Nevermind, Ben. More extra detail: numbers.bmp..
If you (Tanker) follow our (Ben and me) advice, don't forget to modify the numbers.bmp according to your new colour scheme, i.e. if you decide to use red icons instead of the original blue ones and put i.e. units_1_red_0.bmp into the scenario's graphic directory, renaming it to units_1_blue_0.bmp (let's say this is used originally in the scenario) and you dont change the colours in numbers.bmp you will have messy blue squares on your red unit icon. You must find out which row in numbers.bmp the original unit bitmap uses and replace it with the acording colour (best done with copy and paste). Then put this file also into the scenario's graphic folder.
Numbers.bmp is used to display unit strength, movement allowance, loss setting, deployment status and unit size on the unit icon.
As a note for the development team: Modding would be easier if numbers.bmp would use a transparent background.