How long can food on display fall below 63 digrees Celsius?

According to the Food and Drug Administration (FDA) Food Code, potentially hazardous food (PHF) must be held at 63 degrees Celsius (145 degrees Fahrenheit) or above to prevent the growth of harmful bacteria. Food that is displayed for serving to the public should not be left at room temperature for more than two hours, and it should be discarded if it has been held for more than four hours.