.??_  Files ending in "_" are often compressed install files of the same
          name (e.g., .EX_ expands to .EXE, .DL_ expands to .DLL, etc.)
  .H    Header (Usually C Compiler)
  .H3M  Game Map File (used by a large number of games)
  .H4R  Possible Container for .MP3 Files (MUSIC.H4R)
  .H!   Flambeaux Tutorial Database
  .H++  C++ Header File
  .H--  Sphinx C-- Header File
  .HA   Compressed Archive
  .HAD  MixlleniumEngine (Haydee) Web Server Module Style File (XML format)
  .HAK  GameHack File (instruction codes to apply to memory to hack a game)
  .HAL  Mortyr Archive  [Dragon UnPACKer]
  .HAM  Image File
  .HAN  Viewpoint Headline Studio (Viewpoint used to be MetaCreations)
  .HAP  Compressed Archive
  .HAT  HAT (HOORA Analysis Tool) Model
  .HAY  MixlleniumEngine (Haydee) Web Server Module Content File (XML format)
  .HBC  Home Buyers Calculator Suite
  .HBK  Mathcad Handbook
        Humanic Software Accounting Data
  .HC   BI/Suite Hypercube
  .HCM  IBM HCM Configuration
  .HCR  IBM HCD/HCM Production Configuration
  .HCT  Symantec Anti-Virus Live Update File  (usually LIVEUPDT.HCT)
  .HD2  Curious Labs Poser Hand File
  .HDA  HotDocs Document
  .HDB  Nero File (CD burning/design software)
  .HDF  Hierarchical Data Format File
        Help Development Kit Help File
  .HDL  Procomm Plus Alternate Download File Listing
  .HDML  Handheld Markup Language File (WAP phones; browser prior to 4.X)
  .HDP  Magix Music/Video
  .HDR  Procomm Plus Message Header
        PC-File+ Database Header
        Egret Data File
        ArcInfo Binary  [XnView]
        Adobe Photoshop File
        Apollo HDRU  [XnView]
  .HDRU  Apollo HDRU  [XnView]
  .HDW  Harvard Draw Vector Graphics
  .HDX  Help Index (Various)
  .HED  HighEdit Document
        Hi-Eddi  [XnView]
  .HEH  Scarlett Expert System Compiler Facts File (Scarlett is not presently available)
  .HEL  MS Hellbender Saved Game
  .HEX  Hex Dump
        Macintosh BinHex 2.0 File
  .HF   HF File  [XnView]
  .HFI  HP Font Info
  .HFS  Macintosh Disk Image on CD [FAQ]
  .HFV  Simulated Macintosh Volumes on PC Hard Drive [Executor] [HFVExplorer]
  .HFX  HotFax File
        US Robotics Rapid Comm Voice Data File
  .HFZ  Pinnacle Studio Video Editing File
  .HGH  Star Wars - Tie Fighter High Score
  .HGL  HP Graphics Language (plotter) [SwiftView]
  .HGS  HighGrow Virtual Seed File
  .HH   C++ Header
        Help Topic Map File
        HammerHead Drumloop 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
  .HIN  HyperChem Molecule
  .HIR  C64 Hires  [XnView]
  .HIT  HitPlayer Audio File
        Nonags Dialog Killer Data File
        The Sims (Maxis) Sound File
  .HJT  TreePad Hypertext Database File
  .HLB  VAX Help Library
  .HLN  Microstation Hidden Line File (unverified)
  .HLP  Windows Help File
        Stata Statistical Software Help File [Text files whose format predates Windows]
  .HLX  Visual C++ Syntax Coloring Instructions
        ATI Radeon Video Driver Support File
        Hyperlatex File
        Multi-Edit Help File
  .HLZ  Multi-Edit Packed 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
  .HMX  MixlleniumEngine (Haydee) Web Server Module Template File (XML format)
  .HM~  Help&Manual Backup Help File Project
  .HNF  Humax Receiver Settings
  .HNV  TheWord & Bible Companion Hebrew Names Version Bible
  .HO   Magix Music/Video
  .HOF  Hall Of Fame (scores)
