Sima Guang expounded its compilation method in the "Summary" of the Catalogue, saying: "The method is based on the national latitude, its age is in the top, and the number of general reference volumes of each standard is in the bottom. In addition, Liu Yi Cuo's "Long Calendar" contains a new moon, and seven political changes intercepted by history are camped on it, and the essence of the book is scattered in it. " Imitate the chronology and use the old example of Shi Han Shu. Represents the number of volumes, so that you can know that something is in a certain year and in a certain volume in a certain year. Zi Zhi Tong Jian is a chronological general history, which records history in chronological order. So if you want to extract its essence, you can only do it in chronological order. The catalogue is compiled in this way, which is determined by the style of chronological style. Sima Guang creatively compiled the catalogue according to the reality of Tong Jian, which is unique in ancient chronicles.
The catalogue is actually a summary of tongjian. For example, under the serial number of the chronological method of Zhang Shang Yin Dun, it corresponds to the twenty-one-year mourning of the king of Chu, with "the funeral of the king, the ministers and nobles of the crisis, attacking Wuqi, killing it and shooting the king's corpse." Prince Zang ascended the throne, and those who begged for chaos lost more than 70 people. " This paper briefly describes the situation after the death of the king of Chu, and points out in the table that the relevant details are recorded in the first volume of Tong Jian.