| fmt | GAUSS Engine Matrix Data |
| fmt | LinkOne Format Data |
| fmt | Pro/ENGINEER Report Table Format Data |
| fmtr | FileMaker Pro Transfer Data |
| fmu | Functional Mock-up Unit Data |
| fmv | Adobe FrameMaker Picture Data |
| fmv | FME Desktop Viewspace Data |
| fmw | FME Workbench |
| fmwt | FME Desktop Workbench Template |
| fmx | FME Desktop Custom Transformers Data |
| fmxlist | FME Desktop User-defined Transformer List |
| fn | STK Facility Networks File |
| fna | FASTA Sequence |
| fnbk | Food Network Recipe Manager Data |
| fnc | Frogans Player Network Certificate |
| fnc | Vue Functions Data |
| fnet | FileMaker Pro Network Data |
| fng | Font Navigator Group Data |
| fni | FileNet Native Image |
| fnl | EES File Names List |
| 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 |
