Gnus threads articles by default. To thread is to put responses
to articles directly after the articles they respond to—in a
Threading is done by looking at the
References headers of the
articles. In a perfect world, this would be enough to build pretty
trees, but unfortunately, the
References header is often broken
or simply missing. Weird news propagation exacerbates the problem,
so one has to employ other heuristics to get pleasing results. A
plethora of approaches exists, as detailed in horrible detail in
First, a quick overview of the concepts:
- The top-most article in a thread; the first article in the thread.
- A tree-like article structure.
- A small(er) section of this tree-like structure.
- loose threads
- Threads often lose their roots due to article expiry, or due to the root
already having been read in a previous session, and not displayed in the
summary buffer. We then typically have many sub-threads that really
belong to one thread, but are without connecting roots. These are
called loose threads.
- thread gathering
- An attempt to gather loose threads into bigger threads.
- sparse threads
- A thread where the missing articles have been “guessed” at, and are
displayed as empty lines in the summary buffer.