Integrating data from multiple XML sources

Queries can combine information from many sources:

  WHERE <person>
          <name></> ELEMENT_AS $n
          <ssn> $ssn </>
        </> IN "www.a.b.c/data.xml",
  
        <taxpayer>
          <ssn> $ssn </>
          <income></> ELEMENT_AS $i
        </> IN "www.irs.gov/taxpayers.xml"
  CONSTRUCT <result> <ssn> $ssn </>  $n $i </>