《淮南子·兵略训》
所以队伍前后整齐严正、四面像墨线那般笔直，队伍进退有分有合、有散有聚，隔而不断，互不超越；两翼轻捷，四边便利，或前或后，离合散聚，不乱队形：这就是善于训练管理的行军队列和布阵。
故前后正齐，四方如绳，出入解续，不相越凌，翼轻边利，或前或后，离合散聚，不失行伍，此善修行陈者也。
Therefore, the front and rear of the team are neat and orderly, the four sides are as straight as ink lines, the team advances and retreats in an orderly manner, disperses and gathers, always in sight of each other, no one overtakes the other; the two wings are light and agile, and the four sides are convenient. Whether advancing or retreating, separating or gathering, the formation will not be disrupted.