Procedure. Bids may be modified or withdrawn by written notice received in the office designated in the invitation for bids before the time and date set for bid opening. If expressly permitted in the invitation for bids, notification of bid modification or withdrawal may be made by electronic means only in the manner specified in the invitation for bids. Disposition of Bid Security. If a bid is withdrawn in accordance with this regulation, the bid security, if any, shall be returned to the bidder. Records. All documents relating to the modification or withdrawal of bids shall be made a part of the appropriate procurement file.