The most popular unit system was instituted in France during the Revolution as part of the French Revolutionary Calendar:
No country has officially adopted metric time. Given the complexity involved in a changeover from the two universal systems currently used in education and higher technologies, and the practical incompatibility between any two systems, a new adoption would require yet a third universal use: There is no evidence that its adoption is ever likely to occur, beyond dual mode clock novelties. Also, it is necessary to have a concept of both a day and a year, and the two are not in any obvious ratio.
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