+.It Fl o, -option Ns = Ns Ar [HOST.]KEY=VALUE
+Without specifying a
+.Ar HOST ,
+this will set server configuration variable
+.Ar KEY
+to
+.Ar VALUE .
+If specified as
+.Ar HOST.KEY=VALUE ,
+this will set the host configuration variable
+.Ar KEY
+of the host named
+.Ar HOST
+to
+.Ar VALUE .
+This option can be used more than once to specify multiple configuration variables.