subject

• Obligation:  See Application Profiles
• Occurrence:  See Application Profiles
• Conditions:  See Application Profiles
• Scheme:  Varies. See Application Profiles; see also GEM Subjects [RDF], ERIC

Element Semantics (Definition)

The topic of the content of the resource.

General

• Name:  subject
• Label:  Subject and Keywords
• Namespace:  http://purl.org/dc/elements/1.1/
• Registration Authority:  Dublin Core Metadata Initiative (DCMI)
• Notes:  Typically, a Subject will be expressed as keywords, key phrases or classification codes that describe a topic of the resource. Recommended best practice is to select a value from a controlled vocabulary or formal classification scheme.

Best Practices

1. In GEM, the subject of a resource can (and should) be expressed in two distinct ways: (a) by selecting appropriate uncontrolled words and phrases from the text of the resource (i.e., keywords as opposed to a scheme used) as the cataloger sees appropriate; and (b) by selecting words and phrases from one or more controlled vocabularies (i.e., scheme(s) used) as determined by local practice. Systems may display these two categories of subjects separately—one as 'keywords' (see examples 1 & 2 below) and the other as 'subjects' (see example 3 below).
   
   Thus, this element might well include classification data (for example, Library of Congress Classification Numbers or Dewey Decimal numbers) or controlled vocabularies (such as Medical Subject Headings or Art and Architecture Thesaurus descriptors) (see example 3 below).
2. The «subject» element in GEM metadata is to represent the "aboutness" or "topicality" of the resource. The test of whether a term should be assigned by the cataloger is to ask whether an end user looking for something on the topic of the term would be satisfied when retrieving the resource. If the answer is "no", do not assign the term.
3. Select subject keywords (i.e. uncontrolled words or phrases) from either the title or description information. If the subject of the item is a person or an organization, use the same form of the name as you would if the person or organization were a creator or other contributor. Note, however, that names of creators and other contributors should not be included as subjects unless the work is about that person (i.e., it is autobiographical).
4. When using keywords, choose the most significant and unique terms, avoiding those too general to describe a particular item.

Metadata Encodings Examples

• Resource Description Framework (RDF/XML)
  

  Example 1 (uncontrolled keywords using 'value string'):
  
  <?xml version='1.0' encoding='UTF-8'?>
  <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>
      <dc:subject xml:lang='en'>
      Pythagorean Theorem
      </dc:subject>
  </rdf:Description>
  </rdf:RDF>
  
  Example 2 (uncontrolled keywords using 'value string'):
  
  <?xml version='1.0' encoding='UTF-8'?>
  <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>
      <dc:subject xml:lang='en'>
      Science--Physics
      </dc:subject>
  </rdf:Description>
  </rdf:RDF>
  
  Example 3 (controlled vocabulary using 'value URI'):
  
  <?xml version='1.0' encoding='UTF-8'?>
  <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>
      <!-- GEM hierarchical subject: Arts--Photography -->
      <dc:subject rdf:resource='http://purl.org/gem/instance/subject/GEM-S/arts_photography'/>
  </rdf:Description>
  </rdf:RDF>
  
  Example 4 (controlled vocabulary using 'value string')(DDC controlled vocabulary):
  
  <?xml version='1.0' encoding='UTF-8'?>
  <rdf:RDF xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'
      xmlns:rdfs='http://www.w3.org/2000/01/rdf-schema#'
      xmlns:dc='http://purl.org/dc/elements/1.1/'
      xmlns:dcterms='http://purl.org/dc/terms/'>
  <rdf:Description>
      <dc:subject>
          <dcterms:DDC>
              <!-- 'value' expresses the DDC notation -->
              <rdf:value>930</rdf:value>
              <!-- 'label' expresses the DDC human-readable text -->
              <rdfs:label>History of the ancient world (to ca. 499 A.D.)</rdfs:label>
          </dcterms:DDC>
      </dc:subject>
  </rdf:Description>
  </rdf:RDF>
  
  
  

• XML (Tags & Attributes)
  

  Example 1 (keywords):
  
  <?xml version='1.0' encoding='UTF-8'?>
  <record xmlns:dc="http://purl.org/dc/elements/1.1/">
  <dc:subject xml:lang='en'>
      Pythagorean Theorem
  </dc:subject>
  </record>
  
  Example 2 (keywords):
  
  <?xml version='1.0' encoding='UTF-8'?>
  <record xmlns:dc="http://purl.org/dc/elements/1.1/">
  <dc:subject xml:lang='en'>
      Science--Physics
  </dc:subject>
  </record>
  
  Example 3 (controlled vocabulary using 'value URI'):
  
  <?xml version='1.0' encoding='UTF-8'?>
  <record xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'>
    <!-- GEM hierarchical subject: Arts--Photography -->
  <dc:subject xsi:type='dcterms=URI'>
    http://purl.org/gem/instance/subject/GEM-S/arts_photography
  </dc:subject>
  </record>
  
  Example 4 (controlled vocabulary using 'value string')(DDC controlled vocabulary):
  
  <?xml version='1.0' encoding='UTF-8'?>
  <record xmlns:dc='http://purl.org/dc/elements/1.1/'
     xmlns:dcterms='http://purl.org/dc/terms/'
     xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'>
  <dc:subject xsi:type='dcterms:DDC'>
     930
  </dc:subject>
  </record>

• Crosswalks
  IEEE LOM: 1.5:General.Keyword
  MARC:
  • No Scheme: 653$a (Index Term—Uncontrolled)
  • Scheme=LCSH: 650 #0$a (Subject added entry—Topical term)
  • Scheme=MeSH: 650 #2$a (Subject added entry—Topical term)
  • Scheme=LCC: 050 ##$a (Library of Congress Call Number/Classification number)
  • Scheme=DDC: 082 ##$a (Dewey Decimal Call Number/Classification number)
  • Scheme=UDC: 080 ##$a (Universal Decimal Classification Number)
  • Scheme=(other): 650 #7$a with $2=code from MARC Code List for Relators, Sources, Description Conventions