If you look at the towers on the playing field, you will see two sets of rails. One set on top, and another single rail right below the first set. I know the height of the top set of rails, but how high is the lower rail?
If you want to hang on it, your opponents will thank you. It’s part of the Ball Return (specifically, the return bars) and covered with black tape (Section 6.2.4). According to <G31>, inadvertent contact is a penalty and intentional contact is a red card.
I can’t find anything on the team drawings or the official field drawings, probably at least partly because that bar is not to be hung on.