A retail liquid measuring device of the meter type must be constructed so that, after a particular delivery cycle has been completed, an effective automatic interlock will prevent a subsequent delivery being started until the indicating elements and recording elements, if the device is equipped and activated to record, have been returned to their correct zero positions. Provisions must be made for the starting lever or equivalent mechanism to be in its designed shutoff position and for the zero-set-back interlock to be engaged before the discharge nozzle can be returned to its designed hanging position.
Okla. Admin. Code § 165:15-15-45