A Windows-based FOSS solution
Windows-based shareware for creating .chm files, such as Angel Writer and GridinSoft Notepad, is relatively common, but beyond the scope of this article. The only FOSS .chm generator that is anywhere near ready for prime time is HelpMaker.
Unlike AurigaDoc or DocBook, HelpMaker offers the graphical interface that Windows users expect. If the editing window looks crude compared to RoboHelps, it is at least familiar to its target audience. More to the point, HelpMaker includes functions such as a search and replace function for Unicode -- which HTML Help doesn't support -- and dialogs for assigning Topic IDs and keywords to additional pages. Like RoboHelp, it also manages files destined for the same .chm file in a project tree view.
Its only eccentricity is its definition of styles. These are not the styles you would expect in a word processor-like program like HelpMaker, but font characteristics such as the weight, alignment, and position. Even more strangely, these characteristics are placed, apparently randomly, into two sub-menus labeled Styles 1 and Styles 2.
The one drawback to HelpMaker is that its exact status is unclear. The project's SourceForge page lists its license as the GPL. However, the online help for the software lists the product as freeware. The help also contains a section entitled Why Not Open Source that suggests that the product was withdrawn because of lack of community support and negative comments. Yet above that section is an unofficial license that reads like an informal version of the GPL. To deepen the mystery, the SourceForge page does not contain source code, and, while the product's home page contains a link to a more recent build, a link on the page to a newsgroup no longer works. Nothing else is on the home page, nor do the developers listed on SourceForge respond to email.
This uncertainty makes HelpMaker as unsatisfactory a solution as AurigaDoc or DocBook. In theory, if it were ever released under the GPL, its code would be available for other developers, but locating it might be a challenge.