Classification of bedding sets:
Four-piece bed sheet set (1 bed sheet, 1 duvet cover, 2 short pillowcases);
Four-piece bed cover (1 bed cover, 1 duvet cover, 2 short pillowcases);
Three-piece bed sheet set: a quilt cover, a pillowcase, and a bed sheet
Three-piece bedspread: one bed cover, one pillowcase, one bed sheet