Complaints or orders issued by the inspector shall be served upon persons either personally or by registered or certified mail. If the whereabouts of such person are unknown and the same cannot be ascertained by the inspector in the exercise of reasonable diligence, the inspector shall make an affidavit to the effect, and the serving of such complaint or order upon such person may be made by publishing the same at least once no later than the time at which personal service would be required under the provisions of this ordinance in a newspaper having general circulation in the city. Where service is made by publication, a notice of the pending proceedings shall be posted in a conspicuous place on the premises affected by the complaint or order. (Ord. of 10/5/87)