“The DoDAF-described Models within the Systems Viewpoint describes systems and interconnections providing for, or supporting, DoD functions. DoD functions include both warfighting and business functions. The Systems Models associate systems resources to the operational and capability requirements. These systems resources support the operational activities and facilitate the exchange of information. The Systems DoDAF-described Models are available for support of legacy systems. As architectures are updated, they should transition from Systems to Services and utilize the models within the Services Viewpoint.” [DoDAF V2.0 Volume II]

The basic modeling principles are demonstrated in the demo  UPDM: Systems viewpoint.

Some elements in the demo are different from UAF Plugin but the modeling principles are the same.