/etc/sgml/docbook/ is in docbook 4.5-5.1.
This file is owned by root:root, with mode 0o755.
..
/etc/sgml/docbook/2.4.1/
/etc/sgml/docbook/2.4.1/dbgenent.mod
/etc/sgml/docbook/3.0/
/etc/sgml/docbook/3.0/dbgenent.mod
/etc/sgml/docbook/3.1/
/etc/sgml/docbook/3.1/dbgenent.mod
/etc/sgml/docbook/4.0/
/etc/sgml/docbook/4.0/dbgenent.mod
/etc/sgml/docbook/4.1/
/etc/sgml/docbook/4.1/dbgenent.mod
/etc/sgml/docbook/4.2/
/etc/sgml/docbook/4.2/dbgenent.mod
/etc/sgml/docbook/4.3/
/etc/sgml/docbook/4.3/dbgenent.mod
/etc/sgml/docbook/4.4/
/etc/sgml/docbook/4.4/dbgenent.mod
/etc/sgml/docbook/4.5/
/etc/sgml/docbook/4.5/dbgenent.mod