Drum and bugle corps
The organizing structure in DCI did not always work this way. There once were 3 Classes called Divisions, I, II, & III. There used to be a structure of Open Class, "A" Class, and "A60" Class (where Corps could only have a maximum of 60 marching members). There also used to be an All-Girls Class, for Corps that were all Female, with the other Rules the same as "A" Class, or Division II for them.