All groups in a topic will inherit group parameters from the parent (and ancestor) topic parameters. All valid group parameters are valid topic parameters (see Group Parameters). When the agent is enabled, all agent parameters (See Agent Parameters in Category Syntax) are also valid topic parameters.
In addition, the following parameters are only valid as topic parameters:
subscribe
When subscribing new groups by topic (see Subscription Methods), the
subscribe
topic parameter says what groups go in what topic. Its
value should be a regexp to match the groups that should go in that
topic.
subscribe-level
When subscribing new groups by topic (see the subscribe
parameter),
the group will be subscribed with the level specified in the
subscribe-level
instead of gnus-level-default-subscribed
.
Group parameters (of course) override topic parameters, and topic parameters in sub-topics override topic parameters in super-topics. You know. Normal inheritance rules. (Rules is here a noun, not a verb, although you may feel free to disagree with me here.)
Gnus Emacs 3: comp.emacs 2: alt.religion.emacs 452: alt.sex.emacs Relief 452: alt.sex.emacs 0: comp.talk.emacs.recovery Misc 8: comp.binaries.fractals 13: comp.sources.unix 452: alt.sex.emacs
The ‘Emacs’ topic has the topic parameter (score-file
. "emacs.SCORE")
; the ‘Relief’ topic has the topic parameter
(score-file . "relief.SCORE")
; and the ‘Misc’ topic has the
topic parameter (score-file . "emacs.SCORE")
. In addition,
‘alt.religion.emacs’ has the group parameter (score-file
. "religion.SCORE")
.
Now, when you enter ‘alt.sex.emacs’ in the ‘Relief’ topic, you will get the relief.SCORE home score file. If you enter the same group in the ‘Emacs’ topic, you’ll get the emacs.SCORE home score file. If you enter the group ‘alt.religion.emacs’, you’ll get the religion.SCORE home score file.
This seems rather simple and self-evident, doesn’t it? Well, yes. But
there are some problems, especially with the total-expiry
parameter. Say you have a mail group in two topics; one with
total-expiry
and one without. What happens when you do M-x
gnus-expire-all-expirable-groups? Gnus has no way of telling which one
of these topics you mean to expire articles from, so anything may
happen. In fact, I hereby declare that it is undefined what
happens. You just have to be careful if you do stuff like that.