+This will let tinc read all configuration files from
+.Pa @sysconfdir@/tinc/ Ar NETNAME .
+Specifying
+.Li .
+for
+.Ar NETNAME
+is the same as not specifying any
+.Ar NETNAME .
+.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.