| Extension | File Description |
| .OP0 | Uncommon Files |
| .OP1 | Uncommon Files |
| .OP2 | Uncommon Files |
| .OP3 | Uncommon Files |
| .OP4 | Uncommon Files |
| .OP5 | Uncommon Files |
| .OP6 | Uncommon Files |
| .OP7 | Uncommon Files |
| .OP73 | Uncommon Files |
| .OP8 | Uncommon Files |
| .OP9 | Uncommon Files |
| .OPA | Uncommon Files |
| .OPB | Uncommon Files |
| .OPC | Uncommon Files |
| .OPE | Uncommon Files |
| .OPEN | Uncommon Files |
| .OPENYOURMI | Uncommon Files |
| .OPG | Uncommon Files |
| .OPH | Uncommon Files |
| .OPI | Uncommon Files |
| .OPK | Uncommon Files |
| .OPL | Uncommon Files |
| .OPM | Uncommon Files |
| .OPN | Uncommon Files |
| .OPO | Uncommon Files |
| .OPOS | Uncommon Files |
| .OPP | Uncommon Files |
| .OPQ | Uncommon Files |
| .OPR | Uncommon Files |
| .OPTIONAL | Uncommon Files |
| .OPTNS | Uncommon Files |
| .OPU | Uncommon Files |
| .OPUS | Uncommon Files |
| .OPV | Uncommon Files |
| .OPW | Uncommon Files |
| .OPY | Uncommon Files |
| .OPZ | Uncommon Files |
| .OQ0 | Uncommon Files |
| .OQ1 | Uncommon Files |
| .OQ2 | Uncommon Files |
| .OQ3 | Uncommon Files |
| .OQ4 | Uncommon Files |
| .OQ5 | Uncommon Files |
| .OQ6 | Uncommon Files |
| .OQ7 | Uncommon Files |
| .OQ8 | Uncommon Files |
| .OQ9 | Uncommon Files |
| .OQA | Uncommon Files |
| .OQB | Uncommon Files |
| .OQC | Uncommon Files |
| .OQD | Uncommon Files |
| .OQE | Uncommon Files |
| .OQF | Uncommon Files |
| .OQG | Uncommon Files |
| .OQH | Uncommon Files |
| .OQI | Uncommon Files |
| .OQJ | Uncommon Files |
| .OQK | Uncommon Files |
| .OQL | Uncommon Files |
| .OQM | Uncommon Files |
| .OQN | Uncommon Files |
| .OQO | Uncommon Files |
| .OQP | Uncommon Files |
| .OQQ | Uncommon Files |
| .OQR | Uncommon Files |
| .OQS | Uncommon Files |
| .OQT | Uncommon Files |
| .OQU | Uncommon Files |
| .OQV | Uncommon Files |
| .OQW | Uncommon Files |
| .OQX | Uncommon Files |
| .OQZ | Uncommon Files |
| .OR | Uncommon Files |
| .OR0 | Uncommon Files |
| .OR1 | Uncommon Files |
| Extension | File Description |
| .OR7 | Uncommon Files |
| .OR8 | Uncommon Files |
| .OR9 | Uncommon Files |
| .ORB | Uncommon Files |
| .ORCA | Uncommon Files |
| .ORD | Uncommon Files |
| .ORGAN | Uncommon Files |
| .ORH | Uncommon Files |
| .ORIGINAL | Uncommon Files |
| .ORJ | Uncommon Files |
| .ORK | Uncommon Files |
| .ORL | Uncommon Files |
| .ORM | Uncommon Files |
| .ORMV | Uncommon Files |
| .ORN | Uncommon Files |
| .ORO | Uncommon Files |
| .ORP | Uncommon Files |
| .ORR | Uncommon Files |
| .ORT | Uncommon Files |
| .ORU | Uncommon Files |
| .ORV | Uncommon Files |
| .ORW | Uncommon Files |
| .ORX | Uncommon Files |
| .ORY | Uncommon Files |
| .ORZ | Uncommon Files |
| .OS0 | Uncommon Files |
| .OS1 | Uncommon Files |
| .OS2 | Uncommon Files |
| .OS3 | Uncommon Files |
| .OS4 | Uncommon Files |
| .OS5 | Uncommon Files |
| .OS6 | Uncommon Files |
| .OS7 | Uncommon Files |
| .OS8 | Uncommon Files |
| .OS9 | Uncommon Files |
| .OSA | Uncommon Files |
| .OSD | Uncommon Files |
| .OSE | Uncommon Files |
| .OSF | Uncommon Files |
| .OSG | Uncommon Files |
| .OSH | Uncommon Files |
| .OSI | Uncommon Files |
| .OSJ | Uncommon Files |
| .OSK | Uncommon Files |
| .OSL | Uncommon Files |
| .OSM | Uncommon Files |
| .OSMALLER | Uncommon Files |
| .OSN | Uncommon Files |
| .OSO | Uncommon Files |
| .OSp | Uncommon Files |
| .OSQ | Uncommon Files |
| .OSR | Uncommon Files |
| .OSTANDARD | Uncommon Files |
| .OSU | Uncommon Files |
| .OSV | Uncommon Files |
| .OSW | Uncommon Files |
| .OSX | Uncommon Files |
| .OSY | Uncommon Files |
| .OSZ | Uncommon Files |
| .OT0 | Uncommon Files |
| .OT1 | Uncommon Files |
| .OT2 | Uncommon Files |
| .OT3 | Uncommon Files |
| .OT4 | Uncommon Files |
| .OT5 | Uncommon Files |
| .OT6 | Uncommon Files |
| .OT7 | Uncommon Files |
| .OT8 | Uncommon Files |
| .OT9 | Uncommon Files |
| .OTA | Uncommon Files |
| .OTD | Uncommon Files |
| .OTE | Uncommon Files |
| .OTHERFOLDE | Uncommon Files |
| .OTHERS | Uncommon Files |
| .OTJ | Uncommon Files |
