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Besser--UC Librarians Metadata 5/19/00 1
Introduction toMetadata for Digital Libraries
Howard Besser
UCLA School of Education & Information
http://www.gseis.ucla.edu/~howard
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Metadata for Digital Libraries- Models for Digital Libraries Importance of Metadata Standards Types and Uses of Metadata Discovery Metadata: The Dublin Core Administrative and Structural Metadata: The Making of
America II Project Longevity Metadata Identification/Provenance The 4/99 NISO/DLF Image Metadata Workshop Various other Metadata
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Key problems we’re facing
Discovery Longevity- Interoperability-
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Serious Longevity Problems
What we know from prior widespread digital file formats
Images separating from their metadata Inaccessibility of software needed to view
an image Inability to even decode the file format of
an image
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Traditional Digital Library Model
DL
DL
DL
DL
useruser
search & presentation
search & presentation
search & presentation
search & presentation
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Ideal Digital Library Model
DL
DL
DL
DL
useruser
search & presentation
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For Interoperability Digital Libraries Need Standards
Descriptive Metadata for consistent description
Discovery Metadata for finding Administrative Metadata for viewing and
maintaining Structural Metadata for navigation ... Terms & Conditions Metadata for
controlling access...
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Why are Standards and Metadata consensus
important? Managing digital files over time Longevity Interoperability Veracity Recording in a consistent manner Will give vendors incentive to create
applications that support this
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Why Standards? Why do we need standards?
– To make information universally available to users– facilitate sharing and interchange of information– To preserve information (make it safe from
changes in hardware and software) Standards only work if communities widely
accept them, but they’re necessary for communities to work together
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Why are you Managing this Information?
Organizational mission & type Users Uses
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Questions to Ask
What communities is this standard designed for? What type of information is this standard designed to
handle? What functions is this standard designed to serve? What previous standards is it built upon? Does the standard prescribe how to create new records (or
parts of records), or how to map from existing records? How far does the standard go? Semantics: Does it define
element sets? Rules? Syntax?-
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What is Metadata
_ Structured data describing other data used to find or help manage information resources
_ Aids in interoperability_ Titles, dates, captions, cataloging and
indexing data, file headers, rights info, provenance, code books, transaction logs, ...
_ One person’s metadata is another’s data
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Sorting through the Standards Morass
_ Data Structures (DC, CDWA, MARC, VRA Core, TEI, EAD, MESL data dict)
_ Data Interchange (Z39.50)
_ Data Values/vocabularies (LCSH, AAT, ULAN, TGN)
_ Data Content/syntax (AACR2)
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Semantics/Syntax/Structure
_ Semantics– meaning, as defined by a community to meet their particular needs
(DC)
_ Syntax– a systematic arrangement of data elements for machine processing
– facilitates the exchange and use of metadata among various applications (HTML, XML, RDF)
_ Structure– a formal arrangement of the syntax with the goal of consistent
representation of the semantics (rules defining field contents like 1/11/99)
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What is MetadataTypes & Uses
lots of different ways of dividing the clusters
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Uses of Metadata
_ Discovery & Retrieval_ Identification/Provenance_ Rights Management_ Viewing_ Integrity_ Longevity_ Content rating
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Containers and Packages of Metadata
Warwick, not MARC
_ modular_ overlapping_ extensible_ community-based_ designed for a networked world to aid
commonality btwn communities while still providing full functionality within each community
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Some different schemes where Metdata is kept
_ embedded withing the object (HTML tags)_ in a separate related DB maintained by same
organization (OPAC, MOA II)_ in a separate DB maintained by a separate
organization (Books in Print, ratings systems)
_ derived on-the-fly from a different scheme (MARC-to-DC)
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Collaborative Metadata Projects
Dublin Core NSF/ERCIM Digital Collaboratory OCLC CORC Project- Visual Resources Association (VRA) Core Encoded Archival Description (EAD) Computerized Interchange of Museum Information
(CIMI)- Records Export for Art and Cultural Heritage
(REACH)
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CORC--Cooperative Online Resource Catalog
_ both bib records & webliographies (pathfiinders)
_ supports both AACR2/MARC and DC_ began 1/99, scheduled availability 7/00_ 100-200 participants
– Academic libraries– OCLC networks, special libraries, public
libraries, state & national libraries, consortia
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Dublin Core (3/95)
_ improve resource discovery_ anticipate precision problems of Web Crawler-
