(a) when goods are put up for sale in lots, each lot is, in the absence of evidence to the contrary, deemed to be the subject of a separate contract of sale,

(b) a sale is complete when the auctioneer announces its completion by the fall of the hammer, or in other customary manner, and, until that announcement is made, any bidder may retract his or her bid,

(c) if a sale is not notified to be subject to a right to bid on behalf of the seller, it is not lawful for the seller to bid himself or herself or to employ any person to bid at the sale, or for the auctioneer knowingly to take any bid from the seller or any such person, and any sale contravening this rule may be treated as fraudulent by the buyer, and

(d) a sale may be notified to be subject to a reserved or upset price, and a right to bid may also be reserved expressly by or on behalf of the seller, and if a right to bid is expressly reserved, but not otherwise, the seller, or any one person on the seller’s behalf, may bid at the auction.