| hy3 | Hy-Tek Meet Manager Results Data |
| hy3 | Hy-Tek Team Manager Data |
| hyb | HYB Hybrid Data |
| hyc | Corel WordPerfect Internal Data |
| hyd | CARE-S InfoWorks Hydrograph Data |
| hyd | Corel WordPerfect Hyphenation Dictionary |
| hyd | MARIN Hydrodynamic Database File |
| hyd | WRAP Single Hydrology Data |
| hym | Hymarc Hyscan 3D Scan Data |
| hyn | HydroNet Explorer Component Information |
| hyp | HyperLynx BoardSim PCB Layout |
| hyp | SmartWare HYP Dictionary Data |
| hypesymbol | Hype Symbol Cache Data |
| hyq | CARE-S Depth Hydrographs for Gauged Pipes |
| hyv | CARE-S InfoWorks Velocity Hydrograph Data |
| hyv | Team Manager 1 Meet Setup File |
| hzd | SeisWorks Horizon Datafile |
| hzf | Neosat Fixes |
| hzn | Observer Pro Horizon Data |
| hzs | CrossWorks for ARM Session Data |
| i1c | IBM Voice Type Languages Newuser Data |
| i1i | IBM Voice Type Languages Newuser Data |
| i2b | Invoice2go Product Data |
| i2c | IBM Voice Type Languages Newuser Data |
| i2g | Intergeo I2G Geometric File |
| i2s | Green Kenue 2D Lineset Data |
| i32 | LabVIEW I32 Data |
| i3dm | Cesium Instanced 3D Tiles Data |
| i3ml | I3ML Data |
| i3s | Green Kenue 3D Lineset Data |
