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5. Important Concepts from the W3C RDF V... > 5.3. Refining RDF Vocabularies with ...

Refining RDF Vocabularies with Constraints

Within RDF Schema, constraints define class associations for properties. In addition, there are subclasses of both Property and Resource that are specific to constraints.

In Example 5-4, the rdfs:domain property was used to associate a property with the resource it modified. It was used with both the author and title properties to associate them with the Article resource. The RDF Schema property is further constrained to be used only with properties by specifying an rdfs:domain of Property for the rdfs:domain itself.

An RDF property can be used for more than one resource type. Something such as title can then be used for Article but can also be used for Person (a person’s work title), as well as something such as Painting (title of a painting). The only limitation is the domain scope. The rdfs:range property is used to specify the classes the property can reference as values. Unlike the domain element, only one RDF range constraint can be attached to any property—equivalent to the restriction in most programming languages that a variable can be of only one data type, constraining the allowable values that the variable can contain.


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