The Correction of "Xu" in Teng Wang Ge Xu

What is the literary style of Xu in Teng Wang Ge Xu? Experts and scholars always define it basing on the traditional classification. Most of them regard it as preface or parting advice. The article makes some profound analyses and proofs according to its writing background, contents, topics and many references and puts forward a new point of view: on one hand the article has developed three kinds of literary style from the traditional not two; on the other hand to my own view, Xu should be revised into narration .