File format for virtual groups.

	A virtual group (vgr) is defined by a virtual group file (vgr
file).  A virtual group file begins with a "begin virtual" command,
and ends with one of the following:
	* An "end virtual" line.
	* A signature separator (two or more '-' characters at the
	  start of a line.
	* The end of the virtual group file.
...In the first two cases above the virtual group file may resume with
another "begin virtual" command.  All lines "outside" of a
"begin virtual"..."end virtual" [or other terminator] pair will be
ignored.  This means that USENET articles or mail messages may be used
directly as virtual newsgroup files.  Begin-end pairs may also be
concatenated to make larger virtual newsgroups.

	Virtual group files may contain empty/blank lines, and comment
lines starting with the # character, such as:

#Here is a comment

#The previous line was blank.

...Strn recognizes several commands, usually starting with a keyword
followed by more information.  Unrecognized commands will print an
error message, but strn will continue interpreting.  The recognized
commands are:

begin virtual
	Tells strn to start interpreting the following lines as
virtual newsgroup commands.

end virtual
	Tells strn to stop interrpreting lines as virtual newsgroup
commands.  (Interpretation can be resumed again with another
"begin virtual" command.)

group <groupname>
	Tells strn to interpret later message-ids or article numbers
as belonging to the newsgroup <groupname>.  When the group command is
interpreted strn will get the thread or overview file for the named
newsgroup.  (Strn keeps a cache of the last newsgroup's data, so the
following:
group rec.foo.bar
group rec.foo.bar
...would only get the thread/overview files once.)

["<Alternate Subject>"]+<message-id>
["<Alternate Subject>"]+nnnn
	Adds a <message-id> or the article number nnnn to the vgr
if the article meets other filtering criteria (score, read status).
The message-id or article number should be preceeded by a "group"
command which specifies the newsgroup to get the article from.
	If the "<Alternate Subject>" is present, it may be displayed
instead of the article's real subject.  (See the 'S' command in the
virtual scan mode documentation.)

#Examples:
"Nifty message about symmetric CPUs" +<bsdfgcg435@foo.bar.edu>
+<34621@ick.com>
"So many threads..." +<reigfgfdINNasds@hmmm.gov>
"Context Switching" +8732
+91248

+<groupname>
	Adds (to the vgr) all the articles in <groupname> which meet
the current filtering criteria.  The <groupname> may contain '*'
wildcards, in which case all matching newsgroups will be used.  More
than one newsgroup can be specified by separating the newsgroup
patterns with spaces and/or commas.

score min nnn
score min off
	Sets a minimum score filter for inclusion into the virtual
newsgroup.  If an article scores less than nnn points it will not be
included.  The command "score min off" turns off the minimum requirement.

score max nnn
score max off
	Sets a maximum score filter for inclusion into the virtual
newsgroup.  If an article scores more than nnn points it will not be
included.  The command "score max off" turns off the maximum requirement.

include <filename>
	Includes the contents of <filename> into the current virtual
newsgroup.  The <filename> may contain ~ and %-expansions.

filter unread
filter unread+read
	Sets filtering criteria for the virtual newsgroup.  If
"unread" is used, only unread articles will be added to the vgr.  If
"unread+read" is used, both unread and read articles may be added to
the vgr.  (One might want to use unread+read for a vgr of articles
which are already read, but that one might want to read again.)

display unread
display unread+read
	Sets criteria for *displaying* articles in the virtual
newsgroup.  If "unread" is used, then articles which have been read
will not be displayed.  (This status can be changed in the virtual
group scan with the 'U' command.)
	Note: when *entering* a virtual newsgroup, if all articles in
the vgr are read (see "filter"), the virtual scan mode will act as if
"display unread+read" was specified.

display author
display noauthor
	If "author" is selected, virtual scan mode will show the
author of each article.  The "display noauthor" command will turn off
the author display.  The 'a' command may be used to change this selection.

display group
display nogroup
	If "group" is selected, virtual scan mode will show the
newsgroup of each article.  The "display nogroup" command will turn off
the newsgroup display.  The 'G' command may be used to change this
selection.

