<f:a xmlns:f="http://xmlbeans.apache.org/inst2xsd"
    xmlns:fa="http://xmlbeans.apache.org/a"
    xmlns:fb="http://xmlbeans.apache.org/b"
    xmlns:fc="http://xmlbeans.apache.org/c"
    >
    <fa:b>abc</fa:b>
    <fb:c>123</fb:c>
    <fc:d></fc:d>
    <f:d/>
</f:a>