Payables Negative Supplier Balance Report - question about data returned

Hi,

I have run the "Payables Negative Supplier Balance Report" report on an R12.1.3 instance, and it returns the following data for one of the suppliers:

Is there any way I can see, via the front-end screens in AP, where the report is looking to come up with the Remaining Amount figure? I can see the Amount is the invoice amount, so that's clear enough, but I am not clear how the Remaining Amount is calculated?

For the supplier in question, there are 12 AP invoices on the system, totalling 259,199 EUR. 11 of them have a +ve Invoice Amount, 1 has a zero Invoice Amount. None have a negative Invoice Amount.