the term miles is propbably the best, as they (the airlines) base in (nautical?) miles. The same mile-distances were used (long before AA launched the first award-program), for pricing and still now, for example Star-Alliance-round the world tickets have prices depending on the effectiv miles (25'000/32'000 or 37'000) of your flight-miles - or the number of- (500 miles each) upgrade-coupons at UA depend on the same miles-distances. So-at least-the airlines calculate the same mile-distances if they credit or take them - that's fair enough.