| htw | Webhits Template |
| hub | Lattice Reveal Analyzer HUB Data |
| hud | HUD Maker File |
| huf | DtSearch Huffman Compression Table |
| huh | HydroCAD Unit Hydrograph Definitions |
| hun | Personal Paint Hungarian Language Data |
| hv | Microsoft Windows Mobile Hive |
| hvc | HotDocs Variable Collection File |
| hvd | Yamaha HV Voice Dictionary Data |
| hve | Microsoft Windows 8 AMCache Registry Hive |
| hvi | M3601A HVI Data |
| hvs | Yamaha HV-Script |
| hw | Marvelous Designer Hardware ID Data |
| hwdb | Linux Hardware Database |
| hwe | PLINK Hardy-Weinberg Exact Test Statistic Report |
| hwl | BrailleNote Apex License Key File |
| hwrx | Microvellum Hardware File |
| hwt | Huawei Phone Theme |
| hwv | Hades Waveform Viewer Data |
| hwx | RSNetWorx Registration Data |
| hxb | QCTest Data |
| hxd | Microsoft Help 2 Validator Data |
| hxg | Microsoft Help 2 Filter Cache |
| hxh | Microsoft Help 2 Merged TOC |
| hxi | Microsoft Help 2 Compiled Help Index |
| hxq | Microsoft Help 2 Query Data |
| hxr | Microsoft Help 2 Combined Attribute Index |
| hxw | Microsoft Help 2 Merged Index |
| hy1 | Corel Ventura Publisher Hyphenation Algorithm Data |
| hy2 | Corel Ventura Publisher Hyphenation Algorithm Data |
| hy3 | Hy-Tek Team Manager Data |
| hyb | HYB Hybrid Data |
| hyc | Corel WordPerfect Internal Data |
| hyd | MARIN Hydrodynamic Database File |
| hyp | HyperLynx BoardSim PCB Layout |
