| Extension | File Description |
| .ISK | Uncommon Files |
| .ISL | Uncommon Files |
| .ISM | Video Files |
| .ISML | Uncommon Files |
| .ISN | Uncommon Files |
| .ISO | Disk Image Files |
| .ISOD | Uncommon Files |
| .ISP | Settings Files |
| .ISQ | Uncommon Files |
| .ISR | Game Files |
| .ISS | Settings Files |
| .IST | Data Files |
| .ISTG | Uncommon Files |
| .ISTR | Uncommon Files |
| .ISU | Executable Files |
| .ISV | Uncommon Files |
| .ISW | Uncommon Files |
| .ISX | Uncommon Files |
| .ISY | Uncommon Files |
| .ISZ | Disk Image Files |
| .IT | Audio Files |
| .IT0 | Uncommon Files |
| .IT1 | Uncommon Files |
| .IT2 | Uncommon Files |
| .IT3 | Uncommon Files |
| .IT4 | Uncommon Files |
| .IT5 | Uncommon Files |
| .IT6 | Uncommon Files |
| .IT7 | Uncommon Files |
| .IT8 | Uncommon Files |
| .IT9 | Uncommon Files |
| .ITA | Compressed Files |
| .ITAL | Uncommon Files |
| .ITALIC | Uncommon Files |
| .ITB | Uncommon Files |
| .ITC | Misc Files |
| .itcl | Uncommon Files |
| .ITD | Uncommon Files |
| .ITE | Data Files |
| .ITEMS | Uncommon Files |
| .ITF | Uncommon Files |
| .ITG | Uncommon Files |
| .ITH | Uncommon Files |
| .ITHMB | Raster Image Files |
| .ITI | Audio Files |
| .ITJ | Uncommon Files |
| .ITK | Uncommon Files |
| .ITL | Data Files |
| .ITM | Data Files |
| .ITN | Uncommon Files |
| .ITO | Uncommon Files |
| .ITP | Uncommon Files |
| .ITQ | Uncommon Files |
| .ITR | Game Files |
| .ITS | System Files |
| .ITT | Uncommon Files |
| .ITU | Uncommon Files |
| .ITV | Uncommon Files |
| .ITW | Database Files |
| .ITX | Data Files |
| .ITY | Uncommon Files |
| .ITZ | Uncommon Files |
| .IU0 | Uncommon Files |
| .IU1 | Uncommon Files |
| .IU2 | Uncommon Files |
| .IU3 | Uncommon Files |
| .IU4 | Uncommon Files |
| .IU5 | Uncommon Files |
| .IU6 | Uncommon Files |
| .IU7 | Uncommon Files |
| .IU8 | Uncommon Files |
| .IU9 | Uncommon Files |
| .IUA | Uncommon Files |
| .IUB | Uncommon Files |
| .IUC | Uncommon Files |
| Extension | File Description |
| .IUD | Uncommon Files |
| .IUE | Uncommon Files |
| .IUF | Uncommon Files |
| .IUG | Uncommon Files |
| .IUH | Uncommon Files |
| .IUI | Uncommon Files |
| .IUJ | Uncommon Files |
| .IUK | Uncommon Files |
| .IUL | Uncommon Files |
| .IUM | Uncommon Files |
| .IUN | Uncommon Files |
| .IUO | Uncommon Files |
| .IUP | Uncommon Files |
| .IUQ | Uncommon Files |
| .IUR | Uncommon Files |
| .IUS | Uncommon Files |
| .IUT | Uncommon Files |
| .IUU | Uncommon Files |
| .IUV | Uncommon Files |
| .IUW | Uncommon Files |
| .IUX | Uncommon Files |
| .IUY | Uncommon Files |
| .IUZ | Uncommon Files |
| .IV | 3D Image Files |
| .IV-VRML | Uncommon Files |
| .IV0 | Uncommon Files |
| .IV1 | Uncommon Files |
| .IV2 | Uncommon Files |
| .IV2I | Backup Files |
| .IV3 | Uncommon Files |
| .IV4 | Uncommon Files |
| .IV5 | Uncommon Files |
| .IV6 | Uncommon Files |
| .IV7 | Uncommon Files |
| .IV8 | Uncommon Files |
| .IV9 | Uncommon Files |
| .IVA | Uncommon Files |
| .IVB | Uncommon Files |
| .IVC | Data Files |
| .IVD | Data Files |
| .IVE | 3D Image Files |
| .IVF | Video Files |
| .IVG | Uncommon Files |
| .IVH | Uncommon Files |
| .IVI | Uncommon Files |
| .IVJ | Uncommon Files |
| .IVK | Uncommon Files |
| .IVL | Uncommon Files |
| .IVM | Uncommon Files |
| .IVN | Uncommon Files |
| .IVNU | Uncommon Files |
| .IVO | Uncommon Files |
| .IVP | Uncommon Files |
| .IVQ | Uncommon Files |
| .IVR | Raster Image Files |
| .IVS | Video Files |
| .IVT | Game Files |
| .IVU | Uncommon Files |
| .IVUE | Raster Image Files |
| .IVV | Uncommon Files |
| .IVW | Uncommon Files |
| .IVWD | Uncommon Files |
| .IVWL | Uncommon Files |
| .IVWR | Uncommon Files |
| .IVX | Uncommon Files |
| .IVY | Uncommon Files |
| .IVZ | Uncommon Files |
| .IW | Data Files |
| .IW0 | Uncommon Files |
| .IW1 | Uncommon Files |
| .IW2 | Uncommon Files |
| .IW3 | Uncommon Files |
| .IW4 | Uncommon Files |
| .IW5 | Uncommon Files |
| .IW6 | Uncommon Files |
