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5.5. Tables of Equivalents

When the name of a unit is enclosed in brackets (thus, [1 hand] ), this indicates (1) that the unit is not in general current use in the United States, or (2) that the unit is believed to be based on "custom and usage" rather than on formal authoritative definition.

Equivalents involving decimals are, in most instances, rounded off to the third decimal place except where they are exact, in which cases these exact equivalents are so designated.

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The angstrom is basically defined in terms of the wavelength of the red radiation of cadmium under specified conditions by the relation 1 wavelength=6 438.469 6 angstroms.

The international nautical mile of 1 852 meters (6 076.103 33... 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

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