A framework for object preservation in digital repositories

The teen "digital repository" is used in disparate contexts, ill both ill a formal sense to describe a complex and complete preservation system and its policies, and ill a more intuitive but less clearly defined sense, often implying simply a robust storage system, or a content management system. Lack of formalism ill use of this term call impede development of formal requirements for building specific repository systems and, consequently, the widespread rise of such systems. Oil the other hand, the complexity of a formal, system-wide view call impede understanding and implementation ill many environments. To attempt to reconcile these concerns, we present a pragmatic definition and scope for digital repositories (systems whose primary function is the long-term preservation of digital objects). Taking a "bottom-up" approach that builds abstractions of? top of reliable storage systems, we establish a minimal general vocabulary for the expression of digital objects, independent of policy, inthe form of a low-level content model. We show that the "primitives" supplied by this vocabulary call be used to express the particular content and metadata models for several disparate repository case studies.