• Curtis E. Dyreson School of EE and CS, Washington State University, USA
  • Michael H. Bohlen Department of Computer Science, Aalborg University, Denmark
  • Christian S. Jensen Department of Computer Science, Aalborg University, Denmark


This paper presents the METAXPath data model and query language. METAXPath extends XPath with support for XML metadata. XPath is a specification language for locations in an XML document. It serves as the basis for XML query languages like XSLT and the XML Query Algebra. The METAXPath data model is a nested XPath tree. Each level of metadata induces a new level of nesting. The data model separates metadata and data into different dataspaces, supports meta-metadata, and enables sharing of metadata common to a group of nodes without duplication. The METAXPath query language has a level shift operator to shift a query from a data level to a metadata level. METAXPath maximally reuses XPath hence the changes needed to support metadata are few. METAXPath is fully compatible with XPath.