A couple more points of clarification, continuing from your last answer:
Scenario #1: A robot has an extended attachment, which pokes through the fence a foot or so (without touching anything on the opponent’s side, for the purpose of keeping an opponent from reaching the fence to use a dump or similar device. Would this be an illegal block because it restricts your opponents movement on the opposite side of the fence? (yes, I presume)
Scenario #2: What about the same device, poked through the fence (without touching anything on the opponent’s side other than a scoring element), but it is being used to push a scoring object from the near zone to the far zone on the opponent’s side. It is not intentionally blocking the opponents movement, but will nevertheless be in the opponent’s way while the pushing action is taking place if the opponent decides to drive into the mechanism.
The initial response to this question has been edited to reflect the latest changes to the manual. Simply put, you can reach over to the other side of the field, provided that you’re not pinning/trapping/grabbing an opposing Robot.