An electrical device such as this requires reverse leakage current of 500nA @ 6V.During operation, the maximum voltage - Zener (Nom) is reduced to 9.1V volts.
GDZ9V1B-HG3-18 Features
reverse leakage current of 500nA @ 6V 500nA @ 6V is the maximum voltage (Tol)
GDZ9V1B-HG3-18 Applications
There are a lot of Vishay Semiconductor Diodes Division GDZ9V1B-HG3-18 applications of zener single diodes.