A quality digital repository is comprised of standardized data delivered online through a common interface, as opposed to a CD-ROM collection with multiple interfaces. Common metadata standards across collections are already allowing repositories to achieve cross-database access, and this will continue in more and more sophisticated forms.
Digital repositories succeed to the extent that they can re-articulate traditional library skills (cataloging, collection development, acquisitions, preservation, reference, user services, and special collections) in a new medium. Activity in the digital medium allows librarians to state the social, pedagogical, and intellectual roles of the library in an academic institution, and to serve as a rich content provider for many thousands of other users worldwide. Nothing brings people back to an online service like a well-selected, reliable, integrated, and cataloged set of data, especially if it is searchable and can be delivered quickly through a common interface across collections.
Digital repositories should provide reliable, long-term access to managed digital resources to its designated community, now and in the future. Trusted digital repositories may take different forms. For example, the On-Line Books Page was developed and maintained without cost, while Project Bartleby is a commercial site. However, they are quality repositories because they share the following attributes. They accept responsibility for the long-term maintenance of digital resources on behalf of its depositors and for the benefit of current and future users. They have have an organizational system that supports not only long-term viability of the repository, but also the digital information for which it has responsibility. They also design their systems in accordance with commonly accepted standards to ensure the ongoing management, access, and security of materials deposited within them.
The central challenge to preservation in a digital repository is the ability to guarantee the interpretability of digital objects for future users. This includes a guarantee of integrity, authenticity, confidentiality and accessibility to the digital data, which can be compromised by aging storage media and technical advancements. Although the preservation of digital works is in its infancy, the four repositories I reviewed will be taking steps to improve and maintain their data over time by developing strategies to cope with the continuous change of information technology in a responsible—and lossless—way.