Those lines are defining pre-existing troops, so you can 'build' on them with new units. That is to say, if you have:
class CfgVehicles
{
class All{};
class AllVehicles:All{};
class Land:AllVehicles{};
class Man:Land{};
class Soldier:Man{};
class SoldierWB:Soldier{};
class OfficerW:SoldierWB{};
class bdm_OfficerW_new: OfficerW
{
vehicleclass="Bloody Days - US Men";
};
};
You'll be using all the pre-existing data for the Officer(West) such as name, loadout, health, ect, while only changing the vehicle class. You must use the
class NAMEX:NAMEY{}; if you are going to base a unit on a preexisting one.
Do you understand?