The xlink:role attribute

• Identifies the type of the related resource with an absolute URI

• Can be the namespace URI of the root element:

  http://www.w3.org/2000/10/XMLSchema

  XML Schema

  http://www.rddl.org/arcrole.htm#SOCAT

  OASIS Open Catalog

  http://www.ascc.net/xml/schematron

  Schematron

  http://www.xml.gr.jp/xmlns/relaxCore

  RELAX schema

  http://www.w3.org/2000/01/rdf-schema#

  RDF Schema

• Can be a MIME media type URI at http://www.isi.edu/in-notes/iana/assignments/media-types/

  http://www.isi.edu/in-notes/iana/assignments/media-types/application/pdf

  Acrobat PDF version of the document

• Can be a spec-defined URI:

  http://www.rddl.org/natures#SOCAT

  OASIS Open Catalog