/usr/share/xml/docbook/schema/dtd/4.5/docbook.cat is in docbook-xml 4.5-7.3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/xml/docbook/schema/dtd/4.5/catalog
/usr/share/xml/docbook/schema/dtd/4.5/catalog