Knowledge
Metrology Dictionary
The complete VIM vocabulary — all numbered concepts of JCGM 200:2012 as faithful paraphrases with clause citations — plus clearly labeled practice terms from the GUM, ILAC, ISO and NIST guidance.
Accreditation
Third-party attestation, by an authoritative body, of a conformity assessment body's competence to carry out specific tasks — for laboratories, against ISO/IEC 17025, by bodies operating under ISO/IEC 17011.
ISO/IEC 17011:2017 · Quality & Accreditation
Accuracy class
A class of instruments or systems that meet stated metrological requirements intended to keep errors or instrumental uncertainties within specified limits under specified conditions — OIML weight classes E1 through M3 are the canonical example.
VIM (JCGM 200:2012) 4.25 · Instruments
Adjustment of a measuring system
The set of operations carried out on a measuring system so that it provides prescribed indications corresponding to given quantity values. Adjustment changes the instrument; calibration afterwards re-establishes its relation to standards.
VIM (JCGM 200:2012) 3.11 · Calibration
Air buoyancy correction
The correction applied in precise mass comparisons for the differing volumes of the standards and the object weighed, proportional to air density and volume difference — dominant in high-accuracy mass work.
NIST SOP 2 / OIML R 111 · Mass
As-found / as-left data
Calibration results recorded before (as-found) and after (as-left) any adjustment or repair. As-found data support reverse-traceability decisions about product accepted with the instrument since its previous calibration.
Calibration practice; NCSLI RP-1 · Calibration