  New manifestly gauge-invariant forms of two-dimensional generalized
dispersive long-wave and Nizhnik-Veselov-Novikov systems of integrable
nonlinear equations are presented. It is shown how in different gauges from
such forms famous two-dimensional generalization of dispersive long-wave system
of equations, Nizhnik-Veselov-Novikov and modified Nizhnik-Veselov-Novikov
equations and other known and new integrable nonlinear equations arise.
Miura-type transformations between nonlinear equations in different gauges are
considered.
