G2- Sorry, but I recently discovered that a whole series of old floppy disks I had my college stuff on have been corrupted. Sadly, the file is gone.
Blue Knight- I agree with your sentiments in general terms. All I was trying to do was throw up a strawman for classifying the multitude of varying fortifications that mankind has built.
That is why I tried to stay away from what a fortification looks like as a defining term. I tried to denote it by function, rather than form.
But to your point, perhaps I need to find another term for what I called a "Castle". In essense, all of these- a mott & bailey, a keep, a 'castle' and a fortress could all be considered castles. And selecting one of them to carry the name castle could be divisive.
Because I did forget Manor/Palace as well. Often these are considered castles in name.