Generally, a collection of requirements for a CI or standard design. Certain types of specifications can, however, contain requirements for processes that are specific to some given project (or class of CI), which sometimes causes confusion with the concept of a Standard. In contracted development, the Specification has lower precedence than the SoW (which is used to call the spec).
See also A-spec, B-spec, and C-spec.
In the commercial world, a specification is often a document listing the committed characteristics of a component, sometimes referred to as a “spec sheet”. The commitment isn’t always worth much.