H = Header File normally with .C or .CPP file
    H = Mime: text/plain
    H = Mime: text/x-h
    H! = Flambeaux Help
    H! = Perfect Database help database
    H++ = unusual C++ Header, normally .H
    H-- = Sphinx C-- header file
    H0 = Magix Musstu file
    H1 = Magix Musstu file
    H16 = Msdev Vc98 Include file(16 bit)
    H32 = Bc45 32bit include file
    H6C = Spp file
    H_ = Winhelp file (compressed)
    H__ = seldom used C++ Header same as H++ and H
    HA = Compressed file archive (HA)
    HAI = Ntgraph Nt09b-2b Emx Lib file
    HAIRY = cygnus share file
    HAL = Hyper Access Lite OS/2 data file
    HAM = Novell NetWare disk drivers NPA
    HAP = HAP Compressed file archive
    HAT = Formula 1 car race 2001 Log Hat file
    HAZ = Game: Ms flight Texture file
    HBF = Hanzi Bitmap Font (HBF) File Format version 1.1
    HBK = MathCAD Handbook
    HBM = Hotline BookMark
    HBX = Starmoney Macro file
    HBY = ROM image resources
    HBZ = Starmoney Macro file
    HC = Header file
    HCD = C Poet Examples Advanced Inc file
    HCL = 3DS image
    HCM = IBM HCM Configuration
    HCO = Macintosh Sound + Resource Fork
    HCOM = Sound (Macintosh)
    HCR = IBM HCD/HCM Production Configuration
    HCT = Symantec Liveupdate file
    HCX = Harvard Chart XL chart
    HDA = HotDocs Document
    HDF = Help file (Help Development Kit)
    HDF = Hierarchical Data Format bitmap image (NCSA)
    HDF = Mime: application/x-hdf
    HDF = Procomm Plus alternate download file listing
    HDL = Procomm Plus Alternate Download File Listing
    HDML = Handheld Device Markup Language
    HDML = Mime: text/x-hdml
    HDP = Magix Musstu file
    HDR = Apollo HRDU image format
    HDR = Egret datafile
    HDR = Pc-File+ database Header
    HDR = Procomm Plus/1st Reader Message Header
    HDRU = Apollo HRDU image format
    HDS = Hierarchical Data System
    HDT2 = (MAC FILE_TYPE) Hard Disk Toolkit
    HDV = Formula 1 car race 2001 Season01 Vehicles Arrows file
    HDW = Drawing; Harvard Draw for Windows
    HDX = Help index (AutoCAD/Zortech C++)
    HEA = Game: fifa 2001 data feart legalscr file
    HEATSEEK = Heatseeker mc1.0 format
    HEC = Grafic Pvquan Quant file
    HED = HighEdit document
    HEL = Microsoft Hellbender saved game
    help = (MAC FILE_TYPE) Apple Guide
    Help = (MAC FILE_TYPE) Help File
    HELP = (MAC FILE_TYPE) Microsoft Help File
    HELP = Mime: application/x-helpfile
    HEP = Novell NetWare Help Librarian data file
    HER = Grafic Gif file
    HEX = (Macintosh) BinHex encoded file archive (ASCII)
    HEX = Hex dump
    HF = HF image format
    HFB = Ralcgm file
    HFI = Hp Font Info file (GEM)
    HFX = HotFax data
    HGL = Hewlett-Packard Graphics Language
    HGL = Highlight groups definitions (DN)
    HGL = Mime: application/vnd.hp-HPGL
    HGS = Harvard Graphics : Graphics
    HGT = Battle Zone Data File
    HGT = SRTM terrain data
    HH = C++ header file
    HH = Mime: text/plain
    HH = Mime: text/x-h
    HHC = HTML Help Table Of Contents file, funtional comparable with .cnt
    HHG = THHG EUROPEAN HEADQUARTER
    HHH = Power C precompiled header file
    HHK = MS HTML Help Index
    HHL = Visual basic file
    HHP = HTML Help project file, funtional comparable with .hpj
    HHP = Procomm Plus help information for remote users
    HHTML = Realmedia adstream html file
    HI = High scores (various games)
    HIF = Quicken intuit(old) de online file
    HIG = High scores (various games)
