| gx | GenX Data |
| gx2 | General CADD Pro Image |
| gxa | General CADD Attribute Data |
| gxc | General CADD Pro Component |
| gxh | General CADD Pro Hatch |
| gxkey | GameEx Registy Data |
| gxl | Graph Exchange Language |
| gxm | General CADD Pro Macro |
| gxs | GrafiXML Graph |
| gxv | General CADD Pro Menu |
| gxy | ISIS GIS Visualiser Schematic Data |
| gyg | Gygan Data |
| gz1 | Orgadata LogiKal Data |
| gzf | WebCopier Data |
| gzl | Go!Zilla File List |
| h00 | Flash ROM HEX File |
| h01 | Flash ROM HEX File |
| h02 | Flash ROM HEX File |
| h03 | Flash ROM HEX File |
| h1c | Microsoft Help Collection Definition |
| h1d | Microsoft Help Validator File |
| h1h | Microsoft Help Merged Hierarchy File |
| h1k | Microsoft Help Keywords Index |
| h1q | Microsoft Help Merged Query Index |
| h1s | Microsoft Help Compiled Help Data |
| h1t | Microsoft Help Topic Definition |
| h1v | Microsoft Help VTopic Definition |
| h1w | Microsoft Help Merged Keyword Index |
| h2d | Hydrus-2D Data File |
| h2drumkit | Hydrogen Drum Kit Data |
| h2song | Hydrogen Drum Notes Data |
| h2w | H2testw Data |
| h323 | H.323 IP Telephony Data |
| h3b | Line 6 POD HD300 Edit Bundle |
| h3d | HyperView 3D Model |