Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/eduni/xml-1.1/033.xml
<?xml version="1.1"?> <!-- Has an LSEP character in an NMTOKENS attribute; well-formed in both XML 1.0 and 1.1, but valid only in 1.1 --> <!DOCTYPE foo [ <!ELEMENT foo ANY> <!ATTLIST foo bar NMTOKENS #IMPLIED> ]> <foo bar="abc def"/>