《明史·志·卷五十八》
凡是亲王的世子，与已封的郡王相同。郡王嫡长子袭封郡王的，是始封郡王的一半。
凡亲王世子，与已封郡王同，郡王嫡长子袭封郡王者，半始封郡王。
All the heirs of the prince are the same as the princes of the county who have been enfeoffed. When the eldest son of the prince inherits the title of prince of the county, it is half of the initial fiefdom of the prince of the county.