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OCLC Online Computer Library Center
Metadata Standards
Eric Childress
OCLC
Washington, DCNovember 18, 2003
FEDLINK OCLC Users Group Meeting
OverviewOverview
Fundamentals– Types of metadata– Document mark-up languages &
character encodings
MetaMap
Metadata formats:– MARC, MODS– DC, ONIX– TEI, EAD, METS, MIX– RDF, FGDC, COSATI
FundamentalsFundamentals
Descriptive– Title, author, summary, topic, etc.
Technical & Structural– File size, software needed, file type(s),
presentation instructions, etc.
Administrative (a.k.a. “meta-metadata”)– Record number, record date, record source, etc.
Rights– Copyright ownership, use privileges, etc.
Management– [Typically by/for owning agency]: price paid,
circulation restrictions, etc.
5 types of metadata
FundamentalsFundamentals
Markup languages:– Address the structure of a document– Convey instructions to software that will process text
to: • Index the text for searching• To render the text (e.g., for screen display or print) • Transform the text (e.g., for a voice synthesizer) for some
output device(s) – The markup is generally invisible to end-users
Extensible Markup Language (XML):– XML is a metalanguage
• Agencies define their own XML to suit their task – By creating Document Type Definitions (DTDs) or XML schema
– Data is separate from presentation instructions• Presentation instructions go in a style sheet
– Offers just the right mix of flexibility and structure
Markup languages
FundamentalsFundamentals
Character encoding:– Used for communicating text characters in a
computing environment– Hundreds of character encoding standards exist– Character conversion is complex and expensive
Unicode: – A single, “comprehensive” global encoding
standard– Includes characters from scripts of all major
modern, most minor, and selected ancient languages
Character Encodings
http://mapageweb.umontreal.ca/turner/meta/english/metamap.html
MetaMapMetaMap
MARC 21MARC 21
MARC 21 (ISO 2709)– ISO 2709-based metadata communications protocol– Choice of two character encoding options:
• MARC 8 (ASCII, ANSEL, selected ISO, EACC)• Unicode (limited to equivalents of MARC 8 repertoire)
– XML expression is now also an option– Maintenance agency: Library of Congress w/ NLC, BL
Strengths:• Well-maintained, mature standard• Widely adopted by library communities• Large universe of MARC 21 records available• Wide choice of software vendors
Weaknesses (in the present & future): • Virtually unused outside of libraries • Limits on field and record size• Restricted range of scripts supported • Limited ability to convey complex relationships,
hierarchy, attributes at tag/subfield level
MODSMODS
Metadata Object Description Schema (MODS) – Essentially MARC 21 recast in an XML-native framework
• Text-based tags rather than numeric ones, • Selected clusters of related MARC 21 attributes condensed into
single MODS element– MARC 21 readily converts to MODS, but you can’t do a
lossless reverse conversion of MODS to MARC 21– Maintenance agency: Library of Congress
Value of MODS:– A rich, library-oriented XML metadata schema– Optimized for from-MARC conversion of legacy records– Well-suited as a metadata format for OAI harvesting
Applications of MODS:– LC planning to convert 100K American Memory records– Minerva project, U of Chicago Press, California Digital
Library, others using or planning to use for records for web sites, e-texts.
