Each application that uses the Help System (including Helpview) has a helpOnHelpVolume resource that identifies a help volume to be accessed for help on help topics. For Helpview, this resource is set as follows:
DtHelpview*helpOnHelpVolume: Help4Help
If you provide your own help on help volume, be sure to give it a unique name so it doesn't conflict with another help on help volume that may be installed on the system.