Never make the same mistake twice-using configuration control anderror analysis to improve software quality

To provide a controlled environment, changes to the Space Shuttle primary avionics system software have been grouped into operational increments (OIs) that identify a predefined set of changes and discrepancy corrections (a baseline) for that OI. Two early processes implemented were an automated configuration management database and a prologue in all the code modules. This allows a causal analysis program that permits each problem to be analyzed to determine the change authorization that caused the code modification that results in the problem. This causal analysis provides the information that is used for process improvement and to measure effectiveness