gensgmlenv(1) on Linux
The text c4dc8b0a3b8d, as Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze), Debian 5.0 (Lenny), Debian 4.0 (Etch), Debian 3.1 (Sarge), Debian 3.0 (Woody) shipped it. The page shows this text now.
Generate /etc/sgml/sgml.env and /etc/sgml/sgml.cenv