    #help_index "Topic/SubTopic;OtherTopic"
    The help index preprocessor compiler directive sets the topics for syms
    subsequently defined.  You specify subtopics with a '/' tree hierarchy and
    separate multiple topics with a ';'.  The index ctrls HI:index links.

    public causes a sym to appear in help_index reports.

    #help_file "filename[.DD.Z]"
    The help file preprocessor directive makes a file into the heading of a
    HI:index report for the current help index.