Partial understanding of RDF

Pontential scenario: received RDF description contains predicates from N sources

• How to deal with unknown predicates?

<RDF xmlns="http://www.w3.org/TR/WD-rdf-syntax#"
        xmlns:a="URI1"
        xmlns:b="URI2" >
  <Description about="http://www.isoc.de/opennet98/">
    <a:location>123P23I</a:location>
    <b:location>55'23</b:location>
    <b:region>Potsdam</b:region>
  </Description>
</RDF>