"Yard, Side" means a yard between the main building and the side line of the lot, and extending from the required front yard to the required rear yard.
In the case of Through Lots, side yards shall extend from the rear lines of the front yards required. In the case of Corner Lots there shall be only one side yard, adjacent to an interior lot.
Width of required side yards shall be measured at right angles to a straight line joining the ends of front and rear lot lines on the same side of the lot. The inner side yard line of a required side yard shall be parallel to the straight line so established.