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. (october 2012)
a ruler, depicting two customary units of length, the centimetre and the inch
a unit of length refers to any arbitrarily chosen and accepted reference standard for measurement of length. the most common units in modern use are u.s. customary units in the united states and metric units elsewhere. british imperial units are still used for some purposes in the united kingdom and some other countries. the metric system is sub-divided into si and non-si units.