Function point counts can be associated with either projects or applications. There are three major types of software projects (Development, Enhancements and Maintenance). In accordance with these types of function points there are three different types of function point counts (Development, Enhancement and Application).
Function Points can be counted at all phases of a development project from requirements up to and including implementation. This type of count is associated with new development work. Scope creep can be tracked and monitored by understanding the functional size at all phase of a project. Frequently, this type of count is called a baseline function point count.
It is common to enhance software after it has been placed into production. This type of function point count tries to size enhancement projects. All production applications evolve over time. By tracking enhancement size and associated costs a historical database for your organization can be built. Additionally, it is important to understand how a development project has changed over time.
Application counts are done on existing production applications. This “baseline count” can be used with overall application metrics like total maintenance hours. This metric can be used to track maintenance hours per function point. This is an example of a normalized metric. It is not enough to examine only maintenance, but one must examine the ratio of maintenance hours to size of the application to get a true picture.
Additionally, application counts can assist organizations in understanding the size of the entire corporate portfolio (or inventory). This type of count is analogous to taking an inventory for a store. Like inventory, a dollar value can be associated with any application function point count and for the entire organization portfolio.