Help index file created when multiple Compiled HTML Help (.CHM) files are merged together; stores the combined table of contents for the Help content and also includes references to each CHM file; must be rebuilt each time any of the referenced CHM files are updated or the table of contents will not be valid.

CHW files may be very large in size because they are not compressed. However, if you use a program such as KeyCHW or The Helpware Group's FAR, you can compress CHW files and decrease the file size substantially. The FAR software allows you to view the contents of a CHW file. Choose Authoring → Help File Explorer... from the application menu and then select your CHW file.