The X
按字母分类：
extension name file type Classification
U10 UFile 2010 Tax Return data file
U11 UFile 2011 Tax Return data file
U12 UFile 2012 Tax Return data file
UBJ Universal Binary JSON File data file
UBOX Universe Sandbox Data File data file
UCCAPILOG Microsoft UCC API Log File data file
UD OmniPage User Dictionary data file
UDC Adobe InDesign User Dictionary data file
UDEB Debian Package File data file
UDS Sierra Generations File data file
UDS Uniform Data System File data file
ULF Universal List File data file
ULP EAGLE User Language Program data file
ULZ USBlyzer Data Capture File data file
UMF MediaHolder Universal Media Format File data file
UNITYPACKAGE Unity Package File data file
UOP Uniform Office Presentation data file
UPDATE ISAPI Update File data file
UPOI iGO Points of Interest File data file
UPR FileMaker User Dictionary data file
UPR Fractal Parameters File data file
USEQ USeq Genome Data File data file
USR SmartMusic Custom File data file
USTAR Uniform Standard Tape Archive Format File data file
UVF Uncertain Value Format data file
UVW UVW Coordinates File data file
UWL User Word List File data file
UWRF Universal Web Radio File data file