| hw | Marvelous Designer Hardware ID Data |
| hwas | eXtendable Wad Editor HWAS Data |
| hwdb | Linux Hardware Database |
| hwe | PLINK Hardy-Weinberg Exact Test Statistic Report |
| hwf | Hantek HDG2000B Wave Format Data |
| hwl | BrailleNote Apex License Key File |
| hwl | HttpWatch Watch Log |
| hwof | Microsoft Office for Mac Help Data |
| hwpml | Hangul Word Processor Markup Language Data |
| hwrx | Microvellum Hardware File |
| hwt | Huawei Phone Theme |
| hwv | Hades Waveform Viewer Data |
| hwx | RSNetWorx Registration Data |
| hx | Amira 3D Mesh Data |
| hx1 | Microsoft Windows HX1 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 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 |
