Sourcing Scenario in which item code is not yet known

 I have a scenario when using sourcing and i am hoping a solution can be provided.I dont know at the time of the Sourcing RFQ that which is my item(item is not specific at the time of RFQ it is only a general description). I know that in a Sourcing RFQ line item is not mandatory but category is mandatory. But even if i use category then the problem is that the PO would be made with the item category and not the specific though at the time of purchase order created from sourcing quote i want the purchase order