In his preface Lang Jinqi insists that the Xiyuan lu text is not easy to use for post-mortems (檢驗) without risking errors: this is what he found out during a 30-year career with many difficult cases to solve. The insufficiencies and contradictions of Xiyuan lu are particularly in evidence regarding the human skeleton: the checklists accompanying the plates representing the body and the skeleton lack explanations and are not always in agreement with each other. Together with his colleagues and private secretaries, Lang went through the Xiyuan lu text and commentaries to collect all data concerning bones; then they took the spots listed in the checklist (屍格) appended to the plate representing the body one by one and either indicated the name of the corresponding bone inside the body, quoting the relevant sources and explaining the congruence or discrepancy between the outside and the inside, or indicated the absence of a corresponding bone. The Jianyan hecan text, which can be described as a checklist of the body parts cross-referenced with data on the skeleton, represents the results of this effort. The appended Jianyan jizheng (q.v.) serves as a repository of examples of difficult cases. At the same time, Lang Jinqi oversaw the fabrication of two wooden dummies, one representing the body (lit., the corpse, shi 屍), and one the 365 parts of the skeleton (骨), each piece bearing an inscription to identify it; they were stored at the prefecture of Guilin 桂林 (Guangxi) for future reference.