the ior rule was also used to define "level rating classes," where each class had a maximum ior rating, and the first boat to finish was the winner, with no handicapping. the first of these was the one ton class, so named because there was a spare trophy from the defunct one ton rating class, and this then spawned the mini ton, 1/4 ton, 1/2 ton, 3/4 ton and two ton classes, as well as unofficial 50-footer, uldb 70, and maxi classes. the official classes each had an annual world championships.