The difficulty is in coercing the users into putting the right labels on
their messages before sending them. Most users just aren't used to it,
and if someone forgets to label a message, most of the replies (made by
pressing the REPLY button) will also have the wrong topic. Anyway, here
is some info from the 1.7f release notes.
Eric
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* Usability: Support for list topics *
**************************************
List topics provide a way to run a mailing list (preferrably moderated)
where several sub-topics are being discussed in parallel but some
subscribers are only interested in a subset of the topics. For instance,
a working group might have general discussions, decisions, and messages
related to meetings. People who cannot attend the meetings can then opt
out of last calls for hotel reservations and discussions about seafood
restaurants, whereas people who have no time to follow the discussions
can elect to get just the decisions. At any rate, such a compartmented
list requires a certain discipline in order to be successful, as the
posters must label their messages to indicate which topic(s) they belong
to.
Through the "Topics=" keyword, the list owner can define up to 11 topics
for the list. For instance, the list owner could code:
Topics= News,Benchmarks,Meetings,Beta-tests
********************************************************
* WARNING - YOU MUST NEVER REORDER THE TOPICS= KEYWORD *
********************************************************
To save disk space, LISTSERV remembers which topics users have selected
through their ordering in the "Topics=" keyword. That is, "News" is
"topic number 1" for LISTSERV, "Benchmarks" is "topic number 2", and so
on. This means you can change the name of a topic without requiring users
to alter their subscriptions (for instance, you could decide that "Tests"
is a better name than "Beta-tests" and just make the change). However,
you must never change the order of the topics in the "Topics=" keyword.
If you want to remove a topic, replace it with a comma. For instance, to
remove the "Meetings" topic, you would change the keyword to:
Topics= News,Benchmarks,,Beta-tests
This restriction might be removed in a future release.
Topic names can contain any character except space, colon and comma; the
use of double quotes or equal signs is discouraged, as they require
special attention when coding list header keywords. In addition, topic
names may not start with a plus or minus sign, and the words ALL, NONE,
RE, OTHER and OTHERS are reserved.
Posters label their messages through the subject field. LISTSERV first
skips any possible sequence of 'Re:' keywords, and takes anything to the
left of a colon as a list of topics, separated by commas. The posting is
considered to belong to all the topics listed before the colon. If none
of these topics is valid for the list, it is classified in a special,
12th topic, "Other". If some of the topics are valid but others are
undefined, the invalid ones are ignored. At any rate the subject field is
left unchanged. Here is an example:
Subject: Benchmarks,News: Benchmarks for XYZ now available!
Messages which should be read by everyone can be posted to the special
topic "All". Topic names can be shortened to any unambiguous
abbreviation. In our example, "Be" is ambiguous because it could be
either "Beta-tests" or "Benchmarks", but "Bench" is acceptable.
Subscribers select the topics they wish to receive with the SET command.
The syntax is 'SET listname TOPICS: xxx' where 'xxx' can be:
- A list of all the topics the user wishes to receive. In that case these
topics replace any other topics the user may have subscribed to before.
For instance, after 'SET XYZ-L TOPICS: NEWS BENCH', the user will
receive news and benchmarks, and nothing else.
- Updates to the list of topics the user currently receives. A plus sign
indicates a topic that should be added, a minus sign requests the
removal of a topic. For instance, 'SET XYZ-L TOPICS: +NEWS -BENCH' adds
news and removes benchmarks. If a topic name is given without a + or -
sign, + is assumed: 'SET XYZ-L TOPICS: +NEWS BENCH' adds news and
benchmarks. The first topic name must have the plus sign to show that
this is an addition, and not a replacement.
- A combination of the above, mostly useful to enable all but a few
topics: 'SET XYZ-L TOPICS: ALL -MEETINGS'.
The colon after the keyword TOPICS: is optional, and TOPICS= is also
accepted. Do not forget to include the special OTHER topic if you want to
receive general discussions which were not labelled properly. On the
other hand, if you only want to receive properly labelled messages you
should not include it. ALL does include OTHER.
A "Default-Topics=" list header keyword is available to define the
initial topics for new subscribers. The syntax is the same as for the SET
command, except that topic names are separated by commas in the usual
fashion and that the first topic may not start with a + or - sign (there
is nothing to add to, as this is a new subscription). This is similar to
"Default-Options=" in that it does not affect existing subscribers. Users
who signed up before topics were enabled on the list are automatically
subscribed to all topics.
Finally, it is important to note that topics are active only when your
subscription is set to MAIL. Digests are indexes always contain all the
postings that were made, because the same digest is prepared and sent to
all the subscribers. Depending on the success of topics support, this
restriction might be lifted in a future release.
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