| irt | Graphicon Interactive RealTime PHIGS |
| irt | IRIT 3D Model |
| irtp | Graphicon Interactive RealTime PHIGS |
| irx | Brewer Lamp Irradiance File |
| is1 | SmartWare Input-Screen File |
| is1 | Komori PCC Intermediate Ink Profile |
| is2 | SmartWare Input-Screen File |
| is3 | SmartWare Input-Screen File |
| is4 | SmartWare Input-Screen File |
| isale | iSale Auction Data |
| isallic | iSale License Data |
| isam | ISAM Database |
| iscf | Intel Schematic Connectivity Format Data |
| iscorrupt | Skype Corrupted Data |
| iscsi | Daemon Tools ISCSI Target Data |
| isd | Altair FEKO Calculated Field Distribution Data |
| isdb | iThink Database |
| ise | InstallShield Express File |
| iset | ARToolKit NFT Image Set |
| isg | HSC Chemistry Solgasmix Solver Data |
| ish1 | Animation-ish Wiggledoodle-ish Document |
| ish2 | Animation-ish FlipBook-ish Document |
| ish3 | Animation-ish Advanced-ish Document |
| isi | Web of Science Databases Output |
| isk | Druvaa inSync Client Key |
| isl | Inno Setup List |
| ism | ISAM Database |
| isml | IIS Smooth Streaming Publishing Point Definition |
| isoe | ISO Builder Data |
| ispc | Image Surfer Pro Collection |
