WinHelp

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). It remained a popular Help platform from Windows 3.0 through Windows XP. WinHelp was removed in Windows Vista purportedly to discourage software developers from using the obsolete format and encourage use of newer help formats. Support for WinHelp files would eventually be removed entirely in Windows 10.

A WinHelp file has a ".hlp" suffix. It can be accompanied by an optional table of contents (.cnt) file if the help developer created one. When Windows opens a WinHelp file, it creates a .gid file in the same directory or in "%LOCALAPPDATA%\Help", 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 (full text search) extension. Annotations and bookmarks for each Windows help file have the extension ".ann" and ".bmk".

A number of software tools can decompile a WinHelp file into its source documents: HPJ, CNT, RTF, BMP, and SHG. An HPJ file is the project file that is created and edited in the Help Workshop (or a third party help authoring tool). The HPJ contains information about what RTF files to compile into the help, the MAP IDs and Aliases that provide links from a calling application to the help file, and help file appearance (window size, default buttons, color schemes, etc.). The CNT file provides the table of contents for the help file. An SHG file is a "SHED" graphics file that essentially creates an image map of help calls for a graphic file (e.g., a BMP).

A number of tools can read and explore these files. (See, for example, Help to RTF and winhelpcgi.)

Source files required to compile a .hlp file consist of one or more documents in Rich Text Format and a help project file with the extension .hpj, along with any image files (.bmp, .wmf, or .shg) that are used within the Help file. An optional table of contents file with the extension .cnt can also be created for use with the .hlp file.

Within the .rtf files, topics are separated by page breaks. Each topic has a series of footnotes that contain information for the help compiler:

Only the # footnote is required. All others are optional.

Text in each topic can contain limited formatting, including bold text, italics, and colors. Superscript and subscript are not allowed. Jumps between topics in the same Help file usually appear in the source document as double-underlined text (green by default, though this can be overridden) followed by a topic ID in hidden text. Popup links appear in the source document as text with a single underline (also green by default) followed by a topic ID in hidden text. (In the .hlp file, the jumps show up as green text with a single underline, and popups show up as green text with a dotted underline.)