HIPO / IPO Diagrams

HIPO / IPO Diagrams

HIPO stands for Hierarchy Input Process Output

The hierarchy chart is a top-down visual representation of the main process in the system. Since they use only two symbols they are simple to use and provide a good guide to the components of the problem. They can be expanded to any necessary level of detail, although usually a few levels will be adequate for most problems.

The only major disadvantage of hierarchy diagrams is that they show only the structure of the program. It is hard to deduce much about the processing logic from just a hierarchy diagram. For complete documentation it is customary to supplement the hierarchy diagrams with IPO charts.
Hierarchy chart example

IPO charts amplify the components of each module of the hierarchy diagram in either English or Pseudocode. IPO diagrams simply lists the inputs and outputs of the individual processes in tabular form.

There are only two symbols for hierarchy diagrams:

1.

Rectangle - represent a group of activities or module.
2.

Connecting line - connects the process boxes.

Hierarchy charts are read from top to bottom and from left to right. The top module of the chart is a statement of the problem. At each lower level of the chart the problem is broken down into smaller parts.

There are no special symbols for the IPO part of the task. Each numbered process box in the hierarchy chart would have one IPO diagram that identifies the process, lists its inputs and outputs, and lists the intervening processing.