An area not generally understood when counting function points is the concept of record element types. Record element types are necessary to rate internal logical files and external interface files. This brief article provides definitions, theoretical examples and then a practical example to help improve the understanding record element types (RET).
Internal Logical Files (ILF) - a user identifiable group of logically related data that resides entirely within the applications boundary and is maintained through External Inputs. An external interface file is very similar to an internal logical file except it is maintained by external inputs of another application.
Record element types is one of the most difficult
concepts in function point analysis. Most record element types are dependent on a
parent - child relationship. The child information is a subset of the parent information.
In a parent child relationship there is a one to many relationship. These type
of relationships represent one or more record types. On the other hand, files can be
inter-related by key information. In this case, the files are not subsets of each
other, but they may share information.
The first diagram represents two separate logical groups of data A and B (with key information between). In this case some A are B. This represents two internal logical files on RET each.
The second diagram represents one logical group of data A with two record types. In this case All B are A. B is a complete subset of A.
Imagine storing information contained on a music CD. The music CD contains the following layout, Singer, Group, Producer, Label, Date, and Songs. Of course, there are multiple songs on each CD. For each song, the name of the song, author, and length of song is included.
In this case, there are two Record Elements (RET's). The CD information and the song information. There are 5 data elements (singer, group, producer, label, date) for the CD RET and there are 3 data elements (song name, author, and length) for the Song RET. Hence in this example, there are 2 record element types and 8 data elements.
In this simple example, songs are a subset of a music CD. They do not exist independent of this relationship. They will be used in conjunction with the music CD information. Hence, forth all Songs are part of the Music CD (all B are A).
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