Includibility of packing cost: packing necessary for marketability must be included in assessable value under valuation rules Include in assessable value the cost of that extent of packing required to make articles marketable; exclude packing whose primary purpose is protection. How much packing is necessary is a question of fact to be determined by applying the marketability test; tribunals must inquire whether goods are usually sold in a given packed form rather than merely whether they could be sold without additional packing.