This would be very useful when dealing with Customer Prepayments.
Clients often receives prepayments against projects and needs to be able to do partial allocations against billing as they go.
Customer wants the prepayment to show up automatically on the Pro-forma. So far so good. We process an AR Invoice for the Prepayment. An allocation rule moves it to the balance sheet. The billing rule picks it up and its shown on the Pro-forma invoice. User then wants to change the amount to be offset on this invoice.
But the "Hold Remainder" is not available probably because the amount is a negative.
If only a partial application occurs then entire amount is reversed.