“I don’t know where I am!”





Time traveler Clara Oswald becomes disoriented once again, in a scary encounter with a taxonomy displayed in flat format.

Taxonomies can be displayed in a variety of ways. One of the display types that we occasionally see is known as the flat format display. It’s described in the main U.S. standard for controlled vocabularies, ANSI/NISO Z39.19 (Guidelines for the Construction, Format, and Management of Monolingual Controlled Vocabularies, published by the National Information Standards Organization) as follows:

“The flat format is the most commonly used controlled vocabulary display format. It consists of all the terms arranged in alphabetical order, including their term details, and one level of BT/NT hierarchy.”

At the top level, this format might (or might not) look like that of other hierarchical vocabularies when they are collapsed. What happens, though, when you start navigating to deeper levels? Let’s take a look at the ERIC Thesaurus published by the U.S. Department of Education’s Institute of Education Sciences. Here’s the initial view, when you choose to browse the thesaurus:



Aha, top terms, yes? Unfortunately, no. These are non-hierarchy category labels into which the actual terms are grouped, without regard for hierarchical placement. Clicking on any of these category labels results in a flat alphabetical display of all the terms in that category. This is something that thesaurus publishers can get away with when they use a flat format display.

If you click on the first category, Agriculture and Natural Resources, you see a flat alphabetical list of terms, including Agricultural Education. Clicking on that, you would discover that its one broader term is Education (no, not Agriculture and Natural Resources), and that its one narrower term is Young Farmer Education. What you see is basically a term record, and that’s all. That’s flat format display.


Are there problems with this? I think so. Even if the vocabulary is viewed only by the people constructing and maintaining it, those people will have difficulty spotting gaps and redundancies. And even if the vocabulary is used only by in-house human indexers, they will have difficulty exploring it to find the most appropriate terms to apply for indexing, and they will tend to use the first terms they come across that seem to fit. In the latter scenario, the ignored terms are apt to fall victim to usage statistics, even if they’re good terms that should have been used. (I’ve seen this happen to at least one taxonomy.)

While the format may have simplified things in the days of printed taxonomies, taxonomists and indexers have problems with this format. Think of the problems encountered by searchers looking for information resources. Searchers benefit from being able to navigate and explore a taxonomy, and to take full advantage of its hierarchical structure. The flat format doesn’t present a hierarchy; instead, it presents obstacles.

Blind Alleys








While you’re traveling down one path, you don’t have an opportunity to see what’s in nearby pathways, or in distant but related pathways.

Dead Ends








You can’t see where you’re headed, or how far the path goes. The path that you originally saw as promising might only lead to a stone wall, after you’ve already traveled one term at a time to get there. (Some flat format taxonomies, though, turn out to be unexpectedly shallow, so you’re more apt to hit a dead end sooner than later.)










Because you can’t see more than one level before and after the term you’re in, and you can’t see over the hedge to other pathways, you may end up zigzagging and backtracking through the taxonomy in a frustrating guessing game.

Getting a Better View



Ideally, you should be able to view the full panorama of a taxonomy’s coverage. At the same time, you should be able to focus on the areas of interest to you. And you should be able to view more than one branch at the same time, and to view entire branches. To accomplish those goals, you need a full hierarchical display that you can expand and collapse as needed. The example below is a screenshot of the MediaSleuth thesaurus, some branches of which I’ve temporarily exposed to an expanded view with a click of the mouse.



With this kind of view, we can see our way in all directions, from wherever we are. We can see where we might want to go from there, and how to get there. We know exactly where we are.

Barbara Gilles, Taxonomist
Access Innovations