What is defined as a suspension system that allows a worker to descend in a controlled manner and, as needed, to stop at any point to perform work

A rope descent system is defined as a suspension system that allows a worker to descend in a controlled manner. The worker can move along the length of the rope for different purposes such as cleaning a window or mend something at a high level. 

If the line intersect than it would should how a perpendicular works.