Design spaces for link and structure versioning

This paper reflects upon existing composite-based hypertext versioning systems, and presents two high-level design spaces that capture the range of potential choices in system data models for versioning links, and versioning hypertext structure. These two design spaces rest upon a foundation consisting of a containment model, describing choices for containment in hypertext systems, and the design space for persistently recording an object's revision history, with applicability to all versioning systems. Two example points in the structure versioning design space are presented, corresponding to most existing composite-based hypertext versioning systems. Using the presented design spaces allows the data models of existing hypertext versioning systems to be decomposed and compared in a principled way, and provides new system designers significant insight into the design tradeoffs between various link and structure versioning approaches.