The RDF/XML parser emits an error for tags whose namespace is declared within that same tag. For example, endDate in the following snippet uses the namespace that appears inside the endDate tag:

<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
  <rdf:Description rdf:about="http://eurovoc.europa.eu/1">
    <endDate xmlns="http://publications.europa.eu/ontology/euvoc#" rdf:datatype="http://www.w3.org/2001/XMLSchema#date">1995-10-01</endDate>
  </rdf:Description>
</rdf:RDF>

The error message reads as follows:

ParseError: Found both non-rdf:* property attributes and rdf:datatype (http://www.w3.org/2001/XMLSchema#date).

The W3C RDF/XML validation service is able parse the data and resolves it to this triple:

<http://eurovoc.europa.eu/1> <http://publications.europa.eu/ontology/euvoc#endDate> "1995-10-01"^^<http://www.w3.org/2001/XMLSchema#date>.