In this model , the concept of version set is introduced , version set includes the concept of scm system in common use , such as components , repositories , workspaces , variant set , revision histor _ ies etc . feature logic is used for the base of describing version set in this paper , the boolean expression that composed of ( feature : value ) versus is used for expressing common or independent version character , and operations such as intersection , union , and complement are executed on version sets in order to express and generalize the basic activity of scm 该模型引入了版本集的概念，版本集包括常用的构件、库、工作空间、变种集、修订版历史等。论文使用特征逻辑作为描述版本集的基础，通过( feature ： value )对的属性组成的布尔表达式来表示公共或独立的版本性质，并对版本集进行交、并、补等操作以表达和概括scm的基本活动。由此可以描述变更和工作空间的管理。
