Microsoft Compiled HTML Help: Difference between revisions

Revision as of 22:44, 7 February 2022

Revision as of 22:45, 7 February 2022

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'''Microsoft Compiled HTML Help''' is a [[Microsoft]] proprietary [[online help]] format, consisting of a collection of [[HTML]] pages, an index and other navigation tools. The files are compressed and deployed in a binary format with the extension .CHM, for Compiled HTML. The format is often used for [[software documentation]].

It was introduced as the successor to [[Microsoft WinHelp]] with the release of [[Windows 95#Internet Explorer|Windows 95 OSR 2.5]]<ref>{{note|a}}since IE 4 is bundled with OSR 2.5, hence adding the CHM file support for the first time{{note|a}}</ref> and consequently, [[Windows 98]]. Within the Windows NT family, the CHM file support is introduced in [[Windows NT 4.0]]<ref>{{Cite web|url=https://docs.microsoft.com/en-us/security-updates/securitybulletins/2002/ms02-055|title=Microsoft Security Bulletin MS02-055 - Critical|website=docs.microsoft.com|language=en|access-date=2020-10-29}}</ref><ref>{{Cite web|url=https://seclists.org/fulldisclosure/2004/Jul/679|title=Full Disclosure: HtmlHelp - .CHM File Heap Overflow|website=seclists.org|language=en|access-date=2020-10-29}}</ref><ref>{{note|a}}The information available is scarce, but any VM installation of WinNT 4.0 appears to give .CHM file support out of the box. It seems like it wasn't introduced in
in Windows NT 3.51 due to NT 3.51 being intentionally limited to Internet Explorer 16-bit versions{{note|a}}</ref> and is still supported in [[Windows 11]].<ref>{{Cite web|url=https://community.spiceworks.com/topic/1961503-solved-windows-10-chm-help-files-showing-up-blank|title=[SOLVED] Windows 10 CHM Help Files showing up blank. - Spiceworks|website=community.spiceworks.com|language=en|access-date=2020-10-29}}</ref> Although the format was designed by Microsoft, it has been successfully [[Reverse engineering|reverse-engineered]] and is now supported in many document viewer applications.

==History==