Common Application Services (CAS) consists of development facilities that are used to define CAS components and run-time services that control interaction with these components during execution.
CAS application components are defined using the MODS maintenance facilities.
NCL based applications must use a controlling NCL procedure to invoke CAS run-time services through the CAS application programming interface (API), $CACALL. The relationship between panels, CAS application component definitions, and CAS run-time services is shown in the figure below.