(1)   

      (a)    “Commercial unit” means such a unit of goods as by commercial usage is a single whole for purposes of sale and division of which materially impairs its character or value on the market or in use. A commercial unit may be a single article (as a machine) or a set of articles (as a suite of furniture or an assortment of sizes) or a quantity (as a bale, gross, or carload) or any other unit treated in use or in the relevant market as a single whole.

      (b)    Goods must be both existing and identified before any interest in them can pass. Goods which are not both existing and identified are “future” goods. A purported present sale of future goods or of any interest therein operates as a contract to sell.

      (c)    “Goods” means all things (including specially manufactured goods) which are movable at the time of identification to the contract for sale other than the money in which the price is to be paid, investment securities (ch. 408) and things in action. “Goods” also includes the unborn young of animals and growing crops and other identified things attached to realty as described in s. 402.107 on goods to be severed from realty.

      (d)    “Lot” means a parcel or a single article which is the subject matter of a separate sale or delivery, whether or not it is sufficient to perform the contract.

   (3)   There may be a sale of a part interest in existing identified goods.

   (4)   An undivided share in an identified bulk of fungible goods is sufficiently identified to be sold although the quantity of the bulk is not determined. Any agreed proportion of such a bulk or any quantity thereof agreed upon by number, weight or other measure may to the extent of the seller‘s interest in the bulk be sold to the buyer who then becomes an owner in common.