The help system is largely based on the Info file format, which GNU Emacs uses for on-line documentation. If you are running Prolog under Emacs, type manual. at the main Prolog prompt to gain access to the on-line help system. Emacs should then locate the Quintus Prolog Info node. If it can't find that node, it will display the information in a special help buffer. See ref-olh-hfi for details.