Interface Control Document - Overview

Overview

An ICD may describe:

• the inputs and outputs of a single system, e.g. "The Wikipedia Interface Control Document."
• the interface between two systems or subsystems, e.g. "The Doghouse to Outhouse Interface Control Document."
• the complete interface protocol from the lowest physical elements (e.g., the mating plugs, the electrical signal voltage levels) to the highest logical levels (e.g., the level 7 application layer of the ISO model), or some subset thereof.

The purpose of the ICD is to communicate all possible inputs to and all potential outputs from a system for some potential or actual user of the system. The internal interfaces of a system or subsystem are typically not documented in an ICD, but rather in a system design document (such as a software design document).

Interface control documents are a key element of systems engineering as they define and control the interface(s) of a system, and thereby bound its requirements.