Tomy/Trackmaster Serial Number types and meanings

They could simply be batch numbers or maybe even the serial number of the machine tools (moulds) used to make that train or component if there are different numbers on multiple parts. This could be used to track down a faulty mould/machine if some components come off the production line with consistent faults or similar bearing in mind they will probably have multiple machines or sets of moulds on a machine producing them at any one time.