Armor types help

This may have been asked before but I did several forum searches and came up dry.

I'm sure the information I'm looking for is somewhere incredibly obvious, but I haven't found it.

Looking for where it controls the type of ship that a weapon will and won't shoot at?

For instance, unmodded in any way, an advent battleship in my games isn't firing at a carrier or repair cruiser, or the flak frigates, that my TEC army has fielded, but it will cheerfully blow away the attack cruisers or even the light frigates, and scouts.

I found the thing in the game constants with Capitol ship, interceptor, and bomber modifications to accuracy based on weapon type, but thats not what I'm looking for.

Any pointers?