- A Framework of Guidance for Building Good Digital Collections
Metadata Principle 1
Metadata Principle 1: Good metadata conforms to community standards in a way that is appropriate to the materials in the collection, users of the collection, and current and potential future uses of the collection.
It is essential to conform to, or at the very least map to, known community standards for metadata, rather than using proprietary or homegrown schemes. However, simply because a particular metadata scheme is considered a standard does not necessarily mean that it is the appropriate standard for any given collection. For example, EAD is a well-established standard for describing intact archival collections with a common provenance, but it is not the best scheme for describing heterogeneous cultural heritage collections composed of objects that all have a different provenance.
One of the very first steps in implementing a metadata strategy is to analyze and identify the most appropriate metadata standard—or set of standards—for your collections. The metadata scheme(s) and controlled vocabularies and thesauri that have been developed for specific communities and types of materials should be carefully researched and analyzed, and the most appropriate ones selected and implemented.
There are a variety of published metadata schemes that can be used for digital objects. The book Metadata Fundamentals for All Librarians (P. Caplan, 2003, see below) describes more than fifteen schemes used by educational, scientific, and cultural institutions. There will often be more than one scheme that could be applied to the materials in a given collection. The choice of scheme will reflect the nature of the collections themselves, the level of resources that the institution has to devote to metadata creation, the level of expertise of the metadata creators, the expected use and users of the collection, the goal of enabling interoperability and sharing digital collections, and other factors.
Organizations should consider the granularity of description, that is, whether to create descriptive records at the collection level, at the series or group levels, at the item level, or at multiple levels, in light of the desired depth and scope of access to the materials. They should also consider which schemes are commonly in use among similar organizations—using the same metadata scheme will improve interoperability among collections.
In some cases, the best strategy may be to utilize two or more metadata schemes in an integrated manner. For example, MARC or EAD might be used at the collection or group level, and MODS or CDWA Lite or VRA Core might be used to describe individual items within those collections or groups. METS could be used as a metadata “wrapper” to associate metadata expressed in various schemes.
Simply identifying the appropriate metadata scheme(s) for your collections is not sufficient; in most cases, institutions also need to develop and implement their own local "application profile" for the selected scheme, specifying exactly what will be done in those areas where the scheme allows for various options. Once a community metadata standard has been selected for application to a particular collection or group of collections, a detailed profile that specifies how that scheme should be implemented locally should be developed and clearly documented.
Application profiles make it possible to combine metadata elements from multiple existing metadata schemes. Definitions, requirements, best practices, and qualifiers from the original schema may be modified or added as needed for the particular application profile. Profiles also make it possible to add local elements to an existing standard scheme.
The following is a selection of metadata schemes used by many cultural heritage institutions.
|Metadata Scheme||Description||Guidelines for Use, and Applications|
|CDWA LITE http://www.getty.edu/research/conducting_research/standards/cdwa/cdwalite.html||An XML schema for core records for works of art and material culture based on Categories for the Description of Works of Art (http://www.getty.edu/research/conducting_research/standards/cdwa/).||
The CDWA site includes the XML schema as well as the specification/data dictionary. Cataloging examples are at http://www.getty.edu/research/conducting_research/standards/cdwa/examples.html.
The CDWA Lite schema assumes the use of Cataloging Cultural Objects (CCO), comprehensive guidelines developed by the art information, visual resources, and museum communities for describing cultural works, including art, architecture, objects of material culture, and their images: http://www.vraweb.org/ccoweb/cco/index.html. As of this writing, OCLC/RLG Programs is hosting a working group to help museums implement the CDWA Lite XML schema: http://www.rlg.org/en/page.php?Page_ID=335.
|CIDOC CRM http://cidoc.ics.forth.gr/||A conceptual reference model or “reference ontology” that provides definitions and a formal structure for describing the implicit and explicit concepts and relationships used in cultural heritage documentation. The CIDOC CRM has been an official ISO standard (ISO 21127) since late 2006: http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=34424&scopelist=PROGRAMME||A variety of tools for implementation and mapping are available at http://cidoc.ics.forth.gr/tools.html.|
|copyrightMD http://www.cdlib.org/inside/projects/rights/schema/||An XML schema for rights metadata developed by the California Digital Library (CDL); designed for incorporation with other XML schemas for descriptive and structural metadata (e.g., CDWA Lite, MARC XML, METS, and MODS).||Full record examples for materials with various types of rights metadata are at http://www.cdlib.org/inside/projects/rights/schema/examples.html.|
|Darwin Core http://wiki.tdwg.org/twiki/bin/view/DarwinCore/WebHome||A metadata element set developed to provide for the geographic occurrence of species and the existence of specimens in collections||
The Darwin Core wiki site http://wiki.tdwg.org/twiki/bin/view/DarwinCore/WebHome describes the Darwin Core elements and extensions, and hosts discussions on revisions.
