ISO 7634:2007 specifies the test procedures for testing the operational performance requirements of towed vehicles of Category O (full trailers, semi-trailers, and centre-axle trailers) as defined in Annex 7 of the UN-ECE Consolidated Resolution on the Construction of Vehicles (R. E. 3). This includes vehicles fitted with compressed air braking systems (with and without an antilock braking system or an electronically controlled braking system), in accordance with the UN-ECE Regulation 13, 09 series of amendments, supplements 1 to 6. Test methods covering lock actuators are not included.