This Regulation applies to: (a) Vehicles of category M1 with regard to their ISOFIX anchorage systems, their ISOFIX top tether anchorages and lower tether anchorages intended for child restraint systems. Other categories of vehicles fitted with ISOFIX anchorages and/or lower tether anchorages have also to comply with the provisions of this Regulation; (b) Vehicles of any category with regard to their i-Size seating positions, if any are defined by the vehicle manufacturer."