imperial units are not metric units
political_unit is unit. universal_unit_of_measure is metric_system. british_imperial_system is system_of_weights_and_measures. metric_unit_of_measure is metric_system. unit_cell is unit. military_unit is unit. imperial is automobile. monetary_unit is unit_of_measurement. metric_linear_unit is metric_unit. metric_unit is unit_of_measurement.