CRM stands for “Certified Reference Material”. Paragraph 5.13 of the VIM defines a Reference Material as material, sufficiently homogeneous and stable with reference to specified properties, which has been established to be fit for its intended use in measurement or in examination of nominal properties. For example, fish tissue containing a determined mass fraction of dioxin used as a measurement standard in a calibration. A certified reference material is a reference material, accompanied by documentation issued by an authoritative body and providing one or more specified property values with associated uncertainties and traceability, using valid procedures. A CRM is a measurement standard. VIM 5.1, Example 6: Reference material providing quantity values with measurement uncertainties for the mass concentration of each of ten different proteins.