Systems rules are constraints on architectures, systems, system hardware/software items, and/or system functions. While other NSV subviews (NSV-1, NSV-2, NSV-4, NSV-11) describe the static structure of the System and Service Views (this is, what the systems can do), they do not describe, for the most part, what the systems must do, or what they cannot do.

At the system or system hardware/software item level, NSV-10a describes the rules which depict how the architecture or its systems should behave under specific conditions. At lower levels, it may consist of rules that specify the pre- and post-conditions of system functions. Such rules can be expressed in a textual form, for example, "If (this condition) exists, and (this event) occurs, (perform these actions)."

The purpose of this subview is to allow an understanding of behavioral rules and constraints imposed on systems and system functions.

The NAF navigation tree shows the constraints grabbed during a deep exploration of the architecture. However, constraints cannot be created from these locations. The constraints displayed are those attached to system items of the architecture (system functions, system nodes, etc.).