This part of ISO 10542 specifies test methods as well as requirements for design and performance, for instructions and warnings to installers and users, and for product marking and labelling of wheelchair tiedown and occupant restraint systems (WTORS). It applies only to WTORS that are intended to be used with particular makes and models of wheelchairs when used as a forward-facing seat by a passenger or a driver of a motor vehicle. This part of ISO 10542 applies to WTORS intended for use with manual or powered wheelchairs, including scooters with three or more wheels, intended for use by children or adults of mass equal to or greater than 22 kg. This part of ISO 10542 applies primarily to complete WTORS, but portions of this International Standard can also be applied to components and subassemblies sold separately and for replacement parts.