This context diagram depicts the system under consideration as a single high-level process, followed by the system's relationship with other external entities (systems, organizational groups, external data stores, etc.). A Context Diagram is also showcased as a Context-Level Data-Flow Diagram or a Level-0 Data Flow Diagram. Because a Context Diagram is a subset of a Data-Flow Diagram, some knowledge of Data-Flow Diagrams is beneficial. A Data-Flow Diagram (DFD) is a graphical representation of data flow through an information system. DFDs are one of the three key elements of the structured-systems analysis and design method (SSADM).