The Mammal Networked Information Systems (MaNIS) utilizes Darwin Core in its data portal: http://manisnet.org/index.html.
|Dublin Core http://dublincore.org||A relatively simple, generic metadata element set applicable to a variety of digital object types. Dublin Core has been adapted by a number of communities to suit their own needs (e.g. GEM, for K-12 education metadata: http://www.thegateway.org/about/documentation/schemas), and has been incorporated into several domain-specific metadata schemes). As of this writing, Dublin Core XML is the required basic XML schema for OAI harvesting, and is often used as the “lowest common denominator” in metadata crosswalks.||
Encoding guidelines from the Dublin Core Metadata Initiative (DCMI) are at http://dublincore.org/resources/expressions/.
See also Collaborative Digitization Program (CDP) Dublin Core Metadata Best Practices http://www.cdpheritage.org/cdp/documents/cdpdcmbp.pdf
Dublin Core XML records can be harvested via the OAI Protocol for Metadata Harvesting (OAI/PMH): http://www.openarchives.org/pmh/ (OAI home page); http://webservices.itcs.umich.edu/mediawiki/oaibp/index.php/Main_Page (Digital Library Federation best practices for OAI data providers).
For other OAI-harvestable XML schemas that may be more appropriate for specific types of collections, see: http://webservices.itcs.umich.edu/mediawiki/ oaibp/index.php/MultipleMetadataFormats/
|Encoded Archival Description (EAD) http://www.loc.gov/ead/||A set of elements and rules for the representation of the intellectual and physical parts of archival finding aids. Often expressed in XML or SGML so that the information can be searched, retrieved, displayed, and exchanged.||
SAA, EAD Working Group, Encoded Archival Description Application Guidelines (SAA, 1999). Guidelines for the latest (2002) version of the format are not yet available; watch http://www.loc.gov/ead/ for news of their release.
Online Archive of California, OAC Best Practice Guidelines for EAD http://www.cdlib.org/inside/diglib/guid elines/bpgead.
The EAD Cookbook, version 2.0 http://www.archivists.org/saagroups/ead/ead2002cookbook.html.
|IPTC Core Schema for XMP http://www.iptc.org/IPTC4XMP/||A metadata schema intended for use within Adobeʹs eXtensible Metadata Platform (XMP) framework (see ). Files created using Adobe’s Creative Suite of software tools (e.g., Photoshop) contain embedded XMP metadata, thus making it possible to automatically capture and embed technical metadata in image files.||
User guidelines can be found at http://www.iptc.org/std/Iptc4xmpCore/1.0/documentation/Iptc4xmpCore_1.0-doc-CpanelsUserGuide_13.pdf.
