| Abbreviation | Definition |
|---|---|
| H-- | Header file (Sphinx C--) |
| H! | Help database (Flambeaux Help - Perfect Database) |
| H++ | Header file (C++) |
| HA | Compressed file archive (HA) |
| HAL | Data file (Hyper Access Lite OS/2) |
| HAM | Novell NetWare Disk Drivers for NetWare Peripheral Architecture |
| HAP | Compressed file archive (HAP) |
| HBK | Handbook (Mathcad) |
| HBM | Hotline bookmark |
| HBO | Hipparchus Binary Object |
| HC | Header file |
| HCE | HydroCAD Stormwater Modeling System Hygrograph file |
| HCOM | Sound (Macintosh) |
| HDF | Help file (Help Development Kit) |
| HDF | NCSA Hierarchical Data File Bitmap graphics |
| HDL | Alternate download file listing (Procomm Plus) |
| HDR | Database header (Pc-File+) |
| HDR | Datafile (Egret) |
| HDR | Message header (Procomm Plus - 1st Reader) |
| HDS | Hierarchical Data System |