Only used once in the decompiled scripts. Seems to be related to scripted vehicle generators.
Modified example from "am_imp_exp.c4", line 6418:
/* popSchedules[0] = ZONE::GET_ZONE_POPSCHEDULE(ZONE::GET_ZONE_AT_COORDS(891.3, 807.9, 188.1));
etc.
*/
STREAMING::SET_MODEL_AS_NO_LONGER_NEEDED(vehicleHash);
ZONE::CLEAR_POPSCHEDULE_OVERRIDE_VEHICLE_MODEL(popSchedules[index]);