Using MPEG-21 DIDL to Represent Complex Digital Objects in the Los Alamos National Laboratory Digital Library

Various XML-based approaches aimed at representing complex digital objects have emerged over the last several years. Approaches that are of specific relevance to the Digital Library community include the Metadata Encoding and Transmission Standard (METS), the IMS Content Packaging XML Binding, the Sharable Content Object Reference Model (SCORM), and the XML packaging approach developed by CCSDS Panel 2. The MPEG-21 Digital Item Declaration Language (DIDL) is another XML-packaging specification that, so far, has received little attention in the Digital Library community. This article gives a brief insight into the MPEG-21 standardization effort, and indicates its potential relevance to the Digital Library community. It also highlights major characteristics of DIDL, and details research conducted at the Research Library of the Los Alamos National Laboratory (LANL) into the applicability of DIDL for the representation of complex objects in the LANL repository. The positive outcome of this research has led to a decision to make DIDL-conformant documents the unit of storage in the LANL repository, and suggests that DIDL could also be a valuable building block for other Digital Library projects.