Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/sun/invalid/attr08.xml
<!DOCTYPE palimpest [ <!ELEMENT palimpest EMPTY> <!ATTLIST palimpest xmlns CDATA #FIXED "http://java.sun.com/historical" > <!-- tests the "fixed attribute default" vc --> ]> <palimpest xmlns="http://over.the.rainbow.com/somewhere"/>