| fn | STK Facility Networks File |
| fna | FASTA Sequence |
| fnbk | Food Network Recipe Manager Data |
| fnc | Frogans Player Network Certificate |
| fnc | Vue Functions Data |
| fnd | Informida Secure Information Database |
| fnet | FileMaker Pro Network Data |
| fng | Font Navigator Group Data |
| fni | FileNet Native Image |
| fnl | EES File Names List |
| fnl | Windows Live Mesh FNL Data |
| fnm | Lucene Field Name Data |
| fnm | SOBEK Filenames Data |
| fno | Folio Infobase Data |
| fnrecipes | Food Network Recipe Manager Data |
| fnsp | Apple FontSync Script |
| 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 |
| folder | Windows Explorer Folder Data |
| foli | Foliaro Data |
| folx | Folx Download Data |
| fom | EZ-Forms Fill Out Master Form |
| fon | COREX Manual Broad Phonetic Transcription Data |
