Boundary lines indicated as a highway, street, alley, railroad, watercourse or other body of water shall be construed to be the centerline or middle thereof.

Boundary lines which approximate a city boundary are to be considered to be the limits of the city boundary.

Where a boundary is shown approximately parallel to a street, railroad or utility, the boundary shall be deemed parallel to the centerline thereof at a distance, in feet, indicated by the figure appearing between the boundary and the centerline.

Where not indicated as above a district boundary shall be deemed to coincide with a property line, as such line existed at the time the ordinance from which this chapter derives or amendment thereto was adopted.

Where the location of a boundary line is derived from the extension of a property line or street or utility centerline, the symbol "ext" appears next to the line.

Where two district boundary lines intersect at a right angle the symbol ? appears in the angle.

Where the location of a boundary line is uncertain the city engineer shall determine its position in accordance with the distance in feet from other lines as given or as measured from the scale of the map.

Where the district boundary line divides a lot, the regulations applying to the portion of the lot in the less restrictive district (such as a business district) may be considered as extending not more than twenty-five feet into the more restricted portion (such as a residential district), but only if the lot has frontage on a street in the less restricted district (such as a business district).

The boundaries of the one-hundred-year floodplain and the flood plain district are designated in the Flood Insurance Rate Maps (FIRMS) prepared for the city by the federal Flood Insurance Administration effective October 16, 1984, as amended. Land which lies within the flood plain district based on the scale of the FIRM, but which is above the base flood elevation specified on the FIRM, is exempt from the flood plain district requirements provided that a registered professional engineer or surveyor certified that the land lies above the relevant base flood elevation and the Revere conservation commission finds in a determination of applicability or Order of Conditions issued under the Wetlands Protection Act, General Laws Chapter 131, Section 40, that the land lies above said base flood elevation. The uses within the designated flood plain area shall be those uses indicated in Section 17.16.040 et seq.