External entity

How to read it

Yourdon calls it a terminator and draws it as a rectangle. He describes it as a person or group, such as an outside organisation or government agency, or another computer system. Terminators are outside the system being modelled, and any relationship between two terminators is not shown on the diagram. The UKHSA guidance gives squares or rectangles for external entities in both Yourdon/DeMarco and Gane and Sarson notation, and Notre Dame’s guide calls them an external source or destination of data.

Also searched as: data flow diagram external entity, dfd external entity, dfd rectangle, dfd terminator, external entity symbol, source and sink.

Look-alikes

In Gane and Sarson notation a rounded rectangle is a Process, so the corners matter. An open-ended rectangle is a data store. In a UML use case diagram, people and systems outside the system are drawn as stick-figure actors.