<AAA> aaa aaa
   <BBB aaa="111" bbb="222"> bbbb bbbb
     <CCC/>
     <CCC xxx="555" yyy="666" zzz="777"/>
   </BBB>
   <BBB aaa="999">
     <CCC xxx="qq"> ccc ccc </CCC>
     <DDD xxx="ww"> ddd ddd </DDD>
     <EEE xxx="oo"/>
   </BBB>
   <BBB>
     <DDD xxx="oo"/>
   </BBB> aaa at end
 </AAA>