Horizontal top rail, horizontal midrail, and toe boards in place.
Okland
Subpart L (13) pg 38
Guardrail, mid-rail and toe-board are required on all scaffolds if at all feasible. Workers do not have the option of utilizing a personal fall arrest system in lieu of completing a scaffold if it is reasonably feasible to install guardrails.
OSHA
1926.451(g)(4)
