From what I can determine, Zheng Manqing’s role in the _Essence and Applications_ book was editorial; he made some stylistic changes to some of the writing, but the actual content of the form instructions was for the most part unchanged from the way it was presented in Yang Chengfu’s earlier book, _Taijiquan shiyongfa_, (which was in turn compiled and edited by Dong Yingjie). The form instructions are based upon Yang Chengfu’s personal demonstration narratives. Zheng Manqing had been Yang Chengfu’s student for two or three years when he edited _Essence and Applications_. That was well before he developed his own shortened interpretation of the Yang form. We know that there are identifiable differences in Zheng’s version of the taijiquan form, but I do not know what the definitive explanation would be for how those differences came about.