(a) Contracting offices should ensure that bids are promptly identified and forwarded, unopened, for deposit in the bid box. Bid envelopes received by mail should be time-stamped immediately upon receipt. Hand-carried bids may not be accepted by government employees but are to be deposited in the bid box by the bidder or his representative. Insofar as possible, bid samples should receive the same degree of security as is afforded bids, and should be accounted for by the maintenance of local records. Under no circumstances are bid samples to be given away, loaned, diverted, or used for any purpose other than that intended.