Payment Entry unallocated amount calculation

I have noticed that the unallocated_amount field in the Payment Entry table is calculated from the base (company currency) value for multicurrency accounts:

	def set_unallocated_amount(self):
	self.unallocated_amount = 0
		total_deductions = sum([flt(d.amount) for d in self.get("deductions")])
		if self.payment_type == "Receive" \
			and self.base_total_allocated_amount < self.base_received_amount + total_deductions \
			and self.total_allocated_amount < self.paid_amount + (total_deductions / self.source_exchange_rate):
				self.unallocated_amount = (self.base_received_amount + total_deductions - 
					self.base_total_allocated_amount) / self.source_exchange_rate
		elif self.payment_type == "Pay" \
			and self.base_total_allocated_amount < (self.base_paid_amount - total_deductions) \
			and self.total_allocated_amount < self.received_amount + (total_deductions / self.target_exchange_rate):
				self.unallocated_amount = (self.base_paid_amount - (total_deductions + 
					self.base_total_allocated_amount)) / self.target_exchange_rate

Is there any particular reason for doing it this way instead of just using the originating values? For a few of my transactions the unallocated amount is fractionally different to the original value of the payment as the base value is rounded to 2 d.p. whereas integer values are stored to 6 d.p.

For example, I have a transaction with a paid amount of €69.230000, converted to £60.960000 @ 0.880600. This is fully unallocated, and the system is showing the unallocated amount as €69.225528.

I don’t think this will cause any issues as once an invoice is allocated then the discrepancy will disappear, it just looks strange on ledger reports.

Edit: This might actually be a problem as received_amount and paid_amount are set to be outstanding_amount, so if this issue occurs on an open payment then the GL entry will be wrong.

Hey were you able to understand the rationale behind the calculation? I am also kind of stuck due to this