Appendix E: Lightswitch Example for IEEE 830 Format

5.1. Lightswitch

5.1.1. Narrative

This function allows the user to turn a light on and off using a switch.

5.1.2. Stimulus/Response pairs

Stimulus: The user flips the lightswitch to the Up position.

Response: The light illuminates.

Stimulus: The user flips the lightswitch to the Down position.

Response: The light goes out.

5.1.3. Functional Requirements

REQ-1.1 Upon the user flipping the lightswitch to the Up position, the light shall illuminate.

REQ-1.2 Upon the user flipping the lightswitch to the Down position, the light shall go out.

REQ-1.3 The light shall run on 115VAC, and is permitted to draw up to 50W of power.

REQ-1.4 The light socket shall permit rapid replacement of the bulb, without the need for tools.

Note that in the functional requirements, the first 2 requirements match the two stimulus/response pairs. There is a 1:1 correspondence between the stimulus/response pairs. We did not say “the system allows the user to control the light.”. Instead, we described how the system allows the user to control the light. Following those requirements, we added some additional requirements. Not all such sections will have such additional requirements, but some may.