Function Point Terminology

• Data Element Type (DET)
  A unique, user-recognizable field/attribute that crosses the application boundary.

• Data Function Type (DTF)
  An ILF or EIF.

• Elementary Process
  A primitive use case; the smallest unit of activity that has meaning to the user.

• File Type Referenced (FTR)
  Count of ILFs + EIFs for a single External Input function.
  

• Record Element Type (RET)
  A user-recognizable subgroup of elements contained in an ILF or EIF.
  e.g. A student record, stored in a file, is one RET.

• Transaction Function Type
  An External Input, External Output or External Inquiry

• Value Adjustment Factor (VAF)
  A function point adjustement based on 14 characteristics of the application.
  Its purpose is to adjust function point counts for different complexity levels.

• External Input
  An elementary process that processes data from outside the application.
  
  1. The data must reside in an ILF.
  2. The process must be self-contained.
  3. The process must leave the application in a consistent state.

• External Output
  An elementary process that generates data that exits the application.
  External outputs are typically displayed to the user or stored in an EIF.
  The processing logic must, at a minimum contain at least one calculation, create derived data or alter the application state.

• External Inquiry
  An elementary process that results in retrieval of data that is sent outside the application. The user is presented data that resides in an EIF or ILF. The logic does no calculations and creates no derived data. The state of the application isn't altered.

• External Interface File (EIF)
  Similar to an ILF but used (not maintained) by the application.
  An EIF is a Data Function Type.

• Internal Logical File (ILF)
  A user-identifiable group of logically related data maintained within the boundary of the application. The ILF holds data maintained through one or more elementary use cases of the application.
  An ILF is a Data Function Type.