While trying out 8.0-SNAPSHOT I get something strange.  There is an exists query which gives true where the answer should be false.  There is no dataset with @name='DiMu__abm', yet exists gives "true".  The subsequent query shows what is actually in the XML.

> xquery exists(doc('narthex_dimcon/narthex_dimcon.xml')/narthex-datasets/dataset[@name='DiMu__abm'])

true

Query executed in 5.14 ms.

> xquery doc('narthex_dimcon/narthex_dimcon.xml')

<narthex-datasets>

  <dataset name="RCE_Beeldbank__adlib">

    <origin>

      <type>origin-drop</type>

      <who>?</who>

      <time>2014-09-23T10:05:34.436+02:00</time>

    </origin>

    <status>

      <state>state-saved</state>

      <time>1411460347570</time>

      <percent>0</percent>

      <workers>0</workers>

      <error/>

    </status>

    <delimit>

      <recordRoot>/adlibXML/recordList/record</recordRoot>

      <uniqueId>/adlibXML/recordList/record/priref</uniqueId>

      <recordCount>401960</recordCount>

    </delimit>

    <namespaces>

      <xsi>http://www.w3.org/2001/XMLSchema-instance</xsi>

    </namespaces>

    <harvest/>

  </dataset>

</narthex-datasets>

Query executed in 3.03 ms.