based searching tools_ existing metadata could be “dumbed down”_ elements should be simple to understand and use,
so that any individual should be able to assign terms him/herself
_ software might eventually automatically generate very base-level metadata
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Dublin Core
Title Creator Subject Description Publisher Contributors Date Type
Format Identifier Source Language Relation Coverage Rights
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Dublin Core
every element is both optional and repeatable elements are cross-disciplinary elements are extensible by organized communities can employ a syntax such as html’s
<META> tagset for use by Spiders and HarvestersMay 2000 DLF Metadata Harvesting Project
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DC Qualifiers
_ allows one community to express important nuances and qualifications, while still making the basic importance available to communities with simple needs
_ our community can reflect alternate title, transliterated title, and main title, yet they will all be found under a simple Web search under “title”
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Discovery Metadata:Recent History
_ Dublin Core (3/95)_ Warwick Framework (4/96)_ Image Metadata Workshop (9/96)_ Canberra, Helsinki, ... DC (98)_ Digital Library Collaboratory (97-)_ DC-8, Frankfurt 10/99
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Dublin Core--further work
_ Warwick Framework– metadata packages for extensible functions
– layed groundwork for RDF
_ Canberra Qualifiers– refining the semantics of the element set to provide more precise info
– SUBELEMENT, SCHEME, LANG
_ Granularity– no hierarchical relationships w/i a given DC record; only one record
per discrete object (collection or item-level), and relationship field plus qualifier links them
The Research Process and Functional Categories of
Metadata_ Discovery_ Retrieval_ Collation_ Analysis_ Re-presentation
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Making of America II-
Background of the DLF Project Administrative Metadata Structural Metadata
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DLF Metadata for Interoperability Testbed:
the MOA II Project R & D Distributed Repositories Transportation, 1869-1900 Testbed Project Best Practices Structural and administrative metadata
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Previous Projects/Background
Library Standards Background UC Berkeley Background Finding Aids EAD SGML EAD “Digital Archives”
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MOA II Classes of Objects
Continuous Tone Photos Photo Albums Diaries, journals, letterpress books Ledgers Correspondence
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MOA II Metadata
_ Administrative Metadata– for enhancing resource management
_ Structural Metadata– for reflecting internal hierarchies and
relationships btwn parts
_ Raw/Seared/Cooked
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MOA II Best practices
Use/Users/Collection: Benchmarking Masters vs. Derivatives Scanning- Administrative Metadata- Structural Metadata-
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Scanning Best Practices
_ Think about users (and potential users), uses, and type of material/collection
_ Scan at the highest quality that does not exceed the likely potential users/uses/material
_ Do not let today’s delivery limitations influence your scanning file sizes; understand the difference between digital masters and derivative files used for delivery
_ Many documents which appear to be bitonal actually are better represented with greyscale scans
_ Include color bar and ruler in the scan
_ Use objective measurements to determine scanner settings (do NOT attempt to make the image good on your particular monitor or use image processing to color correct)
_ Don’t use lossy compression_ Store in a common (standardized)
file format_ Capture as much metadata as is
reasonably possiple (including metadata about the scanning process itself)
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Administrative Metadatato uniquely identify a digital resource and manage it
over time
_ Information about where the various pieces/versions of the object reside
_ Information to view the digital object_ Information about the scanning process
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Structural Metadata:that which is relevant to presentation of the
digital object to the user
_ metadata defining the "object”: a book, a diary, a photo album
_ metadata defining the “sub-objects”: pages (physical) or chapters and subheads (intellectual)
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SGML, XML, HTML
_ TEI for structured humanities text_ EAD for Finding Aids
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Other Types of Metadata-
_ Longevity_ Identification/Provenance_ Rights Management
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The Short Life of Digital Info: Digital Longevity Problems-
Disappearing Information The Viewing Problem The Scrambling Problem The Inter-relation Problem The Custodial Problem The Translation Problem
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The Viewing Problem
Digital Info requires a whole infrastructure to view it
Each piece of that infrastructure is changing at an incredibly rapid rate
How can we ever hope to deal with all the permutations and combinations
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The Scrambling Problem
Dangers from: Compression to ease storage & delivery Container Architecture to enhance digital
commerce
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The Inter-relation Problem
-Info is increasingly inter-related to other info
-How do we make our own Info persist when it points to and integrates with Info owned by others?
