nil, Gnus will attempt to build old threads by fetching more old headers—headers to articles marked as read. If you would like to display as few summary lines as possible, but still connect as many loose threads as possible, you should set this variable to
someor a number. If you set it to a number, no more than that number of extra old headers will be fetched. In either case, fetching old headers only works if the back end you are using carries overview files—this would normally be
nnmaildir. Also remember that if the root of the thread has been expired by the server, there's not much Gnus can do about that.
This variable can also be set to
invisible. This won't have any
visible effects, but is useful if you use the A T command a lot
(see Finding the Parent).
The server has to support NOV for any of this to work.
This feature can seriously impact performance it ignores all locally
cached header entries. Setting it to
t for groups for a server
that doesn't expire articles (such as news.gmane.org), leads to very
slow summary generation.
gnus-fetch-old-headers, but only used for ephemeral newsgroups.
some. Gnus will then look at the complete
Referencesheaders of all articles and try to string together articles that belong in the same thread. This will leave gaps in the threading display where Gnus guesses that an article is missing from the thread. (These gaps appear like normal summary lines. If you select a gap, Gnus will try to fetch the article in question.) If this variable is
t, Gnus will display all these “gaps” without regard for whether they are useful for completing the thread or not. Finally, if this variable is
more, Gnus won't cut off sparse leaf nodes that don't lead anywhere. This variable is
If you don't use those, then it's safe to leave this as the default
nil. If you want to use this variable, it should be a regexp
that matches the group name, or
t for all groups.