The (charged) free fermion formulation of the N-component KP hierarchies is
used for the description of quadrilateral lattices in terms of multicompon
ent KP eigenfunction potentials. Tan functions for these hierarchies are ex
plicitly calculated, giving rise to Grammian and Casorati determinant solut
ions to the (discretized) Darboux or Laplace equations describing the latti
ces. An example of localized tau functions and eigenfunction potentials is
given. (C) 1999 Published by Elsevier Science B.V.