The help module provides support to create both on-line and off-line documentation on Prolog programs. Documentation must be defined by the hook predicate help_info/4. Documentation on a per module basis is provided if a help_info(module,Module,TitleString,DescriptionString) definition is given for Module. In that case the system also checks for Module:help_info/4 definitions.
The module supports production of the help information on standard output, (which can be converted into html format), and there also is an interface to a graphical user interface based on library(tcltk).