《儀禮》素稱難讀，讀之如聚訟。古之門闑之制，經注不明，後世傳疏又頗多異說，學者或持「一闑」說，或持「二闑」說，不能定于一。又《儀禮》經文多用「左還」、「右還」，其含義究竟如何，後世學者雖有論及，然其意並未明晰。在前人研究基礎之上，通過對經文、記文、後世各家之說及先秦文獻的詳加考證，門實當有一闑；「左還」、「右還」含義有二：一是「還」與「旋」通，「左還」、「右還」即「左旋」、「右旋」。左旋是向右轉之意，右旋是向左轉之意。二是「還」與「環」是古今字，「左還」、「右還」可作「左環」、「右環」。左環是自左向右繞行，右環是自右向左繞行。

The Ceremony has always been difficult to understand. The prayers are not clear about Ancient door and Nie system and the later complexity although have some different views. Someone have the one Nie view, someone have the two NIE(闑) view. They can’t decide which one is right. In addition, There are many‘ZUO HUAN(左還)’and‘YOU HUAN(右還)’in Ceremony, what are the meanings of them? Their meanings are also unclear, although later scholars have studied before. Though carefully study, the door actually has one NIE, and that ‘ZUO HUAN’ and ‘YOU HUAN’ have two meanings. First, ‘HUAN(還)’ and ‘XUAN(旋)’ are same. ‘ZUO HUAN’ is ‘ZUO XUAN(左旋)’, ‘YOU HUAN’ is ‘YOU XUAN(右旋)’. ‘ZUOXUAN’ is right turn; ‘YOU XUAN’ is left turn. Second, ‘HUAN(還)’ and ‘HUAN(環)’ are past and present words. ‘ZUO HUAN’ and ‘YOU HUAN’ can be written as ‘ZUO HUAN(左環)’ and ‘YOU HUAN(右環)’.‘ZUOHUAN(左環)’is right-circling; ‘YOU HUAN(右環)’ is left-circling.