计量长度的单位是用米或是米的分数单位作为基本单位之一的单位,都是米制的范畴。例如,厘米克秒制、米千克力秒制(工程制)、米吨秒制等,这类单位制中的单位,都是米制单位。但是,用米制单位定义的单位,并不都是米制单位。例如,毫米汞柱、厘米水柱等。又如,英联邦给予码的定义为0.9144米等。1790年5月8日,法国政府颁布法令,建立米制以解决当时计量单位的混乱问题,米制的创 Metric length unit is the unit of meter or meter unit as one of the basic units, are metric system. For example, the centimeter-kilogram system, the kilogram-kilogram system (engineering system) and the metric system of second-and-a-half units are all made in metric units. However, units defined in metric units are not all metric units. For example, mm Hg, cm water column and so on. In another example, the definition given by the Commonwealth code is 0.9144 meters. May 8, 1790, the French government enacted a decree to establish the metric system to solve the problem of chaos at the time of measurement.