In this context it refers to the card that is sent to reorder a standardquantity of parts as and when they have been used up in the manufacturing process.
Under a true gold standard, the optimal quantity of money is determined by market forces the money supply spontaneously adjusts to the demand for money, and long-run price stability is achieved.
Unlike the classical gold standard, there is no market feedback mechanism to bring the quantity of money in line with the demand for money while maintaining long-run price stability.