Ideally, only the devices that show up as A-grade support on the Device Support Grid would return as true on the gradeA() function. Not supplying this functionality as part of the framework requires each of us who are using JQM to check the Device Support Grid after each release and write our own custom device detection logic to match what is supported in the new version. Please consider having a function in the framework that would accomplish this more accurately than gradeA() does today.