Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/xml-1.1/valid/P77/ibm77v12.xml
<?xml version='1.1'?> <!DOCTYPE doc [ <!ELEMENT doc (更root*)> <!ELEMENT 更root EMPTY> <!ENTITY e SYSTEM "ibm77v12.ent"> ]> <doc>&e;</doc>