Used Machine - Unique item, actual physical machine.
New Machine - You can order from a catalog, at whatever quantity.
Used Machines:
When a machine is first entered, it is an S, which means For-Sale. When you have bought the machine, and need to add it to your inventory, it will become an I. If you enter the BACK OFFICE, #44 MACHINE ACQUSITION, the TARGET system will automatically change everything. The same machine number is kept from the sale to adding it in the inventory. Once someone has bought the machine from you, the I will change to a B.
New Machines:New machines start off the same way as used machines, with an S. However, when the machine is added into your inventory, the system will create a new number for it in MACHINE ACQUSITION and it will copy all the machine's information. Then when you go to finalize the sale, #43 FINALIZE SALE, the system will ask you for the machine number. This is because you can have many of one type of new machine.