IMDS (International Material Data System) requirements are not part of the IATF 16949 standard requirements, but are rather part of customer specific requirements. IMDS is a global data repository that contains information on materials used by the automotive industry. Several leading auto manufacturers use the IMDS to maintain data for various reporting requirements.
It was originally created as a collaboration of Audi, BMW, Daimler, EDS (now part of HP, the system administrator), Ford, Opel, Porsche, VW and Volvo. Since inception the list of participating vehicle manufacturers and suppliers has grown greatly. If you are supplier of one of the companies that adopted IMDS, you are obliged to apply it as a part of their requirements, not requirements of the standard.