sgml Linuxdoc-Tools is a small bug-fix version of SGML-Tools 1.0.9, and is a toolset for processing LinuxDoc DTD SGML files. This system is tailored for LinuxDoc DTD sgml files, and other DTDs are not supported. If you need the tool for DocBook DTD (which is now a more popular DTD than LinuxDoc in writing technical software documentation), then you should check other packages such as SGMLTools-Lite and OpenJade.