Normative base

Every design answers to a collection of documents, and the normative base is that collection considered as a whole. In CIS practice the term is literal and institutional: the normative base is codified, registered and maintained by the state, and expert review checks designs against it as a defined corpus. In other systems the same object exists less formally, as "the applicable codes and standards" — assembled per project, listed in the design basis, and no less binding for being uncodified.

The base's defining property is motion. Standards are amended, superseded and withdrawn continuously; regulations change on political timescales; and the set that was in force when a design started differs from the set in force when it is reviewed. Projects therefore freeze a basis — the specific editions that govern this design — and manage departures from the freeze as changes.

The failure is checking against different snapshots: the designer against the editions from project start, the reviewer against today's register, the specification citing a third vintage from the master spec it was copied from. All three are checking diligently; none are checking the same base.