| fdt | Impromptu Function Description Table |
| fdt | Lucene Field Data |
| fdt | Natural Field Definition Table |
| fdt | Visilogic Utilities Full Data Table |
| fdu | Natural ADAFDU Data |
| fdx | Food Data Exchange File |
| fdx | Lucene Field Index |
| fdxsl2 | FeedDemon Newspaper Style |
| fdxsl4 | FeedDemon Newspaper Style |
| fe | Surface Evolver Data File |
| fea | AFDKO Feature Definitions File |
| feap | Enterprise Architect Repository |
| feat | Feature Chemical Modeller Output Data |
| feb | Corel WordPerfect FE Buttons Data |
| feb | Sybase PowerDesigner Free Model Backup |
| fed | FORMIK Form Data |
| fedb | ANSYS Workbench FE Modeler Data |
| fee | Precision Fees Data |
| feed | JRiver Media Center Feed Data |
| feed-ms | Microsoft RSS Feed Store |
| feedback | Microsoft Expression SketchFlow Feedback Data |
| feedsdb-ms | Microsoft Edge RSS Feeds Store |
| fef | Steuer 2001 FEF Data |
| fek | Altair FEKO Input Data |
| fel | Fugawi Elevation Library Data |
| fem | Algor Simulation FEA Model |
| fem | FEFLOW Problem Settings Data |
| fem | Sesam GeniE FEM Data |
| fem | Sybase PowerDesigner Free Model |
| fen | Forsyth–Edwards Notation Data |
| feq | SuperEQ Equalizer Settings Data |
| ferp | Extensions Manager Preferences Data |
| fes | Topicscape Fileless Link Export |
| fet | FET Data |
| fetchmirror | Fetch Mirroring Data |
