Five standard ``functions''

In counting FPs there are five standard ``functions'' that you count. The first two of these are called Data Functions, and last three are called Transaction Functions. The names of these functions are listed below.

1. Data Functions:
   1. Internal logical files
   2. External interface files
2. Transactional Functions:
   1. External Inputs
   2. External Outputs
   3. External Inquiries

Using this terminology, when a person that counts FPs looks at a software system, they see something like this:

Figure 1: The view of a software application from the eyes of a Function Point practitioner.