Best Measurement Capability (BMC) Ousted in Favor of Calibration & Measurement Capability (CMC)

By international agreement, the phrase traditionally used by calibration labs to describe the accuracy which they can achieve in their measurements was replaced during 2010. The following announcement was made by the International Laboratory Accreditation Cooperation to explain the reasons for the change.

Best Measurement Capability (BMC)
Change in Terminology to
Calibration and Measurement Capability (CMC)

Metrological traceability is disseminated to the market by Accredited Laboratories under the ILAC Mutual Recognition Arrangement (MRA) and by National Metrology Institutes under the CIPM MRA. This provides reliability without frontiers for measurements across the world.

The capabilities provided by accredited calibration laboratories have in the past been described by the Best Measurement Capability (BMC) which expresses the lowest uncertainty of measurement that could be achieved during a calibration. This terminology has been widespread in accreditation around the world.

The National Metrology Institutes (NMIs) have had a similar description of the services provided to their clients. Within the NMI community the term has been Calibration and Measurement Capability (CMC). The BIPM and the Regional Metrology Organizations (RMOs) have in cooperation with ILAC and the Regional Accreditation Bodies (RABs) investigated the difference in terminology and have arrived at the following conclusion:

"In the context of the CIPM MRA and the ILAC Arrangement, and in relation to the CIPM-ILAC Common Statement, the following shared definition is agreed:
a CMC is a calibration and measurement capability available to customers under normal conditions:
(a) as published in the BIPM key comparison database (KCDB) of the CIPM MRA; or
(b) as described in the laboratory’s scope of accreditation granted by a signatory to the ILAC Arrangement."

In pursuit of harmony and co-operation between the communities; ILAC has decided to make a change in the terminology used and in the future the BMC will be named as the CMC. The intention is to achieve harmonization of terminology in the dissemination of metrological traceability worldwide regardless of source.