The IPTC Core specification can be found at http://www.iptc.org/IPTC4XMP/
|Learning Object Metadata http://ltsc.ieee.org/wg12/||Learning Object Metadata is used to describe educational resources in course management systems and learning management systems. Learning objects are also collected in institutional and statewide repositories. The main standard is the IEEE Standard for Learning Object Metadata (1484.12.1-2002) (http://ieeexplore.ieee.org/iel5/8032/22180/01032843.pdf?arnumber=1032843), also called the LOM, which must be ordered from IEEE. However, the LOM has been incorporated into a number of other standards, including the IMS Global Learning Consortium's Meta-Data Specification (http://www.imsproject.org/metadata/), which is freely available from the IMS.||IMS Meta-data Best Practice Guide for IEEE 1484.12.1-2002 Standard for Learning Object Metadata, Version 1.3, Public Draft http://www.imsglobal.org/metadata/mdv1p3 pd/imsmd_bestv1p3pd.html. CanCore is the official site for documents, presentations and other resources related to the CanCore Learning Resource Metadata Initiative, which uses LOM: http://www.cancore.ca/en/index.html.|
|MARC 21 http://lcweb.loc.gov/marc/||A long-established standard for exchanging bibliographic records, developed and maintained by the library community. Over the last several years, MARC has been enhanced to support descriptive elements for electronic resources. There is a MARC Lite scheme (http://www.loc.gov/marc/bibliographic/lite/), as well as a MARC XML schema (http://www.loc.gov/standards/marcxml/).||Library of Congress, Understanding MARC Bibliographic: Machine-Readable Cataloging, 7th Edition http://lcweb.loc.gov/marc/umb/. OCLC’s Bibliographic Formats and Standards (http://www.oclc.org/bibformats/) provides tagging guidelines and rules for inputting MARC records into WorldCat. Most libraries that use MARC21 use AACR (currently evolving into Resource Description and Access, RDA). Anglo-American Cataloguing Rules, second edition, 2002 revision (Chicago: ALA Editions, 2005. However, MARC21 is language- neutral and data-content-standard-neutral, and can also be used in conjunction with DACS, CCO, and descriptive cataloging codes developed for non-English-language catalogs. Information on RDA, still an evolving cataloging standard at the time of publication, can be found at http://www.collectionscanada.ca/jsc/rdaprospectus.html.|
|Metadata Encoding and Transmission Standard (METS) http://www.loc.gov/standards/mets||An XML schema for encoding structural metadata about complex digital objects. METS also acts as a container with places to insert descriptive, administrative, and technical metadata.||The METS Implementation Registry includes projects that have been fully implemented, as well as projects in the planning and implementation stages: http://www.loc.gov/standards/mets/mets-registry.html. Registered METS profiles are available at http://www.loc.gov/standards/mets/mets-registered-profiles.html.|
|MIX (NISO Metadata for Images in XML) http://www.loc.gov/standards/mix/||An XML schema comprising a set of technical data elements required to manage digital image collections. The schema provides a format for interchange and/or storage of data.||An example of a MIX XML document is at: http://www.loc.gov/standards/mix/instances/test_mix10.xml.|
|MODS (Metadata Object Description Schema) http://www.loc.gov/standards/mods||An XML schema for descriptive metadata compatible with the MARC 21 bibliographic format.||MODS User Guidelines are at: http://www.loc.gov/standards/mods/v3/mods-userguide.html.|
|MPEG-7, Multimedia Content Description Interface (ISO/IEC 15938) http://www.chiariglione.org/mpeg/standards/mpeg-7/mpeg-7.htm". The standard can be purchased from the International Organization for Standardization (ISO) http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=34232||MPEG-7 is a multimedia description and indexing system that combines XML-based content description with non-textual indexing of physical features (color, movement, shape, sound, etc.) via processing of the media bit stream for multimedia information—audio, video, and images. Part 5 of the standard (ISO/IEC 15938-5) provides descriptive, technical, and usage metadata.||The Moving Image Collections (MIC) project has published an application profile with user guide, PowerPoint tutorials, a crosswalk to Dublin Core, and a prototype MPEG-7 cataloging utility in Microsoft Access, available for free download (http://gondolin.rutgers.edu/MIC/text/how/cataloging_utility.htm). The IBM alphaWorks development team has released a downloadable MPEG-7 Annotation Tool (http://www.alphaworks.ibm.com/tech/videoannex) to annotate video sequences with MPEG-7 metadata.|
