Payment orders with "conditions" should not be confused with "conditional payment orders". Conditional payment orders are pre-contract instruments consisting of a documented fee agreement between the beneficiary and the payer, proof of ability for the payer to pay which is often issued by Swift MT799 to the recipient's bank, and occasionally may include bank instructions for the establishment of a payment order following contract execution. Either payment orders or conditional payment orders are assumed to be irrevocable unless otherwise stated.[citation needed]