Abstract: The mat etiquette in the Classic of Rites (《仪礼》) emphasizes the ways of entering and leaving.The rule for sitting on the mat dictates that one must enter from the lower place and not from the higher place.Typically,leaving the mat is also done from the lower place,although there are occasional exceptions where leaving from the higher place is permitted.The distinction between the higher or the lower place is contingent upon the head and end of the mat.In cases where the text is not explicit,scholars often have divergent interpretations.For example,where should the noble guest’s（“遵者”） mat be considered as head? Why do the mats for assistants have differences in leaving from the higher or the lower place? To resolve these questions,it is essential to clarify Zheng Xuan’s annotations on terms such as “for convenient”(“由便”) and “overstepping the mat”(“躐席”).Once these concepts are clearly understood,the merits and demerits of various scholarly interpretations will become evident.