At a recent event my VEX IQ teams attended, drivers were instructed that there had been a rule clarification, and that robots which were parked and balanced, but were being supported by the fence would NOT be scored as balance, only parked.
I expected to find that new rule here but can not find anything about being supported by the fence. I did however find this:
As you can see, there is nothing in the definitions that prevent a Robot from being supported by the Fence. As long as the Robot(s) and Bridge meet the criteria listed in the two definitions, they would be legally Parked and Balance.
Now, there is one other rule that applies.
Robots may not grasp or attach to the Fence. But simply being supported by the Fence (i.e. resting upon it, or touching it) is legal.