The rawdata API has different fields for the odometer of a device and each field has it’s own function.

vo – Virtual odometer, raw value from the device, calculated by the GPS positions
dev_dist – Adjusted odometer, fills nulls values and has useful filters
vehicle_dev_dist – Odometer defined by the user, this value is commonly set as the odometer of the vehicle, and it increments along with the dev_dist value.

vo – should not be used, it’s a raw value that can be null from the device
dev_dist – should be used to calculate distances traveled, it has filters fills null values
vehicle_dev_dist – since this value is user editable, it’s useful to know the total final value of the vehicle’s odometer.

When you use the ECU monitor accesory, the value can come in as:
ecu_distance – raw value from the vehicle’s engine
ecu_dist – adjusted value with filters and no null values
vehicle_ecu_dist – engine odometer editable by the user, increases with the ecu_dist

ecu_distance – should not be used, it can contain null values
ecu_dist – should be used to know the actual total distance traveled by the vehicle
vehicle_ecu_dist – it’s optional, but we have seen cases where the odometer on the vehicle’s dashboard is not the same as the odometer being read by the ECU monitor.

The vehicle’s odometer can be edited from the application using the Vehicle Counters app, visit the following forum for more information.
How to set the odometer of a vehicle