The System i program needs to be defined as an API function within the Plex model. The API function must then be assigned an implementation name that matches the name of the System i program that needs to be called. Optionally, if the program to be called has parameters, these parameters need to be defined on the API function. The API function cannot be generated or built because it is already an executable program on the System i. Once the API function definition is complete, the function can be called with a 'Call' statement from any Plex function.