The district boundaries are either streets or alleys unless otherwise shown, and where the districts designated on the map accompanying and made a part of this ordinance are bounded approximately by street or alley lines, said street or alley shall be construed to be the boundary of such district.

Where the district boundaries are not otherwise indicated and where the property has been or may hereafter be divided into blocks and lots, the district boundaries shall be construed to be lot lines, and where the districts designated on the map accompanying and made a part of this ordinance are bounded approximately by lot lines, said lot line shall be construed to be the boundary of such districts unless said boundaries are otherwise indicated on the map.

In unsubdivided property, the district boundary lines on the map accompanying and made a part of this ordinance shall be determined by use of the scale contained on such map, unless dimensions are shown.