With qualifiers, "mile" is also used to describe or translate a wide range of units derived from or roughly equivalent to the Roman mile, such as the nautical mile (now 1.852 km exactly), the Italian mile (roughly 1.852 km), and the Chinese mile (now 500 m exactly). The Romans divided their mile into 5,000 feet but the greater importance of furlongs in pre-modernEngland meant that the statute mile was made equivalent to 8 furlongs or 5,280 feet in 1593. This form of the mile then spread to the British-colonized nations who continue to employ the mile. The US Geological Survey now employs the metre for official purposes but legacy data from its 1927 geodetic datum has meant that a separate US survey mile (6336/3937 km) continues to see some use. While most countries replaced the mile with the kilometre when switching to the International System of Units, the international mile continues to be used in some countries, such as Liberia, Myanmar, the United Kingdom, the United States, and a number of countries with fewer than one million inhabitants, most of which are UK or US territories, or have close historical ties with the UK or US.
The mile was usually abbreviatedm. in the past but is now sometimes written as mi to avoid confusion with the SImetre; road signs in the United Kingdom continue to use m as the abbreviation for mile, though some (notably, height or width restrictions) use m as the abbreviation for metre, so drivers need to pay attention to context. However, derived units, such as miles per hour and miles per gallon, continue to be universally abbreviated as mph, mpg, and so on.
The present international mile is usually what is understood by the unqualified term "mile". When this distance needs to be distinguished from the nautical mile, the international mile may also be described as a "land mile" or "statute mile". In British English, the "statute mile" may refer to the present international miles or to any other form of English mile since the 1593 Act of Parliament, which set it as a distance of 1,760 yards. Under American law, however, the "statute mile" refers to the US survey mile. Foreign and historical units translated into English as miles usually employ a qualifier to describe the kind of mile being used but this may be omitted if it is obvious from the context, such as a discussion of the 2nd-century Antonine Itinerary describing its distances in terms of "miles" rather than "Roman miles".
The mile has been variously abbreviated—with and without a trailing period—as m, M, ml, and mi. The American National Institute of Standards and Technology now uses and recommends mi in order to avoid confusion with the SImetre (m) and millilitre (ml). However, derived units, such as miles per hour and miles per gallon, continue to be abbreviated in the United States, United Kingdom, and Canada as mph, mpg, etc. rather than mi/h or mi/gal. The BBC style holds that "There is no acceptable abbreviation for 'miles'" and so it should be spelt out when used in describing areas.