This part of IEC 61587 specifies seismic test requirements for chassis, subracks, and plug-in units as defined in the IEC 60297 and IEC 60917 series. It applies in whole or in part, only to the mechanical structures of chassis, subracks, and plug-in units for electronic equipment, according to the IEC 60297 and IEC 60917 series, and does not apply to electronic components, equipment or systems within the mechanical structures. Note: Subracks may be an integral part of a chassis (often called in the industry a shelf or a crate).