liquid-vapor interface in the case of a saw-like corrugated
substrate are discussed analytically
