This International Standard specifies requirements for certified reference materials and the content of their supporting documentation, in order for them to be considered of higher metrological order in accordance with ISO 17511. It is applicable to certified reference materials classifiable as primary measurement standards, secondary measurement standards and international conventional calibrators that function either as calibrators or trueness control materials. This International Standard also provides requirements on how to collect data for value determination and how to present the assigned value and its measurement uncertainty. This International Standard applies to certified reference materials with assigned values of differential or rational quantities. Annex A provides information on nominal properties and ordinal quantities. This International Standard does not apply to reference materials that are parts of an in vitro diagnostic measuring system, although it is possible that many elements are helpful.