I believe that you have to qualify to the AQHA World Show in 6 or 7 different disciplines. I don't believe you have to win in each discipline, but you have to get a certain amount of points overall the other horses...I think its something like that.
"It is awarded to the horse that earns the most points in three or more events in two categories during the show."
"The team earned a total of 38 points. Un Forgettable won a world championship in senior pleasure driving, reserve championship in senior hunter under saddle, placed fifth in senior hunter hack, sixth in performance halter stallions and 12th in senior working hunter."