/usr/share/xml/xhtml/schema/dtd/1.1/xml1.dcl is in w3c-dtd-xhtml 1.2-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/xml/xhtml/schema/dtd/1.1/../../../../declaration/xml.dcl
/usr/share/xml/xhtml/schema/dtd/1.1/../../../../declaration/xml.dcl