Components within units are not tracked. A unit is either completely working or completely dead. As enough damage is done to destroy a unit, it is removed from the stack/group. It's like the ship stacks in the orignial MOO. Yes, armor on a unit does NOT protect the internals it just increases the total hit points of the unit. But that amounts to the same effect -- it takes longer to destroy the unit.
So, any 'damages only X' weapon type used on units is just like a normal weapon except that it might skip shields. Since these weapons are usually shorter ranged than standard weapons they're generally not a good idea to use against large forces of units.
[ 01 December 2001: Message edited by: Baron Munchausen ]