The CLIV IWG 20th session reviewed its draft proposal for a bus and coach UN Regulation submitted to GRSP in December 2026, retaining operational isolation terminology with editorial corrections, defining scope as M2 and M3 class B and III vehicles designed for carrying children, and adopting a journey definition covering engine or motor operation until 15 minutes after the vehicle master control switch is turned off. The IWG adopted a 1.5 ± 0.5 Hz repetition rate for warning signals and deferred light-vehicle UN Regulation drafting to a September face-to-face meeting in Paris.