/etc/sgml/debiandoc-sgml.cat is in debiandoc-sgml 1.2.28-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | CATALOG /usr/share/sgml/debiandoc/dtd/sgml/1.0/catalog
CATALOG /usr/share/sgml/debiandoc/entities/catalog
|