controls the wall penetrability, the limit $p \to \infty$ corresponding to a perfectly rigid (impenetrable) wall. It has been shown previously that for both the MN1 and the MN2 classes the magnitude of $p$ does not influence the asymptotic properties at criticality [@MN1; @MN2] (its sign, however, is important, as it determines whether the wall is a lower or an upper one). The same property applies to equilibrium systems ([*i.e.*]{}, for $\lambda =0$) [@lipowskyfisher]. $\eta$ is a stochastic white noise with $\langle \eta \rangle =0$ and $\langle \eta(x,t) \eta(x',t') \rangle = 2 \delta(t-t') \delta (x-x')$, where $\langle \cdot \rangle$ denotes an average over the distribution of the noise.

For a fixed value of $b$ the interface experiences a pinning-depinning transition at some value $a=a_c$.

Some remarks concerning the connection of the previous equation with wetting problems follow. When $h(x,t)$ is viewed as the distance separating a liquid-gas interface from a solid wall, Eq. (\[BKPZ\]) can then be interpreted as a dynamic model for nonequilibrium wetting. Under this perspective $a$ is the chemical potential difference between the liquid and the gas phases, $\langle h \rangle$ is the thickness of the wetting layer, and the wall is a rigid, physical substrate. At 