| hmskin | Help and Manual Skin Data |
| hmt | HighMAT File |
| hmx | Haydee Web Server Module Template |
| hnd | HNSKY Deep Sky Database |
| hnf | HUMAX Receiver Settings Data |
| hnk | Internet Explorer HTML Help Index |
| hnr | iGO Primo Defined Routes |
| hns | Hallo Northern Sky Data |
| hnv | Hetero Number Viewer Input Data |
| ho | Knowledge Explorer Hierarchy Outline |
| hob | CARIS Hydrographic Object Binary Data |
| hobj | HALCON v12 Iconic Object |
| hobo | Onset HOBO Data Logger Data |
| hoe | Subaru HDS++ OPE File Editor Data |
| hol | Microsoft Outlook Holiday Data |
| hola | Human-like Orthogonal Layout Algorithm Data |
| hom | PLINK Homozygosity Data |
| homog | PLINK Homogeneity Test Report Data |
| hor | Heliosoft AttriGenPlus Input Horizon File |
| hot | WRAP HYD Output Data |
| hotlist | Internet Explorer Hotlist Data |
| hpb | IRAM Plateau de Bure Interferometer Header |
| hpdata | Heat Pump Design Model Data |
| hph | Designer Graphics System 2 Data |
| hpid | HP Instant Delivery Software Data |
| hpkg | Halotea Media Package |
| hpm | HAHTsite Runtime Project Map |
| hpr | Adobe RoboHelp Internal Data |
| hprof | Java Hprof Data |
| hps | HP Digital Sender Information |
| hpx | MetaVR 3D Model |
| hpz | Helpinator Zipped Archive |
| hqf | QuiltCAD Stitch Data |
| hqp | CP/M Disk Utility Data |
| hqx | Macintosh BinHex Encoded File |
