Demonstrated = it has been done, and if you are current on type should also be able to do it,
Not approved = there are good reasons why you should not try it, and if you do, you better really understand those good reasons first, and, even then, ensure you dont make the mistake of making any of them,
Prohibited = there are very very good reasons for not trying it, and even if you understand those reasons you are unlikely to be able to avoid them,
Anything else = it is either so stupid no one thought you would even think of it, or it is so obviously possible that it wasnt worth commenting on - make sure you know which is which!