《明史·志·卷四十八》
流官八等，左右都督，都督同知，都督愈事，都指挥使，都指挥同知，都指挥翕事，正留守，副智守，以世官升授，或由武举任用，都不能世袭。
流官八等，以世官升授，或由武举用之，皆不得世。
There are eight levels of non-hereditary officials, including Lieutenant Governors and Deputy Lieutenant Governors. The appointments are made based on the recommendations of the Department of Personnel, or from successful candidates of the imperial examination. They are not hereditary positions.