If the story is updated, it goes out again with the same slug. We use this to cancel the old story before issuing the update, so only one version of the story exists on each computer at any given time. Most slugwords are one to three English words, separated by hyphens. Slugwords don't really have a particular pattern. Generally the most important part of a story will be included in the slugword, but not always.
Sidebars are small stories that are related to a larger story.
We assume a story is a sidebar if its slugword contains a previous slugword. Threaded newsreaders like trn and tin understand this linking. Sometimes more than one level will appear. We don't link sidebars to some very common slugwords. You can track a standing story by looking for its slug.