The original function point method was presented in the paper “Measuring Application Development Productivity” in 1979 as a result of the research of Dr. Allan Albrecht and his research team. This was a successful attempt to measure the amount of software (the software size) in terms of its data processing capacity rather than its number of bytes, lines of code, or other factors. The size of the software’s data processing capacity, from this viewpoint, is called its “functionality” and one unit of that functionality is defined as a “function point.” In the language of that time, Dr. Albrecht writes “We found that the basic value of the application function was consistently proportional to a weighted count of the number of external user inputs, outputs, inquiries and master files. … These cover all the functions in an application.” (ALBR 1979). This was the original function point metric, what might be called “Function Points 1.0.”

In addition, his team’s research wanted to show, additionally, “some factors that affected productivity and to show how we determined their relative importance.” These factors were weighted in importance from 0 (none) to 5 (essential). These original other factors which affected productivity are paraphrased from his paper below. It is important to recognize that these are not positioned as being “functional.”

1. Reliable backup, recovery, and/or system availability.
2. Data communications.
3. Distributed processing functions.
4. Performance considerations.
5. Heavily utilized configuration.
6. On-line data entry.
7. On-line data entry, and in addition the data entry is conversational requiring that an input transaction be built up over multiple operations.
8. On-line update of master files.
9. Inputs, outputs, files, or inquiries are complex.
10. Complex internal processing.

Since 1979, there has been significant continuous improvement in the technology of software metrics. The 1979 original function point metric is much more fully developed, and one ISO standard version is now codified in the International Function Point Users Group’s (IFPUG) Function Point Counting Practices Manual (CPM) 4.3 (IFPUG 2010), which carries its ISO standard ISO/IEC 20926:2009. (ISO 2019)

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