Where an ignition source could cause fire or explosion in a hazardous area, the PCBU ensures no ignition source is introduced, from outside or within. It ensures so far as reasonably practicable that hazardous chemicals do not become unstable, decompose or change so as to create a new hazard or significantly increase risk, maintains ingredient proportions on which stability depends as the SDS or manufacturer states, and keeps chemicals known to be unstable above a temperature at or below it (deliberate processes excepted).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.