Logistic network statistics - robots maximum

[Xecutor]

I always thought that numbers in statistics - available/maximum are number of idle bots and total number of bots.
But I just noticed that max number is fluctuating!
No new bots were inserted into roboport, and no bots died in combat (there were no combat),
but max number was changing over time (decreasing and increasing).
Difference might be quite big. I spotted 270 and 310 on the same network without me activating new robots.

So, what is 'logistic robots maximum' in network statistics exactly?

[Boogieman14]

I believe construction robots are also counted whenever they're doing logistics work (such as deconstructing a belt or chest and moving the contents someplace)