It can be, for example, various organizations eg a bankgroups of people e.
Keep your diagrams small, as I did above. A rectangle represents an external entity They either supply data or receive data They do not process data Notation A customer submitting an order and then receive a bill from the system A vendor issue an invoice External Entity Example External entities also are called terminators because they are data origins or final destinations.
Next, the analyst creates a child diagram for each of the processes in Diagram 0. Create, use, and explode logical DFDs to capture and analyze the current system through parent and child levels. An external entity must be connected to a process through a data-flow.
Does it all make sense? As shown in the Figure, DFD Leveling is first displaying the targeted system as a single process, and then showing more detail until all processes are functional primitives. Visually, the biggest difference between the two ways of drawing data flow diagrams is how processes look.
All external entities are shown on the context diagram as well as major data flow to and from them. You can see how the improperly filled out forms are returned to the applicant if required.