and has slope $0.8$.](Fig5.eps "fig:"){width="6cm"} \[fattaheta\]

We have also considered different variations of the model in which the interface can penetrate the wall at some points, [*i.e.*]{} the wall is not perfectly rigid. None of the universal features seem to be affected by this change.

In conclusion, all these results support strongly the existence of robust universality in the MN2 class.

As a matter of consistency, we have modified the algorithm of the model to simulate a lower wall, and therefore a case expected to be in the MN1 class. We obtain the set of exponents $ \beta_n=1.69, \theta_n= 1.19$ and $\eta = -0.4$, all of them in agreement we previously reported results and showing that the upper and lower problem belong to different universality classes [@Review; @MN2; @MN4].

Numeric integration of stochastic differential equations
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As a further test for universality, we have numerically integrated Eq. (\[BKPZ\]) using a Milshtein’s algorithm [@Maxi]. A system size of $L=2000$ was considered and the time step and mesh size were set to $\Delta t =0.001$ and $\Delta x=1$, respectively. For simulation times up to $t=10^{6}$ ($10^9$ trials per site) our results lie far from the asymptotic regime. We do not discard numerical 