Whenever uncertainty exists with respect to the boundaries of the various districts as shown on the Zoning Map, the following rules shall apply:
   (a)   District boundary lines are either the center lines of railroads, highways, streets, alleys or easements, or the boundary lines of sections, quarter sections, divisions of sections, tracts or lots, or such lines extended otherwise indicated.
   (b)   In areas not subdivided into lots and blocks, wherever a district is indicated as a strip adjacent to and paralleling a street or highway, the depth of such strips shall be in accordance with the dimensions shown on the maps measured at right angles from the center line of the street or highway, and the length of frontage shall be in accordance with dimensions shown on the map from section, quarter section or division lines, or center lines of streets, highways or railroad rights of way unless otherwise indicated.
   (c)   Where a lot held in one ownership and of record on the effective date of this section (Ordinance 10-16-67, passed November 20, 1967) is divided by a district boundary line, the entire lot shall be construed to be within the less restricted district, provided that this construction shall not apply if it increases the less restricted frontage of the lot by more than twenty-five feet.
      (Ord. 10-16-67. Passed 11-20-67.)