| udcx | Universal Data Connection |
| uec | UltraEdit Saved Settings |
| ufi | UFOCapture V2 Settings |
| umb | MemMaker Configuration Backup File |
| unit | Systemd Unit Data |
| uns | Visual Navigation Suite Export Settings |
| upf | Bentley MicroStation User Preference File |
| upload | WebSTAR File Upload Option |
| upp | Unified Printer Parameter |
| upv | UniversalPlantViewer Configuration Data |
| usc | USC Module Definition |
| utl | SAP BACKINT Interface Profile |
| uvopt | µVision v4 Project Options |
| uvoptx | µVision v5 Project Options |
| ux | XMetaL XML Configuration File |
| v22 | V-22 Controller Settings Data |
| vbox | Oracle VM VirtualBox VM Settings |
| vbox-prev | Oracle VM VirtualBox VM Settings Backup |
| vcfg | Microsoft Lync Voice Routing Configuration |
| vcl | Varnish Configuation Language File |
| vcomps | V-Comp Setup |
| vgr | Voyager Settings File |
| vgw | Sybase ASE VGW File |
| vimrc | Vim Runtime Configuration |
| vio | VIMNet Explorer Configuration |
| vis | FDS Imaging Software HW Configuration |
| vkm | VICE Keyboard Map |
| vmac | VMware Workstation Configuration |
| vmc | Virtual Machine Configuration |
| vmcx | Virtual Machine Shell Information |
| vmoptions | Java Virtual Machine Configuration |
| vmpl | VMware ACE Virtual Machine Policy File |
| vmtd | VMware Virtual Disk Template |
| vmtm | VMware Virtual Machine Team Data |
| vmtx | VMware ESX Virtual Machine Configuration Template |