There is no specific abbreviation for the term WIRE because when the payment is being made using this option, you will not see the physical movement of funds. It is all electronic. It is just like a current passes through Wire.
Therefore Electronic movement of funds is campared with WIRE.
For material/Goods Purchases, the Po is required. In the Po, QTY, Product Name, Where is delivery price, Terms and Conditions. In the po there is no matter of final amount. It is just the approximate amount.