Measurement uncertainty in calibration

Whenever standards are used as testing means, they have to be traceable to national or international standards. As far as calibrated testing means are concerned, the measurement uncertainty is normally indicated; however, as far as verified measuring instruments are concerned, the measurement uncertainty is not explicitly given in all cases. The reason for this is explained to be due to the maximum permissible errors on verification and of the maximum permissible errors in service. As a rule, the requirements for calibration and testing are met by legal metrology; however, some measures have to be taken to ensure transparency and documentation.