Prior to the advent of paper currency, bills of exchange were a common means of exchange. They are not used as often today. A bill of exchange is essentially an order made by one person to another to pay money to a third person. A bill of exchange requires in its inception three parties—the drawer, the drawee, and the payee. The person who draws the bill is called the drawer. He gives the order to pay money to the third party. The party upon whom the bill is drawn is called the drawee. He is the person to whom the bill is addressed and who is ordered to pay. He becomes an acceptor when he indicates his willingness to pay the bill. The party in whose favor the bill is drawn or is payable is called the payee. The parties need not all be distinct persons. Thus, the drawer may draw on himself payable to his own order. A bill of exchange may be endorsed by the payee in favour of a third party, who may in turn endorse it to a fourth, and so on indefinitely. The "holder in due course" may claim the amount of the bill against the drawee and all previous endorsers, regardless of any counterclaims that may have disabled the previous payee or endorser from doing so. This is what is meant by saying that a bill is negotiable. In some cases a bill is marked "not negotiable"—see crossing of cheques. In that case it can still be transferred to a third party, but the third party can have no better right than the transferor. In the United States In the United States, Articles 3 and 4 of the Uniform Commercial Code (UCC) govern the issuance and transfer of negotiable instruments, unless the instruments are governed by Article 8 of the UCC. The various state law enactments of UCC §§ 3–104(a) through (d) set forth the legal definition of what is and what is not a negotiable instrument: Thus, for a writing to be a negotiable instrument under Article 3, the following requirements must be met: The promise or order to pay must be unconditional; The payment must be a specific sum of money, although interest may be added to the sum; The payment must be made on demand or at a definite time; The instrument must not require the person promising payment to perform