owl:DatatypeProperty                          

Definition

A datatype property is one of two main categories of properties. It links individuals to data values, and is defined as an instance of the built-in OWL class owl:DatatypeProperty.

An owl:DatatypeProperty is a subclass of the RDF class rdf:Property

Schema

    rdfs:Class rdf:ID="DatatypeProperty">

        <rdfs:label>DatatypeProperty</rdfs:label>

        <rdfs:subClassOf rdf:resource="&rdf;Property"/>

    </rdfs:Class>

Example listing

Triple

If a property q is used where a data property is expected then there should be a triple

    q   rdf:type   owl:DatatypeProperty

RDF/XML

When using datatypes, please note that even if a property is defined to have a range of a certain datatype, RDF/XML still requires that the datatype be specified each time the property is used.

    <owl:DatatypeProperty rdf:about="#timeStamp">

        <rdfs:domain rdf:resource="#Measurement"/>

        <rdf:range rdf:resource="&xsd;dateTime"/>

    </owl:DatatypeProperty>

An example could be the declaration of "timeStamp" that we use in the Measurement example below:

    <Measurement>

        <observedSubject rdf:resource="#JaneDoe"/>

        <observedPhenomenon rdf:resource="#Weight"/>

        <observedValue>

            <Quantity>

                <quantityValue rdf:datatype="&xsd;float">59.5</quantityValue>

                <quantityUnit rdf:resource="#Kilogram"/>

            </Quantity>

        </observedValue>

        <timeStamp rdf:datatype="&xsd;dateTime">2003-01-24T09:00:08+01:00</timeStamp>

    </Measurement>

Other information

In OWL Full all data values are considered also to be part of the individual domain. In fact, in OWL Full the universe of individuals consists of all resources (owl:Thing is equivalent to rdfs:Resource). This means that object properties and datatype properties are not disjoint. Because data values can be treated as individuals, datatype properties are effectively subclasses of object properties.

In OWL Full owl:ObjectProperty is equivalent to rdf:Property. The consequence is that datatype properties are effectively a subclass of object properties. (Note: the fact that owl:ObjectProperty and owl:DatatypePropertyare both subclasses of rdf:Property is not inconsistent with this).  In practice, this mainly has consequences for the use of owl:InverseFunctionalProperty (an owl:DatatypeProperty may be an owl:InverseFunctionalProperty in OWL Full).

We use the term "property extension" in a similar fashion to "class extension". The property extension is the set of instances that is associated with the property. Instances of properties are not single elements, but subject-object pairs of property statements. In relational database terms, property instances would be called "tuples" of a binary relation (the property).

If a node x has rdf:type  owl:Restriction then the following should be the case: It is the subject of exactly one triple with predicate owl:onProperty, with the object of that triple being an owl:ObjectProperty or owl:DatatypeProperty.

Use in ISO 15926