Definitions
The number of extra spots _available_, i.e. free. This value must aggregate free spots from all groups mentioned below: A/ Those reserved for special purposes and usually require a permit. Permit details will be found at parking group level (entity of type `ParkingGroup`). B/ Those reserved for other vehicle types different than the principal allowed vehicle type. C/ Any other group of parking spots not subject to the general condition rules conveyed by this entity.
The number of extra spots available, i.e. free. Extra spots are those reserved for special purposes and usually require a permit. Permit details will be found at parking group level (entity of type `ParkingGroup`). This value must aggregate free spots from all groups devoted to special parking conditions. Allowed values: A positive integer number, including 0. `extraSpotNumber` plus `availableSpotNumber` must be lower than or equal to `totalSpotNumber