Metadata in Digital Libraries

Jewel Ward <jewelw@lanl.gov>
Visiting Scholar, Keio University
Colloquium of the Research Center for Knowledge
Communities, University of Tsukuba
11 June 2003

Acknowledgements• Herbert Van de Sompel (LANL)• Irma Holtkamp (LANL)• Jane Greenberg (UNC-CH)• John MacMullen (UNC-CH)• Naomi Dushay (Cornell University)2What is Metadata?
Metadata is structured information that
describes, explains, locates, or otherwise
makes it easier to retrieve, use or manage an
information resource. Metadata is often called
data about data or information about
information (Hodge, 2001).

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Types of Metadata
The Library of Congress Making of America IIproject has identified a threefold division ofmetadata (Making of America II 1998):– Descriptive metadata - primarily used for resource
discovery. Formats currently used include theMARC formats, Encoded Archival Description(EAD) and Dublin Core.
– Structural metadata - data that a system can use
to help present a particular digital object to a user.
– Administrative metadata - data that allows themanagement of a digital collection (Day, 1999).
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Administrative Metadata• “Policy” would be another term foradministrative metadata.
• Administrative metadata facilitates both shortterm and long-term management andprocessing of digital collections– includes technical data on creation and quality
control– includes rights management, access control anduse requirements– preservation action information(Cornell University Library/Research Department,2003).
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Administrative Metadata• Preservation is essentially aboutmanagement. In this scheme, preservation
metadata (as with rights metadata) is a
specialized form of administrative metadata(Day, 1999).
• For further information on preservation
metadata, refer to Michael Day’s article
and/or OAIS.

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Administrative Metadata
Sample Elements:
Technical data such as scanner type and model,resolution, bit depth, color space, file format,
compression, light source, owner, copyrightdate, copying and distribution limitations,license information, preservation activities(refreshing cycles, migration, etc.) (Cornell
University Library/Research Department,2003).

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Administrative Metadata
Implementations:– MOA2, Administrative Metadata Elements
http://www.clir.org/pubs/abstract/pub87abst.html– National Library of Australia
Preservation Metadata for Digital Collections
http://www.nla.gov.au/preserve/pmeta.html– CEDARS
http://www.leeds.ac.uk/cedars/metadata.html(Cornell University Library/Research Department,2003).
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Descriptive Metadata• To repeat the Library of Congress’ definition:
Descriptive metadata - primarily used for resource
discovery. Formats currently used include theMARC formats, Encoded Archival Description(EAD) and Dublin Core.

• These formats are used for resource
discovery and resource description (example,the Open Archives Initiative Protocol for
Metadata Harvesting).
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OAI-PMH Metadata• Repositories are required to expose their
metadata as the Dublin Core Metadata
Element Set (DCMES).
• Repositories are strongly encouraged toexpose their metadata in more expressiveformats.
• Examples of other formats in use:
– MARC– RFC-1807– Open Languages Archives Community Metadata
Set– Electronic Theses and Dissertation Metadata Set(Nelson, 2001)
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Example OAI_DC Record- <record>- <header><identifier>oai:arXiv.org:acc-phys/9411001</identifier><datestamp>2003-02-05</datestamp><setSpec>physics:acc-phys</setSpec><setSpec>physics:physics</setSpec></header>- <metadata>- <oai_dc:dc xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/"
xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchemainstance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/
http://www.openarchives.org/OAI/2.0/oai_dc.xsd"><dc:title>Symplectic Computation of Lyapunov Exponents</dc:title><dc:creator>Habib, Salman</dc:creator><dc:creator>Ryne, Robert D.</dc:creator><dc:subject>Accelerator Physics</dc:subject><dc:description>..</dc:description><dc:description>Comment: 12 pages, uuencoded PostScript (figures included)</dc:description><dc:date>1994-10-31</dc:date><dc:type>text</dc:type><dc:identifier>http://arXiv.org/abs/acc-phys/9411001</dc:identifier></oai_dc:dc></metadata>11</record>

Problems with Metadata• Missing Data
Data missing from the DC “format” and “type”
elements• Incorrect Data
– Content that should be in one kind of element wasin a different kind of element. For example,“creator” content in the “language” content.
– Default strings showing no content available:“unknown”, “—”, “…”, etc. (Dushay & Hillmann,2003).
12Problems with Metadata• Confusing Data
– Strings of names inconsistently ordered:• Smith, John, George Jackson, Humphrey Little andStanley Black• A more correct format should read: Smith, John; Jackson,George; Little, Humphrey; Black, Stanley.

