  We consider a non-equilibrium three-state model whose dynamics is Markovian
and displays the same symmetry as the three-state Potts model, i.e., the
transition rates are invariant under the permutation of the states. Unlike the
Potts model, detailed balance is in general not satisfied. The aging and the
stationary properties of the model defined on a square lattice are obtained by
means of large-scale Monte Carlo simulations. We show that the phase diagram
presents a critical line, belonging to the three-state Potts universality
class, that ends at a point whose universality class is that of the voter
model. Aging is considered on the critical line, at the voter point and in the
ferromagnetic phase.
