Reference material, accompanied by a certificate, one or more whose property values are certified by a procedure which establishes its traceability to an accurate realization of the unit in which the property values are expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence.
[Definition according to MDCG 2022-2 No. 4, also corresponds to WHO TGS-8 definition: Quality control for in vitro diagnostic medical devices for WHO prequalification]