Heat ham as directed on label or at 325F 1 1/2 hours. Remove from oven and score, cutting diagonal lines 1/2-inch deep and 1-inch apart. Cut across lines to form diamond shapes. Combine jelly, mustard and horseradish. Spoon mixture, small amounts at a time, at intervals, over ham throughout remainder of baking. Increase temperature to 425F and bake until ham is browned and glazed, about 30 to 45 minutes. (C) 1992 The Los Angeles Times