Yard Machines Rear Engine Rider transmission question

So I recently acquired this mower. I've got a quick question about how the transmission works. It has a F-N-R shifter below the seat, then 6 speeds up on the front. It says shift on the go, does that mean it's basically a hydrostat with set positions (6 in this case)? I drove it around the yard and the transmission works great.

Yard Machines Rear Engine Rider transmission question