| ho | Knowledge Explorer Hierarchy Outline |
| hob | CARIS Hydrographic Object Binary Data |
| hobo | Onset HOBO Data Logger Data |
| hol | Microsoft Outlook Holiday Data |
| hom | PLINK Homozygosity Data |
| hor | Heliosoft AttriGenPlus Input Horizon File |
| hph | Designer Graphics System 2 Data |
| 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 |
| hqx | Macintosh BinHex Encoded File |
| hr2 | Poser Hair Data |
| hrb | TIBCO Hawk Rulebase Data |
| hrc | Softimage 3D Model |
| hrd | MSC Patran Device-dependent Hardcopy Output File |
| hrm | Polar Heart Rate Monitor Data |
| hrp | AviSys Bird Watcher Database |
| hrs | HRS Pro NAUPA II File |
| hru | SWAT HRU Data |
| hrv | HRVTool Data |
| hrz | Poser Compressed Hair Data |
| hs2 | HyperRESEARCH 2 Study |
| hs3 | HyperRESEARCH 3 Study |
| hs6lic | HyperSnap License Data |
| hs7lic | HyperSnap License Data |
| hsa | Hagaki Studio Address Book |
| hsc | Aspen HYSYS Simulation |
| hscx | HemoSpat Coordinate Exchange Format Data |
| hsh | Microsoft Windows Catalog Search Index Hash |
| hsh | Microsoft Surface Calibration Hash |
| hsh | Microsoft IIS Metabase Hash File |
| hsk | Nimbus 7 SAMS HSK Data |
