> I do not know everything, and one of the things I don't know is what
> a super- or sublist is. Would anyone care to explain what they are
> and how they're useful? The response "It's in the manual" or "We
> discussed this here 18 months ago" will not do.
>
Please note that the LISTSERV maintainer must create the super-list.

In LISTSERV 1.8c it is possible to define a "super-list" (as in opposite
of sub-list), that is, a "container" list that includes all the
subscribers in a predefined set of sub-lists. This can be done recursively
to any depth. Only the LISTSERV maintainer can create a super-list, for
security reasons. Concretely, the "Sub-lists=" keyword is protected from
owner tampering in the same fashion as "Notebook=". The value is a comma
separated list of all the sub-lists, which must all be on the same (local)
machine. For instance:

* Sub-lists= MYLIST-L,MYOTHERLIST-L

The default value for this keyword is null, e.g., to have no sublists.
Please note that the super-list and all of its sublists must reside on the
same LISTSERV server.

The only difference between a normal list and a super-list is what happens
when you post to it. With the super-list, the membership of all the
sub-lists is added (recursively) and duplicates are suppressed. Other than
that, the super-list is a normal list with its own archives, access
control, etc. You can even subscribe to it, and this is actually an
important aspect of the operation of super-lists. If you are subscribed to
the super-list itself, the subscription options used to deliver
super-messages to you are taken from your subscription to the super-list,
just like with any other list. All combinations are allowed, and in
particular NOMAIL is allowed, meaning you don't want to get messages
posted to the super-list. When you are subscribed to multiple sub-lists,
on the other hand, things work differently:

1. NOMAIL subscriptions are ignored. You will get the super-message if you
have an active (not NOMAIL) subscription to at least one sub-list. The
idea is that the super-message must be equivalent to posting to all the
sub-lists, without the duplicates. Since all it takes to get a message
posted to all the sub-lists is a single non-NOMAIL subscription, this is
how the super-list works. The only way not to get the super-messages is to
subscribe to the super-list directly and set yourself to NOMAIL.

2. The DIGEST and INDEX options are ignored and internally converted to
MAIL. The first reason is that, since in most cases the user will be on
multiple sub-lists (otherwise you don't need a super-list in the first
place), the only safe method to set subscription options for
super-messages is by subscribing to the super-list so that there is no
ambiguity. The second reason is that, in most cases, super-lists will be
used for out of band administrative messages rather than for large volume
discussions, so it is actually preferable to have the message sent
directly. The third reason is that the super-list and sub-lists may not
necessarily offer the same options (DIGEST and INDEX). In particular it is
expected that many super-lists will not have archives. If you want a
DIGEST or INDEX for the super-messages, you must subscribe to the
super-list directly.

Topics, if defined, are evaluated on a per-list basis. That is, for every
sub-list (and for the super-list), LISTSERV determines whether the topic
of the message is one that you want to see. If not, it acts as if you were
not subscribed to this particular list. Roughly speaking, this works very
well if all the sub-lists have the same set of topics (or a well-defined
set of common topics), and doesn't work well at all if every list has its
own set of topics.