Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/xml-1.1/not-wf/P04/ibm04n05.xml
<?xml version="1.1" encoding="UTF-8"?> <!DOCTYPE IllegalNameStartChar [ <!ELEMENT IllegalNameStartChar ANY> ]> <!-- IllegalNameStartChar #x2000 --> < IllegalNameStartChar/>