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.).

The NSV-10a report template is supplied with one parameter: the architecture on which the report is based. There are no additional parameters involved. The template comes with two chapters: The NSV-10a Resources Constraints Specification chapter and the NSV-10a Rules Linked to System Items chapter.

This chapter lists the constraints and requirements attached to system items of the architecture. This is an alphabetical list with an additional column for the comments. A paragraph is added for each listed constraint and requirement to explain their constrained objects.

If constraints and requirements are created from objects in Operational node structure diagrams (NOV-2), these constraints and requirements can be retrieved in the Systems Rule Model report provided the "View Type" property of the constraint is set to System. The constraints are then retrieved in the System Constraints folder while the requirements are retrieved in the System Requirements folder of the NSV-10a navigational tree.

It is also possible to generate a chapter that lists all the potential constraints linked to a system item.

This chapter displays a table with an alphabetical list of the constraints that are linked to system items. This helps the user determine if the type of constraints linked are defined according to the scope defined for this system architecture. This definition is based on the "View Type" property.

If a constraint is not typed as System, a warning icon is displayed for this constraint in the Scope column. Although not typed as system, the constraint appears in the table because it is linked to a system item.

This happens if the constraint was not created from the NAF navigation tree but from a diagram and then attached to a system item of this diagram.

The " View Type" property for rule with a warning can, however, be changed from the table (right click the constraint > Properties > NAF > NAF State Level > NAF Architecture Type > etc.).