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ULF - Uniware Layout File
U3D - Universal 3D File
UPM - PenMail Document
U3P - U3 Platform Install File
UT! - µTorrent Incomplete Download
UWS - UniTrader 2006 Website Archive
UIF - Magic ISO Universal Image Format File
UMD - UMD Photobook
UST - WiFi SiStr Exported User Theme
UWT - UniTrader Template Archive
U - Subsampled Raw YUV Bitmap
U - Unreal System File
U - Nitpicker Ipflow File
U2 - Telelogic Tau UML Model
U2E - Unreal Game Translation
U2P - Telelogic Tau UML Program Text File
U4A - UnInstaller Archive
U8 - Raw Unsigned 8-Bit Audio Data
U96 - EasyZip Temporary File
U98 - Urdu 98 Document
UAE - WinUAE 0.8.22 Game Configuration File
UAP - User Agent Wireless Telephony Profile
UAX - Deus Ex
UAX - Harry Potter
UAX - Rune
UAX - Undying
UAX - Unreal / Unreal 2
UB - Audio
UB - Raw Unsigned Byte (8-bit) Data
UBB - BASIC UBAS File
UBD - BASIC UBAS File
UBK - National Construction Estimator 32 User Costbook
UBM - Iphoto Mtwain Install File
UBS - Tracesrv Bugslayer Utility File
UCD - Prosa/ OM Use Case Diagram
UCE - UniCode Extensions
UCF - Xilinx Foundation User Constraint File
UCM - Urban Chaos Game File
UCN - Compressed Archive
UCR - MicroSim PCBoard Unrouted Nets Report
UCS - Universal Classification Standard Database File
UDB - PINO 3-Server File
UDC - Fh5 US English File
UDF - Photostyler Image Filter
UDF - Windows NT Uniqueness Database File
UDW - Raw Unsigned DoubleWord (32-bit) Data
UE2 - Encrypted Archive
UEF - Unified Emulator Format
UFA - UFA Compressed File Archive
UFF - DataWave Physiological Data File
UFO - Total Annihilation
UG - Drawing File
UHA - UHARC Compressed Archive
UHTM - Unreal Tournament File
UI - Geoworks UI Compiler Espire Source
UI - User Interface
UIH - Geoworks UI Compiler Espire Header
UIL - X-Motif UIL Table
UIS - WindowBlinds Skin
UKA - Fifa World Cup Game Data fe Art Legalscr File
UK_ - Mcguiness File
UL - uLAW Audio File
ULD - Procomm Uploaded Files
ULP - Peugeot Diag 2000 File
ULS - Internet Location Service
ULT - UltraTracker Music Module
ULW - ULAW - Sun/NeXT
ULX - Glulx Game
UM - The Land Of UM World File
UMB - MemMaker Backup Archive
UMI - CDDB Database and PC Music Library in PlayCenter
USR - User Database
UNX - Text File
UN_ - Ntgraph Setup30 file
UOL - PhotoImpact Object Library File
UP2 - Cool3d Plug-ins Board File
UPD - dBASE Update File
UPD - ProUpdater Per/Directory Options Setting File
UPD - Universal Print Driver
UPD - Updated Program Data
UPDATE - Program or Data File Update
UTL - QuickBooks Data
USF - Core Media Player XML Universal Subtitle Format File
URI - List of Uniform Resource Identifiers
UPI - ULead Photo Impact Program File
UPJ - ULead Project File
UPL - Starmoney Agent Download File
UPO - dBASE Compiled Update File
UPR - FileMaker User Spelling Dictionary
UPT - Connectivity Memory Model Update Timing Input File
UPX - ULead Photo Express Saved Image File
UPZ - Starmoney Agent Download File
URF - Radar ViewPoint Universal Radar Format
UMX - Deus Ex
UMX - Harry Potter
UMX - Unreal
UND - A86 Assembler Undefined Symbols
UNF - Btreive Unformatted File
UNI - Forcast Pro Data File
UNI - MikMod (UniMod) Format
UNIX - UNIX File
UNL - Informix Binary File Created by UNLOAD Command
UNQ - Fax View File
UNR - Unreal Map File
UNUSED - Photoline4 Defaults File
UNV - BusinessObjects/WebIntelligence Universe File
UNV - SDRC I-DEAS File
UTE - Rukus 110 File
UPF - Universal Picture Format Bitmap
UPG - Grafik Anim File
UPG - Firmware Upgrade File
UPI - Iphoto4 Programs Plug-in File
USF - Nintendo Ultra 64 Sound Format
USP - LaserJet Portrait Font
UMS - Rune
URIS - List of Uniform Resource Identifiers
URL - Internet Location
URT - Utah Raster Image
USA - Unreal Saved Game File
USAGE - Snort File
USB - D-Link FM Radio Update
USB - Syssoft Sandra File
USB - USB Protocol Analyzer Trace
USE - Log File
USE - MKS Source Integrity File
USL - LaserJet Landscape Font
USS - WinUAE Saved State
USTAR - POSIX tar Compressed Archive
UTL - Sound File
UTP - BinPatch Patch Data File
UTX - Unicode File
UTX - Deus Ex
UTX - Harry Potter
UTX - Rune
UTX - Undying
UTX - Unreal / Unreal 2
UU - Compressed Archive File
UUD - Uudecoded
UUE - Uuencoded
UV2 - Jane's Combat Simulations F-15
UVR - Ulead Cool 360 Viewer File
UVV - Listlabl File
UVW - geoManager/geoInterface User View
UW - Audio
UW - Raw Unsigned Word (16-bit) Data
UW - Unitype GlobalWriter File
UWF - UltraTracker Wave File
UX - UNIX File
UYVY - Imagemagick-5.3.2 Perlmagick File
UYVY - Interleaved YUV Raw Image
UZ - Unreal Tournament Server File
UZE - Ultimate Zip Compresion Agent
UZR - UZR 3D Streamable 3D File Format
UDF - X-ray Diffraction Data File Format

Adobe

UDC - Acrobat Spelling File
USP - PageMaker Printer Font

AIPNL

UC2 - UltraCompressor II Compressed Archive

America Online, Inc.

