glib/gio/tests/schema-tests/extending.gschema.xml

<schemalist>
  <!-- c extends b extends a -->
  <schema id='a'/>
  <schema id='b' extends='a'/>
  <schema id='c' extends='b'/>

  <!-- lists of each -->
  <schema id='la' list-of='a'/>
  <schema id='lb' list-of='b'/>
  <schema id='lc' list-of='c'/>

  <!-- extend 'la', override the list-of to 'b' -->
  <schema id='lb-la' list-of='b' extends='la'/>

  <!-- extend 'la', override the list-of to 'c' -->
  <schema id='lc-la' list-of='c' extends='la'/>
  <!-- extend 'lb', override the list-of to 'c' -->
  <schema id='lc-lb' list-of='c' extends='lb'/>
  <!-- extend 'lb-la', override the list-of to 'c' -->
  <schema id='lc-lb-la' list-of='c' extends='lb-la'/>
</schemalist>