  The generalized Zakharov-Shabat systems with complex-valued non-regular
Cartan elements and the systems studied by Caudrey, Beals and Coifman (CBC
systems) and their gauge equivalent are studied. This study includes: the
properties of fundamental analytical solutions (FAS) for the gauge-equivalent
to CBC systems and the minimal set of scattering data; the description of the
class of nonlinear evolutionary equations, solvable by the inverse scattering
method, and the recursion operator, related to such systems; the hierarchies of
Hamiltonian structures. The results are illustrated on the example of the
multi-component nonlinear Schrodinger (MNLS) equations and the corresponding
gauge-equivalent multi-component Heisenberg ferromagnetic (MHF) type models,
related to so(5;C) algebra.
