1. Dublin Core and Digital
Collections
March 18, 2013
Richard Sapon-White
1

2. Overview
Dublin Core (DC)
History
Elements, Principles and Qualifiers
Syntax
Uses
Digital Collections and DC
Discussion of DC and Controlled
Vocabularies
2

3. DC History
2nd International WWW Conference,
Chicago, 1994
1st Dublin Core Workshop, OCLC
headquarters, Dublin, Ohio, USA
Development by Dublin Core Metadata
Initiative – http://dublincore.org
3

4. DC History
Rapid increase in the number of WWW
resources
Problem: retrieval of relevant documents
Solution: a metadata schema that is
Simple enough for resource creators to use
Flexible enough to allow for more detailed
description
Not restricted to any one exchange syntax
4

5. Fifteen DC Elements
Identifier Language Source
Relation Rights Coverage
Format Type Publisher
Description Date Contributor
Subject Title Creator
5

6. Characteristics of the Dublin
Core
•All elements are optional
•All elements are repeatable
•Elements may be displayed in any order
•Extensible
•International in scope
6

7. Dublin Core Principles
Dumb-Down
One-to-One
Appropriate Values
7

8. Dumb-Down
The fifteen core elements are usable with or
without qualifiers
Qualifiers make elements more specific:
Element Refinements narrow meanings, never
extend
Encoding Schemes give context to element values
If software encounters an unfamiliar qualifier,
look it up –or just ignore it!
8

9. The One-to-One Principle
• Describe one manifestation of a resource with
one record
Example: a digital image of the Mona Lisa is not
described as if it were the same as the original
painting
• Separate descriptions of resources from
descriptions of the agents responsible for
those resources
Example: email addresses and affiliations of creators
are attributes of the creator, not the resource
9

10. Appropriate Values
“Best practice for a particular element
or qualifier may vary by context, but in
general an implementer cannot always
predict that the interpreter of the
metadata will always be a machine. This
may impose certain constraints on how
metadata is constructed, but the
requirement of usefulness for discovery
should be kept in mind.”--from Using Dublin
Core by Diane Hillman
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11. Qualified Dublin Core
Includes:
Additional element: Audience
Element Refinements
Value Encoding Schemes
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12. Element Refinements
Make element meanings narrower, more specific:
a Date Created versus Date Modified
an Is Replaced By versus Replaces Relation
Depending on syntax chosen, refinements may appear as
stand-alone tags instead of with elements:
<dct:created>2002-10-04</dct:created>,instead of:
<dc:date><dct:created>2002-10-04
</dct:created></dc:date>
•Requires a schema to dumb-down Date Created to Date
Dublin Core is simple enough to support both usages
12

13. Encoding Metadata Records
Mid-1990s: HTML tags embedded in Web
pages
Simple, easy to deploy, but inflexible, hard to
maintain
Bad tags like DC.Creator.eyecolor imply a non-
existent support for nesting and for entity
distinctions
2000+: Better XML/RDF alternatives
RDF metadata supports complex structures without breaking
simple DC grammar
Open Archives Initiative promotes mass adoption of an XML
schema for simple, unqualified Dublin Core records - along
with a protocol to make them available 13

14. HTML-Encoded DC
<link rel=“schema.DC”
href=http://purl.org/dc/elements/1.1
title=“Dublin Core Metadata Element Set,
version 1.1”>
<meta name=“DC.Element_name”
content=“element_value”>
Example: <meta name=“DC.Title”
content=“Using Dublin Core”>
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15. HTML-Encoded DC (cont.)
<link rel=“schema.DC”
href=http://purl.org/dc/elements/1.1
title=“Dublin Core Metadata Element Set, version 1.1”>
<meta name=“DC.Title”
content=“Using Dublin Core”>
<meta name=“DC.Creator”
content=“Hillman, Diane”>
<meta name=“DC.Identifier”
content=“http://dublincore.org//documents/usageguide/”>
<meta name=“DC.Type”
scheme=“DCMIType”
content=“text”>
<meta name=“DC.Date.created”
content=“2003”> 15

16. Problems with using HTML for
DC
Useful only when web crawlers and
search engine indexers can detect
<meta> tags
HTML not useful for complex
constructions (e.g., when repeated
elements need to be grouped)
HTML only useful with metadata
embedded in documents
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17. RDF/XML-Encoded DC
Allows multiple metadata schemes to
be read by humans and parsed by
machines
Allows multiple objects to be described
All namespaces must first be defined
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18. RDF/XML-Encoded DC Example
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-
syntax-ns#"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<rdf:Description
rdf:about="http://media.example.com/audio/guide.ra">
<dc:creator>Rose Bush</dc:creator>
<dc:title>A Guide to Growing Roses</dc:title>
<dc:description>Describes process for planting
and nurturing different kinds of rose
bushes.</dc:description>
<dc:date>2001-01-20</dc:date>
</rdf:Description>
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19. Value Encoding Schemes
Indicate that the value is:
a term from a controlled vocabulary (e.g.,
Library of Congress Subject Headings)
a string formatted in a standard way (e.g.,
that "05/02" means May 2nd, not February
5th)
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20. Uses of Dublin Core
Subject gateways and portals
Description of resources generated from DC
Digitization projects where full cataloging
would be too time consuming or problematic
http://osulibrary.oregonstate.edu/digitalcollecti
ons/
Union catalogs, search engine indexes, external
databases
Converted from more detailed metadata in a local
database 20