All lots, buildings and structures in the city shall be numbered in accordance with a city number grid map attached as exhibit A to the ordinance codified herein, which is on file in the office of the city clerk. House or building numbers for structures set behind existing buildings shall have the same number as the building in front with a proper fraction added. Apartments, office or business suites, trailer courts, townhouses or condominiums, shall have a street address assigned to the structure with the addition of either a numerical or alphabetical designation for each separate unit. (Ord. 497 § 2, 1985)