A file beginning with INFO ("INFO.txt", "INFO_STRUCTURES.sdf" etc) will be stored but not entered into the database.
You can use INFO files to contain any additional context you might want to include, to assist the Deposition team with understanding your deposited data.
Most datasets should be fully explained by the information in the README.toml file. However, if you have other information you thing we need to no, discuss it in our initial call and we may suggest submitting it as an INFO file.