[B<-C>]
[B<-rand file(s)>]
[B<-genkey>]
+[B<-engine id>]
[B<numbits>]
=head1 DESCRIPTION
B<numbits>. It must be the last option. If this option is included then
the input file (if any) is ignored.
+=item B<-engine id>
+
+specifying an engine (by it's unique B<id> string) will cause B<req>
+to attempt to obtain a functional reference to the specified engine,
+thus initialising it if needed. The engine will then be set as the default
+for all available algorithms.
+
=back
=head1 NOTES