Improving Metadata Interoperability at the Schema Definition Language Level
To improve metadata interoperability at schema definition language metadata model level, the generalized 12 Common Terms and 58 qualifiers of the Common Terminology are represented with XML schema definition language (XSD) and RDF schema language (RDFS). These open for many communities to use CT either in XML or RDF form. Especially, CT in RDF will give more opportunities for it to be developed further enhancing semantic interoperability on the Web. The represented RDF schema for CT will be a foundation to conduct Linked Open Data on the Web to improve metadata interoperability at the repository level.
3.1. ct.xsd (full xml schema is in the web page, ct.xsd)
Practically, in XML schema (W3C, XML Schema), 12 Common Terms of CT are defined as elements, and 58 qualifiers are defined as attributes of type, authority, name, role, and source.
<xs:element name="CT" type="anyCT"/>
<xs:complexType name="anyCT">
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element name="contributor" type="contributorType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="date" type="dateType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="description" type="descriptionType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="format" type="formatType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="identifier" type="identifierType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="language" type="languageType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="publisher" type="publisherType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="relation" type="relationType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="rights" type="rightsType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="subject" type="subjectType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="title" type="titleType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="typeGenre" type="typeGenreType" minOccurs="0" maxOccurs="unbounded"/>
</xs:choice>
</xs:complexType>
<xs:complexType name="contributorType">
<xs:annotation>
<xs:documentation>
The name of a person, organization, or event (conference, meeting, etc.) associated in some way with the resource (MODS). An entity responsible for making contributions to the resource (Contributor of DC).
</xs:documentation>
</xs:annotation>
<xs:simpleContent>
<xs:extension base="valueTypes">
<xs:attribute name="name" use="optional">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="personal"/>
<xs:enumeration value="corporate"/>
<xs:enumeration value="meeting"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="role" use="optional" type="xs:string"/>
<xs:attribute name="authority" use="optional">
<xs:annotation>
<xs:documentation>
Authorities of ‘role’ attribute name are in CTRelators of CTScheme:
LC MARC relators or unknown.
</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="LCMARCrelators"/>
<xs:enumeration value="Unknown"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
…..
<xs:simpleType name="valueTypes">
<xs:union memberTypes="xs:string xs:anyURI"/>
</xs:simpleType>
On the other hand, in RDF schema (W3C, RDF Schema 1.1, 2014), 12 Common Terms of CT are defined as properties, and type, name, role and source qualifiers as sub-properties. For example, CT:subject has type attributes such as type=”spatial” and type=”temporal”in XML schema, but in RDFs, they are defined as sub-property of subject property as the below. They are also defined and connected asnarrower relationships in SKOS concepts (W3C, SKOS Simple Knowledge Organization System Primer, 2009). An authority qualifier in XML is defined as a class in RDFs.
<!-- subject -->
<rdf:Property rdf:about="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject">
<rdfs:label xml:lang="en-US">subject</rdfs:label>
<rdfs:comment xml:lang="en-US">A term or phrase representing the primary topic(s) on which a work is focused (MODS). The topic of the resource (DC).</rdfs:comment>
<dc:description xml:lang="en-US">includes Coverage(DC): The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant (DC).</dc:description>
<rdfs:isDefinedBy rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CommonTerminology.pdf"/>
<skos:narrower rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject/spatial"/>
<skos:narrower rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject/temporal"/>
<skos:narrower rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject/classification"/>
<skos:related rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTSubject/lcsh"/>
<skos:related rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTSubject/lcshac"/>
<skos:related rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTSubject/mesh"/>
<skos:related rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTSubject/csh"/>
…
</rdf:Property>
<rdf:Property rdf:about="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject/spatial">
<rdfs:label xml:lang="en-US">spatial</rdfs:label>
<rdfs:comment xml:lang="en-US">includes coverage and spatial(DC), coordinates, projection, scale, geographic information, publishing country code</rdfs:comment>
<rdfs:subPropertyOf rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject"/>
<rdfs:isDefinedBy rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CommonTerminology.pdf"/>
</rdf:Property>
<rdf:Property rdf:about="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject/temporal">
<rdfs:label xml:lang="en-US">temporal</rdfs:label>
<rdfs:comment xml:lang="en-US">"temporal" is used for chronological subject terms or temporal coverage</rdfs:comment>
<rdfs:subPropertyOf rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject"/>
<rdfs:isDefinedBy rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CommonTerminology.pdf"/>
</rdf:Property>
<rdfs:Class rdf:about="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTSubject" xml:lang="en">
<rdfs:label xml:lang="en">CTSubject</rdfs:label>
<rdfs:comment xml:lang="en">CTSubject is a set of authorities for subject headings and classifications: authority=”lcsh”, "lcshac","mesh", ”csh", ”nal", ”rvm”, ”lcc”, "ddc", ”iso3166”;
for ”classification” : authority=”udc”, ”nlm”, ”sudocs”, ”candocs”, ”tgn”, and ”other”.
