Microsoft WinHelp is a proprietary format for online help files that can be displayed by the Microsoft Help browser winhelp.exe or winhlp32.exe. The file format is based on Rich Text Format (RTF). Although simpler than the later Microsoft Compressed HTML Help format and standard HTML, it is still popular because it is supported by all current Windows versions.
A WinHelp file has a ".hlp" suffix. It can be accompanied by an optional table of contents (.cnt) file if the help compiler created one. When Windows opens a WinHelp file, it creates a .gid file in the same directory, containing information about the .hlp file such as the window size and location. If the user clicks the "Find" tab and enables keyword indexing, Windows creates an index file with a .fts extension.
A limitation of WinHelp is picture support: to support formats other than BMP and WMF, the author must learn how to use Winhelp's support for plug in modules. One such module supports display of large DIB bitmaps. In fact, all the multimedia capability possible in early versions of Encarta are possible in WinHelp because the engines were at the time essentially identical.
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