letter H extensions

.H Header (Usually C Compiler)
.H! Flambeaux Tutorial Database
.H++ C++ Header File
.H-- Sphinx C-- Header File
.HA Compressed Archive
.HAM Image File
.HBK Mathcad Handbook Humanic Software Accounting Data
.HCM IBM HCM Configuration
.HCR IBM HCD/HCM Production Configuration
.HDA HotDocs Document
.HDF Hierarchical Data Format File
.HDL Procomm Plus Alternate Download File Listing
.HDR Procomm Plus Message Header PC-File+ Database Header
.HDW Harvard Draw Vector Graphics
.HDX Help Index (Various)
.HED HighEdit Document
.HEL MS Hellbender Saved Game
.HEX Hex Dump Macintosh BinHex 2.0 File
.HFI HP Font Info
.HFX HotFax File US Robotics Rapid Comm Voice Data File
.HGL HP Graphics Language
.HH C++ Header Help Topic Map File
.HHC Table of Contents File (HHW Application) TurboTax Contents File
.HHH Power C Precompiled Header
.HHK Help Workshop Index File
.HHP Procomm Plus Help Data
.HHP HTML Help Project
.HIT HitPlayer Audio File
.HLP Windows Help File
.HM2 Help&Manual Help File Project
.HMI Descent Human Machine Interfaces MIDI File
.HMM Procomm Plus Alternate Mail Read Option Menu
.HMP Descent Human Machine Interfaces MIDI File
.HM~ Help&Manual Backup Help File Project
.HOF Hall Of Fame (scores)
.HOG Lucas Arts Dark Forces WAD File Descent Mission File
.HPF PageMaker HP LaserJet Fonts HotLine Partial Download File
.HPG Hewlett-Packard Graphics (plotter)
.HPI Gem Font Information Hemera Photo-Object Image
.HPJ Help Project File
.HPK Compressed Archive
.HPL HP Graphics File
.HPM Procomm Plus Alternative Menu
.HPP C++ Program Header InfoMgr Database File
.HPR RoboHELP Configuration File
.HQX Binhex Text Conversion File (Macintosh)
.HRL Herolab EasyWin32
.HPM Procomm Plus Alternate Main Menu
.HPP Zortech C++ Header
.HPR RoboHelp Configuration
.HQX Macintosh BinHex 4 Compressed Archive
.HRM Procomm Plus Alternate Main Menu
.HRX Herolab EasyWin32
.HRZ Image File
.HSC HelpScribble Project
.HSI Handmade Software Graphic File
.HSQ Data File Associated with Qaz Trojan
.HSS Photoshop Hue/Saturation Information
.HST History File Procomm Plus History File Host File
.HT HyperTerminal
.HTA Hypertext Application (run apps from HTML doc)
.HTF WebBase File
.HTI WebBase File
.HTM Hypertext Markup Language (HTML)
.HTT Hypertext Template
.HTX Extenended Hypertext Template Internet Database Connector File
.HWP Hangul (Korean) Word Processor File
.HXM Procomm Plus Alternate Protocol Selection Menu Descent2 HAM File
.HXX C++ Header
.HY1 Ventura Publisher Hyphenation Algorythm
.HY2 Ventura Publisher Hyphenation Algorythm
.HYC WordPerfect Hyphenation File
.HYD WordPerfect Hyphenation Dictionary
.HYP Hypertext File Hyphenation File Compressed Archive
.HZ Chinese