A list of the three-letter abbreviations of the sets which are currently in Legacy but not in Standard.
BFZ, OGW, SOI, EMN, KLD, AER, AKH, HOU, ZVE, XLN, RIX, DOM, M19, ODY, TOR, JUD, GRN, RNA, WAR, M20, ELD, THB, DvK, IKO, M21
