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 chapter are bounded approximately by a street or alley lines, the street or alley shall be construed to be the boundary of the 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 the lot lines, and where the districts designated on the map accompanying and made a part of this chapter are bounded approximately by lot lines, the lot lines shall be construed to be the boundary of the district unless the boundaries are otherwise indicated on the map.

In unsubdivided property, the district boundary lines on the map accompanying and made a part of this chapter shall be determined by use of the scale appearing on the map as measured by the Zoning Chairman.