troff(1) on Linux
The text c5fffabc6842, as Debian 9 (Stretch) shipped it.
the troff processor of the groff text formatting system
Flags it lists
-
-C -
-E -
-F -
-I -
-M -
-R -
-T -
-U -
-W -
-a -
-b -
-c -
-d -
-f -
-i -
-m -
-n -
-o -
-r -
-v -
-w -
-z