To create a search index, URLs in the JavaHelp map file (.jhm) must point to files in a subfolder of the folder where the helpset file is located; the default subfolder is help\html. See §10.2.7.1 .
The folder designated by HTMLSubdir (see §10.2.7.2 ) is the default setting for MapFilePrefix, with "/" added. Use a forward slash, not a backslash, at the end of the prefix; URLs require forward slashes.
MapFilePrefix fixes URLs in the map file, but does not actually move any of the referenced files; see §10.2.7.2 .
> 10 Generating JavaHelp or Oracle Help > 10.2 Setting up a JavaHelp or Oracle Help project > 10.2.7 Creating a folder structure for JavaHelp / Oracle Help > 10.2.7.5 Specifying a path for search-index links