The below image was taken from the Bartolini website. It illustrates one of their prewired harnessed. The mid is a push-pull pot to switch between 2 midrange frequencies: 250Hz and 800Hz. What exactly is a push-pull pot? I'm assuming it simply means you pull out on the shaft (or knob more so) for one frequency (250Hz) and push it down for the other (800Hz). Am I correct in this assumption?