    HImg = (MAC FILE TYPE) Image file created by Toast 3
    HIN = Hyperchem HIN chemical modeller input file
    HIN = Hyperchem HIN chemical modeller output file
    HIN = HyperChem molecule
    HIPS = Bitmap image
    HIR = Hires C64 image format
    HIREX = HIREx Data Specification
    HIS = HIStory of executing/viewing/editing (DN)
    HIT = HitPlayer Audio File
    HIX = System Sysutil file
    HJT = editor treepad file
    HKC = HTML-KIT auto complete short-cuts
    hkdb = (MAC FILE_TYPE) iTunes Music Library
    HKS = Hook Script
    HL$ = MS compressed HLP (DOS help file); decompress with UNPACK.EXE
    HL_ = Compr. Scanner us driver file
    HLB = Mime: text/x-script
    HLB = VMS help library
    HLF = Basic Quickbas Quickb01 file
    HLL = Boulderdash game file
    HLM = Winhelp Vbhilfe file
    HLP = HeLP file : various prgs,for Winhelp.exe or Winhlp32.exe
    HLP = Mime: application/hlp
    HLP = Mime: application/winhlp
    HLP = Mime: application/x-helpfile
    HLP = Mime: application/x-winhelp
    HLS = Winhelp file
    HLX = MultiEdit help file
    HLX2 = (MAC FILE_TYPE) Apple DocViewer
    HLZ = MultiEdit packed help file
    HM = Windows Help context IDs used by MAKEHM.EXE
    HM2 = Help&Manual Help File Project
    HMGD = (MAC FILE_TYPE) Microsoft Grammar File
    HMHD = (MAC FILE_TYPE) Word Hyphenation File
    HMI = MIDI music
    HMM = Procomm Plus Alternate Mail option menu
    HMP = MIDI music
    HMSD = (MAC FILE_TYPE) Microsoft Dictionary
    HMY = Hemingway2.exe (plugin for Hemingyway Content Management System: www.altuit.com)
    HM~ = Help&Manual Backup Help File Project
    HNC = CNC program files Heidenhain dialog??
    HNF = Humax Receiver Settings
    HOB = Z80 Spectrum Emulator Snap/File Formats
    HOF = 'Hall Of Fame' game data = best scores
    HOG = Lucas Arts Dark Forces WAD file
    HOT = Mosaic Internet address
    HOWTO = doxygen file
    HP = Printout file (HP Graphics Language )for HP printers/plotters (HP/GL)
    HP = Thor database primary hash file
    HP$ = Ntgraph Visual c wizzard file
    HP- = Dist Bin file for Hp
    HP-UX = File for Hp-unix
    HP8 = Text in HP Roman8 character set (NewWave Write)
    HP_ = Winhelp file (compressed)
    HPC = System Dll file
    HPF = PageMaker HP LaserJet fonts
    HPFS = OS/2 High Performance File System
    HPG = Mime: application/vnd.hp-HPGL
    HPG = Vector image (HPGL plotter file) (AutoCad/Harvard Graphics)
    HPGL = Mime: application/vnd.hp-HPGL
    HPGL = Vector image (HPGL plotter file) (Hewlett-Packard Graphics Language)
    HPGL2 = Hewlett Packard Graphics Language 2
    HPH = Designer graphics System2 file
    HPI = GEM font information
    HPI = Hemera Photo Image image format
    HPI = Mime: application/vnd.hp-hpid
    HPID = Mime: application/vnd.hp-hpid
    HPJ = Ms Help Compiler Help ProJect file, used to combine .hm and .rtf files to a compiled .hlp file
    HPJ = Printed to file (HP LaserJet)
    HPK = HPack compressed file archive
    HPL = Vector image (Hewlett-Packerd LaserJet)
    hplg = (MAC FILE_TYPE) iTunes Device Plugin
    HPLJ = Vector image (Hewlett-Packerd LaserJet)
    HPM = Alternate Main menu for privileged users (Procomm Plus)
    HPM = Emm text (HP NewWave)
    HPM = Quaestor 1.x High Performance Map
    HPP = C++ header (Zortech C++/Watcom C/C++)
    HPP = Vector image (Hewlett-Packard Printer Control Language)
    HPPCL = Vector image (Hewlett-Packard Printer Control Language)
    HPR = RoboHelp Configuration
    HPS = Mime: application/vnd.hp-hps
