We describe the research dataset “Microdatabase Direct Investment” (MiDi) using a structured metadata schema.1) The MiDi is a dataset on foreign direct investment (FDI) stocks based in official German FDI microdata. This data documentation is meant to be used jointly with the article on the MiDi by Blank, Lipponer, Schild, and Scholz (2020). While the mentioned article focusses more on the general properties of the dataset, this documentation goes deeper on the variable and on the value level. It also contains concepts added to the MiDi recently, which are related to the IMF Balance of Payments Manual, 6th edition (BPM6).