playing area long by wide. This is often used by the American public media for the sizes of large buildings or parks. It is used both as a unit of length (, the length of the playing field excluding goal areas) and as a unit of area (), about . British media also frequently uses the football pitch for equivalent purposes, although soccer pitches are not of a fixed size, but instead can vary within defined limits ( long, and wide, giving an area of ). However the UEFA Champions League field must be exactly giving an area of or . For example, "HSS vessels are aluminium catamarans about the size of a football pitch." Larger areas are also expressed as a multiple of the areas of certain American states, or subdivisions of the UK etc. Energy A ton of TNT equivalent, and its multiples the kiloton, the megaton, and the gigaton. Often used in stating the power of very energetic events such as explosions and volcanic events and earthquakes and asteroid impacts. A gram of TNT as a unit of energy has been defined as 1000 thermochemical calories (). The atom bomb dropped on Hiroshima. Its energy yield is often used in the public media and popular books as a unit of energy. (Its yield was roughly 13 kilotons, or 60 TJ.) One stick of dynamite. Units of currency A unit of measurement that applies to money is called a unit of account in economics and unit of measure in accounting. This is normally a currency issued by a country or a fraction thereof; for instance, the US dollar and US cent ( of a dollar), or the euro and euro cent. ISO 4217 is the international standard describing three letter codes (also known as the currency code) to define the names of currencies established by the International Organization for Standardization (ISO). Historical systems of measurement Throughout history, many official systems of measurement have been used. While no longer in official use, some of these customary systems are occasionally used in day-to-day life, for instance in cooking. Africa Algerian Egyptian Ethiopian Eritrean Guinean Libyan Malagasy Mauritian Moroccan Seychellois Somalian Tunisian South African Tanzanian Asia Arabic Afgan Cambodian Chinese Hebrew (Biblical and Talmudic) Hindu Indonesian Japanese Korean Omani Pakistani Philippine Mesopotamian Persian Singaporean Sri Lankan Syrian Taiwanese Tamil Thai Vietnamese Nepalese Still in use: Myanmar Europe Ancient Greek Belgian Byzantine