Proposal to amend UN Regulation No. 122 (Heating Systems). The 01 series of amendments takes into account vehicles of categories X and Y and aligns provisions in Annex 5 for all occupants. Surface temperature limits for heating systems apply equally to drivers and passengers regardless of seat position or vehicle category, with special care for rear seats of M₁ vehicles. Manufacturers may justify higher temperatures through a safety concept demonstrating no increased burn risk. Transitional provisions allow type approvals under preceding series until 1 September 2028. The proposal amends and supersedes ECE/TRANS/GRSG/2026/7.