Then there is a method which I've encountered less commonly. The attacker puts something in, but gets nothing back. There is neither push nor pull. A process is definitely happening, something significant is transpiring with the data input. But there is nothing really in the way of output. The attack may redirect, or not. The attacker may be unbalanced, or not. Whatever happens is not "done" in the regular sense of doing.
Hi Ross, although I agree with much of what David is saying, I also agree with the above statement.
My own personal thoughts on this are that this is the yin/yang methodology - in which the the body is trained to be predominantly "physically" balanced, with opposing forces, thus when a force is "input"against you, there is no resistance, and no force can be applied. This is also reliant on various spirals.
I think the Aiki body has been discussed to death, but this is what we are talking about, in my eyes