Whenever formal bidding is employed, the purchasing agent shall prepare or cause to be prepared specifications for the articles or services required and shall advertise the requirements of the city for the same for two consecutive weeks in a newspaper of general circulation in the city, inviting suppliers to tender bids in writing for the furnishing of the requirements, the bids to be publicly opened not less than two full weeks following the date of first advertisement, at a time and place specified in the published notice. If the contemplated purchase shall not have been included in the annual appropriation ordinance, a supplementary appropriation shall be required. ('70 Code, § 133.02; amend. Ord. 2291, passed 10-27-81; amend. Ord. 2573, passed 1-13-87)