The purpose of the System Interface Description is to illustrate which systems collaborate, and in what way they do so, to support the operational domain's information and information exchange needs as defined in the Operational View; most notably in NOV-2 and NOV-3.

NSV-1 links together the Operational Viewpoint and the System Viewpoint by depicting which systems and system connections realize which information exchanges. A system is defined as any organized assembly of resources and procedures united and regulated by interactions or interdependences to accomplish a set of specific functions. The term system in the System Viewpoint is used to denote software intensive systems (Federation of Systems (FoS), System of Systems (SoS), subsystems, and system components) and can include web services, network components and other hardware components, such as routers, satellites and network segments.

A system's services are accessed through the system's interfaces. Generally, an interface is a contract between the providers and consumers of (system) services. With software intensive systems, this contract is a declaration of a coherent set of public system functionalities. The system's interfaces specify the system's behaviour without specifying implementation aspects. An NSV-1 connection between system interfaces is the systems representation of an NOV-2 needline or NOV-3 information exchange. A single needline or information exchange may translate into multiple connections between system interfaces.

An NSV-1 documents: