Many scholars have tried to explain the validity of the term understratum since it was put forward in the early 1990s;nevertheless, it remains confusing ,vague and ambiguous.

• 从20世纪90年代初“底层”概念的提出到现在,很多学者对其术语的有效性进行了诸多阐释和批评,然而却始终显得模糊、含混、暧昧,甚至歧义丛生。