At the 77th SLR meeting (Brussels, April 2026), participants reviewed and improved baseline documents for UN Regulations 48, 53, 74, and 86, reflected in SLR-77-08/Rev.1, SLR-77-09, SLR-77-10, and SLR-77-07 respectively. SLR approved a revised proposal to correct errors in Reg. 150-01 (SLR-77-06/Rev.1, superseding GRE-94-02) and a compromise text prohibiting additional lamps unless complying with national requirements. SLR agreed to postpone official document submission to GRE-96 (April 2027) and will submit 11 informal documents to GRE-94, including status report, four baseline documents, four highlights slides, a proposal on technological neutrality, and the revised correction proposal. Discussions on apparent surface, direction indicator visibility, and direction indicator lamp height will resume at SLR-78 (June 2026).

UN R48 baseline text for a 10 series of amendments proposes uniform provisions for vehicle lighting and light-signalling device installation approval. The document consolidates modifications agreed at working group session through dated amendment documents and resolutions. Pending issues include determining “[any] subsequent series” terminology for frozen regulations, renumbering and cross-checking paragraphs, addressing apparent surface visibility, improving daytime running lamp visibility against stop lamps, resolving “prohibited if not allowed” language, and numbering all figures with titles. Editorial polishing includes standardizing hyphenated terminology (“driving-beam,” “passing-beam,” “retro-reflector,” “direction-indicator lamp”), applying consistent UN Regulation references, replacing “communication sheet” with “communication form,” assigning table and figure numbers consistent with similar regulations, and correcting percentage notation to “per cent.”

GTB proposes simplifying UN R48 by developing a single CAD-based method to determine apparent surface at early design stages. The proposal deletes the “light-emitting surface” definition and establishes “apparent surface” as the orthogonal projection of visible light-emitting surfaces in a specified observation direction. Amendments include revised definitions for lens, textured outer lens, illuminating surface, and apparent surface, with modified requirements for single lamps with multiple distinct parts. Distance requirements between adjacent parts are adjusted to 75mm or 200mm depending on lamp type.

The agenda includes corrections to UN R150-01, baseline documents for UN R53, R74, R86, and R48, simplification of paragraphs 6.×.4 and 6.×.5, transitional provisions, harmonisation of requirements, apparent surface considerations, and direction indicator visibility improvements. The next meetings are scheduled for June and December 2026, with a potential September 2026 session in Tokyo.