We read many papers and experimented with MVP-L before we began our process definition efforts, but we found that process definition was still difficult. We found that it is of particular importance to define the process under study at the appropriate level of abstraction rather than attempting to include all details. It was tempting to try to account for every possible variation of the processes, but we found that it was impossible to define all of these variations in a formal language within the time constraints of our study.