The terms “Verify” and “Calibrate” are often mixed up. With a calibration, the deviation of the measured value from a standard is determined and certified. Verification, on the other hand, is the state-required testing. Measuring instruments that are subject to compulsory state validation may only be used after this verification. Pressure gauges, for example, must only be verified if their suitability (for example because of a specific measurement accuracy) serves to protect the health and safety of people or to measure dimensions in the free movement of goods.