gnus: Topic Topology

 
 2.16.4 Topic Topology
 ---------------------
 
 So, let’s have a look at an example group buffer:
 
      Gnus
        Emacs -- I wuw it!
           3: comp.emacs
           2: alt.religion.emacs
          Naughty Emacs
           452: alt.sex.emacs
             0: comp.talk.emacs.recovery
        Misc
           8: comp.binaries.fractals
          13: comp.sources.unix
 
    So, here we have one top-level topic (‘Gnus’), two topics under that,
 and one sub-topic under one of the sub-topics.  (There is always just
 one (1) top-level topic).  This topology can be expressed as follows:
 
      (("Gnus" visible)
       (("Emacs -- I wuw it!" visible)
        (("Naughty Emacs" visible)))
       (("Misc" visible)))
 
    This is in fact how the variable ‘gnus-topic-topology’ would look for
 the display above.  That variable is saved in the ‘.newsrc.eld’ file,
 and shouldn’t be messed with manually—unless you really want to.  Since
 this variable is read from the ‘.newsrc.eld’ file, setting it in any
 other startup files will have no effect.
 
    This topology shows what topics are sub-topics of what topics
 (right), and which topics are visible.  Two settings are currently
 allowed—‘visible’ and ‘invisible’.