• Insufficient Data
– Minimal DC requirements combined withinconsistent usage make it difficult to interpret themetadata for more refined services, like searching(Dushay & Hillman, 2003).
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Problems with Metadata• The top five elements are used 71% of thetime while the bottom five elements are onlyused 6% of the time
– Most- to least- used: creator, identifier, title, date,and type– Most- to least- used: language, format, relation,contributor, and source• 54% of DPs use only two elements (creator,identifier) for approximately 50% of all element

usage
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Problems with Metadata• The DCMES is not used to its fullest extent<understatement>• Due to this underutilization of the DCMES,
it will be difficult for the OAI community tobuild relevant cross-resource services
based on it (Ward, 2003)

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Domain-Specific Metadata
Bioinformatics
Multiple Metadata formats:• MAML (Microarray Markup Language)• GeneXML• GEML• Genbank, PDB, GAME, SBML, CellML, DAS– OLAC– Others: GIS, Genome Sequencing
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Domain-Specific Metadata
Open Languages Archive Community
Metadata Elements:
Contributor, Coverage, Creator, Date, Description,
Format, Format.cpu, Format.encoding,Format.markup, Format.os, Format.sourcecode,
Identifier, Language, Publisher, Relation, Rights,Source, Subject, Subject.language, Title, Type,Type.functionality, and Type.linguistic
http://www.language-archives.org/OLAC/olacms.html
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Metadata Conversion
LaRC MARC to DC Mapping (excerpt)

Liu, et al. (2002)

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Metadata Conversion
DC to Sandia MappingLiu, et al. (2002)
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Bibliography
Cornell University Research Library/Research Department. (2003).
Retrieved 5 June 2003 fromhttp://www.library.cornell.edu/preservation/tutorial/metadata/tabl
e5-1.html.
Day, M. (1999). Issues and Approaches to Preservation Metadata.
Retrieved 5 June 2003 fromhttp://www.rlg.org/preserv/joint/day.html.
Dushay, N. & Hillmann, D. (2003). Analyzing Metadata for
Effective Use and Re-use. Draft submitted to the 2003 Dublin
Core Conference. Available
http://www.cs.cornell.edu/naomi/DC2003/dushay_hillmann__draft.pdf.
Hodge, G. (2001). Metadata Made Simpler. NISO Press.
Retrieved 5 June 2003 fromhttp://www.niso.org/news/Metadata_simpler.pdf.

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Bibliography
Liu, X., Maly, K., et al. (2002). Technical Report Interchange ThroughSynchronized OAI Caches. Proceedings of the 6th European
Conference on Research and Advanced Technology for Digital
Libraries..
Nelson, M. (2001). Better Interoperability Through the Open Archives
Initiative. The New Review of Information Networking. 7, 133-146.
Ward, J. (2003). A Quantitative Analysis of Unqualified Dublin CoreMetadata Element Set Usage within Data Providers Registered with theOpen Archives Initiative. Proceedings of the Third ACM/IEEE Joint
Conference on Digital Libraries, 315-317.

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Further Information• Open Archives Initiative– http://www.openarchives.org• UKOLN Metadata Resources– http://www.ukoln.ac.uk/metadata/• RLG – Issues and Approaches toPreservation Metadata– http://www.rlg.org/preserv/joint/day.html• Open Archival Information System– Preservation Metadata and the OAIS Information
Model
http://www.oclc.org/research/pmwg/pm_framewor
k.pdf
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Further Information• Digital Libraries: Metadata Resources– http://www.ifla.org/II/metadata.htm• MARC– http://lcweb.loc.gov/marc/RFC-1807• Open Languages Archives Community
Metadata Set– http://www.languagearchives.org/OLAC/olacms.html• Electronic Theses and Dissertation MetadataSet– http://www.ndltd.org/standards/metadata/etd-msv1.01.html
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Questions?

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