Proposal to amend para. 2.8 of Annex 8 to add a new requirement that braking forces from combined service and parking braking systems shall hold a laden trailer as required in Annex 4 para. 3.2.1 at any time when service brake energy reservoir pressure reduces from 850 kPa to 0 kPa, ensuring continuous trailer immobilisation during service brake pressure depletion while establishing a performance-based requirement rather than prescribing specific technical solutions.