| ufx | Ultimate 3D Effects Data |
| ugf | Go Game Data |
| ugi | Go Game Data |
| ugp | Aroma Unit Genome Position Data |
| ugr | Apophysis Gradient File |
| ugrid | Delft3D Flexible Mesh Suite UGRID Data |
| ugs | Universal G-Code Sender Data |
| ugz | Compressed Go Game Data |
| uhh | Eurotherm 6100a Binary Data |
| uhh | Eurotherm Hydra History Data |
| uhi | Eurotherm 6100a Printer Driver Import Data |
| uhq | Eurotherm 6100a Support Data |
| uhr | Eurotherm 6100a User Resource Data |
| uhs | Universal Hint System Hints File |
| uht | Eurotherm 6100a Table Data |
| uhu | Eurotherm 6100a User Screen Data |
| ui | Gimp Plug-ins UI Data |
| uid | IBM VoiceType User Data |
| uid-zps | Zoner Photo Studio Changes Backup Data |
| uil | AIX User Interface Language |
| uin | ICQ 2001 Saved ICQ Contacts Information |
| uis | Stardock WindowsBlinds Style Description |
| uiz | SpyBot Search and Destroy Updater Data |
| uke | Ulead VideoStudio Data |
| ukm | UltraMixer Key Mapping Data |
| ukr | Adobe Acrobat Reader Ukrainian Language Data |
| uks | Microsoft Works UKS Data |
| uky | UltraMixer Licence Key Data |
| ul | Windows Updates Downloader Update List |
| uld | DIALux Unified Luminaire Data |
