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Next: Details on the Five Up: Overview Previous: A simple five step

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.

These five functions will be discussed in greater depth in the sections that follow.