Here the counter unit graphic is modified (all three sizes). Let’s look at that in more detail:
Here I’ve marked all the icons that have special features associated with them. I count 45 that don’t. So, if you need to edit more icons of a certain special feature than are available, some of those 45 may also be used (assuming they are not already in use by the scenario), with the special feature added via the alternate icon feature. Some of the others may be usable as well, depending upon the scenario – if the scenario has no helicopters, the Airmobile icons can be reused without consequence, for example.
Happy Scenario Editing!