An add-on that allows implements hierarchical categories, where categories can be nested within other categories. In other words, a category could have a category, and a discussion could be started at any level.
Okay, see, while I appreciate the article you linked, Wikipedia sums things up so nicely. Can I ask a more general question, then? I appreciate the idea of a heterarchy, and even acknowledge its supremacy (because the ability for something to have more than one parent is obviously necessary when the complexity passes a certain threshold). However, the reason I asked the question in the first place is because I didn't see a way for a category to be categorized.
Even in a heterarchy, where everything exists on one level, there have to be ways to define interdependence (which is kind of the whole point of a heterarchy, right?). When I looked in the Vanilla documentation, though, it didn't say anything about categories being able to be categorized/related, let alone have multiple categorizations/relations. Did I miss something?
I would also like to point out that the default implementation of Vanilla is not a heterarchy, but is actually a hierarchy with a depth of 1, which is a very different thing. The default implementation, with categories enabled, allows each discussion to be categorized, but only with one category, and does not permit categories to be categorized. Thus, each discussion falls under a category, and categories fall under nothing. So you have a flat level of unrelated categories and a flat level of unrelated discussions.
The idea of a heterarchy is that no process prevents any element from being linked to any other element. If you're truly wanting a heterarchy, then all discussions, and categories, should be able to have an unlimited number of connections between each other at any level. In that case, I could link two discussions together, or three categories, a category and a discussion, or a discussion and ten categories, ad infinatum.
Then we'd be talking about a wicked heterarchy in action.
Okay, well, fine! I now amend my original request to be for hierarchical categories or a directional heterarchy (I'm too lazy to find a definition for that, but think of a directional graph in which some edges can be bidirectional)
I lied, I'm not that lazy; a selective hierarchy comes closest to what I was aiming for, and would be an absolutely ideal way of working with categories.
i second the motion for this, I have been using invision powered boards since I found out about forums and just recently decided to check out Vanilla and what it has to offer and I have to say not having this add-on is probably why more people don't use Vanilla for their forum. It is a very nice feature for organizing categories and posts, someone please make this add-on. ^.^