| hype | Hype Document |
| hypetemplate | Hype Document Template |
| hyy | HiTi Photo Desiree v2 Template |
| hz | Chinese Hanzi Text File |
| i4d | Inform4 Document |
| iam | Autodesk Inventor Assembly Model |
| iba | Lectra Clothing Design Pieces Document |
| ibcd | InstantBingoCard Document |
| ic3d | IronCAD Compose 3D Scene |
| ical | iCalendar Data |
| icalendar | iCalendar Data |
| icdl | Internet Content Description Language |
| icem | ICEM Surf Model |
| icm | ICEM Surf Model |
| icma | Adobe InCopy CS4 Assignment File |
| icml | Adobe InCopy Markup Language Document |
| icmt | Adobe InCopy CS4 Template |
| ics | iCalendar Data |
| ics | IronCAD Scene |
| icw | InterCAD Document |
| id4 | Infini-D Scene |
| ide | Autodesk Inventor iFeature File |
| idea | Adobe Ideas Document |
| idi | I-DEAS Document |
| ido | Infini-D 3D Object |
| idraw | iDraw Document |
| idrw | Claris Impact Drawing Document |
| ids | Infini-D Scene |
| idv | Autodesk Inventor Design View |
| idw | Autodesk Inventor Drawing |
| ifcxml | Industry Foundation Classes XML |
| ifd | InForm Document |
| ife | InfoFind Encrypted Document |
| ig2 | Catia IGES Document |
| ig4 | Image Systems Group 4 Fax Document |