From January 1. 2021, all heavy vehicles in France (both freight and passenger vehicles) must be equipped with blind spot markings on the sides and rear of the vehicle.

All trucks and buses must be equipped with a blind spot warning sign, which must be placed at the rear of the vehicle, to the right of the longitudinal axis of the vehicle, at a height of 0.90 to 1.50 meters from the ground.

• on the cabin: the blind spot is marked within a meter radius of the unglazed surface of the vehicle, on the left and right side, at a height of 0.90 to 1.50 meters from the ground.
• on semi-trailers: the marking must be located on the left and right side within a radius of one meter from the vehicle's coupling device at a height of 0.90 to 1.50 meters from the ground.
• on central axle's and on full trailers: the marking must be located within one meter of the front part of the body on the left and right side at a height of 0.90 to 1.50 meters from the ground.

The marking must be placed so that they are visible in any circumstances without obstructing the driver's field of vision and the visibility of the vehicle's license plates, regulatory records and lighting and signaling devices.

Check out the right placing from the video: