A PCBU proposing to excavate a trench at least 1.5 metres deep secures the work area from unauthorised or inadvertent entry so far as reasonably practicable, and minimises collapse risk by supporting all sides through shoring by shielding or comparable means, benching or battering, unless a geotechnical engineer advises in writing that all sides are safe from collapse (advice stating its period and any natural occurrences that could create a risk).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.