Proposal to modify definitions 2.9 “ISOFIX position” and 2.24 “i-Size seating position”. The revised definition of ISOFIX position specifies which types of ISOFIX child restraint systems as defined in UN R44 and UN R129 may be installed. The definition of i-Size seating position clarifies that such positions are designed to accommodate i-Size child restraint systems as defined in UN R129. The modification bases these definitions on strength test requirements rather than child restraint system category.

UN R145 and UN R173 establish optional ISOFIX installation for vehicles of category M₂ and M₃. ISOFIX seating positions require compatibility with specific Child Restraint Fixture volumes and lower isofix forward strength of 8kN. I-Size seating positions require minimum 440mm distance between adjacent positions, compatibility with ISO/F2X and ISO/R2, and additional support leg strength testing. The document proposes allowing labels on bus windows and removing marking requirements for M₂ and M₃ from UN R145.