– OpenOffice Bibliographic Project
MARC 21 & MODS MARC 21 & MODS Feature MARC
21MARC
21 Unicod
e
MARC XML
MARC Slim
MODS
Structure ISO 2709
ISO 2709
XML XML XML
Encoding MARC 8 Unicode Unicode Unicode Unicode
Repertoire of scripts JACKPHY
JACKPHY JACKPHY JACKPHY Unicode
Conversion from MARC 21 lossless lossless lossless
minimal loss lossless
Conversion to MARC 21 lossless lossless lossless lossless? minor loss
Bibliographic OCLC OCLC R OCLC R OCLC R OCLC DCPS
Authority OCLC OCLC R
OCLC R
OCLC R x
Classification x OCLC R OCLC R x
Community x x x x
Holdings OCLC x x x
Dublin CoreDublin Core
Dublin Core Metadata Element Set– ISO 15836:2003(E) The Dublin Core metadata element set– A standard for cross-domain resource description
• Designed primarily to support discovery and retrieval – Defines semantics but not syntax (i.e. container)– Choice of simple or qualified DC – Maintenance agency: Dublin Core Metadata Initiative (DCMI)
hosted by OCLC Research
Value of Dublin Core:– Simplicity, extensibility, interoperability– Worldwide adoption (DCMES translated into 20+ languages)– Usable as crosswalk between major metadata standards
Applications of Dublin Core:– Open Archives Initiative (OAI) mandates DC metadata– Wide variety of extended versions in use:
• In digital library, archives, museums projects • By e-government programs (AU, CA, DK, FI, IE, NZ, UK)
– OCLC usage: Connexion, DCPS, ContentDM, Research
ONIXONIXONIX International (Online Information Exchange):– Standard data exchange format for publishers & jobbers
• Based on EPICS (EDItEUR Product Information Communication Standards)– For representing and communicating book industry product
information in electronic form• Offers two levels of richness (level 1 & level 2)
– XML schema with Unicode encoding– Maintenance agency: EDItEUR working with input from the
Book Industry Communication (BIC) and the Book Industry Study Group (BISG)
Value of ONIX:– Meets needs of publishers, jobbers, retail sellers for:
• Easier access to richer book data (including bibliographic data, cover art, blurbs, TOCs, UPC data, and much more)
• An inexpensive-to-implement common data exchange format
Applications of ONIX:– Primarily oriented towards publishers, jobbers, retailers
• Most major players (Amazon, Baker & Taylor, etc.) now using/supporting ONIX
– Some interest by libraries & ILS vendors in ONIX
TEITEI
Text Encoding Initiative (TEI):– For complex markup of literary texts– Both SGML & XML DTDs available– TEI “header” (TEIH) can be used as a metadata record– Maintenance agency: TEI Consortium:
• TEI Consortium has executive offices in Bergen, Norway, and is hosted at four university sites worldwide: the Univ. of Bergen, Brown Univ., Oxford Univ., and the Univ. of Virginia
• Maintains “P4” Guidelines for Electronic Text Encoding and Interchange
Value of TEI:– Designed to meet the needs of scholarly research community
(esp. in the humanities) for a variety of activities including:• Adding in-line academic commentary in e-texts• As an aid to research by supporting special indexing points, etc.
Applications of TEI:– Widely used by major humanities electronic text collections
such as CETH, UVa e-text center, many others.
EADEAD
Encoded Archival Description (EAD)– A format for expressing electronic archival finding aids – EAD DTD (Version 2002) is designed to function as both an
SGML and XML DTD– Maintained jointly by the Library of Congress and the Society
of American Archivists (SAA)
Value of EAD: – Effectively an organized presentation of a collection of
documents (typically in an archive or manuscript collection)• EAD header carries metadata for the finding aid• Provides for simple or complex mark-up to support varying
levels of indexing• Well-suited for interweaving narrative with links to specific
objects in a collection (either directly to the object or via a record for the object that may link to the object).
Applications of EAD:– Conversion of existing paper finding aids to electronic form– Widely used by academic institutions and archives in North
America– RLG Archival Resources database host copies of many EADs
METSMETS
Metadata Encoding and Transmission Standard (METS)– A standard “shell” for encoding data essential for retrieving,
preserving, and serving up digital resources • Six modules define descriptive, administrative, structural, rights
and other metadata • Some parts of a METS object may be external (e.g., a MODS
record for the descriptive metadata)– Maintenance agency: Library of Congress
Value of METS:– Need for METS identified at DLF metadata experts meetings
• Varied local approaches to non-descriptive metadata not scaling well & offering little interoperability between agencies
– Offers a standard mode for object “packaging” for preservation, institutional repositories, other activities
