As a way of tracking progress, Houstonians are looking to the Whataburger app to see which restaurants fall where under an informal indicator system: locations that are orange during their usual business hours are presumed to have the lights on; locations that are grey are presumed to still be in the dark. The Whataburger system is reminiscent of the so-called “Waffle House Index,” which even the Federal Emergency Management Agency uses as a measure of weather-related havoc because the chain’s 24-hour diners only close during the most extreme circumstances following hurricanes and tornadoes, among other extreme events.