Building a ship using a Priority Build friendly code costs PBPs. The heavier the ship, the more PBPs it costs. The PBPCostPer100KT option defines how many PBPs you need to build a 100 kt ship. There is a minimum cost, however: PBPMinimumCost. If the build order was a clone order, it costs even more PBPs; the PBPCloneCostRate can be used to scale this up.
For example, let's assume you want to build a 150 kt ship, and the configuration uses the default values:
PBPCostPer100KT = 200 PBPMinimumCost = 400 PBPCloneCostRate = 200
According to PBPCostPer100KT, the cost would be 150*200% = 300 points. Since the minimum cost is 400, you'd have to pay 400 points for building that ship. If that build order were a clone order, it would cost even twice as much.
Note that PHost doesn't force you to do a priority build. If you have most PBPs in your game, but do not use a PBn friendly code, you keep accumulating points (for a really huge battleship, maybe). In contrast, HOST forces you to do a priority build in this case.
► Note: Note that the PBn friendly codes are always active in PHost (subject to the AllowPriorityBuild config option), no matter how many ships there are. If you use PBn early in the game, you will spend PBPs for that ship, even if there were enough ship slots to build the ship normally.
