During initial assessment and reassessment, assessors review proof of metrological traceability for all standards listed on the proposed or existing scope of accreditation. The easiest way to demonstrate traceability is by producing a calibration certificate issued by a national metrology institute, such as the National Institute of Standards and Technology, or by a laboratory accredited for that discipline by an accrediting body, such as ANAB, that is an International Laboratory Accreditation Cooperation (ILAC) signatory. A list of ILAC signatories is available from ILAC. If you can't find an NMI or accredited source for the calibration, contact ANAB for assistance.