A context diagram is a top-level (also known as Level 0) data flow diagram. The chemical tracking system context diagram only contains one process node that generalizes the function of the entire system in relationship to external entities. The chemical tracking system context diagram shows how the chemical stockroom, training database, barcode reader, health safety department, buyer, and chemist influence and affects the entire chemical tracking system. For instance, the diagram shows how a buyer requests to get new chemicals from a chemist, who checks the inventory report and provides the status update. Meanwhile, it also shows how when a member from the health safety department requests new chemicals, they are handed over reports pertaining to the details of chemical usage and disposal.