 With the creation of the Shangqing and Lingbao corpora, Daoism for the first time clearly defined its two main poles, which consist of both individual practices (codified in the Shangqing corpus) and communal practices (codified in the Lingbao corpus). In the 5th century, the relations among these corpora and the other traditions of Jiangnan were formally defined in the system of the Three Caverns (sandong), which is traditionally attributed to Lu Xiujing but clearly reflects the perspectives of the Daoist community as a whole (Schipper and Verellen 2004: 14–17). In this system, the main Daoist traditions and scriptural corpora of southeastern China are arranged into three hierarchical groups, namely (1) Shangqing, (2) Lingbao, and (3) Sanhuang (Three Sovereigns, understood as the Sanhuang wen and related textual materials). Each Cavern corresponds to a heaven and is ruled by one of the three highest Daoist gods: Yuanshi tianzun (Celestial Venerable of the Original Commencement), Lingbao tianzun (Celestial Venerable of the Numinous Treasure), and Daode tianzun (Celestial Venerable of the Dao and Its Virtue, another name of the deified Laozi). The Three Caverns also provided a model for other aspects of doctrine and practice, including the ranks of priestly ordination and the classification of scriptures in the future Daoist Canons (id., 17–37). (On the Daoist Canon see Schipper and Verellen 2004; a shorter survey is found in Bokenkamp and Boltz 1986.)