A design database organizes the description of an artifact, by arranging it as a hierarchical composition of components across multiple representations. It is particularly difficult to manage this complex structure as it evolves over time. In this paper, we present a logical organization for describing designs across time. We also present an operational model, based on workspaces and transactions, that describes how these structures can be manipulated while controlling the sharing and integrity of the design database. These concepts are being implemented in a Version Server under development at the University of California, Berkeley.
