The DFD example here shows the level 1 DFD, which is the decomposition (i.e. break down) of the securities trading platform process shown in the Context DFD. Read through the diagram, and then we will introduce some of the key concepts based on this diagram.
The securities trading platform Data Flow Diagram example contains five processes, three external entities and three data stores. Although there is no design guidelines that governs the positioning of shapes in a Data Flow Diagram, we tend to put the processes in the middle and data stores and external entities on the sides to make it easier to comprehend.
