Geographical mile longitude at the equator is thus exactly 60 geographical miles. It was closely related to the nautical mile, which was originally determined as 1 minute of arc along a great circle of the Earth, but is nowadays defined as exactly 1852 metres. The US National Institute of Standards and Technology (NIST) notes that: "The international nautical mile of 1 852 meters (6 076.115 49...feet) was adopted effective July 1, 1954, for use in the United States. The value formerly used in the United States was 6 080.20 feet = 1 nautical (geographical or sea) mile." (6080.2 feet is 1853.24496 meters.)
Chi (unit) of China, its special administrative region of Hong Kong, and Taiwan. In its ancient and modern forms, the chi is divided into 10 smaller units known as cun (the "Chinese inch"). 10 chi are equal to 1 zhàng. In the People's Republic of China "chi" has been defined since 1984 as exactly 1/3 of a metre, i.e., 33 cm (approximately 1.094 ft). However, in the Hong Kong SAR the corresponding unit, pronounced "chek" in Cantonese, is defined as exactly 0.371475 m (exactly in). The two units are sometimes referred to in English as "Chinese foot" and "Hong Kong foot". In