Hey, Im trying to split the orthogonal regions over differnent translation units, but it doesn't compile. The compiler complains that the type is incomplete, which i try to put on a different translation unit. What i do is: Forward declare the orthogonal region and define than the outermost state "Active" like this: struct StateInDifferentTransUnit; struct Active; struct Start : sc::asynchronous_state_machine< Start, Active >{ ... } struct Active : sc::state< Active, Start, mpl::list< State1, State2, StateInDifferentTransUnit > >{ ... } Is the split in different translationunits not possible with orthogonal regions or what could be my problem? Kind Regards Manuel