You draw functions and data stores on the SV-4 Systems Functionality Description diagram. The SV-4 is the behavioral counterpart to the SV-1 diagram.

SV-4 is a traditional data flow diagram: data flows are drawn between functions, in which you specify the data that is passed between functions. You can also draw data flows between functions and data stores. Data flow and data store both have a list of resources.

Functions are not the same as activities; the two are associated with properties. Functions also have a reference to their associated system.

The scope of functions drawn on the diagram can be capability wide without regard to which resources perform which functions, or it can be resource-specific. To model resource-specific functions, use swimlanes.