| uvtsk | µVision Recorded Task-switching Data |
| uvtt | DECE TTML Data |
| uvutt | DECE TTML Data |
| uvw | Autodesk 3D Studio MAX UVW Coordinates |
| uvz | DECE ZIP Compressed Data |
| uwl | Corel WordPerfect User Word List |
| uwl | Novell GroupWise Custom Dictionary |
| uwrf | Universal Web Radio Data |
| uxd | Bruker RAW Data |
| uxd | URLBase URL Database |
| uxp | IGOR Pro Unpacked Experiment File |
| uxt | IGOR Pro Unpacked Experiment Template File |
| uxy | Barudan Embroidery Outline Data |
| uyl | User Screen Editor Dictionary Data |
| uz1 | JB BAHN Scenery Archive |
| uz2 | JB BAHN Scenery Archive |
| uz4 | JB BAHN Scenery Archive |
| uzg | JB BAHN Scenery Archive |
| uzr | iModeller 3D UZR Model |
| v | Vivid 2.0 Input File |
| v00 | Kretz 3D Ultrasound Image |
| v01 | Genesis 2000 Data |
| v03 | Axialis Screensaver Producer Thumbnail Cache |
| v06 | Nokia 5530 XpressMusic PPM Flash Data |
| v11 | ESR v11 Data |
| v11o | ACDSee Offline Media Data |
| v11p | ACDSee Photo Disc Data |
| v11pf | ACDSee Private Folder Data |
| v12 | All The Right Type Database |
| v16 | BrainVoyager QX MRI 16bit Data |
