The wall body's plan outline in the wall's own frame: origin at Start, +X along the axis, +Y to the left.
Right-start, right-end, left-end, left-start (counter-clockwise).
Axis length, Start to End.
Both ends are square, so the outline is a rectangle.
Body extent across the axis.
The wall body's plan outline in the wall's own frame: origin at Start, +X along the axis, +Y to the left.