Definition 2.2.5 The D behavior F is complete if G; time-invariant if for each H in J and for each K it holds that L is again in M, where N is the shift of B defined in equation (2.8), and V for each C.
As for systems, one also defines V-completeness of behaviors, with respect to any family of controls (for continuous-time systems, these will be the measurable essentially bounded ones.).