High Quality Content by WIKIPEDIA articles! MLS International Roster Slots are an important piece of roster composition in Major League Soccer. MLS employs a variety of mechanisms to promote parity and domestic player development which include player entry drafts, expansion drafts, allocation drafts, weighted lotteries, and a limit on the number of international roster slots available for each club. The limit on the number of international roster slots makes each slot a valuable commodity for clubs to utilize through player signings or trades with other clubs.