The GRE Informal Working Group on Simplification of UN Lighting and Light-Signalling Regulations held its 73rd session in Brussels on 9-11 July 2025. SLR approved reports from the 70th and 71st sessions. The Homework Team R-150 will prepare an updated version of SLR-73-09 including a decision tree and justification for submission to GRE-93 or GRE-94. SLR experts will study the GTB draft proposal in SLR-73-04 (superseded by SLR-73-04/Rev.1) to simplify paragraphs 6.×.4. and 6.×.5. in Reg. 48. SLR-73-07/Rev.1 reflects the latest baseline document for Reg. 48 with agreed modifications. IMMA introduced baseline documents for Reg. 53 and Reg. 74 reflecting simplified definitions. CEMA will prepare a baseline document for Reg. 86. GTB will prepare an updated proposal for a CAD-based method to determine apparent surface for SLR-74. A special SLR session on apparent surface may be held on 10 September 2025 if equipment is available. Discussion continues on harmonisation of requirements, improving direction indicator visibility, and technological neutrality for light sources. The 74th SLR meeting is scheduled for 10-12 September 2025 in Brussels.