What is wrong mark
Mark is a mistake open collector output voltage, when after the output voltage of the rated output voltage below 5% (typical), it will send a signal. Begins, error tags for low, until a rated output voltage output voltage reached 95% so far. In some cases, power conversion of error marker will with a delay. This delay is by external capacitor set, and can be used as a boot reset function will microprocessor resetting to add electricity.
If shown state, output voltage "mistakes" open collector for low case that the output for high (mark transistor shows OFF). When the output voltage in the rated voltage fluctuation 5%, the scope for low mark output.