The Abstraction Hierarchy Notation for processes and products was developed by Christopher Lott at the University of Maryland. He used the notation to describe graphically the decomposition of processes and products [7]. The notation was developed as a supplement to MVP-L, since the MVP-L notation is textually oriented. As such, we expected that the notation would contain simple, understandable graphics that could be used for process communication. We did not expect the notation to provide sufficient information for defining the entire process.