1.1 Purpose [This section describes the system’s decomposition into lightweight processes (single threads of control) and heavyweight processes (groupings of lightweight processes). Organize the section by groups of processes that communicate or interact. Describe the main modes of communication between processes, such as message passing, interrupts, and rendezvous. This view is OPTIONAL. Use this view only if the system has more than one thread of control, and the separate threads interact or are dependent upon one another] 1.2 Scope