  Solvable via Bethe Ansatz (BA) anisotropic statistical model on cubic lattice
consisting of locally interacting 6-vertex planes, is studied. Symmetries of BA
lead to infinite hierarchy of possible phases, which is further restricted by
numerical simulations. The model is solved for arbitrary value of the
interlayer coupling constant. Resulting is the phase diagram in general
3-parameter space. Exact mapping onto the models with some inhomogenious sets
of interlayer coupling constants is established.
