This part of ISO 10326 defines specifications covering laboratory tests for seats designed for passengers and crew in railway tractive and trailer vehicles. It concerns tri-axial rectilinear vibration within the frequency range 0,5 Hz to 50 Hz. It specifies the input test vibration to be used at seat testing. This part of ISO 10326 makes it possible to characterize, in the form of frequency response functions, the manner in which vibration is transmitted to the seat occupant. However, this characterization is fully valid only when the man-seat system can be considered to be sufficiently linear.