OC: Open Collector
OD: Open Drain
OC gate and OD gate are relative to the two devices, OC gate is for the triode, OD gate is for the field effect tube.
OC gate circuit is shown below, Input signal is connected to the chip, when Vinput is high voltage, Q1 is switched on, then Q2 base voltage is 0, Q2 is off, Voutput is VCC2; When Vinput is low, Q1 is off, Q2's base voltage is VCC1, Q2 is on, and Voutput is 0.