I often see examples where people add characteristics to a map or use new definitions for one of the axis. There's nothing wrong with this and I want to encourage people to explore. One recent effort by Manish has the axis as Rookie to Expert which leads to the question - what is an expert?
A map (and I have an entire creative commons book on this, if you want to know more) is a map of capital. The nodes are stocks of capital and the lines are flows of capital. On the x-axis, I normally use the labels for activities - genesis, custom, product (+rental), commodity (+utility). But you can map not only activities but practices, data and knowledge. We use different terms for each stage of evolution of these forms of capital which for reference I've included in the table below.
All of these forms of capital have common characteristics as they evolve. These characteristics are captured in the cheat sheet, which even after nearly a decade, I still find to be a useful tool though to be honest, it's embedded deep in my mind these days.
So what has this got to do with expertise? Well, let us take a grossly simple map of healthcare starting with the public and assuming some form of Government sponsored healthcare system. One of the components is treatment but treatment isn't a static thing. There is constant range of new treatments produced whilst the once remarkable becomes routine, even dull.
So, what do we mean by expertise? Well an expert could be someone who is experienced in a broad range of treatments. They would be a generalist or an expert in general practice.
What is important to understand is that every node on a map can in fact be itself a map. For example, if we expand out Appendicitis into its own map (see below), there will be many components involved in its treatment. A specialist would have in depth knowledge of each of those components.
Now, you might ask me why the nodes on the last map have no labels. Well, it's because I don't know what they are. I've just added some node and links as a way of saying - there will be components involved but I have no idea what they are. If you actually want a map for it then you'll need to talk to an expert on the subject.
The only people who can actually map a space are those with expertise in that space. In the same way, the only people who can draw you a map of London (even a crude one) are people who have either been to London (physically or virtually) or seen a map.
The beauty of maps is we can have many experts (both generalists and specialists), sharing and communicating with each other through the use of maps and hence improving them. This leads to best thing about maps. For a rookie like me, then a map is the fastest way I know of bringing me upto speed of a complex and complicated environment. It's also the fastest way of discovering just how little I know.