A logical controller is a controller that regulates the iterative behavior of it's sub-controllers, and sometimes, it can also affect the behavior of its parent controller indirectly. A logical controller can also modify test samples that pass through it. The essential distinction between a logical controller and a generative controller is that logical controllers create no test samples by themselves. If you add a logical controller to the test tree with no sub-conrollers, then it can have no effect on the test. It's only useful as a parent of other sample generating controllers .