A PCBU must consult, cooperate and coordinate activities with all other persons who have a duty on the same matter so far as is reasonably practicable (WHS Act s 46). More than one business may hold responsibility for plant risk because they share the workplace or activities, so each should exchange information, find out who is doing what and work together. For example an on-hire business should exchange information with the host about whether workers could be exposed to hazardous plant and what each party will do, and an owner of a crane at a shared site should talk to the other businesses about the risks it could create for them.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.