In 2002, OhioLINK's consortia of libraries recognized the need to restructure and standardize the metadata used in the OhioLINK Digital Media Center as a step in the development of a general purpose digital object repository. The authors explore the concept of digital object repositories and mechanisms used to develop complex data structures in a cooperative environment, report the findings and recommendations of the OhioLINK Database Management and Standards Committee (DMSC) Metadata Task Force, and identify lessons learned, addressing data structures as well as data content standards. A significant result of the work was the creation of the OhioLINK Digital Media Center (DMC) Metadata Application Profile and the implementation of a core set of metadata elements and Dublin Core Metadata Element Set mappings for use in OhioLINK digital projects. The profile and core set of metatadata elements are described.
Digital repositories have evolved from relatively simple collections of digital objects with individual metadata schemas to complex online environments needing reliable and flexible metadata structures to accommodate differing demands, platforms, and services. One example of this trend, the OhioLINK Digital Media Center (DMC) developed out of a statewide collaborative environment and continues to be redefined to meet the needs of cooperating libraries. (1) OhioLINK, the Ohio Library and Information Network, is a consortium of eighty-five college and university libraries and the State Library of Ohio. The goal of OhioLINK is to provide easy access to information and swift delivery of materials throughout the state. OhioLINK services include a central online catalog, shared electronic resources, a electronic theses and dissertations center, and an environment for digital project development and access.
By 2002, five years after the DMC was established, the need to restructure and standardize the metadata was clear to OhioLINK staff and member libraries. The DMC provides access to a variety of digital media assets including image, sound, and video files from OhioLINK institutions, other partner organizations, and commercial vendors. A series of subject-specific databases had been created, each with a separate, discipline-appropriate metadata scheme. Little attempt had been made to standardize information across the databases and searching was limited to one database at a time.
OhioLINK's Database Management and Standards Committee (DMSC), composed of technical services representatives from OhioLINK member institutions, appointed the OhioLINK Database Management and Standards Committee (DMSC) Metadata Task Force in spring 2003. The Task Force was charged with providing direction to the DMSC and OhioLINK on the development of the DMC, surveying current and emerging metadata standards, and drafting guidelines for the use of metadata in the DMC.
The primary result of the Task Force's work is the OhioLINK DMC Metadata Application Profile. (2) Complex environmental and historical factors and the great diversity of needs within the OhioLINK environment informed the application profile creation process. This paper describes the mechanisms used to foster the evolution of data structures in a cooperative environment and discusses specific decisions and findings that resulted in the creation of an application profile, including the identification of a core set of metadata elements. The paper presents the Task Force's findings, lessons learned, and recommendations, addressing data structures as well as data content standards. Finally, the paper describes the current status of the DMC as well as plans to incorporate the DMC into the OhioLINK Digital Resource Commons (DRC). (3)
A Review of the Literature
Identifying Appropriate Metadata
Several studies have shown that quality metadata is an important component of digital collections. In their article about the challenges of metadata in university digital libraries, Attig, Copeland, and Pelikan assert that successful digital libraries must have a "robust metadata structure that can accommodate and preserve a variety of discipline-specific metadata while supporting consistent access across collections. …