98 is right, there are only three positions, and one of them is temporary only. They are:
Down = Fire. The firing pin block remains engaged until the trigger is pressed.
Up to horizontal = Safe. The trigger is blocked.
Press up to top = Decock. This is spring-loaded and returns to Safe when released. The safety interferes with the travel of the hammer, and the hammer drops on the hammer's half cock notch. As the safety lever is released the hammer's half-cock notch eases off the safety and it moves forward to the rebound position.
Any position between the Safe position and the Fire position is just a mechanical illusion. I, personally, wouldn't want to experiment with what happens when firing with the safety lever in these positions, because all sorts of ugly things might happen.
Scott