s-o-1036 June 1994

7.6. checkgroups

The   checkgroups  control  message  contains  a  supposedly
authoritative list of the valid newsgroups within some  sub-
set of the newsgroup name space:

     checkgroups-arguments  =
     checkgroups-body       = [ invalidation ] valid-groups
                            / invalidation
     invalidation           = "!" plain-component *( "," plain-component ) eol
     valid-groups           = 1*( description-line eol )

There are no arguments.  The body lines (except possibly for
an initial invalidation) each contain a description line for

INTERNET DRAFT to be        NEWS                    sec. 7.6


a  newsgroup, as defined under the newgroup message (section
7.3).

     NOTE: Some other, ill-defined, forms of the check-
     groups body were formerly used.  See appendix A.

The  checkgroups message applies to all hierarchies contain-
ing any of the newsgroups listed in the  body.   The  check-
groups  message asserts that the newsgroups it lists are the
only newsgroups in those hierarchies.  If there is an inval-
idation,  it asserts that the hierarchies it names no longer
contain any newsgroups.

Processing a checkgroups message MAY cause a local  list  of
newsgroup  descriptions to be updated.  It SHOULD also cause
the local lists of newsgroups  (and  their  moderation  sta-
tuses)  in  the  mentioned hierarchies to be checked against
the message.  The results of the check MAY be used for auto-
matic  corrective  action,  or  MAY  be reported to the news
administrator in some way.

     NOTE:  Automatically  updating   descriptions   of
     existing  newsgroups  is  relatively safe.  In the
     case of newsgroup additions or  deletions,  simply
     notifying  the administrator is generally the wis-
     est action, unless  perhaps  the  message  can  be
     determined to have originated within a cooperating
     subnet whose members are considered trustworthy.

     NOTE: There is a problem with the checkgroups con-
     cept:  not all newsgroups in a hierarchy necessar-
     ily  propagate  to  the  same  set  of   machines.
     (Notably,  there  is  a set of newsgroups known as
     the "inet" newsgroups, which have relatively  lim-
     ited  distribution  but coexist in several hierar-
     chies with  more  widely-distributed  newsgroups.)
     The  advice  of checkgroups should always be taken
     with a grain of salt, and should never be followed
     blindly.

--- ../rfc1036/Checkgroups.out          December 1987
+++ ../s-o-1036/Checkgroups.out          June 1994
@@ -1,8 +1,58 @@
-3.7.  Checkgroups
-    The message body is a list of "official" newsgroups and their
-    description, one group per line.  They are compared against the list
-    of active newsgroups on the current host.  The names of any obsolete
-    or new newsgroups are mailed to the user "usenet" and descriptions
-    of the new newsgroups are added to the help file used when posting
-    news.
+7.6. checkgroups
+
+The   checkgroups  control  message  contains  a  supposedly
+authoritative list of the valid newsgroups within some  sub-
+set of the newsgroup name space:
+
+     checkgroups-arguments  =
+     checkgroups-body       = [ invalidation ] valid-groups
+                            / invalidation
+     invalidation           = "!" plain-component *( "," plain-component ) eol
+     valid-groups           = 1*( description-line eol )
+
+There are no arguments.  The body lines (except possibly for
+an initial invalidation) each contain a description line for
+
+INTERNET DRAFT to be        NEWS                    sec. 7.6
+
+
+a  newsgroup, as defined under the newgroup message (section
+7.3).
+
+     NOTE: Some other, ill-defined, forms of the check-
+     groups body were formerly used.  See appendix A.
+
+The  checkgroups message applies to all hierarchies contain-
+ing any of the newsgroups listed in the  body.   The  check-
+groups  message asserts that the newsgroups it lists are the
+only newsgroups in those hierarchies.  If there is an inval-
+idation,  it asserts that the hierarchies it names no longer
+contain any newsgroups.
+
+Processing a checkgroups message MAY cause a local  list  of
+newsgroup  descriptions to be updated.  It SHOULD also cause
+the local lists of newsgroups  (and  their  moderation  sta-
+tuses)  in  the  mentioned hierarchies to be checked against
+the message.  The results of the check MAY be used for auto-
+matic  corrective  action,  or  MAY  be reported to the news
+administrator in some way.
+
+     NOTE:  Automatically  updating   descriptions   of
+     existing  newsgroups  is  relatively safe.  In the
+     case of newsgroup additions or  deletions,  simply
+     notifying  the administrator is generally the wis-
+     est action, unless  perhaps  the  message  can  be
+     determined to have originated within a cooperating
+     subnet whose members are considered trustworthy.
+
+     NOTE: There is a problem with the checkgroups con-
+     cept:  not all newsgroups in a hierarchy necessar-
+     ily  propagate  to  the  same  set  of   machines.
+     (Notably,  there  is  a set of newsgroups known as
+     the "inet" newsgroups, which have relatively  lim-
+     ited  distribution  but coexist in several hierar-
+     chies with  more  widely-distributed  newsgroups.)
+     The  advice  of checkgroups should always be taken
+     with a grain of salt, and should never be followed
+     blindly.