The zones are explained in section 3.2.4.2 such that level 0 is on the ground, level 1 is above the ground and below the first bar, level 2 is between the first and second bars, and level 3 is above the second bar. The lowest point on your robot as it is hanging is what will be used to determine the level -- and parts A and B of 3.2.4.2 specify what validates a "CLIMB."
Code:
[G22] Robots must contact the pyramid in
A. sequential order (Level 0, 1, 2, 3) during ascent and
B. no more than two (2) Levels simultaneously.
The paragraph at the end means that you cannot skip up bars. So you can climb from the first bar to second bar and hang in level 1 for 10 points, but if you go from the ground to the second bar still in level 1 zone you get no points (invalidated climb) because you didn't climb in sequential order.
Does that help?