Calibration A set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring system, or values represented by a material measure or a reference material, and the corresponding values realised by standards
Conformity Fulfilment by a product, process or service of specified requirements
Conformity assessment An activity concerned with determining directly or indirectly that relevant requirements are fulfilled
International standard Standard recognised by an international agreement to serve internationally as the basis for assigning values to other standards of the quantity concerned
International System of Units (SI) The units of the metric system used universally in science
Legal metrologyLegal metrology comprises all measurements carried out for any legal purpose and includes measurements that are subject to regulation by law or government decree
Measurement A set of operations having the object of determining a value of a quantity
Metre Convention The Metre Convention is an international treaty that provides the basis of all international agreements on units of measurement
Metrology The science of measurement
National standard Standard recognised by a national decision to serve, in a country, as the basis for assigning values to other standards of the quantity concerned
Pattern approval Examination of the pattern (design) of a measuring instrument against national or international specifications
Primary standard A standard that is designated or widely acknowledged as having the highest metrological qualities and whose value is accepted without reference to other standards of the same quantity
Reference materialA material or substance one or more of whose property values are sufficiently homogeneous and well established to be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials
Reference standardA standard generally having the highest metrological quality available at a given location or in a given organisation from which measurements made there are derived
Secondary standard A standard whose value is assigned by comparison with a primary standard of the same quantity
Traceability Traceability is the property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties
Verification by samplingVerification of a homogeneous batch of measuring instruments based on the results of examination of a statistically appropriate number of specimens selected at random from an identified lot​
Verification of a measuring instrumentProcedure (other than pattern approval) which includes the examination and marking and/or issuing of a verification certificate, that ascertains and confirms that the measuring instrument complies with the statutory requirements
Working standard A standard that is used routinely to calibrate or check material measures, measuring instruments or reference materials
Accreditation Authorisation, approval or recognition of meeting a standard