Swing during a fall can make the worker strike objects or snag the lanyard or anchorage line, so single anchorages should be positioned carefully or diversion anchorages or horizontal lifelines used. A fall over a sharp edge with the anchorage behind it stresses the lanyard at the edge and can cause failure or breakage; relocating the anchorage, choosing another anchorage type or covering the edge reduces this. On fragile surfaces such as roofs, both falling through the roof sheeting and falling off its edge must be considered: fall distance (a fixed lanyard can allow a longer fall through the surface near the anchorage), clearance below the surface and its edges, sharp edges below that can cut or snag lines or injure, and lateral obstacles in a swing. Walkways, preferably with handrails, are the preferred way across fragile surfaces and become essential where those issues cannot be resolved.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.