Proposal to amend para. 2.5.2. to change the lower vertical datum point from 5 above the horizontal to 4 above the horizontal, and amend Figure 3 to reflect this adjustment. The modification harmonizes the location of the lower datum point with the angle of obstruction requirement and resolves an inconsistency in UN Regulation No. 43.

Proposal to align UN R43 with a proposed amendment to UN R125 (ECE/TRANS/WP.29/GRSG/2026/23), which resolves a longstanding inconsistency between the lower datum point definition (§5.1.1.3) and the obstruction requirement (§5.1.3) by harmonizing the lower datum point angle from 5° to 4°.