This branch of metrology deals with problems common to all metrological questions irrespective of the quantity measured. It includes: general theoretical and practical problems related to units of measurement; the problems of errors in measurement; and the problems of metrological properties of measuring instruments.
Industry refers to metrological activities in industry such as measurement in production and quality control. Typical issues covered are calibration procedures and calibration intervals, control of measurement processes, and the management of measuring equipment.
Legal metrology relates to mandatory technical requirements. A legal metrology service implements those requirements that would guarantee correct measurements in areas of public interest such as trade, health, the environment and safety.