An electrical device like this requires a reverse leakage current of 10μA @ 1V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 4.3V.
1N4731A_S00Z Features
reverse leakage current of 10μA @ 1V 10μA @ 1V is the maximum voltage (Tol)
1N4731A_S00Z Applications
There are a lot of ON Semiconductor 1N4731A_S00Z applications of zener single diodes.