| idsp | eXtendable Wad Editor IDSP Data |
| idu | Interleaf Desktop Utility |
| idvi | eXtendable Wad Editor IDVI Data |
| idx | Canon ZoomBrowser EX Database Index |
| idx | Citrix Program Neighborhood Database Index |
| idx | dBASE Database Index |
| idx | Easy Timesheets Index Data |
| idx | Galactic IDX Library |
| idx | Intuit Quicken Index Data |
| idx | LaTeX Unsorted Index Data |
| idx | Microsoft Outlook Express Mailbox Index |
| idx | Microsoft SQL Server Constraints |
| idx | PTC Creo Instance Index Data |
| idx | SmartWare Index Data |
| idx | Sunnysoft InterWrite Index Data |
| idx | Treepad Database Index |
| idz | Autodesk Inventor Compressed Content Library |
| idz | I-DEAS Data |
| ie | MyEclipse Image |
| ie3 | Internet Explorer Related Data |
| ied | ISIS Event Data File |
| ief | iCE CFR Raw Data |
| ief | ISIS Control File |
| iei | Image Eye Index Cache |
| iel | ParticleIllusion SE Emitter Library |
| iem | Informix Error Message |
| ienv | iData 3 Envelope Template Data |
| ies | IESNA Photometric Data |
| ie_ | Compressed IEC File |
| if90 | Programmer's Notepad Data |
| ifaith | iFaith SHSH Data |
| ifc | Industry Foundation Classes Data |
| ifczip | Compressed IFC Data |
| iff | SmartWare Temporary Merge Data |
| ifi | inFlow Inventory Database Backup |
