A thought for a checking device: Use a ball with a circle drawn around it like the picture here:
http://planetmath.org/encyclopedia/I...eAndPlane.html
The distance between the plane intersecting the ball that defines the circle, and the plane that is parallel to that plane and is tangent to the ball is 3".
Now stuff the ball into any opening in the robot to see if the circle is swallowed by the robot. If so, there is a violation of <R19>.
Note that <R19> says the robot must be designed so that there can be no incursion greater than 3". Should such an incursion occur, you will get a PENALTY under <G46>. But <R19> says there should be no opportunity to get such a PENALTY, because the robot should have been designed so it can't happen.