/usr/share/doc/libxml++2.6-doc/examples/dom_read_write/example.dtd is in libxml++2.6-doc 2.36.0-2.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 | <?xml version="1.0" encoding="ISO-8859-1"?>
<!--
DTD for libxml++ example.
-->
<!ELEMENT example (examplechild)+ >
<!ELEMENT examplechild (child_of_child)+ >
<!ATTLIST examplechild
id CDATA #REQUIRED
>
<!ELEMENT child_of_child EMPTY >
|