RDFa

RDFa (or Resource Description Framework in Attributes) is a W3C Recommendation that adds a set of attribute-level extensions to HTML, XHTML and various XML-based document types for embedding rich metadata within Web documents. The RDF data-model mapping enables its use for embedding RDF subject-predicate-object expressions within XHTML documents. It also enables the extraction of RDF model triples by compliant user agents. RDFa (or Resource Description Framework in Attributes) is a W3C Recommendation that adds a set of attribute-level extensions to HTML, XHTML and various XML-based document types for embedding rich metadata within Web documents. The RDF data-model mapping enables its use for embedding RDF subject-predicate-object expressions within XHTML documents. It also enables the extraction of RDF model triples by compliant user agents. The RDFa community runs a wiki website to host tools, examples, and tutorials. RDFa was first proposed by Mark Birbeck in the form of a W3C note entitled XHTML and RDF, which was then presented to the Semantic Web Interest Group at the W3C's 2004 Technical Plenary. Later that year the work became part of the sixth public Working Draft of XHTML 2.0.Although it is generally assumed that RDFa was originally intended only for XHTML 2, in fact the purpose of RDFa was always to provide a way to add a metadata to any XML-based language. Indeed, one of the earliest documents bearing the RDF/A Syntax name has the sub-title A collection of attributes for layering RDF on XML languages. The document was written by Mark Birbeck and Steven Pemberton, and was made available for discussion on October 11, 2004. In April 2007 the XHTML 2 Working Group produced a module to support RDF annotation within the XHTML 1 family. As an example, it included an extended version of XHTML 1.1 dubbed XHTML+RDFa 1.0. Although described as not representing an intended direction in terms of a formal markup language from the W3C, limited use of the XHTML+RDFa 1.0 DTD did subsequently appear on the public Web. October 2007 saw the first public Working Draft of a document entitled RDFa in XHTML: Syntax and Processing. This superseded and expanded upon the April draft; it contained rules for creating an RDFa parser, as well as guidelines for organizations wishing to make practical use of the technology. In October 2008 RDFa 1.0 reached recommendation status. RDFa 1.1 reached recommendation status in June 2012. It differs from RDFa 1.0 in that it no longer relies on the XML-specific namespace mechanism. Therefore, it is possible to use RDFa 1.1 with non-XML document types such as HTML 4 or HTML 5. Details can be found in an appendix to HTML 5. An additional RDFa 1.1 Primer document was last updated 17 March 2015. (The first public Working Draft dates back to 10 March 2006.)