A. There is established a uniform system of numbering all buildings in separate ownership or occupancy in the City dividing the City into five general districts. In establishing the system Williams Avenue and the center line of the Willamette River southerly from Glisan Street shall constitute the north and south base line from which the numbers on all buildings running easterly and westerly from said streets shall be extended each way, upon the basis of one number for each ten feet of property frontage, wherever possible, starting at the base line with the number 1 continuing with consecutive hundreds at each intersection, wherever possible; provided, however, that streets running easterly and westerly in that district south of Jefferson Street and lying between Front Avenue and the Willamette River shall have the prefix "0" placed before the assigned number, said numbers starting at Front Avenue with the number 1 and continuing with consecutive hundreds at each intersection, where possible. All even numbers shall be placed upon buildings on the southerly side of streets, avenues, alleys and highways, and all odd numbers shall be placed upon buildings on the northerly side of streets, avenues, alleys and highways. Burnside Street shall constitute the east and west base line from which the numbers on all streets running north and south from said streets shall be extended each way, upon the basis of one number for each 10 feet of property frontage, wherever possible, starting at the base line with number 1 and continuing with consecutive hundreds at each intersection, wherever possible. All even numbers shall be placed upon buildings on the easterly side of streets, avenues, alleys, and highways, and all odd numbers upon buildings on the westerly side of said streets, avenues, alleys, and highways. Freestanding buildings on private streets which are separately owned or occupied shall be separately numbered so as to most closely conform to this system. Each portion of a building which is separately owned or occupied and has a separate entrance from the outside shall have a separate number assigned to it.