During the Yuan Dynasty, Guo Shoujing (郭守敬) wrote the Shoushili zhuanshen zhushi (授时历转神注式, Rotations of the Gods and Forms for Annotating Almanacs Based on the Season-Granting System). In the process of transmission, this was divided into Zhuanshen xuanze (转神选择, Selecting the Rotation God) and Shangzhongxia sanli zhushi (上中下三历注式, Forms for Annotating the Upper Middle and Lower Almanacs), but was lost at the end of Ming Dynasty. Through a literature search, we can find that Zhuanshen fashi (转神法式, Forms for the Methods of Rotations of the Gods) still exists in the Kyujanggak, Seoul National University, which is a Korean woodblock copy of Zhuanshen xuanze. Based on the preface and a comparison of the content and style of each book, it was determined that the existing Ming copy of the Datong wannian li (大统万年历, Great Concordance Eternal System) was made by people during the Ming by changing the title and content of the Shoushili zhuanshen zhushi, while preserving the framework structure and main content of the original book. The Shoushili zhuanshen zhushi was the calendrical system approved and promulgated by Yuan Dynasty, and the nature of this book can be further confirmed by combining it with the excavated fragments of the Yuan dynasty's annotated Season Granting System.
赵江红 (Fri,) studied this question.