| Abbreviation | Definition |
|---|---|
| UDC | Adobe Acrobat Spelling File |
| UDD | Universal Data Dictionary |
| UDF | Excel User Defined Function |
| UDF | Filter (Photostyler) |
| UDF | Photostyler Image Filter |
| UDF | Uniqueness Database File (Windows NT) |
| UDF | Windows NT Uniqueness Database File |
| UDI | Corel Graphics10 Draw Script Textures Bitmap File |
| UDS | Sierra Generations Family File |
| UDW | Raw Unsigned DoubleWord (32-bit) Data |
| UE2 | Encrypted Archive |
| UE2 | UltraCompressor II Encrypted file archive |
| UFA | UFA Compressed file archive |
| UFO | Ulead File for Objects ( Ulead PhotoImpact) |
| UFO | Ulead PhotoImpact Ulead File for Objects |
| UFO | Ulead PhotoImpact Ulead File for Objects |
| UHS | Universal Hint System (binary file) |
| UI | Geoworks U I Compiler Espire language source code file |
| UI | User interface (Sprint) |
| UIB | User Interface Bitmap |