Bureau International des Poids et Mesures

Abstract

In measurement science, the word 'standard' is used with two different meanings: first, as a widely adopted specification, technical recommendation or similar document; and, second, as a measurement standard. This note deals with measurement standards, which can be a physical measure, measuring instrument, reference material or measuring system intended to define, realize, conserve or reproduce a unit or one or more values of a quantity to serve as a reference. For example, the unit of the quantity 'mass' is given its physical form by a cylindrical piece of metal of one kilogram, which represents the international standard, and gauge blocks represent certain values of the quantity 'length'.