    HPUX = File for Hp-ux
    HPW = CompuServe Home Page Wizard
    HP~ = V-help file
    HQR = Little Big Adventure HQR and VOX files
    HQX = BinHex archive format, orig. Macintosh
    HQX = Mime: application/binhex
    HQX = Mime: application/binhex4
    HQX = Mime: application/mac-binhex
    HQX = Mime: application/mac-binhex40
    HQX = Mime: application/x-binhex40
    HQX = Mime: application/x-mac-binhex40
    HR = TRS 80 image format
    HRC = SoftImage model 3D file
    HRF = CADCore bitmap image (Hitachi Raster Format)
    HRH = Common header for resources and C++
    HRL = Herolab EasyWin32
    HRM = Procomm Plus alternate Main menu for limited/normal users
    HRT = Hornet Packer format
    HRU = HRU image format
    HRX = Herolab EasyWin32
    HRZ = SSTV = Slow Scan TeleVision file
    HS = Literate Haskell source code file
    HS2 = Postering monochrome image
    HSC = 2-op FM music file (HSC tracker)
    HSDL = Hierarchical Scan Description Language
    HSI = Handmade Software Inc bitmap image (Image Alchemy)
    HSM = Assembly language header (University of Waterloo Engineering convention)
    HSP = HomeSite WWW page project
    HSQ = Data File Associated with Qaz Trojan
    HSQL = htmSQL : SQL statements embedded in HTML
    HSS = Photoshop Hue/Saturation Information
    HSS = Hue/Saturation data(many prgs)
    HST = Handmade Software graphics histogram (HSI raw file) (Image Alchemy)
    HST = HiSTory file
    HT = HyperTerminal file
    HT3 = HTML file Version 3 (uncommon)
    HT4 = HTML file Version 4 (uncommon)
    HTA = HTML program
    HTA = Mime: application/hta
    HTA = Tonline Bsw4 file
    HTACCESS = Apache Access Configuration File
    HTC = HTML code
    HTC = Mime: text/x-component
    HTF = WebBase File
    HTI = Win Help related file
    HTLC = (MAC FILE_TYPE) Hotline Client
    HTM = HyperText Markup Language file (WWW-page)
    HTM = Mime: text/html
    HTMHJT = Treepad HTML files(with text)
    HTMHTML = 3rdparty html file
    HTML = HyperText Markup Language file (WWW-page)
    HTML = Mime: text/html
    HTMLS = HyperText Markup Language document with server-side include (Internet)
    HTMLS = Mime: text/html
    HTN = Micrografx Picture Publisher 8 printstyles file
    HTR = HTML-like script
    HTT = Microsoft HyperText Template
    HTT = Mime: text/webviewhtml
    HTVW = (MAC FILE_TYPE) HTML Viewer
    HTW = htmlfile open with: Internet Explorer -nohome
    HTX = Mime: text/html
    HTX = MS FrontPage database results, HTML-like query script
    HUF = Huffman encoded/compressed file
    HUN = Dataview file
    HUS = Husqvarna embroidery machines file format
    HUV = graphic files read by Husqvarna Viking Designer 1 sewing machine (embroidery files that control stitching of the designs)
    HUY = Eto Dlia Vas
    HW3 = Hyperwriter! Document
    HWD = Hollywood presentation
    HWL = Corel Shared Writing Tools 9.0 file
    HWOF = (MAC FILE_TYPE) Microsoft Office Help
    HWP = Hangul (Korean) Word Processor File
    HX = Cross-reference hash file (THOR database)
    HX_ = C Poet compressed Disk1 file
    HXM = Alternate Protocol Selection menu for all users (Procomm Plus)
    HXX = C++ header, see H, H++
    HY1 = Ventura Publisher hyphenation algorithms
    HY2 = Ventura Publisher hyphenation algorithms
    HYC = WordPerfect data
    HYD = WordPerfect for Win hyphenation dictionary
    HYM = 3D Image binary file (Hymarc Scandata Scanner)
    HYP = Hyper compressed file archive
    HZ = Chinese text