From time to time and by accident people lose these tables and get a great amount of troubles. As a rule this problem needs immediate decision.
That is the law and these items should be obligatory set there. They can be of different shape and made from various materials. It depends on the country transport regulations. Of example, in the USA we have square metal or plastic boards.
If you have found or lost a license plate that begins on XB, then you can submit your request here.