Transactional Function

Transactional functions represent the functionality provided to the user to process data. Transactional functions are either external inputs, external outputs, or external inquiries.

• An external input (EI) is an elementary process that processes data or control information that comes from outside the application’s boundary. The primary intent of an EI is to maintain one or more ILFs and/or to alter the behavior of the system.
• An external output (EO) is an elementary process that sends data or control information outside the application’s boundary. The primary intent of an external output is to present information to a user through processing logic other than or in addition to the retrieval of data or control information. The processing logic must contain at least one mathematical formula or calculation, or create derived data. An external output may also maintain one or more ILFs and/or alter the behavior of the system.
• An external inquiry (EQ) is an elementary process that sends data or control information outside the application boundary. The primary intent of an external inquiry is to present information to a user through the retrieval of data or control information. The processing logic contains no mathematical formula or calculation, and creates no derived data. No ILF is maintained during the processing, nor is the behavior of the system altered.

Source: Function Point Counting Practices Manual , see the IFPUG web site at http://www.ifpug.org for additional information.

Application System
Subsystem
Data Function
Actor
Relationship