RDF & XML: A Conceptual Correction

We need to make a correction on the last blog post. It was stated that "RDF is a subset of XML programming language..." This is not wholly correct; actually, RDF can be expressed independently of XML. Though XML code can be used to write RDF scripts, properly speaking, RDF is a separate markup language than XML.

The W3C's explanation of the relationship between RDF and XML makes this clear:

4.3. Isn’t RDF simply an XML application?
No. The fundamental model of RDF is independent of XML. RDF is a model describing qualified (or named) relationships between two (Web) resources, or between a Web resource and a literal. At that fundamental level, the only commonality between RDF and the XML World is the usage of the XML Schema datatypes to characterize literals in RDF. In fact, using GRDDL, a way to automate mappings from XML to RDF easily, many XML vocabularies can be considered applications of RDF.

Note that one of the serialization formats of RDF is indeed based on XML (RDF/XML), and this is probably the most widely used format today. But others exist, see the separate question on RDF representation.

Our apologies for any confusion this error caused.