-Optional. Indicates a target for laundered filter arguments in the controller.
-Can be set to C<undef> to disable laundering, and can be set to method named or
-hash keys of the controller. In the latter case the laundered structure will be
-put there.
-
-Defaults to the controller. Laundered values will end up in C<SELF.filter> for
-template purposes.
-
-Setting this to the special value C<__INPLACE__> will cause inplace laundering.