| fmu | Functional Mock-up Unit Data |
| fmw | FME Workbench |
| fn | STK Facility Networks File |
| fna | FASTA Sequence |
| fnbk | Food Network Recipe Manager Data |
| fnc | Frogans Player Network Certificate |
| fnl | EES File Names List |
| fnm | Lucene Field Name Data |
| fno | Folio Infobase Data |
| fnrecipes | Food Network Recipe Manager Data |
| fnw | FLARENET Model Data |
| fnx | Fenix Key Data |
| fo | 602XML Form Filler Data |
| fob | Microsoft Dynamics NAV Object Container |
| foc | FOCUS Database |
| fod | EZ-Forms Form Relationship Data |
| fof | EZ-Forms Filled Out Form |
| fog4 | Fontographer v4 Data |
| fol | PFS First Choice Database |
| fom | EZ-Forms Fill Out Master Form |
| fop | InfoZoom Protected Data |
| fot | InfoZoom Template |
| fov | MORSE FOV Data |
| fow | Family Origins Database |
| fox | InfoZoom Table |
| fp1 | RPOWER.Gift Cards Data |
| fp10 | FileMaker Pro V10 Data |
| fp3 | FileMaker Pro V3 Data |
| fp4 | FileMaker Pro V4 Data |
| fp5 | FileMaker Pro V5 Data |
| fp6 | FileMaker Pro V6 Data |
| fp7 | FileMaker Pro V7 Data |
| fpa | MakeMusic Finale Performance Assessment |
| fpb | FLAMES Playback File |
| fpbf | Mac OS X Finder Burn Folder |