Tags and keywords
Before looking at the 
      addFunction function and how it is used to add a function to the HelpF` helpr registry, the next slides show some examples of the help registry in use. This slides shows helpFunction used to get detailed registered help about addFunction:For reference, an associated Policy Note (you don't need to visit this link yet):
      Notes
 [CONVENTION, NAMING, PATTERN, POLICY]{STRONG} Webel: Mathematica: CONVENTION: A 'type$' indicator for an '$opt$' or '$arg$' is for  documentation only. It may use a "pattern helper", a human-friendly String, or a SysML-similar short-hand type representation. It need not correspond to a valid Pattern.
    