This read-write value, from 1 to 86400 seconds, specifies the duration for which the BERT test is to run. Because bit errors on a marginal line can be intermittent or load and temperature dependent, too short a duration can produce a falsely clean result on a circuit that would show real errors over a longer soak, while an unnecessarily long duration just ties up the interface under test. A quick 60-second BERT might pass on a line with an intermittent connector issue that a full 24-hour run would clearly expose as errored.