|Object ID http://icom.museum/object-id/||An international standard for describing cultural objects, primarily with a few to documenting and protecting them as cultural property and protecting them from illicit traffic. Maintained and disseminated by the International Council of Museums (ICOM) in collaboration with UNESCO.||The Object ID checklist is available at: http://icom.museum/object-id/checklist.html. “Introduction to Object ID” (http://icom.museum/object-id/guide/guide_index.html) provides detailed guidelines for the implementation of this relatively simple set of metadata elements. PBCore Public Broadcasting Metadata Dictionary Project http://www.pbcore.org/|
|A metadata dictionary for television, radio, and web activities.||Implementation just beginning during 2007.|
|PREMIS Data Dictionary for Preservation Metadata http://www.oclc.org/research/projects/pmwg/premis-dd.pdf||A set of core preservation metadata elements developed by an international working group, Preservation Metadata: Implementation Strategies (PREMIS).||The PREMIS working group’s final report (http://www.oclc.org/research/projects/pmwg/premis-report.pdf) includes details on methodology and implementation. A registry of institutions and vendors that are implementing this standard is at http://www.loc.gov/standards/premis/premis-registry.php.|
|Society of Motion Picture and Television Engineers SMPTE Metadata Dictionary http://www.smpte-ra.org/mdd||A registry of metadata element descriptions for use with video, audio, or other data.||None available at time of publication.|
|Spectrum http://www.mda.org.uk/specfaq.htm||The UK standard for museum documentation, consisting of procedures and information requirements.||Guidelines for the use of Spectrum are included in the downloadable version, which is available for licensing fee-free: http://www.mda.org.uk/spectrum.htm|
|VRA Core Categories Version 4.0 http://www.vraweb.org/projects/vracore4/index.html||An XML schema developed by the Visual Resources Association for the description of art, architecture, works of material culture, with emphasis on visual surrogates of such works. The VRA Core Categories were designed with the awareness that there are often multiple representations and views of a work of art, architecture, or material culture.||Like CDWA Lite, VRA Core 4.0 assumes the use of CCO for cataloging guidelines: http://www.vraweb.org/ccoweb/cco/index.html Descriptions of the metadata elements and tagging examples are at http://www.vraweb.org/projects/vracore4/VRA_Core4_Element_Description.pdf.|
General introductions to metadata issues:
- Murtha Baca, editor, Introduction to Metadata: Pathways to Digital Information (version 2.1 available online; version 3.0 forthcoming in 2008) http://www.getty.edu/research/conducting_research/standards/intrometadata/.
- Priscilla Caplan, Metadata Fundamentals for All Librarians (Chicago: ALA Editions, 2003).
- CHIN (Canadian Heritage Information Network), Metadata Standards for Museum Cataloguing website http://www.chin.gc.ca/English/Standards/metadata_intro.html.
- Jane Greenberg, Understanding Metadata and Metadata Schemes (2005). http://www.ils.unc.edu/mrc/pdf/greenberg05understanding.pdf.
- Gail Hodges, “Best Practices for Digital Archiving: An Information Life Cycle Approach,” D-Lib Magazine, v. 6, no. 1 (2000) http://www.dlib.org/dlib/january00/01hodge.html.
- National Information Standards Organization (NISO), Understanding Metadata (2004) http://www.niso.org/publications/press/UnderstandingMetadata.pdf.
- Technical Advisory Service for Images (TASI), Metadata Overview (2006) http://www.tasi.ac.uk/advice/delivering/metadata.html.
- Technical Advisory Service for Images (TASI), Getting Practical with Metadata (2006) http://www.tasi.ac.uk/advice/delivering/metadata-practical.html.
- DLESE (Digital Library for Earth System Education), Metadata Best Practices website http://www.dlese.org/Metadata/collections/metadata-best-practices.htm.
- DLF (Digital Library Federation), Best Practices for OAI Data Provider Implementations and Shareable Metadata http://webservices.itcs.umich.edu/mediawiki/oaibp/?PublicTOC.
Portals to metadata resources:
- International Federation of Library Associations (IFLA), Digital Libraries: Metadata Resources website http://www.ifla.org/II/metadata.htm.
- UKOLN Metadata website http://www.ukoln.ac.uk/metadata/.
- Thomas Baker, et al., Dublin Core Application Profile Guidelines (2005) http://dublincore.org/usage/documents/profile-guidelines/.
- R. Heery, and M. Patel, “Application Profiles: Mixing and Matching Metadata Schemas” in Ariadne 25 (2000) http://www.ariadne.ac.uk/issue25/app-profiles/intro.html.
- International Conference on Dublin Core and Metadata Applications DC-2007 website http://www.dc2007.sg/. The conference theme is “Application Profiles: Theory and Practice.”
- Western States Digital Standards Group Metadata Working Group, Western States Dublin Core Best Practices (2003) http://content.lib.utah.edu/cgi-bin/showfile.exe?CISOROOT=/docs_regional&CISOPTR=1. An example of a general application profile for a digital collections project with many contributing institutions.
- Victoria Online, Metadata Application Profile and Taxonomy Guidelines (2006) http://egov.vic.gov.au/pdfs/VomapGuidelinesTaxv4.1_Final-Dec2006.pdf. A profile for an e-government portal.
Last updated: 09/03/2008