In an email exchange with Naz of Absenter.org, I got to thinking about some of the limitations of the categories feature (Subtraction.com refers to them as ‘tags’) in Movable Type. While powerful, this feature doesn’t allow me to do one thing that would be very handy for me: I’d like to be able to string together a few arbitrarily chosen posts in a kind of ’series’ — almost like a regular category, but more limited in purpose.

Standard Organization by Category

Figure 1, below, demonstrates in a very simplistic manner the way categories work in Movable Type. Basically, given the example of a blog with nine posts, each post is assigned one of four categories: orange, yellow, blue or green.

Blogs are generally ordered by chronology first, but when they are viewed according to subject matter, the organization of a blog is pretty much what you see in Figure 2: each can be accessed along with the other posts with which it shares the same category attribute. Simple enough.

The Sub-Category

However, let’s say that I write a series of posts, two of which are categorized as yellow, one as orange and one as blue — but those posts all share a less prominent yet still significant attribute that doesn’t fit into the categorical schema already in place — in this diagram, that ‘lesser attribute’ is represented by a hollow red box.

How would I organize these posts so that they maintain some sort of relationship? Well, there’s the possibility of assigning them each a secondary category attribute, called say ‘red-outline.’ Movable Type already supports this, but the problem with using this approach is that the secondary category is more or less a peer with the primary category — MT makes a distinction between them, but it’s not a substantial one for this argument. Let’s also say that the fact that these posts share this attribute is an anomaly of sorts, and that I don’t expect any future posts to ever share this red-outline attribute again. What I need is some way to group them together without impacting the main category schema, as shown in Figure 3.

Sub-Categories in Practice

This is perhaps getting a bit abstract, so let me try and give it a slightly more real-world grounding. Say that I have written four posts:

• One about a restaurant I went to on 24 May and filed under the category ‘food’
• One about a bar that I went to on 25 May and also filed under the category ‘food’
• One about a movie that I saw on 25 May and filed under the category ‘movies’
• One about a baseball game I went to on 26 May and filed under the category ’sports’

Each of these posts would appear under their respective categories, of course. But I would also like to see them appear under a limited-purpose sub-category called “Memorial Day Weekend 2003.” I don’t want this sub-category to be listed alongside food, movies and sports, because it just wouldn’t make any sense. And I would probably also like this sub-category to have its own template, so that it can be distinguished from regular category pages.

This feature could be really useful for creating showcases of posts. Here’s one example where I could have used this sub-categories feature; it’s essentially one post that points to six others. Sub-categories could also be used as a way of creating ‘features’ on a blog, much the way that magazines will group two, three or more articles together — perhaps an essay, an interview and a sidebar — to create a cover story.

Granted, this concept begins to push the boundaries of ‘personal publishing,’ the primary purpose of Movable Type, and starts to edge into the realm of a more industrial-strength content management system. A large portion of bloggers don’t even find categories to be useful, or at least they don’t make use for them. But I can see this feature being fairly easily incorporated into the Movable Type infrastructure, and of course it can be easily ignored by those who have no use for it. Maybe we’ll see something like it in the upcoming Movable Type Pro.