Newsletter Discussion

Activities of the PREMIS groups

Digital objects are highly fragile (cf. e.g. http://www.heise.de/tr/artikel/54305). Just like their carriers they are subject to rapid aging processes. In order to keep the data accessible a regular process of updating, refreshing, reformatting or even reconstructing is required.

The fact that technologies are very rapidly developed and become obsolete just as fast makes the long-term access to digital objects more difficult. The hardware as well as the software environment are subject to permanent modification processes. Additionally, digital objects are often insufficiently analyzed and/ or indexed.

In order to secure the access to digital objects as well as their authenticity context information is needed. This includes information about the kind, about the coding, the format as well as information about the processes the data is undergoing. This information is called preservation metadata.

PREMIS

Initialized by OCLC¹ and RLG², the international project PREservation Metadata: Implementation Strategies (PREMIS), develops implementation strategies for preservation metadata and identifies best practices. Furthermore a set of metadata is jointly defined that is specifically tailored to the purpose of long-term preservation.

PREMIS consists of the PREMIS Advisory Committee (supervising board), the Core Elements Subgroup, and the Implementation Strategies Subgroup. It is based on the results of the Preservation Metadata Working Group (PMWG, cf. http://www.oclc.org/research/projects/pmwg/wg1.htm). the precursor of PREMIS. In 2002 this group published a paper with a core set of preservation metadata that was based on OAIS³. It took into account and compared existent implementations. The results gained ample recognition, but soon there was a need for further analysis and enhancement. On this basis the Core Elements Subgroup (cf. http://www.oclc.org/research/projects/pmwg/core_elements.htm) develops, among other things, a current model and set of preservation metadata.

By means of a modular concept it is possible to meet various requirements coming from the fields of archives,libraries, museums, other institutions and companies. There are e.g. mandatory, recommended, and optional metadata elements. First results from this group are expected at the beginning of this year (2005).

In cooperation with the Implementation Strategies Subgroup the developed preservation metadata will then be implemented in test environments and tested in various application scenarios. Based on these experiences a mapping will be generated between existing metadata and PREMIS metadata.

The Core Elements Subgroup will also compile a preservation metadata lexicon.

The Implementation Strategies Subgroup (cf. http://www.oclc.org/research/projects/pmwg/implementation.htm) works on the compilation and documentation of best practices. For this purpose it analyzes occurring problems and questions of current and planned implementations. This group also distributes the cooperatively developed metadata model/ set.

By means of a survey several questions related to implementation practices and trends within the preservation community have been analyzed. The subjects ranged from "What is implemented and how?", to data handling and its methods, to metadata sets and metadata encoding, to applied software, to policies and legal questions. Some of the respondents were later selected for follow-up interviews to gather more information.

Based on these results models were developed that focus on the current practice for managing preservation metadata in digital archiving systems and that illustrate the trends in the practice of preservation. The report can be found at: http://www.oclc.org/research/projects/pmwg/surveyreport.pdf

¹ http://www.oclc.org/
² http://www.rlg.org/
³ The "Reference Model for an Open Archival Information System" (OAIS) is an ISO standard for digital long-term archives developed by the NASA. An overview about OAIS can be found at http://ssdoo.gsfc.nasa.gov/nost/isoas/overview.html, the bluebook at http://ssdoo.gsfc.nasa.gov/nost/wwwclassic/documents/pdf/CCSDS-650.0-B-1.pdf