--generate-parser
--generate-serializer
--generate-aggregate
--root-element transformations
--generate-polymorphic
--custom-type unknown_type=//unknown_type_base/unknown-type.hxx
--custom-parser unknown_type=unknown_type_base_pimpl/unknown-type-pimpl.hxx
--custom-serializer unknown_type=unknown_type_base_simpl/unknown-type-simpl.hxx
