Then please explain it.
As I understand it, your general OS in this game is dependent on the fact that the on-hit window is different than the on-block window. To add to that, if you input a direction, it "washes" your special cancel.
In most cases, both are used. For example, Mileena has a safe low on block or a roll on hit by doing the following (I'm at work, so hopefully my moves and combos are correct):
F12 > Roll > B4 On hit, the Roll comes out during the on-hit window. On block, the B washes the Roll and allows the rest of the safe combo to come out.
I'm not familiar with Raiden's OSs, but I'm guessing it is similar? For example, B2 > DF2 > F so the DF2 comes out on hit, but the F washes the input during the on-block window so it doesn't come out on block.
Yes?