gnus: Terminology
11.4 Terminology
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“news”
This is what you are supposed to use this thing for—reading news.
News is generally fetched from a nearby NNTP server, and is
generally publicly available to everybody. If you post news, the
entire world is likely to read just what you have written, and
they’ll all snigger mischievously. Behind your back.
“mail”
Everything that’s delivered to you personally is mail. Some
news/mail readers (like Gnus) blur the distinction between mail and
news, but there is a difference. Mail is private. News is public.
Mailing is not posting, and replying is not following up.
“reply”
Send a mail to the person who has written what you are reading.
“follow up”
Post an article to the current newsgroup responding to the article
you are reading.
“back end”
Gnus considers mail and news to be mostly the same, really. The
only difference is how to access the actual articles. News
articles are commonly fetched via the protocol NNTP, whereas mail
messages could be read from a file on the local disk. The internal
architecture of Gnus thus comprises a “front end” and a number of
“back ends”. Internally, when you enter a group (by hitting <RET>,
say), you thereby invoke a function in the front end in Gnus. The
front end then “talks” to a back end and says things like “Give me
the list of articles in the foo group” or “Show me article number
4711”.
So a back end mainly defines either a protocol (the ‘nntp’ back end
accesses news via NNTP, the ‘nnimap’ back end accesses mail via
IMAP) or a file format and directory layout (the ‘nnspool’ back end
accesses news via the common “spool directory” format, the ‘nnml’
back end access mail via a file format and directory layout that’s
quite similar).
Gnus does not handle the underlying media, so to speak—this is all
done by the back ends. A back end is a collection of functions to
access the articles.
However, sometimes the term “back end” is also used where “server”
would have been more appropriate. And then there is the term
“select method” which can mean either. The Gnus terminology can be
quite confusing.
“native”
Gnus will always use one method (and back end) as the “native”, or
default, way of getting news. Groups from the native select method
have names like ‘gnu.emacs.gnus’.
“foreign”
You can also have any number of foreign groups active at the same
time. These are groups that use non-native non-secondary back ends
for getting news. Foreign groups have names like
‘nntp+news.gmane.org:gmane.emacs.gnus.devel’.
“secondary”
Secondary back ends are somewhere half-way between being native and
being foreign, but they mostly act like they are native, but they,
too have names like ‘nntp+news.gmane.org:gmane.emacs.gnus.devel’.
“article”
A message that has been posted as news.
“mail message”
A message that has been mailed.
“message”
A mail message or news article
“head”
The top part of a message, where administrative information (etc.)
is put.
“body”
The rest of an article. Everything not in the head is in the body.
“header”
A line from the head of an article.
“headers”
A collection of such lines, or a collection of heads. Or even a
collection of NOV lines.
“NOV”
NOV stands for News OverView, which is a type of news server header
which provide datas containing the condensed header information of
articles. They are produced by the server itself; in the ‘nntp’
back end Gnus uses the ones that the NNTP server makes, but Gnus
makes them by itself for some backends (in particular, ‘nnml’).
When Gnus enters a group, it asks the back end for the headers of
all unread articles in the group. Most servers support the News
OverView format, which is more compact and much faster to read and
parse than the normal HEAD format.
The NOV data consist of one or more text lines (
Motion by
Text Lines (elisp)Text Lines.) where each line has the header
information of one article. The header information is a
tab-separated series of the header’s contents including an article
number, a subject, an author, a date, a message-id, references,
etc.
Those data enable Gnus to generate summary lines quickly. However,
if the server does not support NOV or you disable it purposely or
for some reason, Gnus will try to generate the header information
by parsing each article’s headers one by one. It will take time.
Therefore, it is not usually a good idea to set nn*-nov-is-evil
(Slow/Expensive Connection) to a non-‘nil’ value unless you
know that the server makes wrong NOV data.
“level”
Each group is subscribed at some “level” or other (1–9). The ones
that have a lower level are “more” subscribed than the groups with
a higher level. In fact, groups on levels 1–5 are considered
“subscribed”; 6–7 are “unsubscribed”; 8 are “zombies”; and 9 are
“killed”. Commands for listing groups and scanning for new
articles will all use the numeric prefix as “working level”.
“killed groups”
No information on killed groups is stored or updated, which makes
killed groups much easier to handle than subscribed groups.
“zombie groups”
Just like killed groups, only slightly less dead.
“active file”
The news server has to keep track of what articles it carries, and
what groups exist. All this information in stored in the active
file, which is rather large, as you might surmise.
“bogus groups”
A group that exists in the ‘.newsrc’ file, but isn’t known to the
server (i.e., it isn’t in the active file), is a _bogus group_.
This means that the group probably doesn’t exist (any more).
“activating”
The act of asking the server for info on a group and computing the
number of unread articles is called “activating the group”.
Un-activated groups are listed with ‘*’ in the group buffer.
“spool”
News servers store their articles locally in one fashion or other.
One old-fashioned storage method is to have just one file per
article. That’s called a “traditional spool”.
“server”
A machine one can connect to and get news (or mail) from.
“select method”
A structure that specifies the back end, the server and the virtual
server settings.
“virtual server”
A named select method. Since a select method defines all there is
to know about connecting to a (physical) server, taking the thing
as a whole is a virtual server.
“washing”
Taking a buffer and running it through a filter of some sort. The
result will (more often than not) be cleaner and more pleasing than
the original.
“ephemeral groups”
Most groups store data on what articles you have read. “Ephemeral”
groups are groups that will have no data stored—when you exit the
group, it’ll disappear into the aether.
“solid groups”
This is the opposite of ephemeral groups. All groups listed in the
group buffer are solid groups.
“sparse articles”
These are article placeholders shown in the summary buffer when
‘gnus-build-sparse-threads’ has been switched on.
“threading”
To put responses to articles directly after the articles they
respond to—in a hierarchical fashion.
“root”
The first article in a thread is the root. It is the ancestor of
all articles in the thread.
“parent”
An article that has responses.
“child”
An article that responds to a different article—its parent.
“digest”
A collection of messages in one file. The most common digest
format is specified by RFC 1153.
“splitting”
The action of sorting your emails according to certain rules.
Sometimes incorrectly called mail filtering.
Info Catalog
gnus: On Writing Manuals
gnus: Appendices
gnus: Customization