/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/ is in docbook-website 2.5.0.0-8.
This file is owned by root:root, with mode 0o755.
..
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/ChangeLog
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/autolayout.dtd
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/catalog
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/extensions.mod
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/forms.mod
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/layout.dtd
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/namespaces.mod
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/rddl.mod
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/website-custom.dtd
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/website-full.dtd
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/website.dtd
/usr/share/xml/docbook/custom/website/2.5.0/schema/dtd/website.mod