  .HOG  Lucas Arts Dark Forces WAD File
        Descent Mission File  [Dragon UnPACKer]
  .HOT  The Sims (Maxis) Sound File
  .HP   HP Graphics Language (plotter) [SwiftView]
  .HP8  HP NewWave Write ASCII Roman8 Character Set
  .HPD  Harry Potter Related
  .HPF  PageMaker HP LaserJet Fonts
        HotLine Partial Download File
  .HPG  HP Graphics Language (plotter) [SwiftView]
  .HPGL  HP Graphics Language (plotter) [SwiftView]
  .HPI  Gem Font Information
        Hemera Photo-Object Image  [XnView]
  .HPJ  Help Project File
  .HPK  Compressed Archive
  .HPL  HP Graphics File
  .HPM  Procomm Plus Alternative Menu
        HP NewWave Emm Text
  .HPP  Borland C++ Builder 6 Program Header
        InfoMgr Database File
  .HPR  RoboHELP Configuration File
  .HQX  Binhex Text Conversion File (Macintosh)
        WinXP Game File (sorry no details were in the submission)
  .HR2  Curious Labs Poser Hair File
  .HRF  Hitachi Raster Format Graphic
  .HRL  Herolab EasyWin32
  .HPM  Procomm Plus Alternate Main Menu
  .HPP  Zortech C++ Header
  .HPR  RoboHelp Configuration
  .HQX  Macintosh BinHex 4 Compressed Archive
  .HR   TRS 80 Graphic  [XnView]
  .HRM  Procomm Plus Alternate Main Menu
  .HRU  HRU File  [XnView]
  .HRX  Herolab EasyWin32
  .HRZ  Slow Scan Television  [XnView]
  .HS   Hugs Source Code
  .HS2  Postering Monochrome Image
  .HSC  HelpScribble Project
  .HSE  Dreamweaver Snippet (pre-MX version)
  .HSI  Handmade Software Graphic File
  .HSK  Nimbus 7 SAMS Data File (Daily ASCII files)
  .HSM  The Sims (Maxis) Sound File
  .HSQ  Data File Associated with Qaz Trojan
        CAST Application Mining Suite (Query file to generate HTML from Database Server)
  .HSS  Photoshop Hue/Saturation Information
        Dreamweaver Snippet (pre-MX version)
  .HST  History File
        Netscape History File
        Corel QuickCorrect and Speller History File
        Procomm Plus History File
        File Associated with WordPerfect (history?)
        Symantec Anti-Virus Live Update File  (usually LIVEUPDT.HST)
        Host File
  .HT   HyperTerminal
  .HTA  Hypertext Application (run apps from HTML doc)
        Hemera Thumbnail Archive
  .HTACCESS  Apache Access Configuration File
  .HTC  HTML Component (mechanism for implementing Dynamic HTML in script)
  .HTF  WebBase File
  .HTI  WebBase File
  .HTM  Hypertext Markup Language (HTML)
  .HTML  Hypertext Markup Language (HTML)
  .HTT  Hypertext Template
  .HTX  Extenended Hypertext Template
        Internet Database Connector File
  .HULL  Halflife Map Collision Hull File
  .HUS  Husqvarna Designer I Embroidery Machine Format [possibly read with Melco Sizer Software]
  .HUY  Eto Dlia Vas
  .HVD  chosenOS HoverNews Skin File
        ISIS Hviews File (chemical reaction database)
        CMT Surveyor's Assistant 1.x/2.0x Job
        HerdView Event Data File
  .HWCFG  VersaPro Hardware Configuration File
  .HWD  Hollywood Presentation File
  .HWL  Hangman Deluxe Word List
  .HWP  Hangul (Korean) Word Processor File
  .HX   EARS Component File (EARS = UK Liberal Democrats Election Agents Record System) [Filename starts with E]
  .HXM  Procomm Plus Alternate Protocol Selection Menu
        Descent2 HAM File
  .HXS  Help 2 File (replacement for .CHM)
  .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
        Acrobat Spelling File
        Compressed Archive
  .HZ   Chinese