Are these bumpers legal? (Another bumper thread)

[rich2202]

Jason's post reminded me about something someone said about the bumper rules. Unlike the robot rules, where if it is not illegal, then you can do it, the bumper rules are the opposit: if it does not say you can do it, then you can't.

So, the question is: where in the rules does it allow you put anything but the numbers on the bumper? All the decoration inside the 0 is not allowed. In addition, the font of the 0 is different from the other numbers, which adds confusion.