matched invoice purge

Matched Invoices with PO are not being purged.

We learnt that PO status has to be either Cancelled or Finally Closed. We ran MassCancel process which cancelled many POs but even after that the Purge process does not purge TRANSACTIONS related to those POs.

I also fail to understand the need of PO Status to be Cancelled or Finally Closed. we have closed businesses (unused Ledgers and sub-ledgers) for which we would like to purge all the data but as the business process was to just CLOSE POs and not to finally close them, we can not purge any AP-PO transactions.