Proposal to

1. delete redundant provisions (paragraphs 2.2. and 2.2.1.) in favor of paragraph 5.2.2.13. which requires all O4 trailers to be equipped with Anti-lock Braking Systems (ABS) of Category A.
2. clarify exemptions from electronic stability control requirements, and
3. enable the verification of sufficient movement of the balancer without having to take measurements underneath the trailer.