International Transport Regulations 26 Packing groups letter: X for packing groups I, II and III Y for packing groups II and III Z for packing groups III only "Drum" means a flat-ended or convex-ended cylindrical packaging made out of metal, fibreboard, plastics, plywood or other suitable materials. This definition also includes packagings of other shapes, e.g. round, taper-necked packagings or pail-shaped packagings. Wooden barrels and jerricans are not covered by this definition. "Jerrican" means a metal or plastics packaging of rectangular or polygonal cross-section with one or more orifices. "Box" means a packaging with complete rectangular or polygonal faces, made of metal, wood, plywood, reconstituted wood, fibreboard, plastics or other suitable material. Small holes for purposes of ease of handling or opening or to meet classification requirements, are permitted as long as they do not compromise the integrity of the packaging during carriage.