After decoding, if the file is some sort of archive, Gnus will attempt to unpack the archive and see if any of the files in the archive can be viewed. For instance, if you have a gzipped tar file pics.tar.gz containing the files pic1.jpg and pic2.gif, Gnus will uncompress and de-tar the main file, and then view the two pictures. This unpacking process is recursive, so if the archive contains archives of archives, it'll all be unpacked.
Finally, Gnus will normally insert a pseudo-article for each extracted file into the summary buffer. If you go to these “articles”, you will be prompted for a command to run (usually Gnus will make a suggestion), and then the command will be run.
nil, Emacs will wait
until the viewing is done before proceeding.
automatic, Gnus will not insert
the pseudo-articles into the summary buffer, but view them
immediately. If this variable is
not-confirm, the user won't even
be asked for a confirmation before viewing is done.
gnus-view-pseudos-separately is non-
pseudo-article will be created for each file to be viewed. If
nil, all files that use the same viewing command will be given as
a list of parameters to that command.
gnus-insert-pseudo-articles is non-
pseudo-articles when decoding. It is
t by default.
So; there you are, reading your pseudo-articles in your virtual newsgroup from the virtual server; and you think: Why isn't anything real anymore? How did we get here?