The enhancement proposal, the functional documentation of the current system and the function point analysis of the existing system are used to identify the transactional and data functions within the scope of the enhancement project. A function point analysis of the existing system is an essential prerequisite because all existing functions that are affected either directly or indirectly by the enhancement contribute to the function point size of the enhancement. If, for any reason, a function point analysis of the existing system is not available, one must be undertaken to identify, as a minimum, the functions affected by the enhancement.
The size of the existing system, or that part impacted by the enhancement project, is expressed in standard function points.