Files with the "FP" prefix in these archives generally stand for "Festung Posen." The "12" likely refers to a specific sector, map sheet, or document number within a larger historical series.
Because this file is primarily hosted on peer-to-peer or legacy file-sharing sites, users should exercise caution: FP.12.rar
Historical maps, documents, or data related to the defense and fall of the German fortress at Poznań. Files with the "FP" prefix in these archives