<?xml version="1.0"?>
<employees>
  <employee xmlns:sql="http://boojum.org.uk/NS/XMLServer">
    <name>John Smith</name>
    <managerid1/>
    <managerid2/>
    <managerid4 xmlns:ns1="http://www.w3.org/2001/XMLSchema-instance" ns1:nil="true"/>
  </employee>
</employees>