Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/not-wf/P59/ibm59n02.xml
<?xml version="1.0"?> <!-- syntax test for Production 59--> <!DOCTYPE test [ <!ELEMENT test ANY> <!ELEMENT one EMPTY> <!ELEMENT enum (#PCDATA)> <!ATTLIST one attr (enum #IMPLIED> ]> <test> This is a Negative test Missing the closing brackets </test>