is based on the Structured Analysis and Design Technique (SADT), a graphical approach to system description [8]. It was introduced by Douglas T. Ross in the early 1970s and used at SofTech, Inc. on a variety of problems. In 1981, the U.S. Air Force Program for Integrated Computer-Aided Manufacturing (ICAM) standardized and made public a subset of SADT, called .

was originally used to apply structured methods to better understand how to improve manufacturing productivity [14]. Another notation goal is to provide a straightforward means of locating details of interest easily and quickly.

In keeping with these goals, we expected to contain a high level of support for process understanding, communication, and improvement. We also expected the notation to be concise and rigorous. We expected less support for process management, performance guidance, and execution.