  In the multiple-soliton case, the freedom in the expansion of the solution of
the perturbed KdV equation is exploited so as to transform the equation into a
system of two equations: The (inte-grable) Normal Form for KdV-type solitons,
which obey the usual infinity of KdV-conservation laws, and an auxiliary
equation that describes the contribution of obstacles to asymptotic
inte-grability, which arise from the second order onwards. The analysis has
been carried through the third order in the expansion. Within that order, the
solution of the auxiliary equation is a con-served quantity.
