Class 6 applies to all risks that are both:
Within 5 road miles of a recognized fire station.
Within 1000 feet of a recognized fire hydrant.
Class 9 would apply to those risks that are:
Within 5 road miles of a recognized fire station, but without a fire hydrant within 1000 feet.
Class 10 applies to all risks beyond 5 road miles of a recognized fire station.