Hi Srikanth,
Open item manage determines that this open items are managed for this account. Items posted to accounts managed on an open item basis are marked as open or cleared. The balance of these accounts is always equal to the balance of the open items.
Ex. GR/IR clearing account should be managed on an open item basis so that you can check at any time whether invoices have been received for the goods received for an order.
Regards,
Manish.