An electrical device like this requires a reverse leakage current of 200nA @ 21V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 26.97V.
MTZJ27SD R0G Features
reverse leakage current of 200nA @ 21V 200nA @ 21V is the maximum voltage (Tol)
MTZJ27SD R0G Applications
There are a lot of Taiwan Semiconductor Corporation MTZJ27SD R0G applications of zener single diodes.