The Code applies a systematic process to excavation risks, drawing on WHS Regulations 34 to 38: identify things that could cause harm; where needed, assess the risk (the nature, seriousness and likelihood of harm), a step that may be skipped for a risk whose controls are already well known; then eliminate risks as far as reasonably practicable; where elimination is not reasonably practicable, put in place the most effective reasonably practicable controls following the hierarchy of control measures and keep them effective; and review controls to confirm they work as planned. The separate SWA code on managing WHS risks has more detail.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.