The Duduan 獨斷 "Definitions [in government and administration]" is a short handbook on the political institutions and rules of government ("constitution") of ancient China until the Later Han period 後漢 (25-220). It is traditionally attributed to the scholar Cai Yong 蔡邕 from the very end of the Han period. Yet already the compilers of the collectanea Siku quanshu 四庫全書 were aware that the received version cannot have been written by Cai Yong but must be of a somewhat later date. The oeuvre of Cai Yong is very rich and includes rhapsodies, poems, odes, tomb inscriptions, memorials to the throne, letters, and treatises like the Shihai 釋誨, Xuyue 敘樂, Nüxun 女訓, Nüjie 女誡, Zhuanshi 篆勢, or the Quanxue 勸學.
The information provided in the Duduan corresponds to descriptions in the contemporary ritual classic Liji 禮記, and not to that in the Zhouli 周禮, which allegedly reflects administative rules of the goverment of the Western Zhou period 西周 (11th cent.-770 BCE). Exceptions are some minor differences like the size of official caps. It can also be seen that sources quoting from the Duduan, like the Tang period 唐 (618-907) encyclopedia Chuxueji 初學記, present sentences not included in the received version. The latter nevertheless seems to be a complete overview of the most important ceremonial aspects of the central government. The Song period 宋 (960-1279)
scholar Wang Yinglin 王應麟 reconstructed the Duduan from the literary fragments he could obtain. His Xinding duduan 新定獨斷, a revised version of the Duduan, is lost, and the version compiled for the Siku quanshu 四庫全書 is only rudimentary.
The Duduan begins with definition of a lot of terms centering around the emperor, personal pronouns used by himself and by others, imperial carriages, the palace, seals, and documents issued by the emperor and submitted to him. It goes on to define the different terms for the imperial consorts, the princely establishments, the hereditary states, ancestors and gods, and the various sacrificial lieus. It describes the ritual activities of the emperors through the year, like offerings or hunts. The last part of the Duduan deals with names of ceremonial caps and posthumous honorific titles for emperors and dignified persons.
The Duduan is included in the collectanea Baichuan xuehai 百川學海, Gujin yishi 古今逸史, Gezhi congshi 格致叢書, Han-Wei congshu 漢魏叢書, Congshu jicheng 叢書集成, Sibu congkan 四部叢刊. These editions are based on several prints, one from the Baojing Studio 抱經堂, one faksimile of a Song print by the Ming period scholar Liu Xun 劉遜, and one from Jin Weiyuan 金維垣.
Li Xueqin 李學勤, Lü Wenyu 呂文鬰 (1996). Siku da cidian 四庫大辭典, vol. 2, p. 1914. Changchun: Jilin daxue chubanshe.
Siku quanshu zongmu 四庫全書總目 118, fol. 3a-4a. [Taibei: Yiwen yinshuguan edition from 1964.]