As time passes, all constituencies know more (about what they need, which approach would be best, and how to get it done and still make money). This additional knowledge is the driving force behind most changes and leads to a statement of fact that is difficult for many software engineering practitioners to accept: Most changes are justified!
A baseline is a software configuration management concept that helps you to control change without seriously impeding justifiable change. The IEEE (EEE Std. No. 610.12-1990) defines a baseline as: