Equipment must operate safely and reliably, not create shock, fire, temperature or injury danger under foreseeable abnormal conditions, and be installed per the manufacturer's instructions. Sound work practice covers protection against external influences, access and working space, fixings, the user's needs, conductor identification by function with green or green/yellow reserved for earthing and bonding conductors and never used for live conductors, consistent socket-outlet polarity, no semi-enclosed rewireable fuses, breathing or drainage measures against condensation, and installation that keeps the marked IP rating.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.