Basically, GB test has no ramp up time and thus 
starts from the set test time by user directly. 
However, due to some cases where a buffer 
time before test time is in fact required for GB 
test, e.g., in conveyor where DUTs are tested for 
GB by batches and certain buffer duration 
needed for test leads or jigs connecting with 
DUTs, the GB CONTACT setting practically 
allows user to apply to customized scenarios 
when necessary occurs.