(A) Where district boundary lines are indicated as following streets or extensions thereof, the boundary lines shall be construed to be the center lines of said streets or extensions thereof.
(B) Dimensional district boundary lines shown on the zoning maps are intended usually to (but do not always) coincide with lot lines. Where a dimensioned boundary line coincides approximately but not exactly with a lot line which existed on the effective date of the incorporation of the boundary line into the zoning map, the boundary line shall be construed to be the lot line at that location.
(C) In unsubdivided property the district boundary lines on the zoning map shall be determined by use of the scale appearing thereon.
(D) Streets which are shown on the zoning maps and which have heretofore been vacated, or which may hereafter be vacated, shall be in the same district as the lots, pieces, or parcels abutting each side of the street involved. If the lots, pieces, or parcels abutting each side of the street were located in different districts before the streets were vacated, the center line of the vacated street shall be the boundary line of the respective districts.
('69 Code, App. A, § 5.3)