> I don't know what file it's documented in yet, since I haven't had time
> to carefully review the new release...  The following options (as used
> on the "SET LISTNAME option" command) are mutually exclusive.
 
>   MAIL, NOMAIL, DIGEST, INDEX
 
I've searched the LSTOWN-L, a form of documentation ;-), abstracted
relevent Digest/Index discussion, and had previously posted it to
the help-net list which I reproduce here.  Note that these features
work at current maintenance levels of 1.7e
 
Organization: Penn State University
Date: Thu, 25 Feb 1993 16:27:58 EST
From: Peter M. Weiss <[log in to unmask]>
Message-ID: <[log in to unmask]>
Newsgroups: bit.listserv.help-net
Subject: Re: What's a Digest?
References: <[log in to unmask]>
 <[log in to unmask]>
 
In article <[log in to unmask]>, Peter M. Weiss <[log in to unmask]>
quotes himself --
 
>Also, the list-owner must have previously enabled that option
>for the particular list; it also implies that notebook archives
>exist.  The frequency of distributions can be based upon accumulated
>volume and/or some period of time, daily, weekly, monthly(?).
 
My previous communication is inoperative (;-) ). I fetched and
abstracted the original announcements from Eric Thomas (Revised
LISTSERV author/developer) on the DIGEST and INDEX features.  Note well
that these features have only been implemented on certain maintenance
levels of LISTSERV (the one at TEMPLEVM isn't one of them :-( )
 
     The list owner controls the availability and frequency of digests
     through the new "Digest=" list header keyword, which defaults to
     "Digest= No" for lists without an archive and "Digest=
     Yes,Same,Daily" for archived lists.  It is not necessary for the
     list to be archived to keep a digest, LISTSERV simply attempts to
     enable digests (by default) for as many lists as possible, but
     without ending up having to store large amounts of digest data on
     its A-disk.  Because the default frequency is daily, the
     additional cost in disk space is very low (but might still not
     have fit on the A-disk once multiplied by 100 lists).
 
     (...)
 
     Indexes are automatically available if the list offers digests
     AND the postings are archived.  An index is sent to users who
     have requested this type of subscription (via SET listname INDEX,
     an alternative to MAIL and DIGEST) whenever a digest is issued.
     Thus, there is no need for an "Index=" option - indexes are an
     integral part of the digest system.
 
My personal interpretation is that (for a LISTSERV site supporting it),
DIGEST is automatically enabled by DEFAULT for archived lists (unless
explicitly excluded by the owner), and not available at all for
un-archived lists.  INDEX is NOT available for un-archived list (since
it depends upon the archives for subsequent retrieval), nor is it
available if the owner has explicitly excluded DIGEST.
 
Disclaimer: I only just beginning to use these features.  - news @ 11
 
/Pete ([log in to unmask])
--
Peter M. Weiss                     | oas.psu.edu postmaster
31 Shields Bldg -- Penn State Univ.| "Connectivity is more than a Connection"
University Park, PA USA 16802-1202 | E. Michael Staman, _The Circuit_, Apr 92