+in tarball. Following ones are tested to work with:
+@url{http://www.goredo.cypherpunks.ru/, goredo} (NNCP's author creation),
+@url{https://redo.readthedocs.io/, apenwarr/redo} (@code{contrib/do} is
+from that project), @url{https://github.com/leahneukirchen/redo-c, redo-c},
+@url{https://github.com/gotroyb127/baredo, baredo}.
+
+@vindex PREFIX
+@vindex DESTDIR
+@vindex GO
+@vindex MAKEINFO
+@vindex PLANTUML
+@vindex PREFIX
+@vindex SENDMAIL
+@vindex CFGPATH
+@vindex SPOOLPATH
+@vindex LOGPATH
+@vindex BINDIR
+@vindex INFODIR
+@vindex DOCDIR
+@file{config} file contains some environment variables that are
+respected during installation:
+@env{$PREFIX},
+@env{$DESTDIR},
+@env{$GO},
+@env{$MAKEINFO},
+@env{$PLANTUML},
+@env{$PREFIX},
+@env{$SENDMAIL},
+@env{$CFGPATH},
+@env{$SPOOLPATH},
+@env{$LOGPATH},
+@env{$BINDIR},
+@env{$INFODIR},
+@env{$DOCDIR}.