A physical data flow diagram is a model that shows the implementation of an information system that transports data from entry to exit. The purpose of this diagram is to display a visual reference during the system's design without excessive jargon or wording.
Physical data flow diagrams are one of two diagrams common to information systems. The other type is a logical data flow diagram, which focuses on how the system operates.
Since the path that data travels through in an information system can be complex, different shapes are used to outline the path. A square is used to indicate external entities, which include sources of data. Rounded rectangles are used to represent processes that the data undergoes through a system. Open-ended rectangles represent data storage sites, which can be electronic or physical. To indicate the flow of data through the system, arrows are used. In cases where a decision on the data is needed, there can be multiple arrows to indicate the different pathways the data may take.
The procedures for producing a data flow diagram include identifying the internal and external entities involved, business or other functions included in the system and determining the data connections to the business functions.