RDF Schema

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# RDF Schema (RDFS)

RDF Schema (RDFS) is an extension to RDF.

## RDF Schema and Application Classes

RDF describes resources with classes, properties, and values.

In addition, RDF also need a way to define application-specific classes and properties. Application-specific classes and properties must be defined using extensions to RDF

One such extension is RDF Schema.

## RDF Schema (RDFS)

RDF Schema does not provide actual application-specific classes and properties.

Instead RDF Schema provides the framework to describe application-specific classes and properties

Classes in RDF Schema is much like classes in object oriented programming languages. This allows resources to be defined as instances of classes, and subclasses of classes.

## RDFS Example

The following example demonstrates some of the RDFS facilities:

    <?xml version="1.0"?>

    <rdf:RDF
    xmlns:rdf= "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
    xml:base=  "http://www.animals.fake/animals#">

    <rdf:Description rdf:ID="animal">
      <rdf:type
       rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
    </rdf:Description>

    <rdf:Description rdf:ID="horse">
      <rdf:type
       rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
      <rdfs:subClassOf rdf:resource="#animal"/>
    </rdf:Description>

    </rdf:RDF>

In the example above, the resource "horse" is a subclass of the class "animal".

## Example Abbreviated

Since an RDFS class is an RDF resource we can abbreviate the example above by using rdfs:Class instead of rdf:Description, and drop the rdf:type information:

    <?xml version="1.0"?>

    <rdf:RDF
    xmlns:rdf= "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
    xml:base=  "http://www.animals.fake/animals#">

    <rdfs:Class rdf:ID="animal" />

    <rdfs:Class rdf:ID="horse">
      <rdfs:subClassOf rdf:resource="#animal"/>
    </rdfs:Class>

    </rdf:RDF>

That's it!

From http://www.w3schools.com (Copyright Refsnes Data)