4  BIS Review 158/2008  Multi-ply technology gives the coins unique electromagnetic signatures (EMS) which is how modern coin vending machines are programmed to differentiate different denominations. The technology enables coins of similar size and weight to have different electromagnetic signatures which allows a vending machine to be programmed to accept one and not the other.
Exit from OMTs would take place once their objectives have been achieved or when there is a failure to comply with a programme. OMTs would not take place while a given programme is under review and they would resume after the review period once programme compliance has been assured.