Where did the management system of periodic verification of measuring instruments and testing instruments come from? What is the name of the system?

If there is a verification regulation, it should follow the cycle stipulated by the national verification regulation; If there are no calibration regulations, the calibration regulations shall generally be followed; If there are some proposed calibration regulations, they still don't or don't want to recommend them according to the calibration regulations; They need to calculate themselves according to the national standard jjg 1 139-2005; At the same time, we should pay attention to our own risk control requirements. Long term is risky.