RFC977 3.2.1.  GROUP

   GROUP ggg

   The required parameter ggg is the name of the newsgroup to be
   selected (e.g. "net.news").  A list of valid newsgroups may be
   obtained from the LIST command.

   The successful selection response will return the article numbers of
   the first and last articles in the group, and an estimate of the
   number of articles on file in the group.  It is not necessary that
   the estimate be correct, although that is helpful; it must only be
   equal to or larger than the actual number of articles on file.  (Some
   implementations will actually count the number of articles on file.
   Others will just subtract first article number from last to get an
   estimate.)

   When a valid group is selected by means of this command, the
   internally maintained "current article pointer" is set to the first
   article in the group.  If an invalid group is specified, the
   previously selected group and article remain selected.  If an empty
   newsgroup is selected, the "current article pointer" is in an
   indeterminate state and should not be used.

   Note that the name of the newsgroup is not case-dependent.  It must
   otherwise match a newsgroup obtained from the LIST command or an
   error will result.

3.2.2.  Responses

   211 n f l s group selected
           (n = estimated number of articles in group,
           f = first article number in the group,
           l = last article number in the group,
           s = name of the group.)
   411 no such news group