According to the Catalogue of Subsets of Classics and History, the seven preface is the content of the third volume of Guang Hong Ming Ji, which is a subset of four classics and history, so the seven preface is one of the subsets of classics and history.
The subset of classics and history is the four categories of ancient books divided by the ancients according to their contents. Some large-scale ancient books series often include four books and are named after them, such as Four Ku Quanshu, Four Series and Four Essentials. It can be seen that the four categories are of great significance to ancient books.