This paper describes the change management capabilities of a data management model to support engineering design. Specifically, it addresses the problem of detecting changes made to a design during a CAD session and efficiently maintains an evolving description of a primitive entity through the design process. We propose a hierarchical versioning model to support the independent evolution of alternative deigns for a primitive entity and provide operators to store and manage changes among versions in a particular derivation hierarchy. In addition, we present a scheme to represent the version model in a CAD paradigm. The version model presented in this paper is a component of a larger data management model of versions, assemblies, configurations to address the change management needs of collaborative design.