We define a soft-spins approach to the driven lattice gas model (C-DLG) at
the level of a master equation. As a result, we obtain a Langevin equation
for the C-DLG which depends on the microscopic transition probabilities. We
then show how this dependence affects the critical behavior of the the C-D
LG, placing the finite- and the infinite-driving-field cases into different
universality classes. In the same vein, we propose a continuum description
of two other well-known anisotropic, conservative, nonequilibrium models:
the two-temperature model (C-TT) and the randomly driven model (C-RDLG). We
show that the C-RDLG with infinite averaged field and the C-TT with T-\\ =
infinity fall in the same universality class as the infinitely driven C-DL
G. A Langevin equation For the driven bilayer lattice gas model is also pre
sented.