In the revised edition of the manual it is now referred to as damage.
Example: You have a unit of 6 tanks. All are in good condition. Your entire unit takes 60 damage. The damage is now 60. Your unit is attacked again and takes 80 damage. 60 + 80 = 140. Every 100 points of damage, 1 vehicle is removed. 40 points of damage remain. So you think your damage has gone down, but that's just the overhang after offsetting 100 damages from the loss of a vehicle.