This area is belong to low current area, the voltage and current will meet the ohm law characteristic, the resistor coefficient is about 1012~1013Ω, considered as an insulator. It will affect by temperature, when the temperature is raising, the current will increase through the MLV. This current is called Leakage Current.
This area is the MLV working and breakdown area which the voltage and current doesn’t meet Ohm's law. When the voltage slight change, the current will have significant change. MLV is using this characteristic to protect the circuit
This area is belong to high current area, which the voltage and current meets Ohm’s law and the resistance coefficient is about 1~10Ω. The reason for this condition is because insulation breakdown and the collapse of the insulating layer makes the zinc oxide grains in parallel connection.