[Study on difference of Za (miscellaneous) and Cu (abrupt)].

So far, the contention on the title of Zhang Zhongjing's work, either Shang Han Za Bing Lun or Shang Han Cu Bing Lun, is still unsettled. The present paper probes this problem by several approaches, including the provenance of now extant Zhongjing's book, the stemming of the mystery Za and Cu, the evolution of title of Zhongjing's book before both Song Dynasties; the origin and development of miscellaneous disease; semantic of both Za and Cu. On the above basis, a comprehensive study has come to the conclusion that the "wrong character" hypothesis mentioned by Song scholars is groundless, and the correct title for Zhongjing's work should read Shan Han Cu Bing Lun. The paper also discusses logically the development of nosological system in TCM.