Glossary
The mole and the International System of Units (SI)

National stallion

Standard recognized by a national authority for use in the country (VIM 5.3).

Primary standard

Standard whose value and uncertainty of measurement are established using a primary operating procedure (VIM 5.4).

Reference standard

Standard designated for the calibration of working standards for quantities of the same nature in a given organization or at a given location (VIM 6.6).

Secondary standard

Standard whose value and uncertainty of measurement are assigned by means of calibrations against a primary standard of a quantity of the same nature (VIM 6.5).

Working standard

Standard commonly used to calibrate or check measuring instruments or systems...