Proposal to resolve a longstanding inconsistency in UN R125 between the lower datum point (§5.1.1.3, set at 5°) and the obstruction requirement (§5.1.3, set at 4°), by aligning the lower datum point to 4° while retaining upper and lateral aspects of §5.1.1. unchanged. The 5° datum point has never been used for any technical requirements beyond serving as a reference point, while the 4° obstruction requirement has prior precedent. As this is a vehicle rather than component requirement, the datum point is also proposed for deletion from UN R43, retaining it solely in UN R125.

Proposal to amend para. 5.1.1.3. to adjust the lower vertical datum point from 5 degrees to 4 degrees below the horizontal and update the corresponding figure in Annex 4, Figure 1. This harmonizes the location of the lower datum point with the angle of obstruction requirement in para. 5.1.3., resolving an inconsistency between the allowed area of obstruction and the mandated transparent area of the windscreen.