Questions on rules

Can some one tell me the diference between GM18 and M6 they seem to contradict them selves.
Thanks
Nick237

They feel complementary to me…

While M6 allows the use of the innermost face of the field barrier, it expressly disallows the top and rest of the border. GM18 futher explains… the safety aspect is the reason for them to be there and you should do your business without hurting them. If you touch the side of the barrier without damaging it, then you’ll be fine.

GM18. The outer field barriers are safety features of the playing field and Robots should not be designed to react against them. Incidental contact with the barriers is acceptable. Pushing a
ball against a barrier to allow pickup of the ball or passage of the ball to the students is acceptable if the forces applied are not sufficient to damage the barrier or otherwise deform the playing field.

M6. Robots may be designed to operate by reacting against the carpeted surface of the playing field, the innermost face of the field border, the goals, balls, other robots, and the air. Robots
should not be designed to react off of the top of the field border or other parts of the field border. If your robot inadvertently drives on the top of the field border, you will not be
penalized unless the playing field is damaged.