-What is the boundary of a set of information (or even of a digital object)?
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The Custodial Problem
How do we decide what to save? Who should save it? How should they save it?
– -methods for later access: emulation, migration, etc.
– -issues of authenticity and evidence
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The Translation Problem
Content translated into new delivery devices changes meaning– -A photo vs. a painting– -If Info is produced originally in digital form in
one encoded format, will it be the same when translated into another format?
– Behaviors
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Pieces of the Solution (1/2)
-We need to insist upon clearly readable standardized ways for digital objects to self-identify their formats
-We should discourage scrambling -We need to better understand information
inter-relates to other Info, and what constitutes “boundaries” of Info objects
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Pieces of the Solution (2/2)
-People and organizations wishing to make information persist need guidelines of how to go about doing it
-We need to better understand how translating from one storage or display format to another affects the meaning of a work
-We need to save the “behaviors” of a digital object, not just it’s “contents”
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Metadata can be the first line of defense
Can tell you– where the file is (if you can’t find the file)– where more info about the file is (if you have the
file but most other metadata has become separated)
– what the file format is– what the compression scheme is– what application program and version is needed
for the file
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Groups Working onthe Big Longevity Problem
http://sunsite.Berkeley.EDU/Imaging/Databases/Longevity/
CPA Task Force CPA Study Group Getty “Time & Bits” Conference-
Internet Archive Long Now
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Identification/Provenance (Images)-
The number of variant forms of a work can be enormous Image Families A digital image frequently has many layers of parentage Information about the parentage that can indicate the
quality and veracity of the image (Dublin Core "Source" and "Relation")
how to deal with different versions derived from the same scan or different encoding schemes
Vocabulary Standards to express this
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The number of variant forms of a work can be enormous
different views of the same object different scans of the same photo different resolutions different compression schemes different compression ratios different file storage formats different details of the same image ...
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Identification/Provenance
how to deal with different versions (browse, hi-res, medium res) derived from the same scan or different encoding schemes (TIFF, PICT, JFIF)
Vocabulary Standards to express this– VRA Surrogate Categories– CIMI's "Image Elements”
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NISO/DLF Image Metadata WorkshopPossible Goals
Metadata fields Rules for Field Contents (authority control)
Core set of necessary fields
Syntax for expressing fields and contents (headers)
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Image Metadata
Focus on Metadata that may prove helpful for
management use preservation ...
