1926.501(b)(2) Leading edges.
1926.501(b)(2)(ii) Each employee on a walking/working surface 6 feet (1.8 m) or more above a lower level where leading edges are under construction, but who is not engaged in the leading edge work, shall be protected from falling by a guardrail system, safety net system, or personal fall arrest system. If a guardrail system is chosen to provide the fall protection, and a controlled access zone has already been established for leading edge work, the control line may be used in lieu of a guardrail along the edge that parallels the leading edge.
HAZARD: Employees exposed to fall/death hazards.
ABATEMENT: Each employee on a walking/working surface 6 feet or more above        a lower level where leading edges are under construction, but who is  not engaged in the leading edge work, MUST be protected from  falling by a guardrail system, safety net system, or personal fall arrest  system. If a guardrail system is chosen to provide the fall protection,  and a controlled access zone has already been established for leading  edge work, the control line may be used in lieu of a guardrail along the  edge that parallels the leading edge.
1926.501(b)(1) Unprotected sides and edges. Each employee on a walking/working surface (horizontal and vertical surface) with an unprotected side or edge which is 6 feet (1.8 m) or more above a lower level shall be protected from falling by the use of guardrail systems, safety net systems, or personal fall arrest systems.
HAZARD: Employee exposed to fall/death hazards.
ABATEMENT: Each employee on a walking/working surface with an unprotected side  or edge which is 6 feet or more above a lower level MUST be protected  from falling by the use of guardrail systems, safety net  systems, or  personal fall arrest systems.