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This page includes thoughts about how to implement coordination in SKOS (see SkosDev). Feel free to change and add your thoughts!


  • SKOS-Core : Proposals and Issues: coordination-8: Add support for subject indexing with coordinations of concepts ('pre-coordinate indexing')
  • SkosDev/ClassificationPubGuide - includes a suggestion how to express coordination
  • AlistairMilesThesis ("A Theory of Retrieval Using Structured Vocabularies"), Chapter 6


  • Thesauri may include instructions for coordination ("USE x + y"/"UF+")
  • Queries may be expressed as coordinations (but don't mix them up, there are differences!)



AGROVOC includes the term "Pollution" that links to "Oil spills" with relation "UF+". "Oil spills" is a non-prefered term that links to "Pollution" and "Petroleum" with "USE". So "Oil spills" could be modelled as a coordination of "Pollution" and "Petroleum" if a new class skos:Coordination is introduced:

<skos:Coordination rdf:about="#Oil_spills">
  <skos:altLabel xml:lang="en">Oil spills</skos:altLabel>
  <skos:inCoordination rdf:resource="#Pollution"/>
  <skos:inCoordination rdf:resource="#Petroleum"/>

It's worth to think about whether a coordination is in fact a mapping to multiple concepts.

Indexing in

In an URL can be indexed by multiple users with multiple keywords. For instance the Website of the Library of Congress is indexed by one person with "congress", "reference", and "library" and by another person with "library", "national", "congress". This is how it could be expressed in SKOS. Please note that the order of tags is not included in this model (but it is in

<rdf:Description rdf:about="">
  <dc:title>The Library of Congress</dc:title>
  <skos:subject rdf:resource="#bookmark1"/>
  <skos:subject rdf:resource="#bookmark2"/>

<skos:Coordination rdf:about="#bookmark1">
  <skos:altLabel>congress reference library</skos:altLabel>
  <!-- additional information (creator, date...) here -->
  <skos:inCoordination rdf:resource="#congress"/>
  <skos:inCoordination rdf:resource="#reference"/>
  <skos:inCoordination rdf:resource="#library"/>

<skos:Coordination rdf:about="#bookmark2">
  <skos:altLabel>library national congress</skos:altLabel>
  <!-- additional information (creator, date...) here -->
  <skos:inCoordination rdf:resource="#library"/>
  <skos:inCoordination rdf:resource="#national"/>
  <skos:inCoordination rdf:resource="#congress"/>

Add your examples here