Tail up = Very Happy cat either saying hello or feed me, you stupid bugger.

Tail at medium level = I'm thinking or what's that mean then? or don't stroke me there, you stupid bugger.

Tail between legs = either you or the cat should run.

Of course, your problem is the crucial sentence that said kittens can give two signals at once, or confused ones, because they haven't quite worked the signals out yet.

Hmm. Now I know why I like horses. They're simpler. ;)