SI

The International System of Units, abbreviated SI (for the french name Système International d'Unités), is the most widely used system of units in science, and the legal system in most countries. It was adopted by the 11th [General Conference on Weights and Measures]? (CGPM) in 1960 and is built from the seven SI base units.

Americans frequently spell 'metre' as 'meter', and 'litre' as 'liter'; however 'metre' and 'litre' are the official BIPM names for these units, although the American usage has been approved by the US government. The official US spelling for 'deca' is 'deka', though Americans use the international spelling more often than the American one. The unit 'gram' is also sometimes spelt 'gramme', though that is an older spelling.

See also:

• SI base units and SI derived units
• SI supplementary units
• SI prefixes
• Standards and Units

The reference for "Quantities, Units and Symbols in Physical Chemistry" is ISBN 0632035838 (amazon.com, search).

See also UTC (Coordinated Universal Time)

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