Applications of METS:– LC: planning to use with selected moving images, audio
recordings, folk life mixed media collections– OCLC DCPS, RLG, Harvard, Stanford, UC Berkeley, National
Library of Wales exploring or using for variety of projects
MIXMIX
Metadata for Images in XML (MIX)– XML schema for a set of technical data elements required to
manage digital image collections– Format for interchange and/or storage of the data specified
in the NISO Draft Standard Data Dictionary: Technical Metadata for Digital Still Images (version 1.2)
– Still in early development and testing phases– Collaboration of: Library of Congress and NISO Technical
Metadata for Digital Still Images Standards Committee
Value of MIX:– Provides a common XML schema for expressing technical
data particular to still and moving digital images– Can be used with other schema such as METS and MODS as
part of a comprehensive approach to managing and preserving digital images
Applications of MIX:– OCLC DCPS, LC, others planning or testing – MIX still in nascent stage of development and testing
Summary Summary DC ONIX TEI EAD METS MIX
Structure XML XML XML XML XML
Encoding Unicode Unicode Unicode Unicode Unicode
Repertoire of scripts Unicode Unicode Unicode Unicode Unicode
Conversion from MARC 21Lossiness
variesMinimal
lossHeader only
- lossyHeader
only - lossy
Conversion to MARC 21Minimal
loss
Some ONIX-only data may
be lostHeader only – lossless
Header only –
lossless
Chief purpose Simple description
for discovery &
retrieval
Publisher product
info exchange
Markup of scholarly
Etexts
Markup of electronic
finding aids
Shell with technical
data
Technical data for digital images
Primary user base e-Govt, Libraries, Museums, Archives,
Publishers, Jobbers
Humanities scholars
Archives, Libraries
Archives, Libraries
Archives, Libraries
Maintenance agency
DCMI EditeurTEI
Consortium LC w/ SAA LC LC
RDFRDF
Resource Description Format (RDF)– Graphing theory (i.e. arcs and nodes)-influenced, XML
syntax-based metalanguage for expressing metadata about web resources
– Designed to convey metadata for machine consumption (raw RDF is not very human-readable)
– Fundamental building block of RDF is the triple (subject + predicate + object)
– Maintained by the W3C; RDF specification under revision
Value of RDF:– A subject of debate (typically RDF vs. XML)!– Pro: Model-based expression of metadata critical to the
Semantic Web (i.e. derived connections); more flexible, scalable and forgiving standard than XML
– Con: RDF carries unneeded processing overhead vs. XML; RDF specification has too many flaws; few use RDF
Applications of RDF:– Open Directory Project, selected software (e.g., Siderean)– OCLC Connexion exports Dublin Core in RDF/XML
CSDGM (a.k.a. FGDC)CSDGM (a.k.a. FGDC)
Content Standard for Digital Geospatial Metadata (CSDGM) [better known as “FGDC”]– CSDGM Version 2 - FGDC-STD-001-1998– Defines a common set of terminology and definitions for the
documentation of digital geospatial data – Maintained by Federal Geographic Data Committee (FGDC)
[an interagency committee]– Crosswalk of FGDC to ISO 19115:2003(E) Geographic
information - Metadata available; ANSI technical amendment for ISO-FDGC harmonization in progress
Value of FGDC:– Provides common standard for publishing metadata about
geospatial resources– Widely used by government and business – Many systems and applications support the standard
Applications of FGDC:– Adopted or usable by major geospatial agencies in West.– Usefulness extended with profiles (e.g. Biological Data)
COSATICOSATI
Committee on Scientific and Technical Information (COSATI) – Cataloging rules and record format for the descriptive
cataloging of technical reports and similar documents– Field tags are alpha strings (not numerical like MARC)– Related COSATI subject category list can be used– Owned by CENDI (the Commerce, Energy, NASA, Defense
Information Managers Group) [successor to COSATI]
Value of COSATI:– Supports straightforward capture of useful metadata for
scientific and technical information
Applications of COSATI:– Used by a number of science/technical and defense U.S.
federal agencies– Small number of library systems (e.g., SIRSI) support COSATI
record import/export– COSATI can be converted to MARC if desired
OCLC Online Computer Library Center
Questions
LinksLinksDublin Core: http://www.dublincore.org
EAD: http://www.loc.gov/ead
FGDC: http://www.fgdc.gov/metadata/meta_stand.html
MARC 21: http://lcweb.loc.gov/marc/marcdocz.html
MARCXML: http://www.loc.gov/marc/marcxml.html
METS: http://www.loc.gov/standards/mets
MIX: http://www.loc.gov/standards/mix
MODS: http://www.loc.gov/standards/mods
ONIX: http://www.editeur.org/onix.html
RDF: http://www.w3.org/RDF
TEI: http://www.tei-c.org
OCLC Research: http://www.oclc.org/research