  The scaling limit as T->0 of the antiferromagnetic three-state Potts model on
the square lattice is described by the sine-Gordon quantum field theory at a
specific value of the coupling. We show that the correspondence follows
unambigously from an analysis of the sine-Gordon operator space based on
locality, and that the scalar operators carrying solitonic charge play an
essential role in the description of the lattice model. We then evaluate the
correlation functions within the form factor approach and give a number of
universal predictions that can be checked in numerical simulations.
