Microsoft Compiled Html Help Article Index for
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Microsoft Compiled Html Help




HTML Help files are made with Help Authoring Tool s. Microsoft ships the HTML Help Workshop with supported versions of Microsoft Windows and makes the tool available for free download. There are also a lot of third-party help authoring tools available.

The Microsoft Reader .LIT file format is basically a modification of the HTML Help CHM format.

In in the Windows Vista operating system.


HISTORY

  • February 1996 - Microsoft announced plans to stop development of WinHelp and start development on HTML Help.

  • August 1997 - HTML Help 1.0 (HH 1.0) was released with Internet Explorer 4.

  • February 1998 - HTML Help 1.1a shipped with Windows 98 .

  • January 2000 - HTML Help 1.3 shipped with Windows 2000 .

  • July 2000 - HTML Help 1.32 released with Internet Explorer 5.5 and Windows ME .

  • October 2001 - HTML Help 1.33 released with Internet Explorer 6 and Windows XP .

  • March 2001 - At the WritersUA (formerly WinWriters) conference, Microsoft announced plans for a new help platform Help 2, also HTML based.

  • January 2003 - Microsoft decided not to release Microsoft Help 2 as a general Help platform...



FILE FORMAT

A CHM help file has a ".chm" extension. It has a set of web pages written in a subset of HTML and a Hyperlink ed table of contents. CHM format is optimized for reading, as files are heavily indexed. All files are compressed together with LZX Compression . Most CHM browsers have the capability to display a table of contents outside of the body text of the help file.

The file starts with bytes "ITSF" (in ASCII), for "Info-Tech Storage Format". The format has been partially reverse engineered and there are container and internal files specifications available.

On Windows computers, this help file can be Compiled using hhc.exe, which is distributed at no charge with the HTML Help Workshop .

There are some tools, most importantly a write support.


ADVANTAGES


  • File size smaller than plain HTML

  • Range of formatting options that HTML gives for text presentation

  • Ability to search the full text

  • Ability to assemble several CHM files into one file with common TOC, index and search (see MSDN)

  • Ability to Generate TOC and Topic Folders containing International Characters standard HTML Help will not generate these correctly.



APPLICATIONS


This format was originally intended only for encoding help files, but other uses have since been found. It is very handy for packing saved HTML pages in one compact and browsable archive and for creating compact E-book s. Some people use it to keep personal notes, because it can organize them in an ordered hierarchical table and allows quick text searching. There is a Firefox extension capable of viewing CHM files {Link without Title} .


EXTRACTING TO HTML


On Windows, a CHM file can be extracted to plain HTML with the command:
hh.exe -decompile ''extracted'' ''filename.chm''
This will decompress all files embedded in ''filename.chm'' to folder ''extracted''.

or by using HTML Help Workshop.

On Linux systems which use apt as a packaging tool, a CHM file is extracted to plain HTML with (first command is for a Debian based OS)
$ sudo apt-get install libchm-bin
$ extract_chmLib tero.chm tero/

Another useful set of tools for CHM files in non-Windows environments is the CHM Tools Package . It's available as source code, and includes a program, chmdump, which extracts the HTML from a CHM file into a separate directory.

It's also available for Mac OS X via MacPorts .

If MacPorts is installed on your system, you can type:
$ sudo port install chmdump

at a Terminal prompt to install the package. You can then extract a CHM file with:
$ chmdump chmfile.chm outdir


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