I had hoped that the Safety professionals here would be able to provide at least a pointer. I find it disturbing that there is no clear delineation between 'airside' and 'not airside'.
In the real world there is, what makes you think otherwise?, have you been and looked at the aerodrome in question?
It might not be enclosing the same areas in every aerodrome (that is a matter for the owner operator), but it is always defined