  We define a transverse correlation length suitable to discuss the
finite-size-scaling behavior of an out-of-equilibrium lattice gas, whose
correlation functions decay algebraically with the distance. By numerical
simulations we verify that this definition has a good infinite-volume limit
independent of the lattice geometry. We study the transverse fluctuations as
they can select the correct field-theoretical description. By means of a
careful finite-size scaling analysis, without tunable parameters, we show that
they are Gaussian, in agreement with the predictions of the model proposed by
Janssen, Schmittmann, Leung, and Cardy.
