The pound sign is the symbol for the pound unit of sterling – the currency of the United Kingdom and previously of Great Britain and of the Kingdom of England. The same symbol is used for other currencies called pound, such as the Gibraltar, Egyptian, Manx and Syrian pounds. The sign may be drawn with one or two bars depending on personal preference, but the Bank of England has used the one-bar style exclusively on banknotes since 1975. In the United States, "pound sign" refers to the symbol (number sign). In Canada ”pound sign” can mean or . The symbol derives from the upper case Latin letter , representing libra pondo, the basic unit of weight in the Roman Empire, which in turn is derived from the Latin word, libra, meaning scales or a balance. The pound became an English unit of weight and in England became defined as the tower pound (equivalent to 350 grams) of sterling silver. According to the Royal Mint Museum: It is not known for certain when the horizontal line or lines, which indicate an abbreviation, first came to be drawn through the L. However, there is in the Bank of England Museum a cheque dated 7 January 1661 with a clearly discernible £ sign. By the time the Bank was founded in 1694 the £ sign was in common use. However, the simple letter L, in lower- or uppercase, was used to represent the pound in printed books and newspapers until well into the 19th century. In the blackletter type used until the seventeenth century, the letter L is rendered as . When used for sterling, the pound sign is placed before the numerals (e.g., £12,000) and separated from the following digits by no space or only a thin space. In the UK, the sign is used without any prefix. In Egypt and Lebanon, a disambiguating letter is added (E£ or £E and £L respectively). In international banking and foreign exchange operations, the symbol is rarely used: the ISO 4217 currency code (e.g., GBP, USD etc) is preferred. In Canadian English, the symbol is called the pound sign.