REPORTER REPORTER A Framework for Object Preservation

The term "digital repository" is used in dis- parate contexts, in both in a formal sense to describe a complex and complete preserva- tion system and its policies, and in a more intuitive but less clearly defined sense, of- ten implying simply a robust storage sys- tem, or a content management system. Lack of formalism in use of this term can im- pede development of formal requirements for building specific repository systems and, consequently, the widespread use of such systems. On the other hand, the complexity of a formal, system-wide view can impede understanding and implementation in 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 abstrac- tions on top of reliable storage systems, we establish a minimal general vocabulary for the expression of digital objects, inde- pendent of policy, in the form of a low- level content model. We show that the "primitives" supplied by this vocabulary can be used to express the particular con- tent and metadata models for several dis- parate repository case studies.