ISO 10542-4:2004 specifies test methods and requirements for design and performance, instructions to installers and users, and product marking and labelling of wheelchair tiedown and occupant-restraint systems (WTORS). It is applicable only to WTORS that use clamp-type tiedown to secure wheelchairs when used as a forward-facing seat by an adult passenger or driver of a motor vehicle. ISO 10542-4:2004 is applicable primarily to complete WTORS, but a portion of ISO 10542-4:2004 can also be applied to components and sub-assemblies sold separately and for replacement parts. ISO 10542-4:2004 is applicable to WTORS intended for use with all types of manual and powered wheelchairs, including scooters with three or more wheels.