I think what is being talked about is "live continuous". I'll see if I can sorta define that; a "live" PTO basically means it can be running even it the tractor isn't moving (remember the old Fords with the PTO that could push you right through a fence since the PTO was geared through the drivetrain?). With the hydrostatic transmissions in my B series Kubotas (and many, many other tractors), the PTO could be running while sitting still. And the "continuous" part means it keeps turning even if you have the clutch disengaged. The only ones I'm familiar with are hydraulically engaged and disengaged. You disengaged the clutch with your foot to engage/disengage the PTO on my B series Kubotas, while the old Oliver I used to cut/bale hay had the hydraulically engaged "live continuous" PTO.