The PCBU manages under Part 3.1 the risks of a hazardous atmosphere (one without a safe oxygen level, with oxygen that increases fire risk, with flammable gas, vapour, mist or fumes above 5% of the lower explosive limit, or with combustible dust in a quantity and form that creates a hazardous area) and the risks of ignition sources in a hazardous atmosphere, other than an ignition source that is part of a deliberate process.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.