While the meaning of International and Domestic are obvious, the switches on the station setup can change the behaviour for locations.
First airlines. An airline can be set as domestic in airline setup. Domestic airlines can be excluded from the count if desired.
Locations are set in the location setup as domestic. These can also be set as excluded from counts.
The switch in station setup for international/domestic spit flight changes the status of a flight when one leg is domestic and the other international. If split, both legs are set as the relevant status but, if not split, both legs become international as far as the system is concerned.
The second switch, domestic on international as international also change the behaviour. When set, a domestic flight going on to an international location will be treated as international. This is both for count and apron assign purposes.