The given context diagram divides the single process node into subprocesses in a Level 1 data flow diagram. As more processes are added, the diagram will require more data flows and data stores to connect them. A level 1 data flow diagram emphasizes the primary functions of a system. Visualize the flow of incoming data, processes, and output data. A level 1 DFD describes each of the major sub-processes that comprise the entire system. A level 1 DFD can be considered an exploded view of the context diagram. When a process is expanded to a lower level, the lower level diagram must show all of the same dataflows into and out of the higher-level process that is being developed.
