Preface

One of the recommendations of the report of “Trusted Digital Repositories: Attributes and Responsibilities - an RLG-OCLC Report“[1] is the use of Persistent Identifiers (PI) within digital depot systems in order to provide a long-term access to digital objects in conjunction with an intuitive usable mechanism that enables the enduser to get a desired resource. To achieve these objectives two different aspects must be taken into account within a PI system. The first aspect concerns the unequivocal resource identification, the second aspect is reliable addressing. Both aspects are discussed below.

The existing structural variety of digital objects creates new challenges for an efficient design of identification systems. Examples are multimedia applications, hierarchical, and modular digital objects. However powerful identification systems are not sufficient in order to guarantee long-term availability of digital resources without a method for reliable access to digital resources.

At present there are several mechanisms to maintain URLs relatively constant. But for the long-term not only the adress itself but also the address method for digital objects might change.

Therefore it is necessary to apply an unique, location independent identification system in conjunction with a method for permanent access to digital objects. This can be achieved using PIs.[2]

The efforts of Die Deutsche Bibliothek concerning the introduction of PIs are motivated by several aspects.

• The rapid rise in the number of online publications and the increasing utilization of paperless distribution channels requires the expansion of the mandate for collecting, indexing and archiving digital resources to ensure long-term access.
• The new possibilities to create, present, describe and publish digital content have been caused by an increasing demand for permanent addressing, citation and unique identification of digital objects.
• The active involvement of Die Deutsche Bibliothek in the CDNL (Conference of Directors of National Libraries) and CENL (Conference of European National Libraries) underscore the need to introduce PIs within an international URN name space “National Bibliography Number“ (NBN) of national libraries.

These conditions led to the decision to take an active part in the project CARMEN-AP4 “Persistent Identifiers and Metadata Management in Science“ (1999-2002)[3] in order to install a test URN management system to gain experiences in respect to URN administration and resolution. The positive results demonstrated the necessity to expand the established URN management and to enhance prototyping into a productive system. This will be conducted in the framework of the project „Enhancement of Persistent Identifier Services - Comprehensive Method for unequivocal Resource Identification" (EPICUR, 2002-2004).

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