RDF, Resource Description Framework is “a model for representing metadata as well as a syntax for encoding and transporting this metadata”. The quotation can be found in http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#model along with a description of model and syntax. The syntax is built on top of the XML syntax.
As the name says it is a framework. This framework was made to be filled with metadata. Data that may vary between domains. The framework provides interoperability through syntax definitions and a model for representing metadata as properties. Yet, a program that can parse the syntax of the metadata is still far from getting the semantics. Therefore some standards for metadata have been proposed. They define sets of metadata elements including the semantics of those elements.
The Dublin Core Metadata Element Set defines metadata elements using 10 attributes, which are defined in the ISO/IEC 11179 standard. A listing of those attributes can be found at:.
Six of the attributes apply to all metadata elements of the Dublin core and have always the same value. Those values can be found at the location mentioned above, too. The Dublin core consists of the following 15 metadata elements:
The way they are defined pretty much corresponds to the meaning you would assume intuitionally. Title contains a name given to the described resource, creator contains the entity, which created the resource, and so on.
Identifier is a somewhat interesting element. It should contain an unambiguous identifier. If an URI is not available any other identifier (e.g. an ISBN number) could be provided.
This metadata element set is a subset of metadata elements, which could be build using the RDF framework. Therefore the Dublin Core Metadata Element Set can be encoded in XML. A description and examples can be found at.
In order to provide teachers a standard for providing metadata on educational websites this standard is being introduced. It is designed not only to provide information about the resource but also to tag large parts of data directly with metadata. It seems as if the creators of websites are advised or required to have a RDF-file for their site and add tags to the actual resources, probably even to single paragraphs. The tags are to contain information about how the data fits into a subject. Therefore this standard goes way further than the Dublin Core standard.
The standard definition includes the definition of 15 XML elements at the top level, which are supposed to be used in the RDF-file. Those elements differ from the elements provided by the Dublin Core standard. They are:
Some of those elements have children. It is obvious that this set of elements is supposed to be domainspecific.
The standard further provides for each subject long lists of keywords, which are supposed to be used in tags added to the actual resource. If a website contains an article about mathematics this article is supposed to contain information about that and more precise specifications about the content such as level. This specification can and probably should be provided for single paragraphs as well.
More information can be found at.