| hdk | HotDocs Registration File |
| hdl | HotDocs Template Library |
| hdpart | hyperDENT Parts Data |
| hdpartz | hyperDENT Parts Archive |
| hdpmx | HotDocs Publisher Mapping XML |
| hdpp | hyperDENT Global Allowance Data |
| hdr | Microsoft IIS NNTP Header Data |
| hdr | Mail.dat Header File |
| hdr | DataFlex Database Header |
| hdumx | HotDocs User Mapping XML |
| hdz | Poser Compressed Hand Data |
| he2 | Hierarchical Data Format File |
| he4 | Hierarchical Data Format Release 4 Data |
| he5 | Hierarchical Data Format Release 5 |
| hea | PhysioBank Header File |
| hec | Pvquan Heckbert Data |
| hedata | HTML Executable Publication Data |
| hef | HEAT Export Data |
| heg | GRABLOX HEG Data |
| heo | NASA Solve getpar Earth Orientation Data |
| hep | Hummingbird HostExplorer Profile |
| heu | Adobe Flash Player Cache Metadata |
| hex | BinHex Encoded Data |
| hf2 | L3DT Compressed Heightfield Data |
| hff | L3DT Heightfield Data |
| hfg | HeroForge-Anew Character Data |
| hfi | HP Printer Font Data |
| hfo | Pinnacle Hollywood FX Object |
| hfx | Hot Fax Data |
| hfz | L3DT Compressed Heightfield Data |
