The world of Sports is reconfiguring into Men’s Sports and Second Rate Men’s Sports. Women are relegated to competing in the also-ran positions.
Maybe that's how they separate the classes: entrants with testosterone levels = "X" (the normal range for a male) compete in the XY class, while those with testosterone levels in the "Z" range and estrogen levels of "A" (normal for women") compete in the XX class.
This just takes silly to a whole new level, but it is the inevitable "progression" of liberal insanity.