UD - AOL 4.0
UTF - AOL Updating Files

Autodesk, Inc.

UNT - AutoCAD Unit Definition

Autometrix

UC - AutoCut Flash Firmware File

Best Software CRM Division

UNQ - ACT! Saved Unknown Attachment

Bibliographisches Institut & F.A. Brockhaus AG

USL - PC-Bibliothek User Dictionary

Business Forecast Systems, Inc.

UNV - Forecast Pro Univariate Forecast File

CadSoft Computer GmbH

ULP - EAGLE Layout Editor Script

Cavedog Entertainment

UFO - Total Annihilation Third-party Unit

Child Language Data Exchange System

ULX - CLAN Lexical File

ControlDraw Ltd.

URS - ControlDraw User Requirements Specifier

CoreCodec, Inc.

USF - Core Media Player XML Universal Subtitle Format File

Corel

UDI - Corel Graphics Ver 10 Draw Script Textures Bitmap File
UIF - WordPerfect Long Prompts
USR - Photo Paint User Defined Filter
UWL - WordPerfect User Word List

Corel Corporation

UIF - WordPerfect Long Prompts
UWL - WordPerfect User Word List

Creative Express Corporation

USR - ERGO Receiver Configuration File

David Harris

USR - Pegasus Mail User Information

Delorme

UNM - XMap Flight Plan or Flight Plan Statistic File

EGGcentric

UPDATE - ISAPI Loader New ISAPI Application

Electronic Arts, Inc.

UV - EA Games Video File

Embiid Inc.

UBK - Embiid Reader eBook

Epic Games

UMOD - Unreal Self-extracting MOD File
UT2MOD - Unreal Tournament 2003 Game Modification File
UT4MOD - Unreal Tournament 2004 MOD Installation Package

Epic Games, Inc.

U - Unreal Tournament 2003 System File
UAX - Unreal Audio File
UAX - Unreal Tournament 2003 Sound
UC - Unreal Tournament Code File
UKX - Unreal Tournament 2003 Animation
UMX - Unreal Tournament 2003 Music
USX - Unreal Tournament 2003 Static Mesh
UT2 - Unreal Tournament Map
UMOD - Unreal Tournament
UMX - Unreal/Unreal Tournament Music File
UTX - Unreal Tournament 2003 Texture
UVX - Unreal Tournament 2003 Saved Game
UXX - Unreal Tournament 2003 Cache

FileMaker, Inc.

USR - FileMaker Pro Runtime Engine Database Application

Genesis 2000, Inc.

UUT - Genesis 2000

Headlight Software, Inc.

URLS - GetRight URL List

HRM Systems AG, CH-Winterthur

UKA - UKA Data Archive

IBM

UCX - Rational XDE
UID - IBM Voice Type Users File

ICQ Inc.

UIN - ICQ 2001+ Saved ICQ Contact Information

ImageMagick Studio LLC

UYVY - ImageMagick Ver. 5.3.2 Perlmagick File

Introversion Software

USR - Uplink Player Information File

J-T-L Development Inc.

UPC - Ultimate Paint

Matinsoft Inc.

URF - AppFace Skin

MicroImages, Inc.

USR - MicroImages User-specific Information

Microsoft

UDB - Works File
UDB - Windows2000 Uniqueness Database File
UDF - Excel User Defined Function
UDL - Data Link
UH - Age of Kings
UKS - Works File
UPS - Works File
USA - Office Header File

Microsoft Corporation

UDC - Systems Management Server

MotCreations

UDM - MapView User-Defined Module

Nokia

UPF - Nokia Phone Digital Photo

Oleh Yuschuk

UDD - OllyDbg Module Information

Orchida Soft

UXY - Orchida Embroidery System

PepiMK Software

UTI - Spybot - Search & Destroy Usage Tracking
UTS - Spybot - Search & Destroy Include File

ScanSoft, Inc.

UD - OmniPage User Dictionary

Schneider Electric

URF - ProWORX Nxt User Configurable Register Editor File
USL - ProWORX Nxt USL Loadables

Sierra Entertainment, Inc.

UDS - Sierra Generations Geneology Family File
UCS - Homeworld Localized Unicode Strings

Software995

UPDF - UltraPdf Publication

Symantec

USERPROFILE - Live Update User Profile

Terria Development

UXD - URLBase URL Database
UXP - URLBase URL Database

UAX Project

UAX - Unified Application eXchange Format

Ulead

UFA - GIF Animator Animation Object Information
UFO - PhotoImpact Graphic
UGA - Ulead GIF Animator Project File

Ulead Systems, Inc.

UCG - ULEAD MediaStudio CG Infinity Graphic
UEZ - COOL 3D
USS - PhotoImpact Exported Slicing Pattern
UPD - VideoStudio Scene Information
UVP - ULEAD MediaStudio Video Paint Graphic
UFO - PhotoImpact Graphic

Umetrics AB

USP - SIMCA-P/SIMCA-P+ Project

Uniform Data System for Medical Rehabilitation, a division of UB Foundation Activities, Inc.

UDS - FIMware Database

Unisys

UCN - U-Act Configurator Configuration Storage File

Universal Hint System

UHS - Universal Hint System File

Universite Catholique de Louvain-la-Neuve

USI - UsiXML UI Description File
USZ - UsiXML UI Description File

Visual Object Modelers, Inc.

UML - Visual UML Class Diagram & Model