RDFa

RDFa allows semantic markup of HTML pages to be extracted as RDF triples and linked to an OWL/RDF knowledge base. See an example of how this might be used with the MUC-3 corpus here.

RDFa and XHTML

There is an XHTML+RDFa schema covering the embedding of RDFa markup in XHTML documents. This must be referenced in a DOCTYPE declaration for the document to be valid XHTML. See the RDFa demo page for an example of how to do this. The W3C Markup Validation Service can be used to check the validity of HTML and XHTML.

RDFa is expressed as attributes on XHTML elements, which may mean introducing a new element (that isn’t intended to be displayed) inside a span to add in an extra relationship. To be valid XHTML+RDFa, this element must be from the set of “inline” elements in the XHTML standard – which means you can't use meta or link and are left with using (or misusing) the object element as the best candidate.

RDFa and KML

You can add RDFa markup to KML. For example, this KML file has a guess at the coordinates of where Senator Velez was kidnapped (as described in TST1-MUC3-0080). It includes RDFa markup that can be extracted, using RDF Translator say, to give this result.

RDFa and SVG

You can add RDFa markup to SVG. For example, this ELN flag includes RDFa markup that can be extracted, using RDF Translator say, to give this result.

Notes

• The RDFa Core Initial Context is a list of namespace prefixes that can be used without having to define them in your document.