The help pages can be distributed over different directory trees. This allows storing global help information in a global directory, while the user notes are stored in a local directory. New subtopics are created by creating a directory. New help pages can be added by creating a file with a .H extension in the help directory. Besides the main Help pages, additional help files can be created. They have the same name, but a different extension.
Hints have the extension .I, and notes have the extension .N. Special help information consists of a Tcl script ending with a .S. Special help files allow calling external programs, like ghostscript. To display a postscript file, the Tcl command DisplayPostscript is called. This is a built-in that checks if there exists an environment variable named XF_HELP_PS_CMD. If this variable exists, this is the command that is executed, with the file name as parameter. Otherwise, ghostscript is started. The variable ``runPath'' contains the absolute path name of the help page, and should precede the filename that is passed on to the command.
Help pages can start with two special information lines. One line can begin with ``###Title ''. This is the title for this help page. The second line can begin with ``###Keywords ''. This is a list of keywords attached to this help page. The following text is the help text that is displayed in the help area.