/usr/bin/eqn
/usr/bin/geqn
/usr/bin/gpic
/usr/bin/groff
/usr/bin/grog
/usr/bin/grops
/usr/bin/grotty
/usr/bin/gtbl
/usr/bin/neqn
/usr/bin/nroff
/usr/bin/pic
/usr/bin/preconv
/usr/bin/soelim
/usr/bin/tbl
/usr/bin/troff
You may install this package on Debian with
apt-get
install groff-base