How rebalance inventory evaluate excess or shortage ?

Hi,

What value does the inventory rebalancing function compare against the on-hand quantity within a replenishment plan?

For example, I have a replenishment plan at the subinventory level applied only to subinventory A. What value is compared with the on-hand quantity in subinventory A to determine whether there is an excess or shortage? If the replenishment plan includes only one subinventory but the cluster used for rebalancing includes multiple subinventories (e.g., A and B), based on what value does the system evaluate excess or shortage in subinventory B (which is not included in the replenishment plan)?

Regards