Special hazard environments, where several hazards can combine in unusual or especially hazardous circumstances, need extra precautions or rigour. The guideline treats confined spaces in detail: spaces are identified and access restricted, entry is by permit, and before entry process lines are disconnected, drained, blanked and locked out, mechanical equipment is de-energised and braced, and the atmosphere is tested and monitored, with attendants, rescue arrangements and appropriately designed access hatches. Engineering measures remove or reduce confined spaces where feasible, and lone and isolated workers receive added protection.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.