UPDATE (Sep 2012): Apple has been pushing this concept in their consumer-oriented operating systems by eliminating, hiding, or limiting the file system hierarchy in iOS, iCloud, and OS X Mountain Lion. For a long, interesting analysis of these changes, read “Mountain Lion’s New File System” from Information Architects.
The discussion on my previous post has necessitated a better explanation of the term monocline grouping.
A monocline grouping is a representation of data in a single layer (i.e., without a nested hierarchy). Let’s take my bookshelf for example. On the left are religious and music books, followed to the right by Dutch and German books, and continuing on with literature and poetry books. In between are a few books that don’t really fit one of those generalizations. And some I’ve rearranged out of their groups so they look nice on the shelf.
This is a very natural and understandable way to organize books. I can easily access any book at any time, even if I’ve forgotten (or don’t care) which category it’s in. All the books are arranged in a single layer.
A problem with computer hierarchies is that they allow the user to nest objects of a certain type within objects of that same type: you can have an infinity of folders within folders which you must traverse before you come to a file.
Programmers may feel at home in a hierarchical file system, but normal people viscerally understand monocline groupings. Even my file box is only one level deep: I open the box and see all my folders. That file box doesn’t contain more nested file boxes. (Now I do have manilla folders inside hanging folders, but the point is that I can see them all at once without traversing a hierarchy.)
Monocline grouping is a term coined by Alan Cooper. Despite the term’s limited use, the concept is universal in its application.
As I mentioned previously (and as is described in this blog post, a quote from Cooper’s book About Face 2.0), monocline groupings are not the end-all solution for everything. They can be useful when applied with prudence to certain scenarios.