  Our previous results on the N-soliton interaction in the adiabatic
approximation have been extended. It is shown that the complex Toda chain (CTC)
model is an universal one in the sense that it describes the N-soliton train
interactions for all NLEE from the NLS hierarchy. We derive the perturbed CTC
system and show that the small perturbations affect only the center of mass
motion and the global phase of the N-soliton train. A special reduction of CTC
known as the Toda chain with indefinite metric describes the interaction of the
sine-Gordon solitons and anti-solitons. The peculiarities of the interactions
in the non-adiabatic cases are outlined.
