Expressing the need for background knowledge
Any technical discussion, whether about programming languages, medieval history, fine wines, politics, or whatever, requires some level of background knowledge. A general discussion of Java (the programming language), for example, would require some knowledge of object-oriented programming/design and some knowledge of C syntax. In most settings, it can be simply assumed that the readers/participants have appropriate background. This is true of textbooks and courses in particular.
On the web, however, one can wander pretty far from one's area of expertise (in a series of logical clicked links, of course). It would be helpful if there were a good way of telling potential readers/participants what they need to understand to get anything out of the page or site at which they have arrived. It's possible to have a few preface sentences, but most people's eyes will skip right over it and the core readers/participants will probably find it annoying. There must be a better way.
Let's phrase the issue clearly: How do we inform readers on the web of the topics and depth of background knowledge that are assumed by a particular page or site? The important components are topics and depth. My humble proposal is that we choose Wikipedia topics and express the required depth of knowledge as link depth.
Consider an example article about a supernova. To understand this article, one must have a good grasp of astronomy in general, maybe a little astrophysics, and understanding of stellar evolution, and some knowledge of supernovae in general. To express this required background, we place the following line at the beginning of our article (much like a Technorati tag):
Required background: Astronomy:2
This indicates that the reader should be familiar with the material within two clicks from the Astronomy page on Wikipedia. Arguably, since the stellar evolution page links to both Astronomy and Supernova, we could use "Stellar evolution:1" but as a matter of taste we might decide that since the article is primarily about a particular supernova, we'd prefer "Supernova:2" to get essentially the same coverage.
After all, putting articles and discussions on the web is not (in general) intended to scare off other people, but to draw them in. Regardless of which topic(s) are used in a required background tag, it is effective as long as the reader/participant can learn enough from the entries within the stated depth to get something out of reading or contribute something by participating. I will be using this convention in this blog's posts.
Of course, there is nothing special about Wikipedia. It's a well-linked knowledge base with good (not perfect) coverage of human knowledge, but any link could be used. Indeed, a sufficiently specific term or set of terms could be linked to a Google search for them just as effectively (e.g. Stellar evolution:1).