When defining the metadata structure for Nleyten stories, the crucial principle I always kept in mind was that attributes should be a) orthogonal, b) minimal, and c) relevant for search purposes. I have already discussed the categorisation into sections in a previous post. Now the focus will be on the topics attribute.

So, what is the topic of a story? Well, as implied by its name, this attribute aims to classify a story on the basis of its theme or subject. In Web 2.0 parlance, the term tags is for the most part equivalent to Nleyten topics. So why not call them tags? Well, in people's minds, tags have gained an association with crowd provided metadata and folksonomies. I am still investigating how this sort of arrangement could be applied to Nleyten, though what I have in mind is a bit too fancy and will only make sense to introduce it later. For now, Nleyten will rely on topics. These will still be provided by the user in the sense that the author of story will be responsible for providing them. However, the set of available topics will be a fairly fixed structure defined by the administrators of the site, rather than a crowd created folksonomy. This is the critical difference between tags and topics.

There's a few tricky things about topics. One of them is their inherent hierarchical nature. Consider for example the topic Biology; it is a subtopic of Science, of course. Another one is that often a story cannot be placed unambiguously in a single topic, since it touches on more than one subject, or its topic is an intersection of multiple subjects. The solution to the first problem is obviously to define an hierarchical structure for the expected topics in Nleyten stories. The solution to the second problem is to allow authors to specify multiple topics for the same story.

The top-level topics I have in mind are listed below. As for the subtopics, the list is much larger, and will obviously grow in time.

• Atheism & Scepticism
• Philosophy & Ethics
• Science & Technology
• History
• Arts & Literature
• Politics & Current Affairs
• Economy
• Society & Culture
• Energy & Environment
• Hobbyism
• Health & Medicine
• Meta (About Nleyten)