《左传·僖公·僖公四年》
凡是诸侯在朝会时死去，葬礼加一等；为天子作战而死的，加二等。
凡诸侯薨于朝会，加一等；死王事，加二等。
Any feudal lord who dies at court will be buried with the rites of one rank higher; those who die in battle for the emperor will be buried with the rites of two ranks higher.