Back in the mid 1950s, British Railways developed a device to allow wagons to be checked, and their movements monitored using a system of codes, with a plate attached to a wagon, and a reader/scanner fixed to the track. Like all such systems, they were designed to track the type or owner of the wagon, its location, etc.
Ultimately the idea could have been implemented to replace the use of labels attached to wagons, and identification numbers, type, use, etc., and replace more manual methods of recording where and what use the asset was being put to, including any maintenance needs.
Similar trials were carried out in the USA, by the Association of American Railroads, and each of these systems could be identified as the forerunner of modern RFID and bar or QR code systems.
Who would have thought barcodes in the age of steam on British Railways. But then, the days of steam also included road-railers, and intermodal as well as container systems.