libopc/third_party/libxml2-2.7.7/test/valid/t10.xml

<?xml version="1.0" standalone="yes"?>
<!DOCTYPE root [
<!ELEMENT root  (cont1, (cont1, cont2?)+)>
  <!ELEMENT cont1  EMPTY>
  <!ELEMENT cont2  EMPTY>
]>
<root>
  <cont1/>
  <cont1/>
  <cont1/>
  <cont1/>
</root>