it is only fairly recently that the utility of associating a structure with the system equations themselves has been recognized. Kevorkian [l] stressed the role played by certain structurally determined subsystems in analyzing controllability, observability, and stability, and discussed a completely uncontrollable, completely unobservable nonlinear system by way of example. Mayeda and Wax [2] made explicit use of structural subsystem stability in deducing overall system stability for both linear and nonlinear systems. Callier, Chan, and Desoer [3] used a feedback loop of stable subsystems to investigate an input-output stability problem. A brief review of the canonical formulation of the dynamical equations [l] is given below. It is this description which yields the subsystems of the original system and their interconnections, thereby defining the structure of the system. We use this canonical form, in Section 2, to generalize some of the results on stability obtained in [2], and in Section 3, to treat zero state neighborhood, and complete C’ path, controllability. Sufficient conditions