sequentially, i.e. Cl controls zI, possibly changing the values ~2, . . , zp. then Liz controls ZZ, possibly changing the values of ~3, . . , zp, with the requirement that z1 be left unaffected and so forth, with d, controlling zp without influencing zl, . . , zp_, (‘here the Li, are vectors such that ul, . . . , u,) = (cl, . . . 6,)). For linear systems the -triangular Decoupling Problem has been solved completely, sed [3, 11, 12,211. In the solution we present here we use as key tools the so called regular controllability distributions, introduced in [14]. In this way our approach completely fits in the systematic work on the generalization of the geometric approach to linear systems, see e.g. [6-10, 13-181. Note that in the T.D.P. the partial decoupling of the outputs is weaker than achieving complete dynamic interacting, which for a special case-the Restricted Decoupling Problem-has been solved in [16].