2.4 Documentary Notes
Semantic relationships are crucial to the definition of concepts, as many KOS guidelines emphasize it. However, next to these structured characterizations, concepts sometimes have to be further defined using human-readable („informal“) documentation, such as scope notes or definitions.
SKOS provides a skos:note property for general documentation purposes. Inspired by existing KOS guidelines, such as [ISO2788] or [BS8723-2], this property is further specialized into skos:scopeNote, skos:definition, skos:example, and skos:historyNote to fit more-specific types of documentation.
skos:scopeNote supplies some, possibly partial, information about the intended meaning of a concept, especially as an indication of how the use of a concept is limited in indexing practice. The following example is adapted from [ISO2788]:
ex:microwaveFrequencies skos:scopeNote "Used for frequencies between 1GHz to 300Ghz"@en.
skos:definition supplies a complete explanation of the intended meaning of a concept. The following example is adapted from [ISO2788]:
ex:documentation skos:definition "the process of storing and retrieving information in all fields of knowledge"@en.
skos:example supplies an example of the use of a concept:
ex:organizationsOfScienceAndCulture skos:example "academies of science, general museums, world fairs"@en.
skos:historyNote describes significant changes to the meaning or the form of a concept:
ex:childAbuse skos:historyNote „estab. 1975; heading was: Cruelty to children [1952-1975]“@en.
In addition to these notes that are intended for users of a concept scheme, SKOS includes two specializations of skos:note that are useful for KOS managers or editors: skos:editorialNote and skos:changeNote.
skos:editorialNote supplies information that is an aid to administrative housekeeping, such as reminders of editorial work still to be done, or warnings in the event that future editorial changes might be made:
ex:doubleclick skos:editorialNote "Review this term after company merger
complete"@en.
ex:folksonomy skos:editorialNote "Check spelling with Thomas Vander Wal"@en.
skos:changeNote documents fine-grained changes to a concept, for the purposes of administration and maintenance:
ex:tomato skos:changeNote
"Moved from under 'fruits' to under 'vegetables' by Horace Gray"@en.
It is important to notice that the hierarchical link between skos:note and its different specializations allows all the documentation associated with a concept to be retrieved in a straightforward way. Every skos:definition is a skos:note, every skos:scopeNote is a skos:note, and so on.
As illustrated above, SKOS documentation properties can be simply used with RDF plain literals. Section 4.2 will show that there are other possible patterns, as the range of these properties is not be restricted to literals. One important feature of simple literals, however, is the ability to use language tags, as done for labeling properties. Documentation may thus be provided in multiple languages:
ex:pineapples rdf:type skos:Concept;
skos:prefLabel "pineapples"@en;
skos:prefLabel "ananas"@fr;
skos:definition "The fruit of plants of the family Bromeliaceae"@en;
skos:definition
"Le fruit d'une plante herbacée de la famille des broméliacées"@fr.
Before concluding this section, it is important to note that other, non-SKOS properties could be used to document concepts. The dct:creator property from Dublin Core [DC] can for instance be used to point to a person that created the concept:
ex:madagascarFishEagle dct:creator [ foaf:name "John Smith" ].