← All chapters Chapter 05

The Standard Model of a Function

A fixed vocabulary of every way a signal can enter or leave a system.

A single generic model names the five categories of input signal — input data, trigger, resources, noise, and the development process itself — and two of output signal. Its value is to make explicit the influences that lie off the normal signal flow and are, for that reason, most easily forgotten. Kept as a checklist, it turns construction from invention into derivation along the signal path.