For the purposes of this chapter, the Township of Middletown is hereby divided into the following classes of districts, which shall be designated as follows:

The boundaries of said districts shall be as shown on the map attached to and made a part of this chapter, which map shall be known as the "Zoning Map of Middletown Township." Said map and all notations, references, and data shown thereon are hereby incorporated by reference into this chapter and shall be as much a part of this chapter as if all were fully described herein.

The boundaries between districts are, unless otherwise indicated, either the center lines of streets or railroad rights-of-way, or such lines extended, or lines parallel or perpendicular thereto. Where figures are shown on the Zoning Map between a street and a district boundary line, they indicate that the district boundary line runs parallel to the street line at a distance therefrom equivalent to the number of feet so indicated.

Where a district boundary line divides a lot held in single and separate ownership at the effective date of this chapter, the regulations applicable to the less restricted district shall extend over the portion of the lot in the more restricted district a distance of not more than 50 feet beyond the district boundary line.