Pound (mass) for the weight of certain precious metals, especially in the trade; these are normally quoted just in ounces (e.g. "500 ounces") and, when the type of ounce is not explicitly stated, the troy system is assumed. Historically, the pound sterling was a Tower pound of silver. In 1528, the standard was changed to the Troy pound. The avoirdupois pound, also known as the wool pound, first came into general use c. 1300. It was initially equal to 6992 troy grains. The pound avoirdupois was divided into 16 ounces. During the reign of Queen Elizabeth, the avoirdupois pound was redefined as
Pound sterling the monetary policy of their own currencies (where they exist), and have their own ISO 4217 codes. The Falkland Islands pound, Gibraltar pound, and Saint Helena pound are set at a fixed 1:1 exchange rate with the British pound by local governments. Legal tender in the United Kingdom is defined such that "a debtor cannot successfully be sued for non-payment if he pays into court in legal tender." Parties can alternatively settle a debt by other means with mutual consent. Strictly speaking it is necessary for the debtor to offer the exact amount due as there is no obligation for