If you are working with a large HTML Help project, you can combine individual .CHM files and deliver them as a group. You do this by adding .CHM files into a single, master .CHM file.
The .CHM files that you add are secondary to the master project. You add them and then compile the master .CHM file so it knows to use them. The secondary .CHM files are not compiled into the master .CHM. Each file must be delivered separately. The master .CHM file is the one that you launch from a Windows application (or as standalone Help).
Users access information in the secondary .CHMs from the Index, Contents, and Search tabs in the HTML Help viewer. Links to topics in secondary .CHM files are accessed via external topic links and ALinks that you add to topics.
To combine index files, you add the secondary .CHM files to the master project and compile the project so it uses the Binary Index feature. This combines keywords in all .CHM files into one master index file. Users see them as an alphabetized list from the Index tab.
Full-text search is automatically included when you merge index files. However, each individual .CHM file must be compiled to include full-text search for this feature to work.
To combine contents files, you add external TOC files (.HHC) to the table of contents in the master project. Each external TOC is its own book. Users see them in the order that they are added to the table of contents.
Keywords, TOC books and pages, and HTML topics can all link to external topics in any of the .CHM files that are included in the master project.
If topics in any of the .CHM files use identical ALink names, all the topics that are assigned to the common ALink name are displayed when users click the ALink button. (This only applies to merged index files and not to external TOC files.)
When you work with merged HTML Help files, you need to distribute all the .CHM files and they need to be saved in the same folder.
If the source files for the secondary .CHM files are in their own folders (not in the master folder), the master folder includes a copy of the .CHM files whenever you add external tables of contents or add new .CHM files from the Project Settings dialog - Advanced tab. Your authoring system includes two sets of secondary .CHM files for each project. Whenever you compile the secondary project, be sure to copy the compiled .CHM file into the master project folder so it includes the latest copy. (Use the Windows Explorer.)
Make sure you distribute the most current versions of all compiled .CHM files.
WARNING! Merged HTML Help files are not supported with Microsoft HTML Help 1.0. Therefore, do not set the compatibility option to Version 1.0 (Project Settings dialog - Advanced tab).