</rdfs:comment>
<skos:narrower>
<skos:Collection>
<skos:member rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTSubject/lcsh"/>
<skos:member rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTSubject/lcshac"/>
<skos:member rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTSubject/mesh"/>
…
</skos:Collection>
</skos:narrower>
</rdfs:Class>
The Common Terminology that has 12 Common Terms (elements/properties) and 58 qualifiers (sub-properties) with authorities (classes) is defined in SKOS as concepts with URIs. The defined SKOS concepts of CT clarify the relationships between properties(sub-properties) and CTSchemes in XML and RDF. CT is defined as a Concept Scheme in SKOS that has 12 top concepts for 12 Common Terms (properties) as the below (W3C, SKOS Simple Knowledge Organization System Reference, 2009). For example, CT:contributor is top concept of CT in CT 1.1 scheme and has two narrower terms (sub-properties), name and role. The role sub-property of contributor has narrower terms to designate the role of contributor such as author, creator, etc. that are defined the related CTRelator of CTScheme. The full SKOS concepts of CT are in Appendix C.
<!-- Scheme: Common Terminology 1.1 -->
<skos:ConceptScheme rdf:about="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1" xml:lang="en">
<dc:title>Common Terminology 1.1</dc:title>
<dc:description>Common Terminology 1.1 is common terms of MARC, MODS, DC and QDC.
It is to achieve and improve metadata interoperability among different schemas that have some different degree of generality or specificity.</dc:description>
<dc:rights>Free to all.</dc:rights>
<dcterms:issued>2014-05-26</dcterms:issued>
<dcterms:modified>2014-05-26</dcterms:modified>
<skos:prefLabel>Common Terminology</skos:prefLabel>
<skos:altLabel>Common Terminology(CT)</skos:altLabel>
<skos:altLabel>CT</skos:altLabel>
<skos:altLabel>ct</skos:altLabel>
<skos:altLabel>ct1.1</skos:altLabel>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/contributor"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/date"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/description"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/format"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/identifier"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/language"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/publisher"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/relation"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/rights"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/subject"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/title"/>
<skos:hasTopConcept rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/typeGenre"/>
</skos:ConceptScheme>
<!-- Concept: contributor -->
<skos:Concept rdf:about="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/contributor" xml:lang="en">
<skos:inScheme rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1"/>
<skos:topConceptOf rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1"/>
<skos:prefLabel xml:lang="en">contributor</skos:prefLabel>
<skos:definition xml:lang="en">The name of a person, organization, or event (conference, meeting, etc.) associated in some way with the resource (MODS).
An entity responsible for making contributions to the resource (Contributor of DC).
An entity primarily responsible for making the resource (creator of DC).</skos:definition>
<skos:narrower rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/contributor/role"/>
<skos:narrower rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/contributor/name"/>
</skos:Concept>
<skos:Concept rdf:about="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/contributor/role" xml:lang="en">
<skos:inScheme rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1"/>
<skos:prefLabel xml:lang="en">role</skos:prefLabel>
<skos:definition xml:lang="en">Define a role of contributor. The role is defined in CTRelator in CTScheme.</skos:definition>
<skos:related rdf:resource="http://courseweb.lis.illinois.edu/~sunjin/CT/1.1/CTScheme/CTRelator"/>
<skos:narrower>author</skos:narrower>
<skos:narrower>creator</skos:narrower> ….
</skos:Concept>
CT 1.1 diagram indicates relationships between properties and sub-properties with authorities. The blue nodes represent properties and the yellow nodes represent sub-properties. The 12 Common Terminology 1.1 diagram shows all 12 properties (Common Terms) and 58 sub-properties (qualifiers) with authorities that are defined in CTScheme. All detail CT diagrams are in CT Diagram 1.1 web page.
