| Extension | File Description |
| .UN_ | Uncommon Files |
| .UO0 | Uncommon Files |
| .UO1 | Uncommon Files |
| .UO2 | Uncommon Files |
| .UO3 | Uncommon Files |
| .UO4 | Uncommon Files |
| .UO5 | Uncommon Files |
| .UO6 | Uncommon Files |
| .UO7 | Uncommon Files |
| .UO8 | Uncommon Files |
| .UO9 | Uncommon Files |
| .UOA | Uncommon Files |
| .UOB | Uncommon Files |
| .UOC | Uncommon Files |
| .UOD | Uncommon Files |
| .UOE | Uncommon Files |
| .UOF | Text Files |
| .UOG | Uncommon Files |
| .UOH | Uncommon Files |
| .UOI | Uncommon Files |
| .UOJ | Uncommon Files |
| .UOK | Uncommon Files |
| .UOL | Uncommon Files |
| .UOM | Uncommon Files |
| .UOML | Data Files |
| .UON | Uncommon Files |
| .UOO | Uncommon Files |
| .UOP | Uncommon Files |
| .UOQ | Uncommon Files |
| .UOR | Uncommon Files |
| .UOS | Uncommon Files |
| .UOT | Uncommon Files |
| .UOU | Uncommon Files |
| .UOV | Uncommon Files |
| .UOW | Uncommon Files |
| .UOX | Uncommon Files |
| .UOY | Uncommon Files |
| .UOZ | Uncommon Files |
| .UP | Uncommon Files |
| .UP0 | Uncommon Files |
| .UP1 | Uncommon Files |
| .UP2 | Uncommon Files |
| .UP3 | Uncommon Files |
| .UP4 | Uncommon Files |
| .UP5 | Uncommon Files |
| .UP6 | Uncommon Files |
| .UP7 | Uncommon Files |
| .UP8 | Uncommon Files |
| .UP9 | Uncommon Files |
| .UPA | Executable Files |
| .UPB | Uncommon Files |
| .UPC | Uncommon Files |
| .UPCASE | Uncommon Files |
| .UPD | Text Files |
| .UPDATE | Data Files |
| .UPDATEALL | Uncommon Files |
| .UPDATEINFO | Uncommon Files |
| .UPDATES | Uncommon Files |
| .UPDF | Uncommon Files |
| .UPE | Uncommon Files |
| .UPF | Settings Files |
| .UPG | Misc Files |
| .UPH | Uncommon Files |
| .UPI | Uncommon Files |
| .UPJ | Uncommon Files |
| .UPK | Game Files |
| .UPL | Uncommon Files |
| .UPM | Uncommon Files |
| .UPN | Uncommon Files |
| .UPO | Uncommon Files |
| .UPP | Uncommon Files |
| .UPQ | Uncommon Files |
| .UPR | Data Files |
| .UPS | Uncommon Files |
| .UPT | Uncommon Files |
| Extension | File Description |
| .UPU | Uncommon Files |
| .UPV | Uncommon Files |
| .UPW | Uncommon Files |
| .UPX | Executable Files |
| .UPY | Uncommon Files |
| .UPZ | Uncommon Files |
| .UQ0 | Uncommon Files |
| .UQ1 | Uncommon Files |
| .UQ2 | Uncommon Files |
| .UQ3 | Uncommon Files |
| .UQ4 | Uncommon Files |
| .UQ5 | Uncommon Files |
| .UQ6 | Uncommon Files |
| .UQ7 | Uncommon Files |
| .UQ8 | Uncommon Files |
| .UQ9 | Uncommon Files |
| .UQA | Uncommon Files |
| .UQB | Uncommon Files |
| .UQC | Uncommon Files |
| .UQD | Uncommon Files |
| .UQE | Uncommon Files |
| .UQF | Uncommon Files |
| .UQG | Uncommon Files |
| .UQH | Uncommon Files |
| .UQI | Uncommon Files |
| .UQJ | Uncommon Files |
| .UQK | Uncommon Files |
| .UQL | Uncommon Files |
| .UQM | Game Files |
| .UQN | Uncommon Files |
| .UQO | Uncommon Files |
| .UQP | Uncommon Files |
| .UQQ | Uncommon Files |
| .UQR | Uncommon Files |
| .UQS | Uncommon Files |
| .UQT | Uncommon Files |
| .UQU | Uncommon Files |
| .UQV | Uncommon Files |
| .UQW | Uncommon Files |
| .UQX | Uncommon Files |
| .UQY | Uncommon Files |
| .UQZ | Uncommon Files |
| .UR0 | Uncommon Files |
| .UR1 | Uncommon Files |
| .UR2 | Uncommon Files |
| .UR3 | Uncommon Files |
| .UR4 | Uncommon Files |
| .UR5 | Uncommon Files |
| .UR6 | Uncommon Files |
| .UR7 | Uncommon Files |
| .UR8 | Uncommon Files |
| .UR9 | Uncommon Files |
| .URA | Uncommon Files |
| .URB | Uncommon Files |
| .URBS | Uncommon Files |
| .URC | Uncommon Files |
| .URD | Uncommon Files |
| .URD-JOURNA | Uncommon Files |
| .URE | Uncommon Files |
| .URF | Uncommon Files |
| .URG | Uncommon Files |
| .URH | Uncommon Files |
| .URI | Uncommon Files |
| .URIS | Uncommon Files |
| .URJ | Uncommon Files |
| .URK | Uncommon Files |
| .URL | Web Files |
| .URLS | Uncommon Files |
| .URM | Uncommon Files |
| .URN | Uncommon Files |
| .URO | Uncommon Files |
| .URP | Uncommon Files |
| .URQ | Uncommon Files |
| .URR | Uncommon Files |
| .URS | Uncommon Files |
