Let each diagonal box be a person, work group, department, or other organizational unit. Show inputs from outside the organization at the top of the chart above the work groups which process them. In the other boxes show routing of outputs from one group to another. A graph is used to picture a system whose organization is too large or complex for humans to visualize easily. State tables are another representation of the same information.
Emphasis is on system dynamics.
However, internally and away from the user software is often organized around a particular well defined set of modes, also called states. A state diagram and consequent state table are powerful tools because they clearly show all the possible legal and illegal situations the software must react to. The example diagram shows the operation of a computer controlled security door. The door is normally locked. In addition the computer runs a timer to relock the door after granting entry.