A context diagram gives an overview, and it is the highest level in a data flow diagram, containing only one process representing the entire system. It should be split into major processes which give greater detail, and each major process may further split to give more detail. As shown in the service order system context diagram, all external and major data to and from them are depicted perfectly. The context diagram shows how a customer either sends a service request or work assignment to the service order system, which then forwards the billing information to the customer. Use EdrawMax or EdrawMax Online to create context-level data flow diagrams (DFD).