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Image Metadata
Break-out Groups: Work Done
Characteristics and Features of Images Image Production and Reformatting
Features Image Identification and Integrity
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Other Metadata
_ Description of depiction/surrogate (What VRA calls its "Surrogate Categories")
_ Description of original object
_ Rights and Reproduction Information_ Location Information
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Data Structures:The VRA Core
28 elements specifically for visual resource collections
Work Description Categories- Visual Document Description Categories- http://www.oberlin.edu/~art/vra/dsc.html
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VRA Core:Work Description Categories
Work type Title Measurements Material Technique Creator Role Date Repository name Repository place
_ Repository number_ Current site_ Original site_ Style/period/group/
movement_ Nationality/culture_ Subject_ Related work_ Relationship type_ Notes
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VRA Core:Visual Document Description
Categories Visual document type Visual document format Visual document measurements Visual document date Visual document owner Visual document owner number Visual document view description Visual document subject Visual document source
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Data Value Metadata(vocabularies)
LCSH TGM AAT ULAN TGN VRA Core
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Thesaurus for Graphic Materials
designed for subject indexing of pictorial materials, particularly large general collections of historical images
for cataloging and retrieval good for general audiences and broad approaches
to the material TGM-I: Subject Terms & TGM-II: Genre and
Physical Characteristic Terms http://lcweb.loc.gov/rr/print/tgm/toc.html
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AAT
120,000 terms for describing objects, textual materials,
images, architecture, and material culture from antiquity to present
large and complex http://www.getty.edu/gri/vocabularies/
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ULAN
name authority http://www.getty.edu/gri/vocabularies/
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Thesaurus of Geographic Names
over 1 million records hierarchical and global throughout history most records include coordinates and
descriptive notes
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<Indecs>
formal structure for describing and uniquely identifying intellectual property itself, the people and businesses involved in its trading, and the agreements which they make about it (primarily for publishing, music, and visual arts)
will develop high-level specifications for the services that will be required to implement a global IP trading system based on this <indecs> generic data model
focus is on encoding rights at a high level, not on resource discovery likely to involve metadata schma registration and directory to allow
interoperation of personal identifiers for rightsholders and users supported by EEC DG-13 First meeting July 1999 http://www.indecs.org/
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Metadata Mapping-
Crosswalks Resource Description Framework (RDF)
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Crosswalks
mapping btwn differing metadata structures eliminate the need for monolithic,
universally adopted standards focus on flexibility and interoperatiblity RDF-based metadata registries
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Crosswalk ExampleCDWA Object ID
CIMISchema
FDAVRA CoreCategories
USMARCDUBLINCORE
OBJECT/WORK (core)
DocumentClassification-CatalogLevel (core)DocumentClassification-Group Type
Object/Work-Type (core)
Type ofObject
objectNAME DocumentClassification- DocumentType (core)Purpose-Purpose(Broad) (core)Purpose-Purpose(Narrow)
W1. WorkType
655 Genre-Form
Type
Object/Work-Components
quantity DocumentClassification-Extent
300a PhysicalDescription-Extent
ORIENTATION/ARRANGEMENT
Description
TITLES ORNAMES(core)
Title objectTitlebibliographicTitle
Group/ItemIdentification-RepositoryTitleGroup/ItemIdentification-DescriptiveTitle (core)Group/ItemIdentification-InscribedTitle
W2. Title 24Xa Titleand Title-RelatedInformation
Title
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Resource Description Framework (RDF, spec released 2/99)
_ W3C Metadata activity_ designed to move the Web beyond simple links to
semantically-rich relationships btwn resources_ metadata application using XML as a common syntax for
exchange and processing_ flexible architecture for managing diverse application-
specific metadata packets that can be processed by machines_ associates resources, property types, and corresponding
values_ http://www.w3.org/RDF/
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RDF
_ Resources (character strings, names, digital objects)
_ Property (“is the author of”)_ Value
_ resources+properties=relationships_ many different relationships can be reflected
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XML-encoded RDF
_ <?xml:namespace ns=http://www.w3.org/RDF/RDF prefix="RDF" ?>
_ <?xml:namespace ns=http://purl.oclc.org/DC/ prefix="DC" ?>
_ <RDF:RDF>_ <DC:Creator>Howard Besser</DC:Creator>_ </RDF:Description>_ </RDF:RDF>
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Should you start building with RDF today?
_ Tools are primitive_ Standard still likely to evolve
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Metadata for Digital LibrariesHoward Besser
UCLA School of Education & Information
Baca, Murtha (ed). Introduction to Metadata, Los Angeles: Getty Information Institute, 1998
http://www.getty.edu/gri/standard/intrometadata/
http://sunsite.Berkeley.EDU/Imaging/Databases/#standards
http://sunsite.Berkeley.EDU/moa2/
http://sunsite.Berkeley.EDU/Longevity/
http://www.ifla.org/II/metadata.htm
http://purl.oclc.org/metadata/dublin_core/
http://purl.oclc.org/corc/
http://lcweb.loc.gov/ead/
http://www.gseis.ucla.edu/~howard/image-meta.html
http://www.gseis.ucla.edu/~howard/Metadata/UC-May00/
http://sunsite.berkeley.edu/Metadata/sp2000.html