A word for something which occurs between the micro and macro scales

In a scientific domain, I am discussing a series of three concepts, each of which subsume the others, forming three levels. To make this clear to the reader I'm saying that the highest-level concept describes the 'macro scale' behaviour of the system, that the lowest-level concept describes the 'micro scale' behaviour of the system, and that the concept in the middle… is in the middle.

What I have already works, but it'd be more elegant if I could come up with something that sits naturally between 'macro' and 'micro'. Is there such a word or concept? Is there a handy metaphor I could borrow? In my writing I'm specifically talking about the differences between analyses of each of the three levels (ie: analysing the highest level gives you a wider understanding, while analysing the lowest level gives you fine-grained information at the cost of the big picture).

I won't reproduce my writing here, but here's a roughly equivalent example I've made up.

A nation's laws control its behaviour. The government makes the law. The politicians who make up the government propose specific laws (or groups of laws). The laws themselves set the boundaries of how the nation may behave. Thus the government represents the macro-scale behaviour of a nation, the laws the micro-scale behaviour, and the politicians the ______-scale.

Solution 1:

The word you're looking for is meso- (Etymoline):

before vowels mes-, word-forming element meaning “middle, intermediate, halfway,” from Greek mesos “middle, in the middle; middling, moderate; between”

So it sits naturally between micro- (Etymoline) an macro- (Etymoline), as these are also word-forming elements of Greek origin, respectively for the very small and the very large.

There is an article on Levels of Analysi in Wikipedia that discusse your intended use. Here's an excerpt (emphasis mine):

Although levels of analysis are not necessarily mutually exclusive, there are three general levels into which social science research may fall: micro-level, meso-level or middle-range, and macro-level.