Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/not-wf/P62/ibm62n04.xml
<?xml version="1.0"?> <!-- syntax test for Production 62--> <!DOCTYPE animal SYSTEM "ibm62n04.dtd"> <animal> <tiger/> Negative test. Missing the required field INCLUDE. </animal>